Vanilic acid derived aromatic hydrocarbon ruthenium complex as well as preparation method and application thereof

Abstract

The invention discloses a vanillic acid derived aromatic ruthenium complex as well as a preparation method and application thereof, and belongs to the technical field of pharmaceutical chemistry and metal complex synthesis. Aiming at the problems of insufficient antibacterial activity and prominent drug resistance of existing antibiotics to multi-drug-resistant and pan-drug-resistant salmonella typhimurium, the method comprises the following steps: synthesizing vanillic acid esterification and etherification derivatives, respectively coupling with 3-picolinic acid and 4-picolinic acid to generate an esterification ligand and an etherification ligand, and then reacting with a dimeric ruthenium precursor in an inert atmosphere to obtain the antibacterial antibiotic for the multi-drug-resistant and pan-drug-resistant salmonella typhimurium. And preparing the aromatic ruthenium complex. According to the method, a ligand structure is modified and optimized through a carboxylic ester bond and an ether bond, and the antibacterial activity is remarkably enhanced by combining the synergistic effect of a ruthenium metal center. The obtained complex has an efficient inhibition effect on clinically separated pan-drug-resistant and multi-drug-resistant salmonella typhimurium, the minimum inhibitory concentration (MIC90) of the complex is as low as 0.06 mu g / mL, and the complex is low in hemolytic toxicity and suitable for developing novel drugs for resisting drug-resistant bacterial infection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical fields of medicinal chemistry and metal complex synthesis. More particularly, the present application relates to a vanillic acid derivative arene ruthenium complex, and a preparation method and application thereof. BACKGROUND

[0002] Salmonella typhi infection is a significant public health problem worldwide, especially with the emergence of multi-drug resistant (MDR) and extensively drug-resistant (XDR) strains, which significantly increases the difficulty of clinical treatment. Currently, the treatment of such drug-resistant strains mainly relies on traditional antibiotics, such as β-lactams (e.g., ampicillin), fluoroquinolones (e.g., ciprofloxacin), macrolides (e.g., azithromycin), and third-generation cephalosporins (e.g., ceftriaxone). However, with the widespread use of antibiotics, the problem of drug resistance is becoming increasingly severe. For example, clinically isolated drug-resistant strains commonly exhibit cross-resistance to trimethoprim-sulfamethoxazole, ampicillin, chloramphenicol, and other drugs, and even the sensitivity to broad-spectrum antibiotics such as ciprofloxacin and ceftriaxone is significantly reduced. Some strains still retain certain sensitivity to carbapenems such as meropenem, but the high treatment cost and potential side effects limit their widespread application.

[0003] The limitations of existing antibiotics mainly manifest in two aspects: first, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of drug-resistant strains are significantly increased. For example, the MIC value of clinically isolated extensively drug-resistant Salmonella typhi CL1 to ampicillin exceeds 128 μg / mL, and the MIC value of azithromycin is as high as 96 μg / mL, which is much higher than the conventional therapeutic dose, resulting in reduced or even ineffective drug efficacy. Second, the high concentration requirement of antibiotics may induce host toxicity, for example, ciprofloxacin at high doses may non-specifically inhibit DNA synthesis, affecting normal cell function. In addition, long-term use of a single antibiotic easily induces vertical transmission or horizontal transfer of bacterial drug resistance genes, further exacerbating the spread of drug resistance.

[0004] The mechanisms of drug resistance are complex and diverse, including target protein mutation, drug efflux pump activation, and enzyme modification to inactivate antibiotics. For example, fluoroquinolones exert their effects by inhibiting DNA gyrase, but drug-resistant strains often reduce the affinity of the drug to the target by mutating the gyrA or parC gene. The resistance of β-lactam antibiotics is related to the production of β-lactamase by bacteria or the structural change of penicillin-binding protein (PBPs). Although some inhibitors (such as β-lactamase inhibitors) have been developed against these mechanisms, their effectiveness is limited by the rapid evolution of bacteria and the superposition of multiple drug resistance phenotypes. In addition, the structural modification space of traditional antibiotics is limited, making it difficult to overcome multiple drug resistance mechanisms simultaneously, resulting in slow progress in new drug development.

[0005] The main challenge in developing new antibacterial drugs is to balance the antibacterial activity and safety. On the one hand, the drug needs to have high bactericidal capacity, especially at low concentration to inhibit drug-resistant strains; on the other hand, the toxicity to host cells such as hemolysis of red blood cells or tissue damage needs to be avoided. In addition, the drug molecule needs to have good physicochemical properties such as stability, solubility and transmembrane permeability to ensure the bioavailability at the infection site. However, the existing metal complex antibacterial agents such as silver and copper complexes show certain potential, but their unclear mechanism of action, poor selectivity and potential metal ion toxicity limit their clinical application. Therefore, it is urgent to design new metal complexes with high antibacterial activity, low toxicity and clear target to meet the treatment needs of drug-resistant strains. SUMMARY

[0006] An object of the present application is to provide a vanillic acid derivative arene ruthenium complex and a preparation method and application thereof, by step-by-step synthesis of esterification and etherification derivatives and combining the coordination of the ruthenium metal center, the structural diversity and antibacterial activity of the complex are significantly improved.

[0007] In order to achieve these objects and other advantages of the present application, according to one aspect of the present application, a preparation method of a vanillic acid derivative arene ruthenium complex is provided, comprising the following steps:

[0008] Step one, vanillic acid esterification derivatives or vanillic acid etherification derivatives are synthesized by using vanillic acid as raw material;

[0009] Step two, the vanillic acid esterification derivatives synthesized in step one are coupled with 3-pyridine carboxylic acid or 4-pyridine carboxylic acid through carboxylic acid ester bond to prepare esterification ligand; the vanillic acid etherification derivatives synthesized in step one are coupled with 4-hydroxyphenol and then reacted with 3-pyridine carboxylic acid or 4-pyridine carboxylic acid to prepare etherification ligand;

[0010] Step three, in an inert atmosphere, the esterification ligand and the etherification ligand generated in step two are respectively reacted with a dimeric ruthenium precursor [Ru2(η 6 -Ar)2(μ-Cl)2Cl2] in chloroform or dichloromethane to generate a vanillic acid derivative arene ruthenium complex with a general formula of [Ru(η 6 -Ar)Cl2(ligand)];

[0011] Wherein, Ar is selected from one of benzene, p-methylisopropylbenzene and hexamethylbenzene.

[0012] The esterification and etherification derivatives of vanillic acid were synthesized by a step-by-step method, and the coordination of the ruthenium metal center was combined, which significantly improved the structural diversity and antibacterial activity of the complex. The synergistic modification of carboxylate bonds and ether bonds enhances the binding ability of the ligand to the bacterial target, making the complex significantly lower than traditional antibiotics in inhibiting the growth of multiple drug-resistant and pan-drug-resistant Salmonella typhi. The complex exerts a bactericidal effect by destroying the integrity of the bacterial cell membrane and inhibiting DNA replication, and has very low toxicity to host cells, showing potential for clinical application.

[0013] Preferably, in step one, the synthesis method of the esterified derivative of vanillic acid is specifically as follows:

[0014] Vanillic acid is mixed with C1-C4 linear or branched alkyl alcohol, wherein the mass concentration of vanillic acid in the mixed solution is 18-22 g / L, and 9-11% of the molar amount of vanillic acid is added as a Bronsted acid catalyst;

[0015] The reaction is refluxed at 65-85°C for 18-24 hours. After the reaction is completed, it is neutralized to pH 7-8 with a 10% sodium bicarbonate aqueous solution, and the organic phase is collected by dichloromethane extraction, and the solvent is removed by reduced pressure distillation to obtain a crude product;

[0016] The crude product is purified by silica gel column chromatography with an eluent of n-hexane and ethyl acetate in a volume ratio of 8-10:1 to obtain a plurality of esterified derivatives of vanillic acid.

[0017] The optimized esterification reaction conditions of vanillic acid (such as catalyst dosage, temperature control and purification method) improve the yield of the product and reduce the generation of by-products. The high-purity esterified derivative provides a reliable basis for the subsequent ligand coupling reaction, ensuring the chemical stability and reaction efficiency of the intermediate.

[0018] Preferably, in step two, the synthesis method of the esterified ligand is specifically as follows:

[0019] The esterified derivative of vanillic acid is mixed with 3-pyridine carboxylic acid or 4-pyridine carboxylic acid at a molar ratio of 0.8-1.2:1, and is dissolved in anhydrous dichloromethane or anhydrous DMF;

[0020] Under nitrogen protection, the reaction system is cooled to 0°C, and then 0.8-1.2 times the molar amount of dicyclohexyl carbodiimide and 0.08-0.12 times the molar amount of 4-dimethylamino pyridine of the esterified derivative of vanillic acid are added;

[0021] The reaction mixture is warmed to room temperature, stirred for 12-24 hours, the filtrate is collected by filtration, and the filtrate is concentrated under reduced pressure to obtain a crude product;

[0022] The crude product is purified by silica gel column chromatography with eluent of n-hexane and ethyl acetate in a volume ratio of 8-10:1 to obtain the nicotinic acid esterified ligand or isonicotinic acid esterified ligand.

[0023] The synthesis time of the esterified ligand is significantly shortened and the reaction efficiency is improved by using the synergistic effect of low-temperature coupling reaction and specific catalyst. The silica gel column purification step effectively removes unreacted impurities and by-products, ensuring the accuracy of the final ligand structure and the functional integrity.

[0024] Preferably, in step one, the synthesis method of the vanillic acid etherified derivative is specifically as follows:

[0025] The vanillic acid esterified derivative is dissolved in acetone, the concentration of the vanillic acid esterified derivative in acetone is 18-22 g / L, potassium carbonate is added, the molar ratio of potassium carbonate to vanillic acid esterified derivative is 1.8-2.2:1, alkyl bromide is added dropwise, and the reaction is refluxed at 65-85°C for 16-30 hours. The reaction process is monitored by TLC until the substrate is completely reacted; wherein the molar ratio of alkyl bromide to vanillic acid esterified derivative is 1.05-1.15:1.

[0026] After the reaction is completed, the reaction mixture is neutralized and extracted with ethyl acetate to collect the organic phase. After the solvent is rotary evaporated under reduced pressure, the purified product is obtained by silica gel column chromatography with eluent of n-hexane and ethyl acetate in a volume ratio of 8-10:1.

[0027] The purified product is cooled to 0°C, and 1M NaOH is added for ester alkaline hydrolysis. After neutralization with 1M hydrochloric acid, the vanillic acid etherified derivative is obtained.

[0028] By optimizing the ratio of solvent system (acetone) and base (potassium carbonate), the etherification reaction efficiency of vanillic acid esterified derivative is significantly improved, while the occurrence of side reactions is reduced. The gradient addition strategy of different chain length alkyl bromide enhances the selectivity of ether bond formation, combined with dynamic monitoring by TLC, to ensure the completeness of the reaction and the uniqueness of the product. The silica gel column chromatography purification step effectively removes unreacted alkyl bromide and by-products, greatly improving the purity of the etherified derivative. The low-temperature hydrolysis condition protects the stability of the ether bond structure, and the obtained lipophilic etherified derivative has controllable hydrophobic properties, providing high-purity and high-activity intermediates for subsequent ligand coupling and metal complex functional modification, thereby enhancing the antibacterial activity and application potential of the final product.

[0029] Preferably, the specific process of TLC monitoring is as follows:

[0030] Thin layer chromatography (TLC) plate is used, the stationary phase is silica gel, and the developing agent is n-hexane and ethyl acetate in a volume ratio of 5:1-7:1.

[0031] Sample every 2 hours, spot and develop, observe the substrate spot under UV lamp 254 nm, and spray 10% phosphomolybdic acid ethanol solution and heat to develop color;

[0032] When the substrate spot disappears and only a single product spot remains, determine the reaction endpoint;

[0033] If the substrate is not completely consumed after 24 hours of reaction, add alkyl bromide or coupling reagent, and continue to react until TLC shows that the reaction is complete.

[0034] The strategy of dynamic TLC monitoring combined with quantitative reagent addition can significantly improve the completion rate of the reaction and reduce reagent waste. This method shortens the synthesis cycle by adjusting the reaction conditions in real time, while avoiding the difficulty of subsequent purification caused by residual substrate.

[0035] Preferably, the amount of alkyl bromide or coupling reagent added is dynamically adjusted, and the specific steps include:

[0036] When the substrate is not completely consumed after 24 hours of reaction, the residual proportion of the substrate is analyzed quantitatively by TLC, and the reagent is added according to the following rules:

[0037] If the residual amount of the substrate is 10%-20%, add 5%-8% of the initial amount of the reagent;

[0038] If the residual amount of the substrate is 20%-40%, add 8%-12% of the initial amount of the reagent;

[0039] If the residual amount of the substrate is >40%, add 12%-15% of the initial amount of the reagent;

[0040] After adding, increase the temperature to 70-80°C and continue to react for 2-4 hours;

[0041] Sample every 1 hour for TLC monitoring. If the residual amount of the substrate is still >5%, add the corresponding amount again according to the above residual amount interval, but the total amount of addition should not exceed 20% of the initial amount of the reagent;

[0042] If the total amount of addition reaches 20% and the substrate is still not completely consumed, terminate the reaction and perform purification treatment.

[0043] The precise addition rule based on the residual proportion of the substrate significantly reduces the occurrence of side reactions and shortens the total reaction time. This strategy avoids the negative effects of excess reagents on the product, ensuring the stability of the reaction system and the high purity of the product.

[0044] Preferably, in step two, the synthesis method of the etherified ligand is as follows:

[0045] Step a, under an inert atmosphere, mix the vanillic acid ether derivative and 4-benzyloxyphenol at a molar ratio of 0.8-1.2:1, and dissolve in anhydrous dichloromethane;

[0046] Step b, cooling the reaction system to 0°C, adding 4-dimethylaminopyridine in a molar amount of 0.08-0.12 times the vanillic acid ester derivative and dicyclohexyl carbodiimide in a molar amount of 0.8-1.2 times the vanillic acid ester derivative;

[0047] Step c, warming the reaction mixture to room temperature, stirring for 18-24 hours, collecting the filtrate by filtration, and concentrating the filtrate under reduced pressure to obtain a crude product;

[0048] Step d, purifying the crude product by silica gel column chromatography with a mixed solvent of hexane / ethyl acetate / chloroform in a volume ratio of (4.8-5.0):0.1:(0.8-1.2) as the eluent to obtain intermediate one;

[0049] Step e, dissolving intermediate one in a mixed solvent of ethanol and dichloromethane in a volume ratio of 8-10:1, adding palladium-carbon catalyst in a mass of 8-12% of intermediate one, stirring at room temperature under a hydrogen atmosphere for 12-16 hours, collecting the filtrate by filtration, and concentrating under reduced pressure to obtain intermediate two;

[0050] Step f, mixing intermediate two with 3-pyridine carboxylic acid or 4-pyridine carboxylic acid in a molar ratio of 0.8-1.2:1, dissolving in dichloromethane under an inert atmosphere, adding 4-dimethylaminopyridine in a molar amount of 0.08-0.12 times intermediate two and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride in a molar amount of 0.8-1.2 times intermediate two at 0°C, stirring the reaction mixture at room temperature for 12-16 hours, extracting the filtrate with dichloromethane, and purifying by silica gel column chromatography after rotary evaporation under reduced pressure to obtain a nicotinic acid ester etherified ligand or an isonicotinic acid ester etherified ligand. The combination of step-by-step coupling and hydrogen reduction significantly improves the synthesis efficiency of the etherified ligand, while enhancing the stability of the intermediate. The diversified structure of the etherified ligand expands the target of the complex, enabling it to inhibit bacterial growth through multiple mechanisms.

[0051] Preferably, the synthesis method of the vanillic acid derivative arene ruthenium complex in step three is specifically:

[0052] Under nitrogen protection, dissolving the esterified ligand or etherified ligand in anhydrous chloroform or dichloromethane, adding a dimeric ruthenium precursor, the molar ratio of the esterified ligand and etherified ligand to the dimeric ruthenium precursor being 1.8-2.2:1, stirring the reaction at room temperature for 12-24 hours, removing the solvent under reduced pressure to obtain a crude product, washing the crude product with dichloromethane, and drying under vacuum to obtain a vanillic acid derivative arene ruthenium complex. By precisely controlling the ratio of the ruthenium precursor to the ligand and the selection of the solvent, the crystallinity of the complex and the coordination integrity of the metal center are significantly improved. The optimized synthesis conditions enable the complex to have higher antibacterial activity and chemical stability, which is superior to the traditional preparation method.

[0053] The application also provides a vanillic acid derivative arene ruthenium complex prepared by the preparation method of the vanillic acid derivative arene ruthenium complex.

[0054] The application also provides application of the vanillic acid derivative arene ruthenium complex in preparation of a drug for resisting drug-resistant Salmonella typhi.

[0055] The application at least has the following beneficial effects: the application is directed to vanillic acid etherification and esterification sites, and a series of derivatives are synthesized by long-chain alkyl etherification and esterification with different groups, as ligands of arene ruthenium complexes. Then, an arene ruthenium complex precursor is prepared, and a series of arene ruthenium complexes with vanillic acid derivatives as ligands are synthesized by docking with 3 / 4-picolinic acid as a medium. On this basis, the activity of the obtained vanillic acid derivative arene ruthenium complex against drug-resistant Salmonella typhi is screened, and the effect is significantly better than that of a control antibiotic, and the vanillic acid derivative arene ruthenium complex has great potential for treating drug-resistant Salmonella typhi infection.

[0056] Other advantages, objects, and features of the application will be apparent from the following description, and will be appreciated by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 A synthesis route map of the vanillic acid derivative arene ruthenium complex in the application;

[0058] Figure 2 An evolutionary relationship map of pan-drug-resistant Salmonella typhi (CL1 and CL15) and multi-drug-resistant Salmonella typhi (CL5);

[0059] Figure 3 A time killing curve map of the vanillic acid derivative arene ruthenium complex 15 against pan-drug-resistant Salmonella typhi CL15;

[0060] Figure 4 A time killing curve map of the vanillic acid derivative arene ruthenium complex 17 against pan-drug-resistant Salmonella typhi CL15;

[0061] Figure 5 An ultrastructure morphological change map of effects of ampicillin, azithromycin, and ciprofloxacin on pan-drug-resistant S.Typhi CL15;

[0062] Figure 6 An ultrastructure morphological change map of effects of the vanillic acid derivative arene ruthenium complexes 15 and 17 on pan-drug-resistant S.Typhi CL15;

[0063] Figure 7 A high-resolution atomic force microscope image of effects of ampicillin and azithromycin on pan-drug-resistant S.Typhi CL15;

[0064] Figure 8High-resolution atomic force microscopy images of the effects of vanillic acid-derived aromatic ruthenium complexes 15 and 17 on pan-drug-resistant S. Typhi CL15;

[0065] Figure 9 This is a comparison chart of the hemolysis test. Detailed Implementation

[0066] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description.

[0067] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0068] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0069] like Figure 1 As shown, the synthetic route for vanillic acid-derived aromatic ruthenium complexes is as follows: targeting the etherification and esterification sites of vanillic acid, a series of derivatives are synthesized via long-chain alkyl etherification and esterification with different groups, serving as ligands for the aromatic ruthenium complexes. Then, aromatic ruthenium complex precursors are prepared, and using 3 / 4-pyridinecarboxylic acid as a medium, a series of aromatic ruthenium complexes with vanillic acid derivatives as ligands are synthesized.

[0070] Based on this, the activity of vanillic acid-derived ruthenium aromatic hydrocarbon complexes against drug-resistant Salmonella typhi was screened; and the hemolytic toxicity of the ruthenium aromatic hydrocarbon complexes was determined. Highly effective and non-toxic ruthenium aromatic hydrocarbon complexes were selected and tested using MIC. 90 Its antibacterial properties were further clarified by MBC, time-based sterilization curves, and scanning electron microscopy.

[0071] <Example>

[0072] 1. Synthesis of vanillic acid alkyl esterified derivatives 1-4

[0073] Vanillic acid is reacted with alkyl alcohols such as methanol, ethanol, propanol, or isopropanol via a Fischer-Speier reaction. The reaction mixture of vanillic acid, alkyl alcohol, and a catalytic amount of Bronsted acid is refluxed overnight, then neutralized and extracted with dichloromethane. This step yields vanillic acid esterified derivatives 1-4.

[0074] Methyl vanillate (1)

[0075] A solution of vanillic acid (1 g, 5.95 mmol) in methanol (50 mL) was refluxed and then p-toluenesulfonic acid (0.1 g, 0.59 mmol) was added. After 24 h, the reaction mixture was cooled and neutralized with a 10% aqueous sodium bicarbonate solution. The mixture was extracted with dichloromethane (3x) and the organic phase was collected and evaporated to dryness under reduced pressure. Further purification by column chromatography on silica gel using n-hexane and ethyl acetate (9:1, v / v) as eluent afforded 0.99 g of methyl vanillate (1) as a white solid.

[0076] Methyl vanillate (1) white solid; yield: 92%; 1 H NMR (400 MHz, CDC13): δ 7.62 (dd, 1H, J = 8.3, 1.9 Hz, 6-CH), 7.53 (d, 1H, J = 1.9 Hz, 2-CH), 6.92 (d, 1H, J = 8.4 Hz, 5-CH), 3.93 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3); LR-EI-MS (m / z): 182.1 [M] + .

[0077] Ethyl vanillate (2)

[0078] A solution of vanillic acid (1 g, 5.95 mmol) in ethanol (50 mL) was refluxed and then p-toluenesulfonic acid (0.1 g, 0.59 mmol) was added. After 24 h, the reaction mixture was cooled and neutralized with a 10% aqueous sodium bicarbonate solution. The mixture was extracted with dichloromethane (3x) and the organic phase was collected and evaporated to dryness under reduced pressure. Further purification by column chromatography on silica gel using n-hexane and ethyl acetate (9:1, v / v) as eluent afforded 1.05 g of ethyl vanillate (2) as a white solid.

[0079] Ethyl vanillate (2) white solid; yield: 90%; 1 H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.3, 1.9 Hz, 6-CH), 7.53 (d, 1H, J = 1.9 Hz, 2-CH), 6.92 (d, 1H, J = 8.4 Hz, 5-CH), 4.33 (q, J = 7.1 Hz, 2H, H-9), 3.90 (s, 3H, 8-CH3), 1.36 (t, J = 7.1 Hz, 3H, H-10); LR-EI-MS (m / z): 196.1 [M] + .

[0080] Propyl vanillate (3)

[0081] A solution of vanillic acid (1 g, 5.95 mmol) in propanol (50 mL) was refluxed and then p-toluenesulfonic acid (0.1 g, 0.59 mmol) was added. After 24 h, the reaction mixture was cooled and neutralized with a 10% aqueous sodium bicarbonate solution. The mixture was extracted with dichloromethane (3x) and the organic phase was collected and evaporated to dryness under reduced pressure. Further purification by column chromatography on silica gel using n-hexane and ethyl acetate (9:1 by volume) as eluents afforded 1.12 g of vanillic acid propyl ester (3).

[0082] Vanillic acid propyl ester (3) white solid; yield: 90%; 1 H NMR (400 MHz, CDC13): δ 7.64 (dd, 1H, J = 8.3, 1.9 Hz, 6-CH), 7.53 (d, 1H, J = 1.9 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.23 (t, 2H, J = 6.7 Hz, 9-CH2), 3.90 (s, 3H, 8-CH3), 1.76 (h, J = 7.3 Hz, 2H, 10-CH2), 1.47 (t, 3H, J = 7.0 Hz, 11-CH3); LR-EI-MS (m / z): 210.1 [M] + .

[0083] Vanillic acid isopropyl ester (4)

[0084] A solution of vanillic acid (1 g, 5.95 mmol) in isopropanol (50 mL) was refluxed and then p-toluenesulfonic acid (0.1 g, 0.59 mmol) was added. After 24 h, the reaction mixture was cooled and neutralized with a 10% aqueous sodium bicarbonate solution. The mixture was extracted with dichloromethane (3x) and the organic phase was collected and evaporated to dryness under reduced pressure. Further purification by column chromatography on silica gel using n-hexane and ethyl acetate (9:1 by volume) as eluents afforded 1.1 g of vanillic acid isopropyl ester (4).

[0085] Vanillic acid isopropyl ester (4) white solid; yield: 88%; 1 H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.3, 1.9 Hz, 6-CH), 7.52 (d, 1H, J = 1.9 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 5.21 (sept, 1H, J = 6.5 Hz, 9-CH), 3.91 (s, 3H, 8-CH3), 1.34 (d, 6H, J = 6.5 Hz, 10,10'-CH3); LR-EI-MS (m / z): 210.1 [M] + .

[0086] 2. Synthesis of 2-methoxy-4-(alkoxycarbonyl)phenyl nicotinic acid esters 5-8

[0087] Vanillyl alkyl ester (1.0 eq) and 3-pyridine carboxylic acid (1.0 eq) were dissolved in dry DMF (15 mL) and cooled to 0 °C under a nitrogen atmosphere. Dicyclohexyl carbodiimide (DCC, 1.0 eq) and 4-(dimethylamino)pyridine (DMAP, 0.1 eq) were added sequentially. The reaction mixture was allowed to warm to room temperature and stirred for 24 h. The resulting dicyclohexyl urea by-product was removed by filtration and the filtrate was concentrated under reduced pressure. Purification by flash column chromatography on silica gel afforded the desired 2-methoxy-4-(alkoxycarbonyl)phenyl nicotinic acid esters 5-8.

[0088] 2-methoxy-4-(methoxycarbonyl)phenyl nicotinic acid ester (5)

[0089] Vanillyl alkyl ester (1) (0.70 g, 3.84 mmol), nicotinic acid (0.47 g, 3.84 mmol) and DMAP (0.046 g, 0.38 mmol) were dissolved in dry CH2Cl2(10 mL) and DCC (0.79 g, 3.84 mmol) was added after stirring at 0 °C under N2protection. The reaction mixture was allowed to warm to room temperature and stirred for 12 h. The precipitated DCU was removed by filtration and the filtrate was concentrated under vacuum. The crude product was purified by column chromatography on silica gel using eluent of n-hexane / ethyl acetate 9:1 (v / v) to give ester 5 as a white crystalline solid in 89% yield; Rf= 0.32 (hexane / ethyl acetate 3.5:1.5). 1 H-NMR (400 MHz, CDC13): δ 9.41 (d, J = 3.56 Hz, 1H, CH), 8.86 (d, J = 3.56 Hz, 1H, CH), 8.47 (d, 7.96 Hz, 1H, CH), 7.75-7.72 (m, 2H, CH), 7.50-7.12 (m, 1H, CH), 7.26 (d, 8.12 Hz, 1H, CH), 3.95 (s, 3H, OCH3), 3.89 (s, 3H, OCH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 166.29 (CO), 162.93 (CO), 153.97 (CH Ar ), 151.45 (CH Ar ), 151.08 (CH Ar ), 143.31 (CH Ar ), 137.79 (CH Ar ), 129.22 (C Ar ), 125.18 (C Ar ), 123.49 (C Ar ), 122.76 (CH Ar), 122.64 (CH Ar ), 113.5 (CH Ar ), 56.11 (OCH3), 52.33 (O C H3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 3440 (231); IR data (KBr, cm -1 ): 2997 (m), 1743 (s), 1716 (m), 1604 (s), 1411 (w), 1242 (s), 1175 (s), 1019 (m), 892 (w); HRMS-EI: {m / z} calcd. for C 15 H 13 NO5[M] + 287.0794, found 287.0791.

[0090] 2-Methoxy-4-(ethoxycarbonyl)phenyl nicotinate (6)

[0091] Ethyl vanillate (2) (0.85 g, 4.33 mmol), nicotinic acid (0.53 g, 4.33 mmol) and DMAP (0.052 g, 0.433 mmol) were dissolved in dry CH2Cl2(15 mL) and after stirring DCC (0.89 g, 4.33 mmol) was added at 0 °C under nitrogen atmosphere. The reaction mixture was allowed to warm to room temperature and stirred for 12 h. The precipitated dicyclohexylurea was filtered off and the filtrate was concentrated in vacuo. The crude product was purified by column chromatography on silica gel with eluent n-hexane: ethyl acetate = 9:1 (v / v) to give ester 6 as a white crystalline solid. Yield 78%; Rf= 0.31 (hexane-ethyl acetate = 3.5:1.5). 1 H NMR (400 MHz, CDC13): δ 9.38 (d, J = 1.52 Hz, 1H, CH), 8.84 (dd, J = 1.56, 4.84 Hz, 1H, CH), 8.45-842 (m, 1H, CH), 7.72-7.68 (m, 2H, CH), 7.47-7.44 (m. 1H, CH), 7.22 (d, 8.16 Hz, 1H, CH), 4.38 (q, 7.16 Hz, 2H, CH2), 3.86 (s, 3H OCH3), 1.39 (t, 7.12 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1): 1920 (289); IR data (KBr, cm -1 )ν: 3048 (w), 2939 (m), 2334 (w), 1748 (s), 1709 (m), 1608 (s), 1504 (s), 1414 (w), 1279 (s), 1171 (m), 1030 (s), 729 (w); HRMS-EI: {m / z} calcd. for C 16 H 15 NO5[M] + 301.0905; found 309.0955.

[0092] 2-Methoxy-4-(propoxycarbonyl)phenyl nicotinate (7)

[0093] Propyl vanillate (3) (0.90 g, 4.28 mmol), nicotinic acid (0.52 g, 4.28 mmol) and DMAP (0.052 g, 0.428 mmol) were dissolved in dry CH2Cl2(20 mL) and treated with DCC (0.86 g, 4.28 mmol) at 0 °C under nitrogen. The reaction mixture was allowed to warm to room temperature and stirred for 14 h. The resulting white precipitate of dicyclohexylurea was filtered off and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography on silica gel with eluent n-hexane / ethyl acetate 9:1 v / v to give ester 7 as a white crystalline solid. Yield 66%; Rf= 0.34 (hexane / ethyl acetate 3.5:1.5). 1 H NMR (400 MHz, CDC13): δ 9.38 (d, J = 1.6 Hz, 1H, CH), 8.84 (dd, J = 1.6, 4.84 Hz, 1H, CH), 8.43 (dt, J = 7.96 Hz, 1H, CH), 7.72-7.96 (m, 2H, CH), 7.47-7.44 (m. 1H, CH), 7.21 (d, J = 8.68 Hz, 1H, CH), 4.28 (t, J = 6.68 Hz, 2H, CH2), 3.86 (s, 3H, OCH3), 1.77 (q, J = 7.24 Hz, 2H, CH2), 1.02 (t, J = 7.44 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 3560 (275); IR data (KBr, cm -1)ν:3059(w),2939(m),2360(w),1748(s),1709(m),1605(s),1504(s),1415(w),1279(s),1121(m),1015(s),730(w); HRMS-EI: {m / z} calcd for C 17 H 17 NO5[M] + 315.1107; found 315.1122.

[0094] 2-Methoxy-4-(isopropoxycarbonyl)phenyl nicotinate (8)

[0095] Vanillic acid isopropyl ester (4) (0.50 g, 2.38 mmol), nicotinic acid (0.292 g, 2.38 mmol) and DMAP (0.0291 g, 0.238 mmol) were dissolved in dry CH2Cl2(15 mL) and treated with DCC (0.49 g, 2.38 mmol) at 0 °C under nitrogen protection. The reaction mixture was allowed to warm to room temperature and stirred for 16 h. The resulting white precipitate of dicyclohexylurea was filtered off and the filtrate was concentrated under reduced pressure. The crude product was purified by column chromatography on silica gel with eluent n-hexane / ethyl acetate 9:1 (v / v) to give ester 8 as a white crystalline solid. Yield 65%; Rf= 0.40 (hexane / ethyl acetate 3:2); 1 H NMR (400 MHz, CDC13): δ 9.38 (d, J = 1.36 Hz, 1H, CH), 8.84 (dd, J = 1.40, 4.76 Hz, 1H, CH), 8.44 (d, J = 7.96 Hz, 1H, CH), 7.71-7.68 (m, 2H, CH), 7.47-7.44 (m. 1H, CH), 7.21 (d, 8.12 Hz, 1H, CH), 5.24 (sept, 6.28 Hz, 1H, CH), 3.86 (s, 3H OCH3), 1.37 (s, 3H, CH3), 1.35 (s, 3H, CH3); UV-Vis. (in CHCl3): λ max ,nm (ε / 10 -3 M -1 cm -1 ): 2860 (231); IR data (KBr, cm -1 )ν: 1740 (s), 1716 (m), 1607 (s), 1505 (s), 1411 (w), 1277 (s), 1102 (m), 1030 (s), 775 (w); HRMS-EI: {m / z} calcd for C 17 H 17 NO5[M] +315.1107; found 315.1111.

[0096] 3. Synthesis of arene ruthenium complexes 9-20

[0097] Under inert atmosphere, a stirred solution of the corresponding ligand (5-8 1.0 equiv.) in dry chloroform or dichloromethane (5 mL) was treated with a dimeric ruthenium precursor - [Ru2(η 6 -C6H6)2(μ-Cl)2Cl2], [Ru2(η 6 -p-cymene)2(μ-Cl)2Cl2] or [Ru2(η 6 -C6Me6)2(μ-Cl)2Cl2] (0.5 equiv.). After completion of the reaction, the solvent was removed under vacuum to obtain the crude product as an air stable solid. The complexes were obtained as yellow to yellow-brown powders or crystalline solids in quantitative yields (>99%). All the compounds were readily soluble in polar organic solvents (CH2Cl2, CHCl3), slightly soluble in water.

[0098] (η 6 -C6H6)RuCl22- methoxy-4-(methoxycarbonyl)phenyl nicotinate (9)

[0099] Light yellow to brown solid, Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.82 (d, J = 1.56 Hz, 1H, CH), 9.35 (d, J = 1.08, 5.68 Hz, 1H, CH), 8.51 (d, J = 7.96 Hz, 1H, CH), 7.72-7.68 (m, 2H, CH), 7.50-7.47 (m. 1H, CH), 7.21 (d, 8.16 Hz, 1H, CH), 5.71 (s, 6H, CH), 3.92 (s, 3H, OCH3), 3.86 (s, 3H, OCH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 166.24 (CO), 161.17 (CO), 158.80 (CH Ar ), 156.59 (C Ar ), 142.93 (CH Ar ), 139.46 (CH Ar ), 129.53 (C Ar ), 126.65 (C Ar ), 124.33 (C Ar ), 122.63 (CH Ar ), 113.57 (CH Ar ), 84.50( C H Ar),56.14(O C H3), 53.40 (C), 52.38 (O) C H3); UV-Vis. (in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):6180(230); IR data(KBr,cm -1 )ν:3093(m),2360(m),1697(s),1506(w),1127(s),1275(s),927(m),790(w); HRMS-FAB + :{m / z}calcd.for C 21 H 19 NO5ClRu[M-Cl] + 501.9995; found 502.0024.

[0100] (η 6 -C6H6)RuCl22-methoxy-4-(ethoxycarbonyl)phenyl nicotinate (10)

[0101] Pale yellow to brown solid, yield >99%; 1 H NMR (400MHz, CDCl3): δ9.82(d,J=1.56Hz,1H,CH),9.36(d,J=4.64Hz,1H,CH),8.51(d,J=7.92Hz,1H,CH),7.72-7.68(m ,2H,CH),7.50-7.47(m.1H,CH),7.21(d,J=8.16Hz,1H,CH),5.71(s,6H,CH),4.41(q,J=7.12Hz,2H,CH2),3.86(s,3H,OC H3 ),1.39(t,J=7.12Hz,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):7060(244); IR data(KBr,cm -1 )ν:3069(m),1753(s),1716(s),1607(m),1505(w),1434(s),1177(s),1080(s),784(w); HRMS-ESI + :{m / z}calcd.for C 22 H 21Cl2NO5Ru[M] + 550.9840; found 573.9688([C 22 H 21 Cl2NO5Ru]+Na) + .

[0102] (η 6 -C6H6)RuCl22-methoxy-4-(propoxycarbonyl)phenyl nicotinate (11)

[0103] Pale yellow to brown solid, yield >99%; 1 H NMR (400MHz, CDCl3): δ9.82 (d, J=1.48Hz, 1H, CH), 9.36 (d, J=4.64Hz, 1H, CH), 8. 43(d,J=7.96Hz,1H,CH),7.72-7.68(m,2H,CH),7.50-7.47(m.1H,CH),7.21(d,J =8.68Hz,1H,CH),5.71(s,6H,CH),4.28(t,J=6.68Hz,2H,CH2),3.86(s,3H,OCH3 ),1.82(q,J=6.96Hz,2H,CH2),1.02(t,J=7.4Hz,3H,CH3); UV-Vis.(inCHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 :7160(244); IR data(KBr,cm -1 )ν:2921(m),1728(m),1504(s),1419(w),1268(s),1175(s),1076(m),918(w); HRMS-ESI + :{m / z}calcd.forC 23 H 23 ClNO5Ru[M-Cl] + 530.0308; found 530.0321[C] 23 H 23 ClNO5Ru] + .

[0104] (η 6 -C6H6)RuCl22-methoxy-4-(isopropoxycarbonyl)phenyl nicotinate (12)

[0105] Pale yellow to brown solid, yield >99%; 1H NMR (400MHz, CDCl3): δ9.82(d,J=1.52Hz,1H,CH),9.36(d,J=4.64Hz,1H,CH),8.49(d,J=7.96Hz,1H,CH),7.71-7.67(m,2H,CH),7.5 0-7.47(m.1H,CH),7.20(d,8.16Hz,1H,CH),5.71(s,6H,CH),5.26-5.20(m,2H,CH2),1.37(s,3H,CH3),1.36(s,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):6570(243); IR data(KBr,cm -1 )ν:2928(m),1727(s),1716(m),1502(s),1416(w),1269(s),1170(m),1050(s),736(w); HRMS-ESI + :{m / z}calcd.for C 23 H 23 ClNO5Ru[M-Cl] + 530.0308; found 530.0288 [C] 23 H 23 ClNO5Ru] + .

[0106] (η 6 p-MeC6H4Pr i RuCl22-methoxy-4-(methoxycarbonyl)phenyl nicotinate (13)

[0107] Yellow to orange solid, yield >99%; 1H NMR (400 MHz, CDC13): δ 9.77 (d, J = 1.40 Hz, 1H, CH), 9.31 (d, J = 4.64 Hz, 1H, CH), 8.48 (d, J = 7.96 Hz, 1H, CH), 7.71-7.68 (m, 2H, CH), 7.48-7.45 (m, 1H, CH), 7.21 (d, 8.2 Hz, 1H, CH), 5.47 (d, 6.0, 2H, CH), 5.27 (d, 6.0 Hz, 2H, CH), 3.92 (s, OCH3), 3.85 (s, 3H, OCH3), 2.98 (sept, 6.92 Hz, 1H, CH), 2.13 (s, 3H, CH3), 1.31 (s, 3H, CH3), 1.29 (s, 3H, CH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 166.24 (CO), 161.32 (CO), 158.48 (CH Ar ), 156.61 (C Ar ), 150.06 (C Ar ), 143.04 (C Ar ), 139.11 (C Ar ), 129.50 (C Ar ), 126.55 (C Ar ), 124.19 (CH Ar ), 122.66 (CH Ar ), 122.63 (CH Ar ), 113.61 (CH Ar ), 97.43 (CH Ar ), 56.16 (OCH3), 52.35 (OCH3), 30.71 (CH), 22.25 (2x C H3), 18.31 (CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 6100 (231); IR data (KBr, cm -1 ): v: 1748 (m), 1719 (s), 1602 (s), 1506 (w), 1273 (s), 1273 (s), 1170 (s), 1029 (m), 759 (w); HRMS-FAB + : {m / z} calcd. for C 25 H 28 ClNO5Ru [M+1] +558.0621; found 558.0722.

[0108] (η 6 p-MeC6H4Pr i )RuCl22-methoxy-4-(ethoxycarbonyl)phenyl nicotinate (14)

[0109] Yellow to orange solid, Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.77 (d, J = 1.24 Hz, 1H, CH), 9.31 (d, J = 4.64 Hz, 1H, CH), 8.48 (d, J = 7.96 Hz, 1H, CH), 7.72-7.68 (m, 2H, CH), 7.48-7.45 (m, 1H, CH), 7.21 (d, 8.2 Hz, 1H, CH), 5.47 (d, 4.84, 2H, CH), 5.27 (d, 5.92 Hz, 2H, CH), 4.39 (q, 7.16, 2H, CH2), 3.85 (s, 3H, OC H3 ), 3.00 (sept, 7.04 Hz, 1H, CH), 2.13 (s, 3H, CH3), 1.39 (t, 7.12 Hz, 3H, CH3), 1.31 (s, 3H, CH3), 1.30 (s, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 2990 (232); IR data (KBr, cm -1 ) v: 3062 (w), 2965 (m), 2359 (s), 1748 (s), 1717 (m), 1604 (w), 1506 (m), 1414 (s), 1293 (s), 1169 (s), 1087 (s), 1050 (s), 757 (m); HRMS-FAB + : {m / z} calcd for C 26 H 29 ClNO5Ru[M-Cl] + 572.077; found 572.0799.

[0110] (η 6 p-MeC6H4Pr i )RuCl22-methoxy-4-(ethoxycarbonyl)phenyl nicotinate (14)

[0111] Yellow to orange solid, Yield >99%; 1H NMR (400 MHz, CDC13): δ 9.77 (d, J = 1.44 Hz, 1H, CH), 9.31 (d, J = 2.8 Hz, 1H, CH), 8.48 (dd, J = 1.52 Hz, 6.44 Hz, 1H, CH), 7.72-7.68 (m, 2H, CH), 7.49-7.45 (m, 1H, CH), 7.21 (d, J = 8.16 Hz, 1H, CH), 5.47 (d, J = 5.96 Hz, 2H, CH), 5.27 (d, J = 6.0 Hz, 2H, CH), 4.30 (t, J = 6.68 Hz, 2H, CH2), 3.85 (s, 3H, OCH3), 3.00 (sept, 6.92 Hz, 1H, CH), 2.13 (s, 3H, CH3), 1.80 (sext, 7.28 Hz, 2H, CH2), 1.31 (s, 3H, CH3), 1.30 (s, 3H, CH3), 1.02 (t, 7.4 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max nm (ε / 10 -3 M -1 cm -1 ): 4480 (244); IR data (KBr, cm -1 ) v: 2933 (m), 2355 (w), 2033 (w), 1747 (s), 1716 (m), 1605 (s), 1505 (s), 1416 (w), 1285 (s), 1197 (m), 1084 (s), 779 (w); HRMS-FAB + {m / z} calcd for C 27 H 31 NO5ClRu[M-Cl] + 586.0934; found 586.0962.

[0112] (η 6 p-MeC6H4Pr i )RuCl22-methoxy-4-(isopropoxycarbonyl)phenyl nicotinate (16)

[0113] Yellow to orange solid, Yield >99%; 1H NMR (400MHz, CDCl3): δ9.77(d,J=1.28Hz,1H,CH),9.31(d,J=4.56Hz,1H,CH),8.49(d,J=7.92 Hz,1H,CH),7.71-7.67(m,2H,CH),7.49-7.44(m,1H,CH),7.20(d,J=8.16Hz,1H,CH),5.47(d,J =5.96Hz,2H,CH),5.28-5.22(m,CH),3.85(s,3H,OCH3),2.98(sept,J=6.92Hz,1H,CH),2.13(s ,3H,CH3),1.37(s,3H,CH3),1.36(s,3H,CH3),1.31(s,3H,CH3),1.30(s,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M - 1 cm -1 ):2700(231); IR data(KBr,cm -1 )ν:2928(m),2360(s),1755(s),1708(m),1601(s),1506(w),1415(m),1265(s),1173(s),1019(s),736(m); HRMS-FAB + :{m / z}calcd.forC 27 H 31 ClNO5Ru[M] + 586.0934; found 586.0954.

[0114] (η 6 -C6Me6)RuCl22-methoxy-4-(methoxycarbonyl)phenyl nicotinate (17)

[0115] Bright orange to orange-red solid; Yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.55(s,1H,CH),9.11(d,J=5.32Hz,1H,CH),8.44(d,J=7.92Hz,1H,CH),7.72-7.68(m,2H,CH),7 .47-7.43(m,1H,CH),7.21(m,1H,CH),4.41(q,7.12,2H,CH2),3.92(s,3H,OCH3),3.85(s,3H,OCH3),2.00(s,18H,CH3); 13C-NMR (DMSO-d6, 100 MHz): δ 166.26 (CO), 161.48 (CO), 158.31 (CH Ar ), 156.51 (C Ar ), 150.90 (C Ar ), 143.05 (C Ar ), 138.64 (CH Ar ), 129.37 (C Ar ), 126.47 (C Ar ), 124.17 (CH Ar ), 122.69 (CH Ar ), 122.58 (CH Ar ), 113.51 (CH Ar ), 91.48 (CH Ar ), 56.12 (OCH3), 52.36 (OCH3), 15.41 (CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 4930 (230); IR data (KBr, cm -1 ) v: 3094 (m), 2359 (s), 1697 (s), 1506 (w), 1263 (s), 1116 (s), 973 (m), 518 (s); HRMS-FAB + : {m / z} calcd. for C 27 H 31 ClNO5Ru [M-Cl] + 586.0934; found 586.0961.

[0116] (η 6 -C6Me6)RuCl2 2-methoxy-4-(ethoxycarbonyl)phenyl nicotinate (18)

[0117] Bright orange to orange red solid; Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.54 (s, 1 H, CH), 9.11 (d, J = 4.84 Hz, 1 H, CH), 8.44 (d, J = 7.92 Hz, 1 H, CH), 7.72-7.68 (m, 2 H, CH), 7.47-7.43 (m, 1 H, CH), 7.23 (d, 8.28 Hz, 1 H, CH), 4.41 (q, 7.12, 2 H, CH2), 3.85 (s, 3 H, OCH3), 3.82 (s, 3 H, OCH3);13C NMR (100 MHz, CDC13): δ 166.48 (CO), 161.48 (CO), 158.31 (CH), 156.51 (C), 150.90 (C), 143.05 (C), 138.64 (CH), 129.37 (C), 126.47 (C), 124.17 (CH), 122.69 (CH), 122.58 (CH), 113.51 (CH), 91.48 (CH), 56.12 (OCH3), 52.36 (OCH3), 15.41 (CH3); UV-Vis. (in CHCl3): λ H3), 2.00 (s, 18H, CH3), 1.39 (t, J = 7.12 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 4470 (241); IR data (KBr, cm -1 ) v: 3079 (w), 2928 (m), 1731 (s), 1588 (w), 1515 (m), 1416 (s), 1260 (s), 1122 (s), 1068 (s), 1017 (s), 730 (m); HRMS-FAB + : {m / z} calcd for C 28 H 33 ClNO5Ru[M-Cl] + 600.1091; found 600.1121.

[0118] (η 6 -C6Me6)RuCl2 2-methoxy-4-(propoxycarbonyl)phenyl nicotinate (19)

[0119] Bright orange to orange red solid; Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.54 (s, 1H, CH), 9.11 (d, J = 4.84 Hz, 1H, CH), 8.43 (d, J = 7.92 Hz, 1H, CH), 7.72-7.68 (m, 2H, CH), 7.47-7.43 (m, 1H, CH), 7.23 (d, 8.40 Hz, 1H, CH), 4.28 (q, 6.68, 2H, CH2), 3.85 (s, 3H, OCH3), 1.82 (s, 18H, CH3), 1.80 (sext, 7.20 Hz, 2H, CH2), 1.02 (t, 7.40 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 6070 (231); IR data (KBr, cm -1 ) v: 3085 (w), 2965 (m), 2360 (w), 1745 (s), 1705 (m), 1605 (s), 1503 (s), 1412 (w), 1279 (s), 1169 (s), 1086 (m), 724 (w); HRMS-FAB + : {m / z} calcd for C29 H 35 NO5ClRu[M-Cl] + 614.1247; found 614.1279.

[0120] (η 6 -C6Me6)RuCl22-methoxy-4-(isopropoxycarbonyl)phenyl nicotinate (20)

[0121] Bright orange to orange-red solid; Yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.54(s,1H,CH),9.11(d,J=4.76Hz,1H,CH),8.44(d,J=7.92Hz,1H,CH),7.71-7.67(m,2H,CH),7.49-7.43(m,1H,CH) ,7.22(d,8.40Hz,1H,CH),4.28(sept,6.28,2H,CH2),3.85(s,3H,OCH3),2.00(s,18H,CH3),1.37(s,3H,CH3),1.36(s,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):6770(230); IR data(KBr,cm -1 )ν:3036(w),2975(m),1753(s),1699(m),1507(s),1413(w),1282(s),1143(m),1042(s),787(w); HRMS-FAB + :{m / z}calcd.for C 29 H 35 NO5Cl1Ru1[M] + 614.1247; found 614.1277.

[0122] Synthesis of 4,2-methoxy-4-(alkoxycarbonyl)phenyl isonicotinate 21-24

[0123] Under an inert atmosphere, dicyclohexylcarbodiimide (DCC) (1 equivalent) and 4-(dimethylamino)pyridine (DMAP) (0.1 equivalent) were added to a DMF mixture of alkyl vanillic acid ester (1 equivalent) and isonicotinic acid (1 equivalent) at 0 °C. The reaction mixture was stirred at room temperature for 24 hours. The precipitate was filtered off, and the filtrate was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane and ethyl acetate in a volume ratio of 9:1 to give the desired 2-methoxy-4-(alkoxycarbonyl)phenylisonicotinic acid esters 21-24.

[0124] 2-Methoxy-4-(methoxycarbonyl)phenylisonicotinic acid ester (21)

[0125] Methyl vanillate (0.5 g, 2.98 mmol) was coupled with isonicotinic acid (0.366 g, 2.98 mmol) in the presence of DCC (0.614 g, 2.98 mmol) and DMAP (0.0364 g, 0.298 mmol) to give 21. White solid; yield 60%, R f =0.31(hexane / EtOAc,3.5:1.5); mp:142-143℃; IR(KBr,cm -1 ):3422(b),2983(m,ν CH ),1756(s,ν C＝O ),1721(s,ν C＝O ),1608(m),1565(w),1508(s),1436(m),1416(m),1289(s,CO),1267(w),1177 (s,CO),1129(m),1058(m),1027(m),848(w),753(m),699(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}250(20.684),290(14.740); 1 H NMR (400MHz, CDCl3): δ8.87(d,2H,J=5.9Hz,H-11),8.02(d,2H,J=5.9Hz,H-10),7.73(m,2 H,H-6),7.70(m,2H,H-2),7.21(d,J=8.1Hz,1H,H-1),3.94(s,3H,H-2'),3.88(s,3H,H-7). 13C NMR (400MHz, CDCl3): δ166.5(C-1′), 163.0(C-8), 151.2(C-3), 150.9(C-11), 143.4(C-4), 136.6(C-9), 129.6 (C-1),123.6(C-10),122.9(C-6),122.8(C-2),113.8(C-5),56.3(C-7),52.6(C-2′); LR-EI-MS(m / z)287.3[M] + ;HR-EI-MS(m / z)calcd.for C 15 H 13 NO5[M] + :287.0794,found:287.0799.

[0126] 2-Methoxy-4-(ethoxycarbonyl)phenylisonicotinate (22)

[0127] Ethyl vanillate (0.5 g, 2.55 mmol) was coupled with isonicotinic acid (0.314 g, 2.55 mmol) in the presence of DCC (0.53 g, 2.55 mmol) and DMAP (0.0312 g, 0.255 mmol) to give 22 g of white solid; yield 75%, R f =0.32(hexane-EtOAc,3.5:1.5); mp:99-100℃; IR(KBr,cm -1 ):3414(b),2976(m,ν CH ),1755(s,ν C＝O ),1716(s,ν C＝O ),1607(m),1508(s),1456(m),1418(m),1366(w),1286(s,CO)1177(s,CO),1127(m),1058(m),1027(m),847(w),752(m),699(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:220(3.015),230(2.185),285(0.710); 1H NMR (400 MHz, CDC13): δ 8.88 (d, 2H, J = 5.6 Hz, H-11), 8.03 (d, 2H, J = 5.9 Hz, H-10), 7.73 (m, 2H, H-6), 7.70 (m, 2H, H-2), 7.23 (d, 1H, J = 8.2 Hz, H-5), 4.40 (q, 2H, J = 7.1 Hz, H-2'), 3.89 (s, 3H, H-7), 1.42 (t, 3H, J = 7.1 Hz, H-3'). LR-EI-MS (m / z) 301.1 [M] + HR-EI-MS (m / z) calcd for C 16 H 15 20 5[M] + : 301.0950, found: 301.0951.

[0128] 2-Methoxy-4-(propoxycarbonyl)phenyl nicotinate (23)

[0129] Vanillic acid propyl ester (0.5 g, 2.38 mmol) was coupled with nicotinic acid (0.293 g, 2.38 mmol) in the presence of DCC (0.49 g, 2.55 mmol) and DMAP (0.0291 g, 0.238 mmol) to give 23. White solid; yield 65%, R f = 0.33 (hexane-EtOAc, 3.5:1.5); IR (KBr, cm -1 ): 3751 (w), 3690 (w), 3629 (w), 2983 (m, v CH ), 1734 (s, v C＝O ), 1717 (w), 1654 (m), 1559 (m) 1507 (s), 1458 (m), 1418 (m), 1281 (m), 1249 (m), 1244 (s, v C-O ), 1191 (s, v C-O ), 1082 (m), 1027 (m), 856 (w), 740 (m), 698 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 230 (2.608), 245 (6.982), 290 (3.291); 250 (20.684), 290 (14.740); 1HNMR (400MHz, CDCl3): δ8.87(d,2H,J=5.9Hz,H-12),8.02(d,2H,J=5.9Hz,H-11),7.74(m,2H,H-6),7.70(m,2H,H-2),7.22(d,1H,J=8Hz,H-5) ,4.30(t,J=6.6Hz,H-2′),3.88(s,3H,H-7),1.81(m,2H,H-3′),1.04(t,3H,J=7.4Hz,H-4′).LR-EI-MS(m / z)315.1,HR-EI-MS(m / z)calcd.for C 17 H 17 NO5:315.1107, found:315.1111.

[0130] 2-Methoxy-4-(isopropoxycarbonyl)phenylisonicotinic acid ester (24)

[0131] Isopropyl vanillate (0.5 g, 2.38 mmol) was coupled with isonicotinic acid (0.293 g, 2.38 mmol) in the presence of DCC (0.49 g, 2.55 mmol) and DMAP (0.0291 g, 0.238 mmol) to give 24. White solid; yield 68%; R f =0.34(hexane / EtOAc,3.5:1.5); mp:85-86℃; IR(KBr,cm -1 ):3443(b),2976(m,ν CH ),1753(s,ν C＝O ),1705(s,ν C＝O ),1607(m),1507(s),1468(m),1415(m),1290(s,ν C-O ),1265(m),1176(s,ν C-O ),1114(m),1058(m),1029(m),944(w),767(m),679(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M - 1 cm -1 )}:220(4.015),240(7.645),290(3.547); 1H NMR (400 MHz, CDC13): δ 8.87 (d, 2H, J = 5.9 Hz, H-12), 8.02, (m, 2H, H-11), 7.72 (m, 2H, H-6), 7.70 (m, 2H, H-2), 7.22 (d, 1H, J = 8.1 Hz, H-5), 5.27, (m, 1H, H-2'), 3.88, (s, 3H, H-7), 1.39 (d, 6H, J = 6.2 Hz, H-3') LR-EI-MS (m / z) 315.1 [M] + HR-EI-MS (m / z) calcd for C 15 H 13 NO5 [M] + : 315.1107, found: 315.1115.

[0132] 5. Synthesis of arene ruthenium complexes 25-36

[0133] The corresponding ligand (21-24 1.0 equiv.) in dry chloroform or dichloromethane under inert atmosphere was treated with a dimeric ruthenium precursor - [Ru2(η 6 -C6H6)2(μ-Cl)2Cl2], [Ru2(η 6 -p-cymene)2(μ-Cl)2Cl2] or [Ru2(η 6 -C6Me6)2(μ-Cl)2Cl2] (0.5 equiv.). After completion of the reaction, the solvent was removed under vacuum to obtain the crude product as an air stable solid. The complexes were obtained as yellow to orange solids in quantitative yield (>99%). All compounds were readily soluble in polar organic solvents (CH2Cl2, CHCl3), slightly soluble in water.

[0134] (η 6 -C6H6)RuCl22-Methoxy-4-(methoxycarbonyl)phenyl isonicotinic acid ester (25)

[0135] Yellow to orange solid; Yield 99.9%; IR (KBr, cm -1 ): 3426 (b), 2978 (m, vCH), 1755 (s, vC=0), 1722 (s, vC=0), 1604 (m), 1508 (s), 1435 (m), 1416 (m), 1275 (s, C-O), 1173 (s, C-O), 1120 (m), 1084 (w), 1057 (m), 1032 (w), 759 (s), 691 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm-1 )}:290(6.408),345(2.414),420(1.258); 1 H NMR (400MHz, CDCl3): δ9.37(d,2H,J=6.6Hz,H-11),8.01(d,2H,J=6.6Hz,H-10),7.74(d,J=1.8Hz,2H,H-2),7.71( dd,J=1.8Hz,6.7Hz,2H,H-6),7.22(d,J=8.2Hz,1H,H-1),5.71(s,6H,H-12),3.94(s,3H,H-2'),3.86(s,3H,H-7); 13 C NMR (400MHz, CDCl3): δ166.5(C-1'), 163.0(C-8), 151.2(C-3), 150.9(C-11), 143.4(C-4), 136.6(C-9) ,129.6(C-1),123.6(C-10),122.9(C-6),122.8(C-2),113.8(C-5),56.3(C-7),52.6(C-2'); LR-MS(FAB + (m / z)502.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 21 H 19 Cl2NO5Ru[M-Cl] + :501.9995,found:502.0021.

[0136] (η 6 -C6H6)RuCl22-methoxy-4-(ethoxycarbonyl)phenylisonicotinic acid ester (26)

[0137] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3435(b),2962(m,ν CH ),1756(s,ν C＝O ),1731(s,ν C＝O ),1605(m),1508(s),1469(w),1414(m),1294(s,ν C-O ),1266(s),1198(m),1172(s,v C-O ),1120(m),1086(m),1061(m),1032(w),871(w),761(s),695(w); UV-Vis{CHCl3,λ maxnm(ε / 10 -3 M -1 cm -1 )}:295(6.337),340(3.523),405(6.614); 1 H NMR (400MHz, CDCl3): δ9.37 (d, 2H, J = 6.6Hz, H-11), 8.01 (d, 2H, J = 6.6Hz, H-10), 7.74 (d, J = 1.4Hz, 2H, H-2), 7.73 (dd, J = 1.8Hz, 8 .0Hz)2H,H-6),7.23(d,1H,J=8.2Hz,H-5),4.40(q,2H,J=7.1Hz,H-2'),3.86(s,3H,H-7),1.41(t,3H,J=7.1Hz,H-3').LR-MS(FAB + (m / z)516.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 22 H 21 Cl2NO5Ru[M-Cl] + =516.0152,found=516.0169.

[0138] (η 6 -C6H6)RuCl22-methoxy-4-(propoxycarbonyl)phenylisonicotinate (27)

[0139] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3435(b),2962(m,ν CH ),1750(s,ν C＝O ),1718(s,ν C＝O ),1604(m),1507(s),1456(w),1414(m),1294(s,CO),1264(s),1199(m),1172(s,C O),1118(m),1082(m),1059(m),1029(w),885(w),762(s),691(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:290(4.874),340(2.657)425(1.069); 1H NMR (400MHz, CDCl3): δ9.37(d,2H,J=6.6Hz,H-12),8.01(d,2H,J=5.9Hz,H-11),7.74(d,J=1.8Hz,2H,H-2),7.71(dd,J=1.8Hz,6.6Hz),2H,H-6) ,7.21(d,1H,J=8.2Hz,H-5),4.30(t,J=6.6Hz,H-2')3.86(s,3H,H-7),1.80(sextet,J=7.3Hz,2H,H-3'),1.03(t,3H,J=7.4Hz,H-4'); LR-MS(FAB + (m / z)530.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 23 H 23 Cl2NO5Ru[M-Cl] + :530.0308,found:530.0336.

[0140] (η 6 -C6H6)RuCl22-methoxy-4-(isopropoxycarbonyl)phenylisonicotinic acid ester (28)

[0141] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3058(b),2977(m,ν CH ),1747(s,ν C＝O ),1718(s,ν C＝O )1606(m),1507(m),1435(w),1416(s),1345(m),1292(s,CO),1198(w),1173(s,CO ),1121(m),1057(m),1025,(m),887(w),838(m),760(s),692(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:295(5.902),340(2.029),420(1.430); 1H NMR (400MHz, CDCl3): δ9.37(d,2H,J=6.5Hz,H-12),8.00(d,2H,J=6.4Hz,H-11),7.72(m,2H,H-6),7.69(d,2H,J=1 .6Hz,H-2),7.20(d,1H,J=8.2Hz,H-5),5.26(m,1H,H-2'),3.85(s,3H,H-7),1.37(d,6H,J=6.2Hz,H-3')LR-MS(FAB + (m / z)530.2[M-Cl] + HR-MS (FAB) + (m / z)calcd.forC 23 H 23 Cl2NO5Ru[M-Cl] + :530.0308,found:530.0335.

[0142] (η 6 p-MeC6H4Pr i RuCl2 2-Methoxy-4-(methoxycarbonyl)phenylisonicotinic acid ester (29)

[0143] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3423(b),2963(m,ν CH ),1758(s,ν C＝O ),1719(s,ν C＝ O)1605(w),1507(m),1466(w),1414(s),1290(s,CO),1197(w),1173(s,CO),1 118(m),1059(m),1031(m),871(w),838(m),761(s),693(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:290(4.304),340(2.849),440(0.432); 1H NMR (400 MHz, CDC13): δ 9.30 (d, 2H, J = 6.6 Hz, H-12), 7.98 (d, 2H, J = 6.6 Hz, H-11), 7.72 (d, 2H, J = 1.8 Hz, 6.2 Hz, H-2), 7.69 (d, 2H, J = 1.6 Hz, H-6), 7.20 (d, 1H, J = 8.2 Hz, H-5), 5.47 (d, 1H, J = 6.0 Hz, H-15), 5.24 (d, 1H, J = 6.0 Hz, H-14), 3.92 (s, 3H, H-2'), 3.85 (s, H-7), 3.01 (m, 3H, H-7), 2.12 (s, 3H, H-12), 1.32 (d, 6H, J = 6.9, H-18). 13 C NMR (400 MHz, CDC13): δ 166.2 (C-1'), 161.6 (C-8), 156.0 (C-11), 150.7 (C-3), 142.9 (C-4), 137.6 (C-9), 129.6 (C-1), 123.9 (C-10), 122.6 (C-6), 122.4 (C-2), 113.6 (C-5), 104.0 (C-16), 97.4 (C-13), 83.0 (C-14), 82.4 (C-15), 56.1 (C-7), 52.4 (C-2'), 30.7 (C-17), 22.3 (C-18), 18.3 (C-12); LR-MS (FAB + )(m / z) 558.1 [M-Cl] + , HR-MS (FAB + )(m / z) calcd. for C 25 H 27 O5NClRu[M-Cl] + : 530.0308, found: 558.0621.

[0144] (η 6 p-MeC6H4Pr i )RuCl2 2-methoxy-4-(ethoxycarbonyl)phenyl isonicotinate (30)

[0145] Yellow to orange solid; Yield 99.9%; IR (KBr, cm -1):3447(b),1756(s,νC=O),1717(s,νC=O)1603(m),1559(w),1507(w),1457(w),1415(s),1345(m),1291(s,C O),1261(m),1199(w),1179(s,CO),1125(m),1083(m),1058(m),1030,(w),764(m),692(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:295(5.643),340(4.312),455(0.875); 1 H NMR (400MHz, CDCl3): δ9.31 (d, 2H, J=6.6Hz, H-12), 7.98, (d, 2H, J=6.6Hz, H-11), 7.73 (d, 2H, J= 1.8Hz,7.5Hz,H-2),7.70(d,2H,J=1.8Hz,7.5Hz,H-6),7.21(d,1H,J=8.2Hz,H-5),5.48(d,1H,J =6.0Hz,H-15),5.25(d,1H,J=6.0Hz,H-14),4.39(q,2H,J=7.1Hz,H-2'),3.86(s,3H,H-7),3.01 (m,1H,H-17),2.13(s,3H,H-12),1.40(t,3H,J=7.2Hz,H-3'),1.33(d,J=6.9,H-18).LR-MS(FAB + (m / z)572.2[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 25 H 27 O5NClRu[M-Cl] + :572.0778,found:572.0808.

[0146] (η 6 p-MeC6H4Pr i RuCl22-methoxy-4-(propoxycarbonyl)phenylisonicotinic acid ester (31)

[0147] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3059(m),2966(m,ν CH ),1747(s,ν C＝O),1718(s,ν C＝O )1606(m),1507(m),1435(w),1416(s),1345(m),1292(s,CO),1198(w),1173(s,CO ),1121(m),1057(m),1025,(m),887(w),838(m),760(s),692(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:295(4.084),340(3.201),445(0.764); 1 H NMR (400MHz, CDCl3): δ9.31 (d, 2H, J = 6.6Hz, H-12), 7.99 (d, 2H, J = 6.6Hz, H-11), 7.73 (d, 2H, J = 1.7Hz, 5.9Hz, H-2 ),7.70(d,2H,J=1.8Hz,7.5Hz,H-6),7.21(d,1H,J=8.2Hz,H-5),5.48(d,1H,J=5.9Hz,H-15),5.25(d,1H,J=6.0Hz ,H-14),4.29(q,2H,J=6.7Hz,H-2'),3.86(s,3H,H-7),3.01(septet,1H,J=6.9Hz,H-17),2.13(s,3H,H-12),4.29 (t,2H,J=6.7Hz,H-2'),1.80(sextet,J=7.2Hz,H-3'),1.32(d,J=6.9,H-18),1.03(t,J=7.4Hz,H-4'); LR-MS(FAB + (m / z)586.0[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 27 H 31 O5NClRu[M-Cl] + :586.0934,found:586.0905.

[0148] (η 6 p-MeC6H4Pr i RuCl22-methoxy-4-(isopropoxycarbonyl)phenylisonicotinic acid ester (32)

[0149] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3447(b),2968(m,νCH ),1752(s,ν C＝O ),1717(s,ν C＝O ),1604(m),1507(s),1458(w),1414(s),1388(w),1288(s,CO),1264(m),1198 (m),1173(s,CO),1081(m),1057(m),886(w),762(m),668(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:295(6.616),340(5.386),445(1.110); 1 H NMR (400MHz, CDCl3): δ9.31: (d,2H,J=6.6Hz,H-12),7.99, (d,2H,J=6.4Hz,H-11),7.72(d,2H ,J=1.8Hz,H-2),7.71(d,2H,J=1.8Hz,6.2Hz,H-6),7.20(d,1H,J=8.2Hz,H-5),5.48(d,1H,J= 6.0Hz,H-15),5.28(m,1H,H-2'),5.25(d,1H,J=5.9Hz,H-14),3.86(s,3H,H-7),3.01(sept,J =6.9Hz,H-17),2.13(s,3H,H-12),1.37(d,J=6.2Hz,H-3'),1.32(d,J=6.9,H-18),LR-MS(FAB + (m / z)586.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 27 H 31 O5NClRu[M-Cl] + :586.0956,found:586.0966.

[0150] (η 6 -C6Me6)RuCl2 2-Methoxy-4-(methoxycarbonyl)phenylisonicotinic acid ester (33)

[0151] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3446(b),2965(m,ν CH ),1765(s,ν C＝O ),1720(s,ν C＝O),1605(m),1506(s),1465(w),1414(s),1388(w),1288(s,CO),1264(m),1240(m), 1198(m),1172(s,CO),1082(m),1058(m),885(w),761(m),691(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:215(11.799),295(7.744),360(4.849); 1 H NMR (500MHz, CDCl3): δ9.30(d,2H,J=6.6Hz,H-12),7.98(d,2H,J=6.4Hz,H-11),7.72(d,2H,J=1.8Hz,H-2),7.69( dd,2H,J=1.8Hz,6.2Hz,H-6),7.20(d,1H,J=8.2Hz,H-5),3.92(s,3H,H-2'),3.85(s,3H,H-7),2.12(s,18H,H-13); 13 C NMR (400MHz, CDCl3): δ166.2(C-1'),161.8(C-8),155.8(C-11),150.8(C-3),142.9(C-4),137.2(C-9),129.6(C-1) ,123.8(C-10),122.6(C-6),122.4(C-2),113.6(C-5),91.6(C-12),56.1(C-7),52.4(C-2'),15.4(C-13); LR-MS(FAB + (m / z)586.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 27 H 31 O5NClRu[M-Cl] + :586.0934,found:586.0963.

[0152] (η 6 -C6Me6)RuCl2 2-Methoxy-4-(ethoxycarbonyl)phenylisonicotinic acid ester (34)

[0153] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3443(b),2979(m,ν CH),1751(s,ν C＝O ),1710(s,ν C＝O ),1606(m),1505(s),1468(w),1416(s),1290(s,CO),1198(w),1172(s,CO),1083(m),1057(m),939(w),839(w),760(m),693(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M - 1 cm -1 )}:205(9.954),295(6.121),360(4.164); 1 H NMR (400MHz, CDCl3): δ9.08 (d, 2H, J = 6.6Hz, H-12), 7.95 (d, 2H, J = 6.4Hz, H-11), 7.72 (d, 2H, J = 1.8Hz, H-2), 7.69 (dd, 2H, J = 1.8Hz, 6.2Hz ,H-6),7.20(d,1H,J=8.2Hz,H-5),4.38(q,3H,J=7.2Hz,H-2'),3.85(s,3H,H-7),2.01(s,18H,H-13),1.39(t,J=7.1Hz,H-3'); LR-MS(FAB + (m / z)600.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 28 H 33 O5NClRu[M-Cl] + :600.1091,found:600.1058.

[0154] (η 6 -C6Me6)RuCl2 2-Methoxy-4-(propoxycarbonyl)phenylisonicotinic acid ester (35)

[0155] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3446(b),2965(m,ν CH ),1756(s,ν C＝O ),1716(s,ν C＝O),1606(m),1507(s),1465(w),1414(s),1287(s,CO),1244(w),1199(w),1174 (s,CO),1110(m),1058(m),1029(w),761(m),691(w),418(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:245(17.621),295(7.113),360(4.974); 1 H NMR (400MHz, CDCl3): δ9.08(d,2H,J=6.6Hz,H-12),7.95,(d,2H,J=6.6Hz,H-11),7.72(d,2H,J=1.8Hz,H-2),7.69(dd,2H,J=1.8Hz,6.3Hz,H-6),7.2 0(d,1H,J=8.2Hz,H-5),4.28(t,2H,J=6.7Hz,H-2'),3.85(s,3H,H-7),2.0 1(s,18H,H-13),1.80(m,2H,H-3'),1.02(t,3H,J=7.4Hz,H-4'); LR-MS(FAB + (m / z)600.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 29 H 35 O5NClRu[M-Cl] + :614.1247,found:614.1271.

[0156] (η 6 -C6Me6)RuCl2 2-Methoxy-4-(isopropoxycarbonyl)phenylisonicotinic acid ester (36)

[0157] Yellow to orange solid; Yield 99.9%; IR (KBr, cm⁻¹) -1 ):3734(w),3674(w),2978(m,ν CH ),1755(s,ν C＝O ),1714(s,ν C＝O), 1606 (w), 1558 (w), 1506 (s), 1456 (w), 1413 (s), 1287 (s, C-O), 1198 (w), 1173 (s, C-O), 1110 (m), 1057 (w), 1027 (w), 762, (m), 668 (w), 418 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 245 (14.868), 295 (5.811) 355 (4.093); 1 H NMR (400 MHz, CDC13): δ 9.08 (d, 2H, J = 6.6 Hz, H-12), 7.95, (d, 2H, J = 6.6 Hz, H-11), 7.71 (d, 2H, J = 1.8 Hz, H-2), 7.71 (dd, 2H, J = 1.7 Hz, 6.4 Hz, H-6), 7.19 (d, 1H, J = 8.2 Hz, H-5), 5.25 (quin, 2H, J = 6.2 Hz, H-2'), 3.85 (s, 3H, H-7), 2.01 (s, 18H, H-13), 1.36 (d, J = 6.3 Hz, 6H, H-3'); LR-MS (FAB + )(m / z) 614.4 [M-Cl] + , HR-MS (FAB + )(m / z) calcd. for C 29 H 35 O5NClRu [M-Cl] + = 614.1247, found = 614.1277.

[0158] 6. Synthesis of vanillic acid ether derivatives 43-48

[0159] The carboxylic acid in vanillic acid was first protected using Fischer-Speier reaction, and next the methyl vanillate was synthesized with different chain length alkyl bromides (a series of alkyl with carbon number n = 2, 4, 6, 8, 10, 12) in potassium carbonate by heating through Williamson etherification reaction. The reaction mixture was neutralized and extracted with dichloromethane. The organic layer was dried and the residue was purified using silica gel column. The purified product was hydrolyzed by carefully adding 1 N NaOH at 0 °C to obtain lipophilic vanillic acid alkyl ether derivatives 43-48.

[0160] 4-ethoxy-3-methoxybenzoic acid methyl ester (37)

[0161] Methyl 4-ethoxy-3-methoxybenzoate (37) was prepared by treating methyl 4-hydroxy-3-methoxybenzoate (3) (0.1 g, 0.55 mmol) with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) and then adding dropwise ethyl bromide (1.1 eq). The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and dried over the solvent under reduced pressure. Further purification was carried out by column chromatography on silica gel eluting with n-hexane / ethyl acetate (9:1 by volume) to give 37.

[0162] Methyl 4-ethoxy-3-methoxybenzoate (37): white powder; yield: 78%; mp: 45-47 °C; 1 H NMR (400 MHz, CDC13): δ 7.64 (dd, 1H, J = 8.4, 2.1 Hz, 6-CH), 7.52 (d, 1H, J = 1.9 Hz, 2-CH), 6.86 (d, 1H, J = 8.4 Hz, 5-CH), 4.14 (q, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.47 (t, 2H, J = 7.0 Hz, 11-CH); LR-EI-MS (m / z): 210.1 [M] + .

[0163] 4-butoxy-3-methoxybenzoate (38)

[0164] Methyl 4-butoxy-3-methoxybenzoate (38) was prepared by treating methyl 4-hydroxy-3-methoxybenzoate (3) (0.1 g, 0.55 mmol) with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) and then adding dropwise butyl bromide (1.1 eq). The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and dried over the solvent under reduced pressure. Further purification was carried out by column chromatography on silica gel eluting with n-hexane / ethyl acetate (9:1 by volume) to give 38.

[0165] Methyl 4-butoxy-3-methoxybenzoate (38): white powder; yield: 78%; mp: 45-47 °C; 1H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.4, 2.0 Hz, 6-CH), 7.52 (d, 1H, J = 2.0 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.04 (t, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.83 (quin, 2H, J = 7.2 Hz, 11-CH2), 1.48 (sext, 2H, J = 7.6 Hz, 12-CH2), 1.83 (t, 3H, J = 7.6, 13-CH3); LR-EI-MS (m / z): 238.1 [M] + .

[0166] 4-Hexyloxy-3-methoxybenzoate (39)

[0167] 4-Hexyloxy-3-methoxybenzoate 39 was prepared by treating methyl 4-hydroxy-3- methoxybenzoate (3) (0.1 g, 0.55 mmol) with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) followed by dropwise addition of bromohexane (1.1 eq). The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and dried over the solvent under reduced pressure. Further purification was carried out by silica gel column chromatography eluting with n-hexane / ethyl acetate (9:1 by volume) to obtain 39.

[0168] 4-Hexyloxy-3-methoxybenzoate 39: white powder; yield: 75%; 1 H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.4, 2.0 Hz, 6-CH), 7.52 (d, 1H, J = 2.0 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.04 (t, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.40-1.20 (overlapped, 8H, 11–14-CH2), 0.86 (t, 3H, J = 5.2 Hz, 15-CH3); LR-EI-MS (m / z): 266.1 [M] + .

[0169] 4-Hexyloxy-3-methoxybenzoate 39: white powder; yield: 75%;

[0170] A solution of 4-hydroxy-3-methoxybenzoic acid methyl ester (3) (0.1 g, 0.55 mmol) was treated with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) and then bromooctane (1.1 eq) was added dropwise. The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and dried over the solvent under reduced pressure. Further purification was carried out by silica gel column chromatography eluting with n-hexane / ethyl acetate (9:1, v / v) to obtain 40.

[0171] 4-Octyloxy-3-methoxybenzoic acid methyl ester (40): white powder; yield: 74%; mp: 33-35 °C; 1 H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.4, 2.0 Hz, 6-CH), 7.52 (d, 1H, J = 2.0 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.04 (t, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.40-1.20 (overlapped, 12H, 11–16-CH2), 0.86 (t, 3H, J = 5.2 Hz, 17-CH3), 13 C NMR (100 MHz, CDC13): δ 166.9 (C-7), 152.6 (C-4), 148.8 (C-3), 123.5 (C-6), 122.3 (C-1), 112.3 (C-2), 111.4 (C-5), 111.4 (C-5), 69.0 (C-10), 56.0 (C-9), 51.9 (C-8), 31.8 (C-11), 29.3 (C-12), 29.2 (C-13), 29.0 (C-14), 25.9 (C-15), 22.6 (C-16), 14.1 (C-17). LR-EI-MS (m / z): 294.0 [M] + ; HR-EI-MS (m / z) calcd. for C 17 H 26 O4[M] + : 294.1831, found: 294.1835.

[0172] 4-Decyloxy-3-methoxybenzoic acid methyl ester (41)

[0173] Methyl 4-decyloxy-3-methoxybenzoate (41) was prepared by treating methyl 4-hydroxy-3-methoxybenzoate (3) (0.1 g, 0.55 mmol) with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) followed by dropwise addition of bromodecane (1.1 eq). The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and the solvent was dried under reduced pressure. Further purification was carried out by silica gel column chromatography eluting with n-hexane / ethyl acetate (9:1, v / v) to give 41.

[0174] Methyl 4-decyloxy-3-methoxybenzoate (41): white powder; yield: 85%; mp: 35-37 °C; 1 H NMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.4, 2.0 Hz, 6-CH), 7.52 (d, 1H, J = 2.0 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.04 (t, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.40 - 1.20 (overlapped, 16H, 11 - 18-CH2), 0.86 (t, 3H, J = 6.4 Hz, 19-CH3); LR-EI-MS (m / z): 322.3 [M] + ; HR-EI-MS (m / z) calcd. for C 19 H 30 O4[M] + : 322.2144, found: 322.2145.

[0175] Methyl 4-dodecyloxy-3-methoxybenzoate (42)

[0176] Methyl 4-dodecyloxy-3-methoxybenzoate (42) was prepared by treating methyl 4-hydroxy-3-methoxybenzoate (3) (0.1 g, 0.55 mmol) with potassium carbonate (0.15 g, 1.1 mmol) in acetone (5 mL) followed by dropwise addition of bromododecane (1.1 eq). The reaction mixture was refluxed for 16-30 h and monitored by TLC until all the substrate was consumed. The cooled mixture was extracted with ethyl acetate (3x) and the organic phase was collected and the solvent was dried under reduced pressure. Further purification was carried out by silica gel column chromatography eluting with n-hexane / ethyl acetate (9:1, v / v) to give 42.

[0177] 4-Dodecyloxy-3-methoxybenzoic acid methyl ester (42): white powder; yield: 75%; mp: 40-42 °C; 1 HNMR (400 MHz, CDC13): δ 7.63 (dd, 1H, J = 8.4, 2.0 Hz, 6-CH), 7.52 (d, 1H, J = 2.0 Hz, 2-CH), 6.85 (d, 1H, J = 8.4 Hz, 5-CH), 4.04 (t, 2H, J = 6.8 Hz, 10-CH2), 3.89 (s, 3H, 9-CH3), 3.87 (s, 3H, 8-CH3), 1.40 - 1.20 (overlapped, 20H, 11 - 20-CH2), 0.86 (t, 3H, J = 6.4 Hz, 21-CH3); LR-EI-MS (m / z): 350.2 [M] + ; HR-EI-MS (m / z) calcd for C 21 H 34 O4[M] + : 350.2457, found: 350.2449.

[0178] 4-Ethoxy-3-methoxybenzoic acid (43)

[0179] Methyl 4-ethoxy-3-methoxybenzoate (37) was deprotected by base hydrolysis of the ester by dropwise addition of aqueous sodium hydroxide (1 M, 1 mL) to an ice-cooled solution of 37 (100 mg, 0.476 mmol) in methanol. The reaction mixture was neutralized with 1 M hydrochloric acid to give 43 in quantitative yield.

[0180] 4-Ethoxy-3-methoxybenzoic acid (43): white powder; yield: 51.4% (Method A), >99% (Method B); 1 H NMR (400 MHz, CDC13): δ 7.62 (dd, 1H, J = 8.3, 1.9 Hz, 6-CH), 7.53 (d, 1H, J = 1.9 Hz, 2-CH), 6.91 (d, 1H, J = 8.3 Hz, 5-CH), 4.33 (q, J = 7.1 Hz, 2H, 9-CH2), 3.93 (s, 3H, 8-CH3), 1.36 (t, J = 7.1 Hz, 3H, 10-CH3); LR-EI-MS (m / z): 196.1 [M] + .

[0181] 4-Butoxy-3-methoxybenzoic acid (44)

[0182] Sodium hydroxide aqueous solution (1 M, 1 mL) was added dropwise to an ice-cooled solution of 38 (100 mg, 0.420 mmol) in methanol to deprotect 4-butyloxy-3-methoxybenzoic acid methyl ester (38) by basic hydrolysis of the ester. The reaction mixture was neutralized with 1 M hydrochloric acid to give 44 in quantitative yield.

[0183] 4-butyloxy-3-methoxybenzoic acid (44): white powder; yield: 60.0% (Method A), >99% (Method B); 1 H-NMR (400 MHz, CDC13): δ 7.70 (dd, J = 8.5, 2.0 Hz, 1H, H-6), 7.56 (d, J = 2.0 Hz, 1H, H-2), 6.88 (d, J = 8.5 Hz, 1H, H-5), 4.07 (t, J = 6.8 Hz, 2H, H-9), 3.90 (s, 3H, H-8), 1.81 (p, J = 7.0 Hz, 2H, H-10), 1.49 (m, 2H, H-11), 0.97 (t, J = 7.4 Hz, 3H, H-12); LR-EI-MS (m / z): 224.1 [M] + .

[0184] 4-hexyloxy-3-methoxybenzoic acid (45)

[0185] Sodium hydroxide aqueous solution (1 M, 1 mL) was added dropwise to an ice-cooled solution of 39 (100 mg, 0.376 mmol) in methanol to deprotect 4-hexyloxy-3-methoxybenzoic acid methyl ester (39) by basic hydrolysis of the ester. The reaction mixture was neutralized with 1 M hydrochloric acid to give 45 in quantitative yield.

[0186] 4-hexyloxy-3-methoxybenzoic acid (45): white powder; yield: 54.6% (Method A), >99% (Method B); 1 H NMR (400 MHz, CDC13): δ 7.72 (dd, J = 8.4, 2.0 Hz, 1H, H-6), 7.57 (d, J = 2.0 Hz, 1H, H-2), 6.88 (d, J = 8.5 Hz, 1H, H-5), 4.07 (t, J = 6.9 Hz, 2H, H-9), 3.91 (s, 3H, H-8), 1.86 (p, J = 7.3 Hz, 2H, H-10), 1.47 - 1.31 (overlapped, 6H, H-11 - 13), 0.89 (t, J = 6.9 Hz, 3H, H-14); LR-EI-MS (m / z): 252.1 [M] + .

[0187] 4-octyloxy-3-methoxybenzoic acid (46)

[0188] Sodium hydroxide aqueous solution (1 M, 1 mL) was added dropwise to an ice-cooled solution of 40 (100 mg, 0.340 mmol) in methanol to deprotect 4-octyloxy-3-methoxybenzoic acid methyl ester (40) by basic hydrolysis of the ester. The reaction mixture was neutralized with 1 M hydrochloric acid to give 46 in quantitative yield.

[0189] 4-octyloxy-3-methoxybenzoic acid (46): white powder; yield: 52.9% (Method A), >99% (Method B); 1 H NMR (400 MHz, CDC13): δ 7.73 (dd, J = 8.4, 2.0 Hz, 1H, H-6), 7.58 (d, J = 2.0 Hz, 1H, H-2), 6.89 (d, J = 8.6 Hz, 1H, H-5), 4.07 (t, J = 6.9 Hz, 2H, H-9), 3.91 (s, 3H, H-8), 1.86 (p, 2H, J = 7.0 Hz, H-10), 1.44 (p, J = 7.5 Hz, 2H, H-11), 1.37 - 1.19 (overlapped, 8H, H-12 - 15), 0.87 (t, J = 6.7 Hz, 3H, H-116); LR-EI-MS (m / z): 280.2 [M] + .

[0190] 4-decyloxy-3-methoxybenzoic acid (47)

[0191] Sodium hydroxide aqueous solution (1 M, 1 mL) was added dropwise to an ice-cooled solution of 41 (100 mg, 0.310 mmol) in methanol to deprotect 4-decyloxy-3-methoxybenzoic acid methyl ester (41) by basic hydrolysis of the ester. The reaction mixture was neutralized with 1 M hydrochloric acid to give 47 in quantitative yield.

[0192] 4-decyloxy-3-methoxybenzoic acid (47): white powder; yield: 54.56% (Method A), >99% (Method B); 1 H NMR (400 MHz, CDC13): δ 7.72 (dd, J = 8.0, 2.1 Hz, 1H, H-6), 7.57 (d, J = 2.0 Hz, 1H, H-2), 6.89 (d, J = 8.6 Hz, 1H, H-5), 4.07 (t, J = 6.9 Hz, 2H, H-9), 3.91 (s, 3H, H-8), 1.86 (p, J = 7.0 Hz, 2H, H-10), 1.44 (p, J = 7.2 Hz, 2H, H-11), 1.36 - 1.24 (overlapped, 14H, H-12 - 17), 0.86 (t, J = 6.7 Hz, 3H, H-18); LR-EI-MS (m / z): 308.1 [M]+ .

[0193] 4-Dodecyloxy-3-methoxybenzoic acid (48)

[0194] Deprotection of methyl 4-dodecyloxy-3-methoxybenzoate (42) was achieved by base hydrolysis of the ester by dropwise addition of aqueous sodium hydroxide (1 M, 1 mL) to an ice-cooled solution of 42 (100 mg, 0.286 mmol) in methanol. The reaction mixture was neutralized with 1 M hydrochloric acid to give 48 in quantitative yield.

[0195] 4-Dodecyloxy-3-methoxybenzoic acid (48): white powder; yield: 40.1% (Method A), >99% (Method B); 1 H NMR (400 MHz, CDC13): δ 7.72 (dd, J = 8.0, 4.0 Hz, 1H, H-6), 7.57 (s, 1H, H-2), 6.88 (d, J = 8.0 Hz, 1H, H-5), 4.06 (t, J = 8.0 Hz, 2H, H-9), 3.90 (s, 3H, H-8), 1.86 (p, J = 8.0 Hz, 2H, H-10), 1.44 (m, 2H, H-11), 1.36 - 1.24 (overlapped, 16H, H-12 - 19), 0.86 (t, J = 6.7 Hz, 3H, H-20); LR-EI-MS (m / z): 336.2 [M] + ; HR-EI-MS (m / z) calcd. for C 20 H 32 O4[M] + : 336.2010, found: 336.2289.

[0196] 7. Synthesis of 4-Alkoxy-3-methoxybenzoic acid esters 49-54

[0197] Under inert atmosphere, 4-alkoxy-3-methoxybenzoic acid (1 equiv.) and 4-benzyloxyphenol (1 equiv.) were dissolved in DCM (5-10 mL). 4-Dimethylaminopyridine (DMAP) and dicyclohexylcarbodiimide (DCC) (0.1 equiv.) were added at 0 °C (1 equiv.). The reaction mixture was stirred at room temperature for 24 h, the formed precipitate was separated and discarded, and the residue was evaporated under reduced pressure. The resulting reaction mixture was purified by flash column chromatography with hexane / ethyl acetate / chloroform (4.9:0.1:1.0) as mobile phase.

[0198] 4-(BENZYLOXY)PHENYL 4-ETHOXY-3-METHOXYBENZOATE (49)

[0199] To a mixture of compound 4-ethoxy-3-methoxybenzoic acid (0.350 g, 1.786 mmol) and 4-(benzyloxy)phenol (0.357 g, 1.786 mmol) in DCM (5 mL) was added DCC (0.368 g, 1.786 mmol) and DMAP (0.0218 g, 0.1786 mmol) to give 49. White solid; yield 72%; R f = 0.42 (hexane / EtOAc, 4:1); mp: 140-141 °C; IR (KBr, cm -1 ): 3650 (w) 3630 (w), 3568 (w), 2983 (m, v CH ), 1734 (s, v C＝O ), 1654 (m), 1507 (s), 1458 (m), 1418 (s), 1387 (w), 1281 (m), 1191 (s, v C-O ), 1082 (m), 1008 (m), 856 (w), 741 (w), 698 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 200 (1.446), 270 (4.099), 295 (2.423); 1 H NMR (400 MHz, CDC13): δ 7.83 (dd, 1 H, J = 1.9 Hz, 8.4 Hz, H-6), 7.67 (d, 1 H, J = 1.9 Hz, H-2), 7.38 (m, 5 H, H-15-17), 7.12 (m, 2 H, H-10), 7.01 (m, 2 H, H-11), 6.94 (d, 1 H, J = 8.5 Hz, H-5), 5.08 (s, 2 H, H-13), 4.20 (q, 2 H, J = 7.0 Hz, H-1'), 3.95 (s, 3 H, H-7), 1.53 (m, 3 H, H-2'). 13C NMR (500MHz, CDCl3): δ165.5(C-8), 156.6(C-12), 153.1(C-4), 149.1(C-3) ,144.9(C-9),137.1(C-14),128.8(C-16),128.2(C-17),127.7(C-15),124. 5(C-6),122.8(C-10),121.9(C-1),115.7(C-11),112.8(C-2),112.5(C-5), 70.6(C-13),64.7(C-1'),56.3(C-7),14.8(C-2').LR-EI-MS(m / z)378.3[M] + ;HR-EI-MS(m / z)calcd.for C 23 H 22 O5[M] + :378.1467,found:378.1467.

[0200] 4-(benzyloxy)phenyl 4-butoxy-3-methoxybenzoate (50)

[0201] Adding DCC (0.509 g, 2.47 mmol) and DMAP (0.030 g, 0.247 mmol) to a mixture of 4-butoxy-3-methoxybenzoic acid (0.553 g, 2.47 mmol) and 4-(benzyloxy)phenol (0.493 g, 2.47 mmol) in DCM (7 mL) yielded 50. White solid; yield 69%; R f =0.59(hexane / EtOAc,4:1); mp:116-117℃; IR(KBr,cm -1 ):3649(w),3629(w),3588(w),2942(m,ν CH ),2872(m,ν CH ),1717(s,ν C＝O ),1598(s),1507(s),1465(m),1418(m),1265(s),1191(s,CO),1141(m),1088(m),1028(s),794(m),741(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:195(4.737),270(9.408),300(5.292); 1HNMR (400MHz, CDCl3): δ7.82 (dd, 1H, J = 1.7, 8.4Hz, H-6), 7.66 (s, 1H, H-2), 7.39 (m, 5H ,H-15-17),7.12(d,2H,J=9Hz,H-10),7.01(d,2H,J=9Hz,H-11),6.94(d,1H,J=8.5Hz, H-5),5.08(s,2H,H-13),4.10(t,2H,J=6.8Hz,H-1'),3.94(s,3H,H-7),1.87(p,2H,J= 6.8Hz,H-2'),1.51(m,2H,H-3'),1.00(t,3H,J=7.4Hz,H-4'); LR-EI-MS(m / z)378.3[M] + :HR-EI-MS(m / z)calcd.for C 25 H 26 O5[M] + :406.1780,found:406.1780.

[0202] 4-(benzyloxy)phenyl 4-(hexyloxy)-3-methoxybenzoate (51)

[0203] To a mixture of 4-hexyloxy-3-methoxybenzoic acid (0.971 g, 3.85 mmol) and 4-(benzyloxy)phenol (0.771 g, 3.85 mmol) in DCM (6 mL), DCC (0.047 g, 0.385 mmol) and DMAP (0.047 g, 0.385 mmol) were added to give 51. White solid; yield 75%; R f =0.66(hexane / EtOAc,4:1);mp:94-95℃ IR(KBr,cm -1 );3751(w),3690(w),3629(w),2940(m,ν CH ),2872(m,ν CH ),1726(s,ν C＝O ),1653(s),1559(s)1507(m),1458(m),1418(m),1289(s),1269(w),1194(s ,CO),1085(m),1030(m),879(w),843(w),735(m),695(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:205(2.050),270(8.3);1 H NMR (400 MHz, CDC13): δ 7.82 (dd, 1 H, J = 2, 8.4 Hz, H-6), 7.66 (d, 1 H, J = 1.9 Hz, H-2), 7.38 (m, 5H, H-15-17), 7.11 (m, 2H, H-10), 7.02 (m, 2H, H-11), 6.93 (d, 1 H, J = 8.5 Hz, H-5), 5.08 (s, 2H, H-13), 4.10 (t, 2H, J = 7 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7 Hz, H-2'), 1.49 (m, 2H, H-3'), 1.36 (m, 4H, H-4'-5'), 0.91 (t, 3H, J = 7 Hz, H-6'). LR-EI-MS (m / z) 434.3 [M] + ; HR-EI-MS (m / z) calcd for C 27 H 30 O 434.2093, found: 434.2083.

[0204] 4-(BENZYLOXY)PHENYL 3-METHOXY-4-(OCTOXY)BENZOATE (52)

[0205] To a mixture of compound 4-octyloxy-3-methoxybenzoic acid (0.995 g, 3.55 mmol) and 4-(benzyloxy)phenol (0.717 g, 3.55 mmol) in DCM (9 mL), DCC (0.733 g, 3.55 mmol) and DMAP (0.043 g, 0.355 mmol) were added to give 52. White solid; yield 86%; R f = 0.72 (hexane / Ethyl acetate, 4:1); mp: 75 °C; IR (KBr, cm -1 ); 3736 (w), 3650 (w), 3567 (w) 2921 (m, v CH ), 2854 (m, v CH ), 1724 (s, v C＝O ), 1596 (m), 1507 (s, v CNpy ), 1474 (w), 1454 (m), 1391 (w), 1278 (s, C-O), 1215 (m), 1197 (s, v C-O ), 1178 (s), 1078 (m), 1029 (m), 851 (m), 863 (w), 754 (s), 694 (m), 531 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M-1 cm -1 )}:195(2.499),270(8.654),295(4.964); 1 H NMR (400MHz, CDCl3): δ7.82(dd,1H,J=2,8.4Hz,H-6),7.66(d,1H,J=1.9Hz,H-2),7.40(m,5 H,H-15-17),7.12(m,2H,H-10),7.02(m,2H,H-11)6.93(d,1H,J=8.5Hz,H-5),5.08(s,2H,H- 13),4.11(q,2H,J=7.0Hz,H-1'),3.94(s,3H,H-7),1.89(p,2H,J=7.0Hz,H-2'),1.48(P,2H, J=6.4Hz,H-3'),1.32(m,8H,H-4'-7'),0.90(t,3H,J=7.0Hz,H-8).LR-EI-MS(m / z)462.2[M] + HREI-MS(m / z)calcd.for C 29 H 34 O5[M] + :462.2406,found:462.2406.

[0206] 4-(benzyloxy)phenyl 4-(decyloxy)-3-methoxybenzoate (53)

[0207] Adding DCC (0.687 g, 3.33 mmol) and DMAP (0.041 g, 0.33 mmol) to a mixture of 4-decyloxy-3-methoxybenzoic acid (1.026 g, 3.33 mmol) and 4-(benzyloxy)phenol (0.666 g, 3.33 mmol) in DCM (10 mL) yielded 53. White solid; yield 86%; R f =0.85(Hexane / Ethyl acetate 4:1); mp:66-71℃; IR(KBr,cm -1 );3735(w),3676(w),3649(w),2920(m,ν CH ),2848(m,ν CH ),1732(s,ν C＝O ),1653(w),1602(m),1596(m),1507(s,ν CNpy ),1463(m),1417(m),1346(w),1274(s,ν C-O), 1239 (w), 1194 (s, C-O), 1133 (m), 1083 (m), 1026 (m), 908 (m), 822 (w), 751 (m), 513 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 225 (30.665), 270 (12.953), 300 (7.271); 1 H NMR (400 MHz, CDC13): δ 7.82 (dd, 1 H, J = 1.9, 8.4 Hz, H-6), 7.66 (d, 1 H, J = 1.9 Hz, H-2), 7.40 (m, 5H, H-15-17), 7.11 (m, 2H, H-10), 7.02 (m, 2H, H-11), 6.94 (d, 1 H, J = 8.5 Hz, H-5), 5.08 (s, 2H, H-13), 4.10 (t, 2H, J = 7 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7 Hz, H-2'), 1.49 (m, 2H, H-3'), 1.32 (m, 12H, H-4'-7'), 0.86 (t, 3H, J = 6.5 Hz, H-8'); LR-EI-MS (m / z) 490.2 [M] + ; HR-EI-MS (m / z) calcd. for C 31 H 38 O5[M] + : 490.2719, found: 490.2707.

[0208] 4-(BENZYLOXY)PHENYL 4-(DODECYLOXY)-3-METHOXYBENZOATE (54)

[0209] To a mixture of compound 4-dodecyloxy-3-methoxybenzoic acid (0.500 g, 1.49 mmol) and 4-(benzyloxy)phenol (0.297 g, 1.49 mmol) in DCM (8 mL) were added DCC (0.307 g, 3.149 mmol) and DMAP (0.018 g, 0.1847 mmol) to give 54. White solid; yield 67%; R f = 0.71 (hexane / EtOAc, 4:1); mp: 88 °C; IR (KBr, cm -1 ); 3675 (w) 3628 (w), 3567 (w), 2918 (m, v CH ), 2849 (m, v CH ), 1733 (s, v C＝O), 1653 (w), 1507 (s), 1457 (m), 1418 (s), 1376 (w), 1273 (s), 1193 (s, C-O), 1084 (m), 1008 (m), 855 (m), 743 (w), 698 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 210 (32.019), 270 (11.416), 300 (6.285); 1 H NMR (400 MHz, CDC13): δ 7.82, (dd, 1H, J = 1.9 Hz, 8.4 Hz, H-6), 7.64 (d, 1H, J = 1.9 Hz, H-2), 7.39 (m, 5H, H-15-17), 7.11 (m, 2H, H-10), 7.01 (m, 2H, H-11), 6.93 (d, 1H, J = 8.5 Hz, H-5), 5.08 (s, 2H, H-13), 4.10 (t, 2H, J = 7.0 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7.0 Hz, H-2'), 1.48 (m, 2H, H-3'), 1.32 (m, 16H, H-4'-9'), 0.89 (t, 3H, J = 6.5 Hz, H-10'). LR-EI-MS (m / z) 518.2 [M] + ; HR-EI-MS (m / z) calcd. for C 31 H 38 O5: 518.3032, found: 518.3048.

[0210] 8.4-Hydroxyphenyl 4-alkoxy-3-methoxybenzoates 55-60

[0211] 4-(benzyloxy)phenyl 4-ethoxy-3-methoxybenzoate (0.231, 0.611 mmol) (49), 4- (benzyloxy)phenyl 4-butoxy-3-methoxybenzoate (0.611, 1.504 mmol) (50), 4- (benzyloxy)phenyl 4-(hexyloxy)-3-methoxybenzoate (1.140 4, 2.63 mmol) (51), 4- (benzyloxy)phenyl 3-methoxy-4-(octyloxy)benzoate (1.293, 2.79 mmol) (52), 4- (benzyloxy)phenyl 4-(decyloxy)-3-methoxybenzoate (1.220, 3.05 mmol) (53), 4- (benzyloxy)phenyl 4-(dodecyloxy)-3-methoxybenzoate (0.084, 0.162 mmol) (54) (1 eq) were dissolved in (EtOH / DCM, 9:1) and 10% Pd / C (0.1 eq) was added. The reaction mixture was stirred under a hydrogen atmosphere at room temperature overnight. After the reaction was completed, the product was isolated by filtration and concentrated to dryness.

[0212] 4-hydroxyphenyl 4-(ethoxy)-3-methoxybenzoate (55)

[0213] White solid; yield 87%; R f = 0.14 (hexane / EtOAc, 4:1); mp: 190 °C; IR (KBr, cm -1 ); 3445 (s), 2983 (m, ν CH ), 1721 (s, ν C＝O ), 1684 (w), 1653 (w), 1602 (m), 1559 (m), 1508 (s), 1458 (m), 1420 (m), 1347 (w), 1270 (s, C-O), 1245 (w), 1191 (s, C-O), 1173 (m), 1142 (m), 1083 (m), 1028 (m), 905 (m), 802 (w), 760 (m), 527 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 210 (18.534), 270 (2.338), 325 (0.961); 1H NMR (400 MHz, CDC13): δ 7.83, (dd, 1H, J = 1.9 Hz, 8.4 Hz, H-6), 7.66 (d, 1H, J = 1.8 Hz, H-2), 7.06 (m, 2H, H-10), 6.94 (d, 1H, J = 8.5 Hz, H-5), 6.85, (m, 2H, H-11), 4.99 (s, 1H, H-13), 4.20 (q, J = 7.0 Hz, 2H, H-1'), 3.95 (s, 3H, H-7), 1.52 (t, 3H, J = 7.0 Hz, H-2'). 13 C NMR (500 MHz, CDC13): δ 165.6 (C-8), 153.5, (C-12), 153.1 (C-4), 149.1 (C-3), 144.8 (C-9), 124.5 (C-6), 122.9 (C-2), 121.9 (C-1), 116.2 (C-10), 112.7, (C-11), 111.5 (C-5), 64.7 (C-1'), 56.3 (C-7), 14.8 (C-2'); LR-EI-MS (m / z) 288.2 [M] + ; HR-EI-MS (m / z) calcd. for C 16 H 16 O5[M] + : 288.0998, found: 288.1006.

[0214] 4-Hydroxyphenyl 4-(butoxy)-3-methoxybenzoate (56)

[0215] White solid; yield 98%; R f = 0.18 (hexane / EtOAc, 4:1); mp: 122-123 °C; IR (KBr, cm -1 ); 3451 (s), 2949 (m, v CH ), 2924 (m, v CH ), 2867 (m, v CH ), 1732 (s, v C＝O ), 1603 (m), 1511 (s), 1474 (w), 1457 (w), 1420 (m), 1346 (w), 1270 (s, C-O), 1213 (m), 1191 (s, C-O), 1177 (s), 1088 (m), 1026 (m), 914 (m), 890 (w), 761 (m), 526 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm-1 )}: 195 (0.696), 270 (6.279), 295 (3.858); 1 H NMR (400 MHz, CDC13): δ 7.82 (dd, 1 H, J = 2, 8.5 Hz, H-6), 7.66 (d, 1 H, J = 2 Hz, H-2), 7.06 (m, 2 H, H-10), 6.94 (d, 1 H, J = 8.5 Hz, H-5), 6.85 (m, 2 H, H-11), 4.95 (s, 1 H, H-13), 4.12 (t, 2 H, J = 7.0 Hz, H-1'), 3.73 (s, 3 H, H-7), 1.88 (p, 2 H, J = 7.0 Hz, H-2'), 1.52 (m, 2 H, H-3'), 1.00 (t, 3 H, J = 7.4 Hz, H-4'); LR-EI-MS (m / z) 316.2 [M] + ; HR-EI-MS (m / z) calcd. for C 18 H 20 O5[M] + : 316.1311, found: 316.1311.

[0216] 4-Hydroxyphenyl 4-(hexyloxy)-3-methoxybenzoate (57)

[0217] White solid; yield 87%; R f = 0.21 (hexane / EtOAc, 4:1); mp: 114-115 °C; IR (KBr, cm -1 ); 3736 (w), 3650 (w), 3567 (w) 2921 (m, v CH ), 2854 (m, v CH ), 1724 (s, v C＝O ), 1596 (m), 1507 (s), 1474 (m), 1448 (m), 1377 (m), 1277 (s, C-O), 1211 (s), 1197 (s, C-O), 1175 (s), 1076 (m), 1028 (w), 870 (w), 752 (s), 645 (m), 529 (w), 463 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 220 (3.179), 270 (10.35), 300 (6.255); 1H NMR (400 MHz, CDC13): δ 7.82, (dd, 1 H, J = 2, 8.5 Hz, H-6), 7.66 (d, 1 H, J = 2 Hz, H-2), 7.04, (m, 2H, H-10) 6.94, (d, 1 H, J = 8.5 Hz, H-5), 6.83 (m, 2H, H-11), 5.18 (s, 1 H, H-13), 4.11, (t, J = 7.0 Hz, 2H, H-1'), 3.94, (s, 3H, H-7), 1.89 (p, 2H, J = 7.0 Hz,, H-2'), 1.48, (m, 2H, 3'), 1.36, (m, 4H, H-4'-5'), 0.91 (t, 3H, J = 7.0 Hz, H-6'). LR-EI-MS (m / z) 344.2 [M] + ; HR-EI-MS (m / z) calcd. for C 20 H 24 O5[M] + : 344.1624, found: 344.1624.

[0218] 4-Hydroxyphenyl 4-(octyloxy)-3-methoxy-benzoate (58)

[0219] White solid; yield 81%; R f f 0.20 (hexane / EtOAc, 4:1); mp: 94-96 °C IR (KBr, cm -1 ): 3430 (s), 2922 (m, v CH ), 2851 (m, v CH ), 1708 (s, v C＝O ), 1601 (s), 1510 (s), 1466 (m), 1420 (s), 1353 (w), 1274 (s, C-O), 1224 (m), 1181 (s, C-O), 1138 (m), 1082 (s), 1036 (w), 920 (w), 870 (w), 754 (m), 530 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (18.517), 300 (11.449); 1HNMR (400 MHz, CDC13): δ 7.82 (dd, 1 H, J = 2 Hz, 8.5 Hz, H-6), 7.66 (d, 1 H, J = 2.0 Hz, H-2), 7.04, (m, 2H, H-10), 6.94 (d, 1 H, J = 8.5 Hz, H-5), 6.83 (m, 2H, H-11), 5.11 (s, 1 H, H-13), 4.11 (t, 2H, J = 7 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7.0 Hz, H-2'), 1.48 (m, 2H, 3'), 1.29 (m, 8H, H-4'-7'), 0.89 (t, 3H, J = 7.0 Hz, H-8'). LR-EI-MS (m / z) 372.3 [M] + ; HR-EI-MS (m / z) calcd for C 22 H 28 O5[M] + : 372.1937, found: 344.1624.

[0220] 4-Hydroxyphenyl 4-(dodecyloxy)-3-methoxybenzoate (58)

[0221] White solid; yield 85%; R f = 0.21 (hexane / EtOAc, 4:1); mp: 92 °C; IR (KBr, cm -1 ): 3736 (w), 3650 (w), 3567 (w) 2921 (m, v CH ), 2854 (m, v CH ), 1724 (s, v C＝O ), 1596 (m), 1507 (s), 1474 (w), 1454 (m), 1391 (w), 1278 (s, C-O), 1215 (m), 1197 (s, C-O), 1178 (s), 1078 (m), 1029 (m), 851 (m), 863 (w), 758 (m), 626 (m), 526 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 210 (3.755), 270 (5.304), 300 (2.794); 1H NMR (400 MHz, CDC13): δ 7.82 (dd, 1 H, J = 2 Hz, 8.4 Hz, H-6), 7.66 (d, 1 H, J = 2.0 Hz, H-2), 7.06 (m, 2H, H-10), 6.93 (d, 1 H, J = 8.5 Hz, H-5), 6.86 (m, 2H, H-11), 4.87 (s, 1 H, H-13), 4.10 (t, 2H, J = 7.0 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7.0 Hz, H-2'), 1.48 (m, 2H, H-3'), 1.30 (m, 12H, H-4'-9'), 0.88 (t, 3H, J = 6.6 Hz, H-10'); LR-EI-MS (m / z) 400.3 [M] + ; HR-EI-MS (m / z) calcd. for C 24 H 32 O5[M] + : 400.2250, found: 400.2249.

[0222] 4-Hydroxyphenyl 4-(dodecyloxy)-3-methoxybenzoate (60)

[0223] White solid; yield 97%; R f f 0.21 (hexane / EtOAc, 4.0:1.0); mp: 100 °C; IR (KBr, cm -1 ): 3422 (b), 2921 (s, v CH ), 2851 (s, v CH ), 1727 (s, v C＝O ), 1601 (s), 1507 (s), 1466 (m), 1418 (m), 1342 (m), 1275 (s, C-O), 1214 (m), 1194 (s, C-O), 1176 (s), 1080 (m), 1025 (m), 915 (m), 873 (w), 756 (m), 510 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 220 (46.719), 270 (7.730), 300 (4.099); 1H NMR (400 MHz, CDC13): δ 7.82 (dd, 1H, J = 1.9, 8.4 Hz, H-6), 7.66 (d, 1H, J = 1.8 Hz, H-2), 7.05 (d, 2H, J = 8.8 Hz, H-10), 6.94 (d, 1H, J = 8.4 Hz, H-5), 6.85 (d, 2H, J = 8.8 Hz, H-11), 4.93 (s, 1H, H-13), 4.10 (t, 2H, J = 7.0 Hz, H-1'), 3.94 (s, 3H, H-7), 1.89 (p, 2H, J = 7.0 Hz, H-2'), 1.48 (p, 2H, J = 7.0 Hz, H-3'), 1.27 (m, 16H, H-4'-11'), 0.89 (t, 3H, J = 7.0 Hz, H-12'); LR-EI-MS (m / z) 428.1 [M] + ; HR-EI-MS (m / z) calcd for C 26 H 36 O5[M] + : 428.2563, found: 428.2563.

[0224] 9. Synthesis of 4-((4-alkoxy-3-methoxybenzoyl)oxy)phenyl nicotinates 61-63

[0225] A mixture of 4-hydroxyphenyl 4-alkoxy-3-methoxybenzoate (1 equiv.) and nicotinic acid (1 equiv.) was dissolved in dichloromethane under inert atmosphere. 4-(Dimethylamino)pyridine (DMAP) (0.1 equiv.) and l-ethyl-3-[3- dimethylaminopropyl]carbodiimide hydrochloride (EDC) (1 equiv.) were added at 0 °C. The reaction mixture was stirred at room temperature overnight, the organic phase was collected by extraction with DCM and dried under reduced pressure. The residue was purified by column chromatography on silica gel.

[0226] 4-((4-ethoxy-3-methoxybenzoyl)oxy)phenyl nicotinate (61)

[0227] A solution of 55 (0.50 g, 1.73 mmol) and nicotinic acid (0.21 g, 1.73 mmol) in dry DMF (10 mL) was cooled to 0 °C under N2protection. EDC HCI (0.365 g, 1.90 mmol) and DMAP (0.04 g, 0.347 mmol) were added sequentially. The reaction mixture was warmed to 25 °C, stirred for 12 h, and then concentrated in vacuo. Purification by flash chromatography afforded 61 as a white crystalline solid. Yield 89%; Rf= 0.26 (hexane / EtOAc 4:1.5); 1H NMR (400 MHz, CDC13): δ 9.39 (d, J = 1.44 Hz, 1H, CH), 8.85 (dd, J = 1.48, 4.80 Hz, 1H, CH), 8.46-8.43 (m, 1H, CH), 7.84 (dd, J = 1.96, 8.44 Hz, 1H, CH), 7.65 (d, J = 1.88 Hz, 1H, CH), 7.46 (dd, 4.96, 7.84 Hz, 1H, CH), 7.65 (s, 4H, CH), 4.21 (q, 7.0 Hz, 2H, CH2), 3.84 (s, 3H, OCH3), 1.52 (t, 7.0 Hz, 3H, CH3); IR data (KBr, cm -1 ) v: 3078 (w), 2984 (m), 1731 (s), 1589 (w), 1502 (m), 1417 (s), 1262 (s), 1141 (s), 1044 (s), 1016 (s), 730 (m); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 1430 (227); HRMS-FAB + : {m / z} calcd. for C 22 H 20 NO6 [M+1] + 394.1212; found 394.1291.

[0228] 4-((4-Hexyloxy-3-methoxybenzoyl)oxy)phenyl nicotinate (62)

[0229] A solution of 57 (0.40 g, 1.16 mmol) and nicotinic acid (0.14 g, 1.16 mmol) in dry DMF (12 mL) was cooled to 0 °C under N2protection. EDC-HCl (0.24 g, 1.27 mmol) and DMAP (0.0283 g, 0.23 mmol) were added successively. The reaction mixture was warmed to 25 °C, stirred for 12 h, and then concentrated in vacuo. Purification by flash chromatography gave 62 as a white solid. Yield 78%; Rf= 0.27 (hexane / EtOAc 3:1.3); 1H NMR (400MHz, CDCl3): δ9.37 (d, J=1.48Hz, 1H, CH), 8.85 (dd, J=1.60Hz, 4.80Hz, 1H, CH), 8.44 (d, J=8.0Hz,1H,CH),7.82(dd,J=1.96,8.46Hz,1H,CH),7.64(d,J=1.92Hz,1H,CH),7.49-7.44(m,1H ,CH),7.27-7.14(s,4H,CH),6.93(d,J=8.52Hz,1H,CH),4.08(t,6.88Hz,2H,CH2),3.92(s,3H,OC H3),1.87(quint,7.0Hz,2H,CH2),1.48-1.23(m,6H,CH2),0.89(t,6.96Hz,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):2840(270); IR data(KBr,cm -1 )ν:2929(m),1726(m),1589(s),1511(w),1262(s),1123(s),1067(m),753(w); HRMS-FAB + :{m / z}calcd.for C 26 H 28 NO6[M+1] + 450.1838; found 450.1917.

[0230] 4-((4-decoxy-3-methoxybenzoyl)oxy)phenyl nicotinic acid ester (63)

[0231] A solution of 59 (0.50 g, 1.24 mmol) and nicotinic acid (0.15 g, 1.24 mmol) dissolved in anhydrous DMF (13 mL) was cooled to 0 °C under N2 protection. EDC·HCl (0.263 g, 1.37 mmol) and DMAP (0.0305 g, 0.249 mmol) were added sequentially. The reaction mixture was heated to 25 °C and stirred for 12 hours, then concentrated under vacuum. Rapid chromatographic purification yielded a white solid, 63. Yield: 68%; Rf = 0.31 (hexane / EtOAc 3:1.5). 1H NMR (400 MHz, CDC13): δ 9.39 (d, J = 1.52 Hz, 1H, CH), 8.85 (dd, 1.60 Hz, 4.64 Hz, 1H, CH), 8.46 (d, 8.0 Hz, 1H, CH), 7.83 (dd, 1.92 Hz, 8.44 Hz, 1H, CH), 7.65 (d, 1.88 Hz, 1H, CH), 7.48 (dd, 4.92, 7.88 Hz, 1H, CH), 7.23 (s, 4H, CH), 6.94 (d, J = 8.52 Hz, 1H, CH), 4.10 (t, 6.88 Hz, 2H, CH2), 3.93 (s, 3H, OCH3), 1.89 (quint, 6.92 Hz, 2H, CH2), 1.49 (quint, 6.56 Hz, 2H, CH2), 1.35-1.25 (m, 12H, CH2), 0.88 (t, 6.44 Hz, 3H, CH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 164.86 (CO), 163.62 (CO), 153.70 (CH Ar ), 153.41 (CH Ar ), 151.07 (C Ar ), 149.07 (C Ar ), 148.85 (C Ar ), 147.79 (C Ar ), 137.93 (CH Ar ), 125.64 (C Ar ), 124.46 (CH Ar ), 123.63 (CH Ar ), 122.89 (C Ar ), 122.42 (CH Ar ), 121.27 (CH Ar ), 112.75 (CH Ar ), 111.50 (CH Ar ), 69.13( C H2), 56.16 (O C H3), 31.88 (CH2), 29.64 (CH2), 29.62 (CH2), 29.56 (CH2), 29.52 (CH2), 29.35 (CH2), 29.29 (CH2), 28.95 (CH2), 25.89 (CH2), 22.66 (CH2), 14.09 (CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1): 2970 (230); IR data (KBr, cm -1 ) v: 2920 (m), 1728 (m), 1504 (s), 1463 (w), 1214 (s), 1176 (s), 1039 (m), 917 (s), 754 (w); HRMS-FAB + : {m / z} calcd for C 30 H 35 NO6[M + 1] + 506.2464; found 506.2543.

[0232] 10. Synthesis of arene ruthenium complexes 64-72

[0233] The corresponding ligand (61-63 1.0 equiv.) in dry chloroform or dichloromethane under inert atmosphere was treated with a dimeric ruthenium precursor - [Ru2(η 6 -C6H6)2(μ-Cl)2Cl2], [Ru2(η 6 -p-cymene)2(μ-Cl)2Cl2] or [Ru2(η 6 -C6Me6)2(μ-Cl)2Cl2] (0.5 equiv.). After completion of the reaction, the solvent was removed under vacuum to obtain the crude product as an air stable solid. The complexes were obtained as yellow to orange solids in quantitative yield (>99%). All the compounds were easily soluble in polar organic solvents (CH2Cl2, CHCl3) and slightly soluble in water.

[0234] (η 6 -C6H6)RuCl24-((4-ethoxy-3-methoxybenzoyl)oxy)phenyl nicotinate (64)

[0235] pale yellow to brown solid; Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.83 (s 1H, CH), 9.36 (d, 5.20 Hz, 1H, CH), 8.52 (d, 9.7 Hz, 1H, CH), 7.84 (dd, 1.84, 8.44 Hz, 1H, CH), 7.65 (d, 1.84 Hz, 1H, CH), 7.49 (t, 6.96 Hz 1H, CH), 7.24 (s, 4H, CH), 6.94 (d, 8.52 Hz, 1H, CH), 5.72 (s, 6H, CH), 3.94 (s, 3H, OCH3), 1.50 (t, 7.00 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ):1760(280); IR data(KBr,cm -1 )ν:3235(w),2932(m),1696(s),1623(s),1540(m),1493(s),1275(s),1129(s),1060(s),971(w),787(s); LRMS-FAB + :{m / z}calcd.forC 28 H 25 ClNO6Ru[M-Cl] + 608.0414; found 608.3.

[0236] (η 6 -C6H6)RuCl24-((4-hexyloxy-3-methoxybenzoyl)oxy)phenyl nicotinic acid ester (65)

[0237] Pale yellow to brown solid; yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.82(d,1.24Hz,1H,CH),9.36(d,4.92Hz,1H,CH),8.50(d,7. 88Hz,1H,CH),7.82(dd,1.88,8.44Hz,1H,CH),7.64(d,1.84Hz,1H,CH),7.50-7.46(m 1H,CH),7.23(s,4H,CH),6.94(d,8.52Hz,1H,CH),5.71(s,6H,CH),4.09(t,6.84Hz,2H,CH2),3.93(s,3 H,OCH3),1.87(quint,7.68Hz,2H,CH2),1.48-1.32(m,6H,CH2),0.89(t,6.44Hz,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):3680(228); IR data(KBr,cm -1 )ν:3118(w),1628(s),1278(w); HRMS-ESI + :{m / z}calcd.for C 32 H 33 Cl2NO6Ru[M] + 699.0728; found 722.0652([C 32 H 33Cl2NO6Ru]+Na) + .

[0238] (η 6 -C6H6)RuCl24-((4-decoxy-3-methoxybenzoyl)oxy)phenyl nicotinic acid ester (66)

[0239] Pale yellow to brown solid; yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.83(d,1.2Hz,1H,CH),9.37(d,4.96Hz,1H,CH),8.52(d,7.9Hz,1H, CH),7.83(dd,1.88,8.44Hz,1H,CH),7.65(d,1.80Hz,1H,CH),7.50(t,6.08Hz,1H,CH),7.2 3(s,4H,CH),6.94(d,8.56Hz,1H,CH),5.72(s,6H,CH),4.11(t,6.84Hz,2H,CH2),3.93(s,3 H,OCH3),1.89(quint,6.96Hz,2H,CH2),1.48-1.25(m,14H,CH2),0.86(t,6.44Hz,3H,CH3); 13 C-NMR(DMSO-d6,100MHz): δ164.81(CO),162.02(CO),158.86(CH Ar ),156.47(CH Ar ),153.43(C Ar ),149.07(C Ar ),149.04(C Ar ),147.47(C Ar ),139.36(CH Ar ),126.95(C Ar ),124.46(CH Ar ),124.44(CH Ar ),122.97(C Ar ),122.39(CH Ar ),121.20(CH Ar ),112.73(CH Ar ),111.49(CH Ar ),84.59(CH Ar), 69.13 (CH2), 56.15 (OCH3), 31.86 (CH2), 29.51 (CH2), 29.34 (CH2), 29.28 (CH2), 28.94 (CH2), 25.87 (CH2), 22.65 (CH2), 14.08 (CH3); UV-Vis. (in CHCI3): λ max , nm (ε / 105 -3 M -1 cm -1 ): 2260 (268); IR data (KBr, cm -1 ) v: 2924 (m), 2852 (s), 1736 (s), 1599 (w), 1416 (m), 1268 (s), 1171 (s), 1078 (s), 736 (m); HRMS-ESI + : {m / z} calcd. for C 36 H 41 Cl2NO6Ru[M] + 755.1354; found 778.1153 ([C 36 H 41 Cl2NO6Ru]+Na) + .

[0240] (η 6 p-MeC6H4Pr i )RuCl24-((4-ethoxy-3-methoxybenzoyl)oxy)phenyl nicotinate (67)

[0241] Yellow to orange solid; Yield > 99%; 1H NMR (400 MHz, CDC13): δ 9.78 (d, 1.44 Hz, 1H, CH), 9.31 (d, 4.60 Hz, 1H, CH), 8.49 (d, 7.90 Hz, 1H, CH), 7.83 (dd, 1.96 Hz, 8.44 Hz, 1H, CH), 7.65 (d, 1.88 Hz, 1H, CH), 7.48 (t, 5.52 Hz, 1H, CH), 7.23 (s, 4H, CH), 6.94 (d, 8.56 Hz, 1H, CH), 5.48 (d, 5.96, 2H, CH), 5.28 (d, 5.96, 2H, CH), 4.20 (q, 7.0 Hz, 2H, CH2), 3.94 (s, 3H, OCH3), 3.00 (sept, 6.86, 1H, CH), 2.14 (s, 3H, CH3), 1.50 (t, 8.76, 3H, CH3), 1.32 (s, 3H, CH3), 1.31 (s, 3H, CH3). UV-Vis. (in CHCI3): λmax, nm (ε / 10 -3 M -1 cm -1 ): 4780 (228); IR data (KBr, cm -1 ) v: 2930 (m), 1727 (m), 1600 (s), 1506 (s), 1418 (w), 1269 (s), 1170 (m), 1034 (s), 739 (w); HRMS-ESI + : {m / z} calcd. for C 32 H 33 ClNO6Ru[M-Cl] + 664.1040; found 688.0854 ([C 32 H 33 ClNO6Ru]+Na) + .

[0242] (η 6 p-MeC6H4Pr i )RuCl24-((4-hexyloxy-3-methoxybenzoyl)oxy)phenyl nicotinate (68)

[0243] Yellow to orange solid; Yield >99%; 1H NMR (400 MHz, CDC13): δ 9.79 (d, 1.32 Hz, 1H, CH), 9.32 (d, 4.76 Hz, 1H, CH), 8.49 (d, 7.96 Hz, 1H, CH), 7.83 (dd, 1.92, 8.40 Hz, 1H, CH), 7.65 (d, 1.88 Hz, 1H, CH), 7.49 (dd, 5.96, 7.8 Hz, 1H, CH), 7.46 (s, 4H, CH), 6.94 (d, 8.52 Hz, 1H, CH), 5.48 (d, 5.96 Hz, 2H, CH), 5.28 (d, 5.96 Hz, 2H, CH), 4.09 (q, 6.84 Hz, 2H, CH2), 3.93 (s, 3H, OCH3), 3.00 (sept, 7.00, 1H, CH), 2.14 (s, 3H, CH3), 1.87 (quint, 7.16, 2H, CH2), 1.49-1.44 (m, 2H, CH2), 1.33 (s, 3H, CH3), 1.31 (s, 3H, CH3), 1.26-1.25 (m, 4H, CH2), 0.86 (t, 7.0 Hz, 3H, CH3); UV-Vis. (in CHCl3): λ max , nm (ε / 10 -3 M -1 cm -1 ): 6790 (229); IR data (KBr, cm -1 ) v: 2927 (m), 2355 (w), 1994 (w), 1739 (s), 1716 (m), 1598 (s), 1453 (w), 1264 (s), 1174 (m), 1081 (s), 778 (w); HRMS-ESI + : {m / z} calcd for C 36 H 41 Cl2NO6Ru[M] + 755.1354; found 778.1130 ([C 36 H 41 Cl2NO6Ru]+Na) + .

[0244] (η 6 p-MeC6H4Pr i )RuCl24-((4-decyloxy-3-methoxybenzoyl)oxy)phenyl nicotinate (69)

[0245] Yellow to orange solid; Yield >99%; 1H NMR (400 MHz, CDC13): δ 9.78 (s 1H, CH), 9.32 (d, 5.52 Hz, 1H, CH), 8.48 (d, 7.88 Hz, 1H, CH), 7.82 (dd, 1.88 Hz, 8.48 Hz, 1H, CH), 7.64 (d, 1.80 Hz, 1H, CH), 7.50-7.45 (m, 1H, CH), 7.18 (s, 4H, CH), 6.94 (d, 8.52 Hz, 1H, CH), 5.48 (d, 5.92, 2H, CH), 5.27 (d, 5.88, 2H, CH), 4.09 (q, 6.88 Hz, 2H, CH2), 3.93 (s, 3H, OCH3), 2.99 (sept, 7.00 Hz, 1H, CH), 2.13 (s, 3H, CH3), 1.87 (quint, 7.87 Hz, 2H, CH2), 1.49-1.23 (m, 20H, 7CH2, 2CH3), 0.89 (t, 6.88 Hz, 3H, CH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 162.08 (CO), 158.44 (CO), 156.43 (CO Ar ), 153.43 (CH Ar ), 149.02 (CO Ar ), 147.51 (CO Ar ), 139.00 (CH Ar ), 126.79 (CO Ar ), 124.47 (CH Ar ), 124.22 (CH Ar ), 122.96 (CH Ar ), 122.33 (CH Ar ), 121.21, 112.73 (CH Ar ), 111.49 (CH Ar ), 103.79 (CH Ar ), 69.13 (CH2), 56.16 (OCH3), 31.88 (CH), 30.71 (CH2), 29.51 (CH2), 29.34 (CH2), 29.29 (CH2), 28.94 (CH2), 25.88 (CH2), 22.26 (CH3), 22.25 (CH3), 22.13 (CH2), 18.33 (CH3), 14.09 (CH3); UV-Vis. (in CHCI3): λ max , nm (ε / 10 -3 M -1 cm -1):7330(230); IR data(KBr,cm -1 )ν:3094(w),2359(w),1994(w),1698(m),1598(s),1506(w),1269(s),1125(m),1071(s),791(w); HRMS-ESI + :{m / z}calcd.for C 40 H 49 Cl2NO6Ru[M] + 811.1980; found 812.2033([C 40 H 49 Cl2NO6Ru]+H) + .

[0246] (η 6 -C6Me6)RuCl24-((4-ethoxy-3-methoxybenzoyl)oxy)phenyl nicotinic acid ester (70)

[0247] Bright orange to reddish-orange solid; Yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.55(s,1H,CH),9.11(d,5.08Hz,1H,CH),8.45(dd,1.92, 8.44Hz,1H,CH),7.84(dd,1.92Hz,8.44,1H,CH),7.65(d,1.92Hz,1H,CH),7.47- 7.44(m,1H,CH),7.23(s,4H,CH),6.94(d,8.52Hz,1H,CH),4.20(q,7.00Hz,2H,C H2),3.94(s,3H,OCH3),2.01(s,18H,CH3),1.51(t,7.00Hz,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 -3 M -1 cm -1 ):6840(267); IR data(KBr,cm -1 )ν:2925(m),2853(w),1740(s),1728(m),1502(s),1416(w),1269(s),1168(m),1092(s),740(w); HRMS-ESI + :{m / z}calcd.for C 34 H 37 Cl2NO6Ru[M] +727.1041; found 750.0986([C 34 H 37 Cl2NO6Ru]+Na) + .

[0248] (η 6 -C6Me6)RuCl24-((4-hexyloxy-3-methoxybenzoyl)oxy)phenyl nicotinic acid ester (71)

[0249] Bright orange to reddish-orange solid; Yield > 99%; 1 H NMR (400MHz, CDCl3): δ9.54(s,1H,CH),9.11(d,4.64Hz,1H,CH),8.43(dd,1.68,3.32Hz,1H,CH ),7.82(dd,1.96,8.48Hz,1H,CH),7.64(d,1.88Hz,1H,CH),7.50-7.43(m,1H,CH),7.14(s,4H, CH),6.94(d,J=8.52Hz,1H,CH),4.09(t,6.84Hz,2H,CH2),3.93(s,3H,OCH3),2.00(s,18H,CH3 ),1.87(quint,7.0Hz,2H,CH2),1.49-1.32(m,6H,CH2),0.89(t,7.04Hz,3H,CH3); UV-Vis.(in CHCl3):λ max ,nm(ε / 10 - 3 M -1 cm -1 ):4070(228); IR data(KBr,cm -1 )ν:3093(w),2925(m),2359(w),1994(w),1734(s),1698(m),1506(s),1416(w),1264(s),1124(m),1027(s),741(w); HRMS-ESI + :{m / z}calcd.for C 38 H 45 Cl2NO6Ru[M] + 783.1667; found 783.1607[C] 38 H 45 Cl2NO6Ru] + .

[0250] (η 6C6Me6)RuCl2 4-((4-decyloxy-3-methoxybenzoyl)oxy)phenyl nicotinate (72)

[0251] Bright orange to red-orange solid; Yield >99%; 1 H NMR (400 MHz, CDC13): δ 9.55 (s, 1H, CH), 9.12 (d, 5.2 Hz, 1H, CH), 8.45 (d, 7.92 Hz, 1H, CH), 7.83 (dd, 1.92, 8.44 Hz, 1H, CH), 7.65 (d, 1.88 Hz, 1H, CH), 7.4-7.44 (m, 1H, CH), 7.24 (s, 4H, CH), 6.94 (d, J = 8.56 Hz, 1H, CH), 4.09 (t, 6.84 Hz, 2H, CH2), 3.93 (s, 3H, OCH3), 2.01 (s, 18h, CH3), 1.87 (quint, 6.92 Hz, 2H, CH2), 1.46 (quint, 7.0 Hz, 2H, CH2), 1.33-1.25 (m, 12H, CH2), 0.86 (t, 6.96 Hz, 3H, CH3); 13 C-NMR (DMSO-d6, 100 MHz): δ 164.86 (CO), 162.18 (CO), 158.32 (CO Ar ), 156.37 (CO Ar ), 153.43 (CH Ar ), 149.07 (CH Ar ), 149.00 (CH Ar ), 147.58 (CH Ar ), 138.51 (CH Ar ), 126.74 (CH Ar ), 124.48 (CH Ar ), 124.19 (CH Ar ), 122.95 (CH Ar ), 122.36 (CH Ar ), 121.24 (CH Ar ), 112.75 (CH Ar ), 111.50 (CH Ar ), 91.51, 69.14 (CH2), 56.17 (OCH3), 31.88 (CH2), 29.53 (CH2), 29.35 (CH2), 29.30 (CH2), 28.96 (CH2), 25.89 (CH2), 22.67 (CH2), 15.45 (6xCH3), 14.09 (CH3); UV-Vis. (in CHCI3): λ max,nm(ε / 10 -3 M -1 cm -1 ):4770(229); IR data(KBr,cm -1 )ν:2917(w),2851(m),1728(s),1597(s),1503(m),1416(w),1209(s),1168(m),1037(s),754(w); HRMS-ESI + :{m / z}calcd.for C 42 H 53 Cl2NO6Ru[M] + 839.2293; found 876.1967([C 42 H 53 Cl2NO6Ru]+K) + .

[0252] Synthesis of 11,4-((4-alkoxy-3-methoxybenzoyl)oxy)phenyl isonicotinate 73-78

[0253] A mixture of 4-hydroxyphenyl 4-alkoxy-3-methoxybenzoate (1 equivalent) and isonicotinic acid (1 equivalent) was dissolved in dichloromethane under an inert atmosphere. 4-(dimethylamino)pyridine (DMAP) (0.1 equivalent) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDAC) (1 equivalent) were added at 0 °C. The reaction mixture was stirred overnight at room temperature, and the organic phase was collected by DCM extraction and dried under reduced pressure. The residue was purified by silica gel column chromatography.

[0254] 4-((4-ethoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (73)

[0255] Compound 55 (0.125 g, 0.44 mmol) was reacted with isonicotinic acid (0.054 g, 0.44 mmol) in DCM (12 mL) under an inert atmosphere. EDAC (0.084 g, 0.44 mmol) and DMAP (0.00534 g, 0.0437 mmol) were added at 0 °C. The mixture was purified by rapid chromatography to give a white solid. Yield: 88%; R f =0.14(hexane / EtOAc,3.5:1.5); mp:171℃; IR(KBr,cm -1 :1743(s,ν C＝O ),1725(s,ν C＝O), 1600 (m), 1508 (s), 1470 (m), 1418 (m), 1272 (s, C-O), 1214 (m), 1173 (s, C-O), 1144 (m), 1094 (w), 1081 (m), 1060 (w), 1029, (w), 910 (w), 750 (w), 698 (w); UV-Vis {CHCI3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (17.748), 295 (10.77); 1 H NMR (400 MHz, CDCI3): δ 8.85 (d, 2H, J = 5 Hz, H-16), 7.99 (d, 2H, J = 5.0 Hz, H-15), 7.83 (dd, 1 H, 2 Hz, 8.5 Hz, H-6), 7.65 (d, 1 H, J = 2.0 Hz, H-2), 7.23 (s, 4H, H-10-11), 6.92, (d, 1 H, J = 8.5 Hz, H-5), 4.18 (q, 2H, J = 7.0 Hz, H-1'), 3.93 (s, 3H, H-7), 1.49 (t, 3H, J = 7.0 Hz, H-2'); 13 C NMR (500 MHz, CDCI3): δ 165.4 (C-8), 164.1 (C-13), 153.8 (C-4), 151.1 (C-16), 149.6 (C-9, C-12), 148.4 (C-3), 137.7 (C-14), 125.1 (C-15), 124.0 (C-6), 123.6 (C-10), 122.9 (C-11), 121.9 (C-1), 113.3 (C-2), 112.0 (C-5), 65.2 (C-1'), 56.7 (C-7), 15.2 (C-2'); LR-EI-MS (m / z) 393.3 [M] + ; HR-EI-MS (m / z) calcd. for C 22 H 19 NO6: 393.1212, found: 393.1200.

[0256] 4-((4-Butyloxy-3-methoxybenzoyl)oxy)phenyl nicotinate (74)

[0257] Compound 56 (0.433 g, 1.37 mmol) was reacted with isonicotinic acid (0.169 g, 1.37 mmol) in DCM (10 mL) under an inert atmosphere. EDAC (0.262 g, 1.37 mmol) and DMAP (0.0167 g, 0.14 mmol) were added at 0 °C. The mixture was purified by rapid chromatography to give a white solid. Yield: 75%; R f =0.16(Hexane / Ethyl acetate 3.5:1.5); IR(KBr,cm -1 ):3621(m),2964(m,ν CH ),1748(s,ν C＝O ),1732(s,ν C＝O ),1720(s),1597(s),1507(s),1462(w),1408(w),1345(m),1270(s,CO),1211(m),1179(s,CO),1169 (s),1136(s),1098(m),1081(m),994(w),789(w),720(w),698(w),674(w),648(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(17.509),295(11.055); 1 H NMR (400MHz, CDCl3): δ8.86(s,2H,H-16),8.00(s,2H,H-15),7.81(dd,1H,J=2.0, 8.4Hz,H-6),7.64(d,1H,J=2.0Hz,H-2),7.24(s,4H,H-10-11),6.92(d,1H,J=8.5 Hz,H-5),4.09(t,2H,J=6.8Hz,H-1'),3.92(s,3H,H-7),1.85(p,2H,J=6.9Hz,H-2 ),1.49(p,2H,J=7.6Hz,H-3),0.97(t,3H,J=7.4Hz,H-4); LR-EI-MS(m / z)421.3[M] + ;HR-EI-MS(m / z)calcd.for C 24 H 23 NO6[M] + :421.1525,found:421.1525.

[0258] 4-((4-hexyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (75)

[0259] Compound 57 (0.679 g, 1.97 mmol) was reacted with isonicotinic acid (0.242 g, 1.97 mmol) in DCM (15 mL) under an inert atmosphere. EDAC (0.378 g, 1.97 mmol) and DMAP (0.023 g, 0.0197 mmol) were added at 0 °C. The mixture was purified by rapid chromatography to give a white solid. Yield: 81%; R f =0.17(hexane / EtOAc,3.5:1.5); mp:123-125℃; IR(KBr,cm -1 ):3441(b),2957(m,ν CH ),2936(m,ν CH ),2860(m,ν CH ),1745(s,ν C＝O ),1733(s,ν C＝O )1602(m),1507(s),1464(m),1444(w),1416(s),1345(m),1292(s,CO),1198(w),1173 (s,CO),1121(m),1057(m),1025(m),887(w),838(m),760(s),692(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(21.961),295(13.873); 1 H NMR (400MHz, CDCl3): δ8.85 (d, 2H, J = 5.9Hz, H-16), 7.99 (d, 2H, J = 5.8Hz, H-15), 7.81 (dd, 1H, J = 1.9 Hz,8.4Hz,H-6),7.64(d,1H,J=1.9Hz,H-2),7.23(s,4H,H-10-11),6.92(d,1H,J=8.5Hz,H-5),4.08 (t,2H,J=6.9Hz,H-1'),3.92(s,3H,H-7),1.86(p,2H,J=7.0Hz,H-2'),1.45(p,2H,J=7.1Hz,H-3'), 1.33(m,4H,H-4'-5'),0.88(t,3H,J=6.9Hz,H-6'); LR-EI-MS(m / z)449.2; HR-EI-MS(m / z)calcd.for C 26 H27 N06[M] + :449.1838; found:449.1843.

[0260] 4-((4-octyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (76)

[0261] Compound 58 (0.700 g, 1.88 mmol) was reacted with isonicotinic acid (0.231 g, 1.88 mmol) in DCM (15 mL) under an inert atmosphere. EDAC (0.360 g, 1.88 mmol) and DMAP (0.023 g, 0.0188 mmol) were added at 0 °C. The mixture was purified by rapid chromatography to give a white solid; yield 78%; R f =0.21(hexane / EtOAc,3.5:1.5); mp:109-110℃; IR(KBr,cm -1 ):3442(b),2953(m, νCH ),1733(s,ν C＝O ),1601(m),1560(w),1507(s),1465(m),1420(s),1346(w),1272(s,ν C-O ),1212(m),1170(s,ν C-O ),1128(w),1061(w),1022(m),885(w),788(w),752(s),642(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:200(5.257),270(13.003),295(8.035); 1H NMR (400MHz, CDCl3): δ8.85, (d, 2H, J = 5.8Hz, H-16), 8.02 (d, 2H, J = 6.0Hz, H-15), 7.81 (dd, 1H ,J=2.0Hz,8.5Hz,H-6),7.63(d,1H,J=1.9Hz,H-2),7.23(s,4H,H-10-11),6.92(d,1H,J=8.5H z,H-5),4.08(t,2H,J=6.9Hz,H-1'),3.92(s,3H,H-7),1.86(p,2H,J=7.0Hz,H-2'),1.45(p,2 H,J=7.1Hz,H-3')1.30(m,8H,H-4'-7'),0.88(t,3H,J=7.0Hz,H-8'); LR-EI-MS(m / z)477.2[M] + ;HR-EI-MS(m / z)calcd.for C 28 H 31 N06[M] + :477.2151,found:477.2152.

[0262] 4-((4-decoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (77)

[0263] Compound 59 (0.825 g, 2.06 mmol) was reacted with isonicotinic acid (0.254 g, 2.06 mmol) in DCM (16 mL) under an inert atmosphere. EDAC (0.395 g, 2.06 mmol) and DMAP (0.025 g, 0.0206 mmol) were added at 0 °C. The mixture was purified by rapid chromatography to give a white solid; yield 75%; R f =0.19(hexane / EtOAc,3.5:1.5); mp:101-103℃; IR(KBr,cm -1 ):2913(m,ν CH ),2848(m,ν CH ),1742(s,ν C＝O ),1720(s,ν C＝O )1599(m),1508(s),1470(m),1418(s),1322(w),1278(s,CO),1220(m),1189(s,C O),1143(m),1098(m),1018(m),887(w),850(w),754(s),527(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1cm -1 )}:270(32.150),300(18.871); 1 H NMR (400 MHz, CDC13): δ 8.85 (d, 2H, J = 5.9 Hz, H-16), 8.01 (d, 2H, J = 5.9 Hz, H-15), 7.81 (dd, 1H, J = 1.9 Hz, 8.4 Hz, H-6), 7.65 (d, 1H, J = 1.8 Hz, H-2), 7.23 (s, 4H, H-10-11), 6.93 (d, 1H, J = 8.5 Hz, H-5), 4.08 (t, 2H, J = 6.9 Hz, H-1'), 3.92 (s, 3H, H-7), 1.86 (p, 2H, J = 7.0 Hz, H-2'), 1.45 (p, 2H, J = 7.2 Hz, H-3') 1.29 (m, 12H, H-4'-9'), 0.85 (t, 3H, J = 7.0 Hz, H-10'); LR-EI-MS (m / z) 505.2 [M] + ; HR-EI-MS (m / z) calcd for C 30 H 35 NO6[M] + : 505.2464, found: 505.2453.

[0264] 4-((4-(Dodecyloxy)-3-methoxybenzoyl)oxy)phenyl nicotinate (78)

[0265] Compound 60 (0.062 g, 0.144 mmol) was reacted with nicotinic acid (0.018 g, 0.144 mmol) in DCM (18 mL) under inert atmosphere. EDAC (0.0223 g, 0.144 mmol) and DMAP (0.00175 g, 0.0144 mmol) were added at 0 °C. After purification by flash chromatography, a white solid was obtained; yield 89%; R f = 0.21 (hexane / EtOAc, 3.5:1.5); mp: 103 °C; IR (KBr, cm -1 ): 3443 (b), 2916 (m, v CH ), 2849 (m, v CH ), 1734 (s, v C＝O ), 1598 (m), 1508 (s), 1469 (m), 1417 (m), 1273 (s), 1216 (m), 1184 (s, C-O), 1129 (w), 1091 (m), 1020 (m), 918 (w), 887 (w) 755 (m), 702 (w); UV-Vis {CHCI3, λ maxnm (ε / 10 -3 M -1 cm -1 )}: 270 (30.843), 300 (18.273); 1 H NMR (400 MHz, CDC13): δ 8.88 (d, 2H, J = 5.7 Hz, H-16), 8.03 (d, 2H, J = 5.8 Hz, H-15), 7.84 (dd, 1H, J = 1.9 Hz, 8.4 Hz, H-6), 7.67 (d, 1H, J = 1.8 Hz, H-2), 7.30 (s, 4H, H-10-11), 6.95 (d, 1H, J = 8.5 Hz, H-5), 4.12 (t, 2H, J = 7.0 Hz, H-1'), 3.96 (s, 3H, H-7), 1.90 (p, 2H, J = 7.0 Hz, H-2'), 1.47 (m, 2H, H-3'), 1.27 (s, 16H, H-4'-11'), 0.89 (t, 3H, J = 6.5 Hz, H-12'); 13 C NMR (500 MHz, CDC13): δ 165.0 (C-8), 163.7 (C-13), 153.4 (C-4), 150.7 (C-16), 149.2 (C-9, C-12), 148.0 (C-3), 137.3 (C-14), 124.7 (C-15), 123.6 (C-6), 123.2 (C-10), 122.5 (C-11), 121.5 (C-1), 112.8 (C-2), 11.6 (C-5), 64.7 (C-1'), 56.3 (C-7), 14.8 (C-2'); LR-EI-MS (m / z) 533.1 [M] + ; HR-EI-MS (m / z) calcd for C 32 H 39 NO6 [M] + : 533.2777, found: 533.2777.

[0266] 12. Synthesis of arene ruthenium complexes 79-96

[0267] Under inert atmosphere, appropriate amount of arene ruthenium precursors [Ru2(η 6 -C6H6)2(μ-Cl)2Cl2], [Ru2(η 6 -(p-Me-C6H4-Pr i )2(μ-Cl)2Cl2] and [Ru2(η 6[-C6Me6)2(μ-Cl)2Cl2] (0.5 equivalents) was added to a stirred solution of ligands 73-78 (1 equivalent) in chloroform (4 mL). The solvent was then removed under reduced pressure, and the final product was collected and dried. All complexes were stable in air and soluble in chloroform.

[0268] (η 6 -C6H6)RuCl2 4-((4-ethoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (79)

[0269] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3566(w),3447(b),2981(m,ν CH ),1734(s,ν C＝O ),1597(m),1507(s),1472(w),1418(s),1345(m),1273(s,CO),1216(m),1175 (s,CO),1139(m),1057(w),1028(w),756(m),668(w),418(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(10.179),300(6.398),345(1.268); 1 H NMR (400MHz, CDCl3): δ9.38 (d, 2H, J = 6.6Hz, H-16), 8.01 (d, 2H, J = 6.7Hz, H-15), 7.84 (dd, 2H, J = 1.9Hz, 8.4Hz, H-6), 7.66 (d, 2H, J = 1.9Hz, H-2), 7.28(s,4H,H-10-11),6.94(d,1H,J=8.5Hz,H-5),5.71(s,6H,H-17),3. 94(s,3H,H-7),4.18(q,2H,J=7.0Hz,H-1'),1.49(t,J=7.0Hz,2H,H-2'); 13C NMR (500MHz, CDCl3): δ165.4(C-8),164.1(C-13),156.2(C-16),153.2(C-4),149.1(C-9),149.0(C-12),147.4(C-3),138.3(C-14),122.2(C-15 ),124.5(C-6),123.9(C-10),123.1(C-11),121.2(C-1),116.0(C-2),11 2.6(C-5),84.7(C-17),64.5(C-1'),56.1(C-7),14.6(C-2'); LR-ESI-MS m / z 610.1[M–Cl+2H] + .

[0270] (η 6 -C6H6)RuCl24-((4-butoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (80)

[0271] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3447(b),2963(m,ν CH ),1735(s,ν C＝O ),1598(m),1507(s),1471(w),1417(m),1271(s,CO),1213(m),1173(s,CO),1134(s),1 088(m),1059(w),1032(w),1016(w),910(w),873(w),754(m),695(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(23.152),295(15.946),340(5.362); 1H NMR (400MHz, CDCl3): δ9.38 (d, 2H, J = 6.6Hz, H-16), 8.01 (d, 2H, J = 6.7Hz, H-15), 7.83 (d d,2H,J=2.0Hz,8.4Hz,H-6),7.66(d,2H,J=1.9Hz,H-2),7.28(s,4H,H-10-11),6.95(d, 1H,J=8.5Hz,H-5),5.71(s,6H,H-17),3.94(s,3H,H-7),4.12(t,2H,J=6.8Hz,H-1'),1. 88(quin,2H,J=7.2Hz,H-2'),1.49(m,2H,H-3'),1.00(t,3H,J=7.3Hz,H-4'),LR-MS(FAB + (m / z)636.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 30 H 29 O6NClRu[M-Cl] + :636.0727,found:636.0749.

[0272] (η 6 -C6H6)RuCl2 4-((4-hexyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (81)

[0273] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3468(b),2928(m,ν CH ),1731(s,ν C＝O ),1598(m),1504(s),1464(w),1415(m),1384(w),1346(w),1271(s,CO),1213(m),1174(s,CO), 1133(m),1085(m),1058(w),1015(m),910(w),882(w),757(m),696(w),523(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:240(18.281),270(20.846),340(5.004); 1H NMR (400MHz, CDCl3): δ9.38 (d, 2H, J = 6.6Hz, H-16), 8.01 (d, 2H, J = 6.6Hz, H-15), 7.83 (dd, 2H, J=2.0Hz,8.4Hz,H-6),7.66(d,2H,J=1.9Hz,H-2),7.28(s,4H,H-10-11),6.94(d,1H,J=8.5Hz ,H-5),5.71(s,6H,H-17),3.94(s,3H,H-7),4.10(t,2H,J=6.9Hz,H-1'),1.89(quin,J=7.1Hz ,2H,H-2'),1.47(m,2H,H-3'),1.35(m,4H,H-4'-5'),0.91(t,3H,J=7.0Hz,H-6'),LR-MS(FAB + (m / z)664.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 32 H 33 O6NClRu[M-Cl] + :664.1040,found:664.1066.

[0274] (η 6 -C6H6)RuCl24-((4-octyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (82)

[0275] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3447(b),1733(s,ν C＝O ),1598(m),1507(s),1457(w),1418(s),1274(s,CO),1214(m),1175(s,CO),1136(m),1092(w),1016(w),757,(m),669(w),419(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(20.613),300(14.341),340(5.538); 1H NMR (400MHz, CDCl3): δ9.38 (d, 2H, J = 6.6Hz, H-16), 8.01, (d, 2H, J = 6.6Hz, H-15), 7.83 (dd, 2H, J=2.0Hz,8.4Hz,H-6),),7.66(d,2H,J=1.8Hz,H-2),7.28(s,4H,H-10-11),6.94(d,1H,J=8.5Hz ,H-5),5.70(s,6H,H-17),3.94(s,3H,H-7),4.10(t,2H,J=6.9Hz,H-1'),1.89(quin,J=7.1Hz, 2H,H-2'),1.47(m,2H,H-3'),1.30(m,4H,H-4'-7'),0.88(t,3H,J=6.9Hz,H-8'),LR-ESI-MSm / z 690.2[M–Cl+2H] + .

[0276] (η 6 -C6H6)RuCl24-((4-decoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (83)

[0277] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3446(b),2961(m,ν CH ),2872(m,ν CH ),1753(s,ν C＝O ),1738(s,ν C＝O ),1598(m),1504(s),1465(m),1417(m),1386(w),1346(w),1273(s,CO),1214(m),1172(s,CO), 1133(m),1086(m),1060(w),1035(w),921(w),873(w),764(w),644(w),527(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(21.831),340(4.771),425(1.387); 1H NMR (400MHz, CDCl3): δ9.38 (d, 2H, J = 6.6Hz, H-16), 8.01 (d, 2H, J = 6.6Hz, H-15), 7.83 (dd, 2H, J=1.9,8.4Hz,H-6),7.66(d,2H,J=1.9Hz,H-2),7.28(s,4H,H-10-11),6.94(d,1H,J=8.6Hz,H- 5),5.71(s,6H,H-17),3.94(s,3H,H-7),4.10(t,2H,J=6.9Hz,H-1'),1.89(quin,2H,J=7.3Hz, H-2'),1.47(m,2H,H-3'),1.26(m,12H,H-4'-9'),0.87(t,3H,J=7.0Hz,H-10'),LR-ESI-MSm / z 720.2[M–Cl] + .

[0278] (η 6 -C6H6)RuCl24-((4-dodecyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (84)

[0279] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3486(b),2957(m,ν CH ),2872(m,ν CH ),1750(s,ν C＝O ),1732(s,ν C＝O ),1633(w),1598(m),1501(s),1464(w),1415(m),1385(w),1346(w),1272(s,CO),1213(m),1173(s,CO), 1132(m),1083(m),1055(w),1031(w),1016(m),919(w),886(w),756(m),696(w),523(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(24.950),295(17.541),340(6.211); 1H NMR (400 MHz, CDC13): δ 9.38 (d, 2H, J = 6.6 Hz, H-16), 8.01 (d, 2H, J = 6.6 Hz, H-15), 7.83 (dd, 2H, J = 1.9, 8.4 Hz, H-6), 7.66 (d, 2H, J = 1.9 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.6 Hz, H-5), 5.71 (s, 6H, H-17), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 1.89 (quint, 2H, J = 7.3 Hz, H-2'), 1.47 (m, 2H, H-3'), 1.26 (m, 14H, H-4'-11'), 0.89 (t, 3H, J = 6.6 Hz, H-12'), LR-ESI-MS m / z 748.2 [M - Cl] + .

[0280] (η 6 -p-MeC6H4Pr i )RuCl24-((4-ethoxy-3-methoxybenzoyl)oxy)phenylisonicotinate (85)

[0281] Yellow to orange solid; yield 99.9%; IR (KBr, cm -1 ); 3734 (w), 3674 (w), 3528 (w), 3058 (m), 2948 (m, ν C H), 1734 (s, ν C＝O ), 1598 (m), 1507 (s), 1435 (w), 1418 (m), 1273 (s, C-O), 1214 (m), 1174 (s, C-O), 1140 (m), 1082 (m), 1015 (m), 838 (w), 690 (w), 649 (w), 419 (w), 409 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (20.192), 295 (13.264), 345 (4.516); 1H NMR (400MHz, CDCl3): δ9.32(d,2H,J=6.6Hz,H-16),7.99(d,2H,J=6.7Hz,H-15),7.84(dd,2H,J=2.0,8.4Hz,H -6),7.65(d,2H,J=1.9Hz,H-2),7.28(s,4H,H-10-11),6.94(d,1H,J=8.5Hz,H-5),5.48(d,2H,J=6.0Hz,H-20 ),5.25(d,2H,J=6.0Hz,H-19),4.20(q,2H,J=7.0Hz,H-1'),3.95(s,3H,H-7),4.10(t,2H,J=6.9Hz,H-1'),3. 01(septet,1H,J=7.0Hz,H-22),2.12(s,3H,H-17),1.52(t,J=7.0Hz,2H,H-2'),1.33(d,6H,J=7.9Hz,H-23); 13 CNMR(500MHz, CDCl3): δ164.8(C-8),162.3(C-13),156.0(C-16),153.1(C-4),149.1(C-9), 149.0(C-12),147.5(C-3),138.0(C-14),123.8(C-15),124.5(C-6),123.0(C-10),122.2(C- 11),121.2(C-1),113.0(C-2),111.4(C-5),104.0(C-21),97.4(C-18),83.2(C-19),82.4(C- 20),64.5(C-1'),56.1(C-7),30.7(C-22),22.3(C-23),18.3(C-17),14.6(C-2'); LR-MS(FAB + (m / z)664.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 32 H 33 O6NClRu[M-Cl] + :664.1040,found:664.1077.

[0282] (η 6 -p-MeC6H4Pr i RuCl24-((4-butoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (86)

[0283] Yellow to orange solid; yield 99.9%; IR (KBr, cm -1 ): 3446 (b), 3063 (b), 2933 (m, v CH ), 2871 (m, v CH ), 1760 (s, v C＝O ), 1735 (s, v C＝O ), 1601 (m), 1518 (s), 1506 (s), 1465 (m), 1416 (m), 1388 (w), 1270 (s, C-O), 1209 (m), 1177 (s, C-O), 1130 (m), 1081 (m), 1057 (w), 1017 (w), 920 (w), 885 (w), 762 (m), 643 (w), 525 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (23.189), 295 (15.591), 345 (6.086); 1 H NMR (400 MHz, CDC13): δ 9.32 (d, 2H, J = 6.6 Hz, H-16), 7.99, (d, 2H, J = 6.5 Hz, H-15), 7.83 (dd, 2H, J = 1.8, 8.4 Hz, H-6), 7.66 (d, 2H, J = 1.8 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.5 Hz, H-5), 5.48 (d, 2H, J = 6.0 Hz, H-20), 5.25 (d, 2H, J = 5.9 Hz, H-19), 4.12 (t, 2H, J = 6.8 Hz, H-1'), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.01 (septet, 1H, J = 6.9 Hz, H-22), 2.12 (s, 3H, H-17), 1.87 (quin, 2H, J = 7.2 Hz, H-2'), 1.51 (m, 2H, H-3'), 1.32 (d, 6H, J = 7.0 Hz, H-23), 0.99 (t, 3H, J = 7.4 Hz, H-4'); LR-MS (FAB + )(m / z) 692.1 [M-Cl] + , HR-MS (FAB + )(m / z) calcd. for C 34 H 38 O6NClRu [M-Cl + H] +: 693.1431, found: 693.1462.

[0284] (η 6 -p-MeC6H4Pr i )RuCl2 4-((4-hexyloxy-3-methoxybenzoyl)oxy)phenyl isonicotinate (87)

[0285] Yellow to orange solid; yield 99.9%. IR (KBr, cm -1 ): 3470 (b), 2950 (m, ν CH ), 2869 (m, ν CH ), 1747 (s, ν C＝O ), 1732 (s, ν C＝O ), 1598 (m), 1512 (s), 1465 (w), 1416 (m), 1385 (w), 1346 (w), 1272 (s, ν C-O ), 1213 (m), 1171 (s, ν C-O ), 1132 (m), 1084 (m), 1055 (w), 1013 (w), 916 (w), 885 (w), 798 (m), 757 (m), 697 (w), 645 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (3.726), 295 (13.272), 345 (3.399); 1H NMR (400 MHz, CDC13): δ 9.32 (d, 2H, J = 6.6 Hz, H-16), 7.99 (d, 2H, J = 6.5 Hz, H-15), 7.83 (dd, 2H, J = 1.9 Hz, 8.4 Hz, H-6), 7.65 (d, 2H, J = 1.8 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.5 Hz, H-5), 5.48 (d, 2H, J = 6.0 Hz, H-20), 5.25 (d, 2H, J = 5.9 Hz, H-19), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.01 (septet, 1H, J = 6.8 Hz, H-22), 2.12 (s, 3H, H-17), 1.88 (quin, 2H, J = 7.2 Hz, H-2'), 1.47 (m, 2H, H-3'), 1.35 (m, 4H, H-4'-5'), 1.32 (d, 6H, J = 6.9 Hz, H-23), 0.90 (t, 3H, J = 6.8 Hz, H-6'); LR-MS (FAB + )(m / z) 720.1 [M-Cl] + ; HR-MS (FAB + )(m / z) calcd. for C 36 H 41 O6NClRu[M-Cl] + : 720.1666, found: 720.1699.

[0286] (η 6 -p-MeC6H4Pr i )RuCl24-((4-octyloxy-3-methoxybenzoyl)oxy)phenylisonicotinate (88)

[0287] Yellow to orange solid; yield 99.9%; IR (KBr, cm -1 ): 3733 (b), 3444 (b), 2935 (m, v CH ), 1749 (s, v C＝O ), 1731 (s, v C＝O ), 1598 (m), 1507 (s), 1465 (w), 1418 (m), 1272 (s, v C-O ), 1214 (m), 1179 (s, v C-O), 1137 (m), 1092 (m), 1058 (w), 1015 (w), 919 (w), 839 (w), 755 (m), 692 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 271 (20.204), 345 (4.916), 445 (1.270); 1 H NMR (400 MHz, CDC13): δ 9.32 (d, 2H, J = 6.5 Hz, H-16), 7.99 (d, 2H, J = 6.5 Hz, H-15), 7.83 (dd, 2H, J = 1.8 Hz, 8.4 Hz, H-6), 7.65 (d, 2H, J = 1.7 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.6 Hz, H-5), 5.48 (d, 2H, J = 5.9 Hz, H-20), 5.25 (d, 2H, J = 5.9 Hz, H-19), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.00 (septet, 1H, J = 6.9 Hz, H-22), 2.12 (s, 3H, H-17), 1.88 (quin, 2H, J = 7.2 Hz, H-2') 1.47 (m, 2H, H-3'), 1.30 (m, 8H, H-4'-7'), 1.32 (d, 6H, J = 6.9 Hz, H-23), 0.88 (t, 3H, J = 7.0 Hz, H-8'); LR-MS (FAB + )(m / z) 748.4 [M-Cl] + ; HR-MS (FAB + )(m / z) calcd. for C 38 H 45 O6NClRu [M-Cl] + : 748.1979, found: 748.1951.

[0288] (η 6 -p-MeC6H4Pr i )RuCl24-((4-decyloxy-3-methoxybenzoyl)oxy)phenylisonicotinate (89)

[0289] Yellow to orange solid; yield 99.9%; IR (KBr, cm -1 ): 3446 (b), 2930 (m, v CH ), 2870 (m, vCH ), 1731 (s, v C＝O ), 1598 (m), 1505 (s), 1465 (w), 1416 (m), 1387 (w), 1347 (w), 1272 (s, v C-O ), 1213 (m), 1174 (s, v C-O ), 1133 (m), 1084 (m), 1058 (w), 1031 (w), 1016 (w), 920 (w), 871 (w), 761 (m), 694 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 ): 270 (19.674), 295 (13.077), 345 (4.530); 1 HNMR (400 MHz, CDC13): δ 9.32 (d, 2H, J = 6.6 Hz, H-16), 7.99 (d, 2H, J = 6.6 Hz, H-15), 7.83 (dd, 2H, J = 1.8 Hz, 8.4 Hz, H-6), 7.65 (d, 2H, J = 1.8 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.6 Hz, H-5), 5.48 (d, 2H, J = 5.9 Hz, H-20), 5.25 (d, 2H, J = 5.9 Hz, H-19), 4.10 (t, 2H, J = 6.8 Hz, H-1'), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.8 Hz, H-1'), 3.00 (septet, 1H, J = 6.9 Hz, H-22), 2.12 (s, 3H, H-17), 1.88 (quin, 2H, J = 7.2 Hz, H-2'), 1.47 (m, 2H, H-3'), 1.27 (m, 4H, H-4'-5'), 1.26 (m, 4H, H-6'-9'), 1.32 (d, 6H, J = 7.0 Hz, H-23), 0.87 (t, 3H, J = 7.0 Hz, H-10'); LR-MS (FAB + )(m / z) 776.4 [M-Cl] + ; HR-MS (FAB + )(m / z) calcd. for C 40 H 49 O6NClRu [M-Cl] + : 776.2292, found: 776.2251.

[0290] (η 6p-MeC6H4Pr i ) RuCl2 4-((4-dodecyloxy-3-methoxybenzoyl)oxy)phenyl isonicotinate (90)

[0291] Yellow to orange solid; yield 99.9%; IR (KBr, cm -1 ): 3480 (b), 2927 (m, v CH ), 2855 (m, v CH ), 1732 (s, v C＝O ), 1598 (m), 1503 (s), 1465 (w), 1415 (m), 1384 (w), 1346 (w), 1271 (s, v C-O ), 1213 (m), 1173 (s, v C-O ), 1133 (m), 1048 (m), 1058 (m), 1015 (m), 918 (w), 882 (w), 757 (m), 695 (w); UV-Vis {CHCl3, λ max nm (ε / 10 -3 M -1 cm -1 )}: 270 (25.267), 300 (16.972), 350 (5.792); 1 H NMR (400 MHz, CDC13): δ 9.32 (d, 2H, J = 6.5 Hz, H-16), 7.99 (d, 2H, J = 6.5 Hz, H-15), 7.83 (dd, 2H, J = 1.8 Hz, 8.4 Hz, H-6), 7.65 (d, 2H, J = 1.7 Hz, H-2), 7.28 (s, 4H, H-10-11), 6.94 (d, 1H, J = 8.6 Hz, H-5), 5.48 (d, 2H, J = 5.9 Hz, H-20), 5.25 (d, 2H, J = 5.9 Hz, H-19), 4.10 (t, 2H, J = 6.8 Hz, H-1'), 3.94 (s, 3H, H-7), 4.10 (t, 2H, J = 6.9 Hz, H-1'), 3.01 (septet, 1H, J = 6.9 Hz, H-22), 2.12 (s, 3H, H-17), 1.88 (quin, 2H, J = 7.2 Hz, H-2'), 1.47 (m, 2H, H-3'), 1.34 (m, 4H, H-4'-5'), 1.32 (d, 6H, J = 7.0 Hz, H-23), 1.25 (m, 12H, H-6'-11'), 0.87 (t, 3H, J = 7.0 Hz, H-12'); LR-MS (FAB + )(m / z) 804.4 [M-Cl] +HR-MS (FAB) + (m / z)calcd.for C 42 H 53 O6NClRu[M-Cl] + :804.2605,found:804.2667.

[0292] (η 6 -C6Me6)RuCl2 4-((4-ethoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (91)

[0293] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3734(b),3566(b),3062(w),2925(m,ν CH ),2854(m,ν CH ),1733(s,ν C＝O ),1598(m),1506(s),1465(w),1435(w),1273(s,ν C-O ),1213(w),1214(m),1176(s,ν C-O ),1136(m),1090(m),1057(w),1015(w),756(m); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(43.377),295(28.522),360(10.284); 1 H NMR (400MHz, CDCl3): δ9.09(d,2H,J=6.6Hz,H-16),7.96(d,2H,J=6.7Hz,H-15),7.84(dd,2H,J=2.0,8.4Hz,H-6),7.65(d,2H,J=1.9Hz,H-2),7 .28(s,4H,H-10-11),6.94(d,1H,J=8.5Hz,H-5),4.20(q,2H,J=7.0Hz,H -1'),3.95(s,3H,H-7),2.12(s,3H,H-18),1.52(t,3H,J=7.0Hz,H-2'); 13CNMR(500MHz, CDCl3): δ164.8(C-8),162.6(C-13),155.9(C-16),153.2(C- 4),149.1(C-9),149.0(C-12),147.5(C-3),138.0(C-14),124.5(C-6),123. 7(C-15),123.7(C-10),123.0(C-11),121.2(C-1),112.6(C-2),111.3(C-5) ,91.6(C-17),64.5(C-1'),56.1(C-7),15.4(C-18),14.6(C-2'); LR-MS(FAB + (m / z)692.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.forC 34 H 37 O6NClRu[M-Cl] + :692.1353,found:692.1393.

[0294] (η 6 -C6Me6)RuCl2 4-((4-butoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (92)

[0295] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3446(b),2926(s,ν CH2CH3 ),2854(m,ν CH2 ),1733(s,ν C＝O ),1599(m),1504(s),1466(m),1416(s),1271(s,ν C-O ),1213(m),1173(s,ν C-O ),1134(m),1088(m),919(s),874(s),762,(s),694(s),525(s); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(24.944),295(16.072),360(4.934); 1H NMR (400MHz, CDCl3): δ9.09(d,2H,J=6.6Hz,H-16),7.96(d,2H,J=6.6Hz,H-15),7.82( dd,2H,J=1.9,8.4Hz,H-6),7.65(d,2H,J=1.9Hz,H-2),7.27(s,4H,H-10-11),6.94(d,1 H,J=8.5Hz,H-5),4.20(q,2H,J=6.8Hz,H-1'),3.93(s,3H,H-7),2.01(s,3H,H-18),2.2 1(quin,2H,J=6.9Hz,H-2'),1.50(m,2H,H-3'),0.99(t,3H,J=7.4Hz,H-4'); LR-MS(FAB + (m / z)720.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 36 H 41 O6NClRu[M-Cl] + :720.1666,found:720.1705.

[0296] [(η 6 -C6Me6)RuCl2 4-((4-hexyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (93)

[0297] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ),3482(b),2925(m,ν CH ),2854(m,ν CH ),1734(s,ν C＝O ),1598(m),1502(s),1465(w),1416(m),1383(w),1346(w),1272(s,CO),1213(m),1173(s,CO), 1134(m),1084(m),1057(w),1015(w),916(w),886(w),757(m),696(w),525(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(0.047),300(14.604),365(3.797); 1HNMR (400MHz, CDCl3): δ9.09 (d, 2H, J = 6.6Hz, H-16), 7.96 (d, 2H, J = 6.6Hz, H-15), 7. 82(dd,2H,J=2.0Hz,8.4Hz,H-6),7.64(d,2H,J=1.9Hz,H-2),7.27(s,4H,H-10-11),6 .93(d,1H,J=8.6Hz,H-5),4.09(t,2H,J=6.8Hz,H-1'),3.93(s,3H,H-7),2.01(s,3H, H-18),1.47(m,2H,H-2'),1.34(m,2H,H-3'-5'),0.89(t,J=6.9Hz,H-6'); LR-MS(FAB + (m / z)748.2[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 38 H 45 O6NClRu[M-Cl] + :748.1979,found:748.1945.

[0298] (η 6 -C6Me6)RuCl2 4-((4-octyloxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (94)

[0299] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3481(b),3064(w),2924(m,ν CH ),2853(m,ν CH ),1734(s,ν C＝O ),1599(m),1506(s),1466(w),1435(w),1347(w),1273(s,CO),1214(m),1175(s,CO),1135(m), 1092(m),1058(w),1032(w),1016(w),919(w),838(w),757(m),691(w),669(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(1.952),295(11.304),355(2.721); 1H NMR (400MHz, CDCl3): δ9.09 (d, 2H, J = 6.6Hz, H-16), 7.96, (d, 2H, J = 6.5Hz, H-15), 7.82 (d d,2H,J=1.9Hz,8.4Hz,H-6),7.64(d,2H,J=1.9Hz,H-2),7.27(s,4H,H-10-11),6.93(d,1H ,J=8.6Hz,H-5),4.09(t,2H,J=6.9Hz,H-1'),3.93(s,3H,H-7),2.01(s,3H,H-18),1.88(m ,2H,H-2'),1.46(m,2H,H-3'),1.30(m,8H,H-4'-7'),0.87(t,J=7.0Hz,H-8'); LR-MS(FAB + (m / z)776.3[M-Cl] + HR-MS (FAB) + (m / z)calcd.for C 40 H 49 O6NClRu[M-Cl] + :776.2292,found:776.2339.

[0300] (η 6 -C6Me6)RuCl2 4-((4-decoxy-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (95)

[0301] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3436(b),3042(b),2923(m,ν CH ),2852(m,ν CH ),1738(s,ν C＝O ),1599(m),1503(s),1466(m),1415(s),1386(w),1347(w),1272(s,CO),1214(m),1173(s,CO),1134 (m),1088(m),1059(w),1033(w),1015(w),920(w),874(w),761(m),693(w),524(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(11.711),300(6.978),365(1.554); 1H NMR (400MHz, CDCl3): δ9.09 (d, 2H, J = 6.6Hz, H-16), 7.96, (d, 2H, J = 6.6Hz, H-15), 7.82 (dd ,2H,J=1.9Hz,8.4Hz,H-6),7.64(d,2H,J=1.8Hz,H-2),7.27(s,4H,H-10-11),6.93(d,1H, J=8.6Hz,H-5),4.10(t,2H,J=6.8Hz,H-1'),3.93(s,3H,H-7),2.01(s,3H,H-18),1.88(m, 2H,H-2'),1.47(m,2H,H-3'),1.26(m,12H,H-4'-9'),0.86(t,J=7.0Hz,H-10'); LR-MS(FAB + (m / z)804.1[M-Cl] + HR-MS (FAB) + (m / z)calcd.forC 42 H 53 O6NClRu[M-Cl] + :804.2605,found:804.2651.

[0302] (η 6 -C6Me6)RuCl2 4-((4-(dodecyloxy)-3-methoxybenzoyl)oxy)phenylisonicotinic acid ester (96)

[0303] Yellow to orange solid; yield 99.9%; IR (KBr, cm⁻¹) -1 ):3480(b),2924(m,ν CH ),2853(m,ν CH ),1748(s,ν C＝O ),1733(s,ν C＝O ),1598(m),1502(s),1465(w),1416(m),1385(w),1346(w),1272(s,CO),1213(m),1173(s,C O),1136(m),1084(m),1056(w),1015(w),914(w),886(w),758(m),696(w); UV-Vis{CHCl3,λ max nm(ε / 10 -3 M -1 cm -1 )}:270(1.767),295(11.077),355(2.597); 1H NMR (400 MHz, CDC13): δ 9.09 (d, 2H, J = 6.6 Hz, H-16), 7.96 (d, 2H, J = 6.6 Hz, H-15), 7.82 (dd, 2H, J = 1.9, 8.4 Hz, H-6), 7.64 (d, 2H, J = 1.8 Hz, H-2), 7.27 (s, 4H, H-10-11), 6.93 (d, 1H, J = 8.6 Hz, H-5), 4.09 (t, 2H, J = 6.9 Hz, H-1'), 3.93 (s, 3H, H-7), 2.01 (s, 3H, H-18), 1.87 (m, 2H, H-2'), 1.46 (m, 2H, H-3'), 1.31 (m, 16H, H-4'-11'), 0.86 (t, J = 6.6 Hz, H-12'), LR-MS (FAB + )(m / z) 832.4 [M-Cl] + ; HR-MS (FAB + )(m / z) calcd. for C 44 H 57 O6NClRu [M-Cl] + : 832.2918, found = 832.2912.

[0304] <Vanillic acid derived arene ruthenium complex against drug resistant Salmonella typhi test>

[0305] 1. Isolation and identification of drug resistant Salmonella typhi strains and drug sensitivity test

[0306] Four drug resistant Salmonella enterica Serovar Typhi strains CL1, CL2, CL5 and CL15 were isolated from different sources of clinical blood samples. The clinical isolates were identified by PCR amplification of the invasion protein specific to Salmonella. The partial sequences obtained by Sanger sequencing were searched on NCBI by BLAST, and had high similarity with Salmonella typhi. The sequences of three clinical isolates were stored in GenBank, and the accession numbers were PQ368001, MZ708960 and PQ368002, respectively. Figure 2 The evolutionary relationship of pan-drug resistant Salmonella typhi (CL1 and CL15) and multi-drug resistant Salmonella typhi (CL5) was deduced. Figure 2Phylogenetic relationship of the taxa inferred using the neighbour-joining method. Analysis involving invA protein, nucleotide sequences obtained from three indigenous multi-drug resistant / pandrug resistant S. typhi strains were compared with 16 sequences retrieved from GenBank showing higher similarity. Evolutionary distances between Salmonella strains were calculated using the p-distance method. The best tree with branch length sum = 1.06205674 is shown. The percentage of replicate trees in which the relevant taxa clustered together in the bootstrap test (1000 replicates) is shown next to the branches.

[0307] The S. typhi strains were characterized for antimicrobial susceptibility against the control antibiotics (as per CLSI guidelines) (Table 1). The Salmonella strains were categorized as multi-drug resistant if found resistant to trimethoprim / sulfamethoxazole, ampicillin and chloramphenicol, while the multi-drug resistant strains resistant to ciprofloxacin and ceftriaxone were categorized as pandrug resistant. S. typhi CL1 and CL5 possibly clustered in branch A, but these isolates had different antibiotic profiles and differentiated as pandrug and multi-drug resistant strains Figure 2 ). S. typhi CL15 clustered in branch B, identified as a pandrug resistant strain and showed susceptibility to meropenem Figure 2 , Table 1).

[0308] Table 1. Antimicrobial susceptibility of pandrug and multi-drug resistant S. typhi clinical isolates detected by Kirby-Bauer disc diffusion method

[0309]

[0310] Key: ZOI = Zone of inhibition, AMP = Ampicillin, SXT = Trimethoprim-sulfamethoxazole, CFM = Cefexime, C = Chloramphenicol, CTX = Cefotaxime, CIP = Ciprofloxacin, AZM = Azithromycin, MEM = Meropenem, CRO = Ceftriaxone, R = Resistant, S = Sensitive

[0311] Method:

[0312] S. typhi species

[0313] Four clinical strains of Salmonella typhi were isolated from blood cultures obtained from clinical laboratories located in Karachi, Pakistan.

[0314] Molecular identification of Salmonella typhi clinical strains

[0315] Genomic DNA extraction and InvA gene amplification

[0316] Genomic DNA was extracted by CTAB (Merck, Germany) method and used as a template for species formation, Salmonella isolates were identified by probing genus-specific invasin primers (i.e. Inv-SW-F 5’-TCGTGACTCGCGTAAATGGCGATA-3’ and Inv-SW-R 5’-GCAGGCGCACGCCATAATCAATAA-3’). Amplification was performed using 2X DreamTaq Master Mix (Thermo Scientific, USA) on a Bio-Rad S1000 PCR thermocycler. The amplicon of approximately 420bp was separated by agarose gel (1.5%) electrophoresis to determine the purity of the PCR product.

[0317] Sequencing and species formation

[0318] InvA gene amplicons were cleaned and concentrated using DNA Clean & Concentrator (Zymo Research®, Murphy Ave. Irvine, USA) as per the manufacturer’s instructions prior to performing dideoxy chain termination sequencing PCR. Sequencing was performed using an Applied BioSystems 3500 Genetic Analyzer (Thermo Fisher Scientific). Species and sequences confirmed by BLAST search (NCBI) were deposited in GenBank at the National Center for Biotechnology Information (NCBI) for accession numbers. Phylogenetic analysis was performed in MEGA7.

[0319] Susceptibility testing

[0320] Susceptibility of drug resistant strains to common antibiotics was tested by disc diffusion method. According to the guidelines of the Clinical and Laboratory Standards Institute (CLSI), bacterial lawn of 1.3 x 10 8 cells / mL was prepared on Mueller-Hinton agar plates and different antibiotic discs, such as methicillin (10 μg), ampicillin (10 μg), trimethoprim-sulfamethoxazole (20 μg), cefixime (5 μg), chloramphenicol (30 μg), cefotaxime (30 μg), ciprofloxacin (5 μg), azithromycin (15 μg), meropenem (10 μg), ceftriaxone (10 μg) etc. were placed on the lawn. After incubation at 37°C for 24-48 h, the zone of inhibition (in mm) was measured and the susceptibility of the drug resistant bacteria was judged as per the guidelines.

[0321] 2. Activity of vanillylic acid derived arene ruthenium complexes against drug resistant Salmonella typhi

[0322] The antibacterial activity of arene ruthenium complexes 9-20 and 64-72 against four drug resistant Salmonella typhi strains was determined. The results, as shown in Table 2, indicated that six complexes inhibited the growth of drug resistant Salmonella typhi clinical strains at a concentration of 2.5 μg with zone of inhibition ranging from 3-13 mm. Among them, complexes 15 and 17 inhibited the growth of all clinical isolates in this study. The above screening results indicated that 15 and 17 were significantly effective against the four drug resistant strains. Therefore, the MIC 90 , MBC, time-kill curves, scanning electron microscopy / atomic force microscopy were used to further define the antibacterial properties of these two complexes and to determine their hemolytic toxicity.

[0323] Table 2. Zone of inhibition (ZOI in mm) of arene ruthenium complexes 15, 17-19, 61, 63 against pan- and multi-drug resistant Salmonella typhi

[0324]

[0325]

[0326] Key: Zone of inhibition (ZOI in mm). No ZOI observed (-).

[0327] The antibacterial activity of arene ruthenium complexes 21-36 and 73-96 against three drug resistant Salmonella typhi strains was determined. The results, as shown in Table 3, indicated that 17 ligands and arene ruthenium complexes inhibited the growth of three drug resistant Salmonella typhi clinical strains at a concentration of 5 μg with zone of inhibition ranging from 3.8-11 mm. Among them, complexes 15 and 17 inhibited the growth of all clinical isolates in this study. The above screening results indicated that 15 and 17 were significantly effective against the four drug resistant strains. Therefore, the MIC 90 , MBC, time-kill curves, scanning electron microscopy / atomic force microscopy were used to further define the antibacterial properties of these two complexes and to determine their hemolytic toxicity.

[0328] Table 3. Zone of inhibition (ZOI in mm) of arene ruthenium complexes 23, 24, 29-32, 35, 36, 74-76, 82, 83, 88, 93, 94, 96 against pan- and multi-drug resistant Salmonella typhi

[0329]

[0330] Key: Zone of inhibition (ZOI in mm). No ZOI observed (-).

[0331] Method

[0332] All the synthesized vanillic acid derived arene ruthenium complexes were tested for their inhibitory effect on each drug resistant strain by disc diffusion method. Bacterial lawn of 1.3 x 108cells / mL was prepared on Mueller-Hinton agar plates and sterile discs were impregnated with arene ruthenium complexes (5 μg / mL) prepared in DMSO (5% w / v) and placed on the lawn. The zone of inhibition (in mm) was measured after 24 h of incubation at 37 °C,

[0333] 3.15 and 17 Anti-drug resistant Salmonella typhi properties

[0334] i. 15 and 17 Minimum inhibitory concentration (MIC 90 ) and minimum bactericidal concentration (MBC) determination

[0335] As shown in Table 4, all the clinical Salmonella typhi strains exhibited high level of resistance to ampicillin with MIC 90 values > 32-128 μg, MBC > 32-256 μg and 74-89% inhibition, and thus were considered as potentially resistant according to CLSI breakpoints. In contrast, both the clinical strains were susceptible to azithromycin, which is the drug of choice in this therapeutic setting, while Salmonella typhi CL1 and CL15 had very high MIC90concentrations that could inhibit 89% of the cells treated with this essential drug (Table 4). Salmonella typhi exhibited lower resistance to the DNA synthesis inhibitor, ciprofloxacin at 16-32 μg concentrations, while 78-87% inhibition was observed at higher concentrations.

[0336] Arene ruthenium complexes 15 and 17 exhibited significant Salmonella typhi killing activity with > 90% inhibition at > 0.06 to > 0.25 μg of 15 and > 2.0 to > 8.0 μg of 17, respectively (Table 4). Notably, the multi-drug resistant strains exhibited higher susceptibility to complex 15 (MIC 90 > 0.06 ± 0.03 and > 1.25 ± 0.05 for S. typhi CL2 and CL5, respectively) and 17 (MIC 90 > 2.0 ± 0.24 and > 4 ± 0.34 for S. typhi CL2 and CL5, respectively).

[0337] Table 4. MIC 90 , % inhibition and MBC

[0338]

[0339]

[0340] Key: AMP = Ampicillin, AZM = Azithromycin, CIP = Ciprofloxacin; * MIC 80 , MBC = Observed after 24 hours of incubation

[0341] Arenet ruthenium complexes 23, 24, 29-32, 35, 36, 74-76, 82, 83, 88, 93, 94, 96 exhibited significant Salmonella typhi killing activity (Table 5). Notably, multiple drug resistant strains exhibited higher susceptibility to complexes 32 and 83.

[0342] Table 5. MIC of arenet ruthenium complexes 23, 24, 29-32, 35, 36, 74-76, 82, 83, 88, 93, 94, 96 and control antibiotics against drug resistant Salmonella typhi 80 / 90 , % inhibition and MBC

[0343]

[0344]

[0345] Key = * = MIC 80 , MBC = Observed after 24 hours of incubation

[0346] Methods

[0347] Determination of Minimum Inhibitory Concentration (MIC 90 )

[0348] Determination of Minimum Inhibitory Concentration (MIC C90 ) of active vanillic acid derived arenet ruthenium complexes by micro broth dilution method. The dilution range of azithromycin standard solution was 0.25-128 pg / mL, and that of ciprofloxacin and ampicillin was 0.016-128 pg / mL, respectively.

[0349] Determination of Minimum Bactericidal Concentration (MBC)

[0350] MBC was determined by re-culturing broth dilutions that inhibited growth of the strain at a concentration equal to or higher than MIC 90 . The broth dilutions were streaked onto Mueller-Hinton agar plates and incubated for 24-48 h. Restricted growth on the plates meant that the cells could not survive, and the lowest broth dilution of the complex or antibiotic that prevented growth was recorded as MBC.

[0351] ② Time-killing curves of CL15 of pan-drug-resistant Salmonella typhi (p. 15 and p. 17)

[0352] The results are as follows Figure 3 , Figure 4 As shown. The initial bactericidal effect of 15 strains against pan-drug-resistant Salmonella typhi CL15 was observed at 0.5X MIC. 90 Appears within seven hours after compound treatment, at MIC 90 Within three hours after treatment with the concentration of the compound, a two-fold reduction in colony-forming units was observed. Figure 3 Placing the inoculum on MHA agar plates supplements the observation results of the time-killing assay, which showed no growth after 24 hours of treatment. 17. This reduced the growth of pan-drug-resistant Salmonella typhi CL15 over time. Figure 4 The results showed that, compared with ampicillin, ciprofloxacin, azithromycin and untreated cells within 24 hours, an increase in the concentration of 17 by 0.5X to 2X reduced the colony-forming units (≥3 log CFU / mL) of pan-drug-resistant Salmonella typhi CL15 within 10 to 4 hours.

[0353] method

[0354] The ruthenium-aromatic complex (RAC) was evaluated for its resistant bacterial-dependent killing effect by measuring optical density (OD) at 600 nm and counting viable cells at different time intervals. Bacterial cells at approximately 10⁶ CFU / mL (OD 0.09 @ 600 nm) were harvested after overnight growth in Mueller-Hinton broth. Aliquots of culture media containing bacterial cells and 0.5×, 1×, and 2× concentrations of MIC90 (final volume 200 μL in microplates), ampicillin, azithromycin, and ciprofloxacin were prepared, with three replicates. Decreased growth was observed at 0, 6, 12, 24, and 48 h at 600 nm for each treatment, along with positive and negative controls (mediums inoculated with and without viable cells). 100 μL of inoculum from each dilution was inoculated onto nutrient agar, and colony counts (CFU / mL) were determined at 37 °C for 24 h. The kill time and bacterial mortality rate were determined by plotting log10 (CFU / mL) against time.

[0355] ③ Effects of 15 and 17 on cell ultrastructure and cell cycle (scanning electron microscopy)

[0356] Figure 5 , Figure 6 The effects of ampicillin, azithromycin, ciprofloxacin, and ruthenium complexes 15 and 17 on the ultrastructure of pan-drug-resistant S. TyphiCL15 were summarized. Figure 5 (A) is the positive control, and (B) is the result when cells are in MIC. 90Cellular destruction pattern observed upon incubation with (A) ampicillin (>128 pg / mL), (B) azithromycin (>96 pg / mL), (C) ciprofloxacin (>32 pg / mL). 5A demonstrates the ultrastructure of healthy live S. Typhi CL15 forming biofilm. Ampicillin is a bactericidal antibiotic that inhibits cell wall synthesis in S. Typhi. In Figure 5 B, disrupted cells and cell debris are visible in the scanning electron micrographs, while some areas of the cell wall surface appear to have reduced electron density, giving them a "shadowed" appearance, the cell wall thickness is visibly altered, and the cells are swollen. However, >128 pg / mL of ampicillin is required to inhibit the multiplication of pan-drug resistant S. Typhi CL15. Cell division is, however, evident in the scanning electron micrographs; structural disorder can be observed in dividing cells Figure 5 B. Azithromycin is a semi-synthetic macrolide that is considered the drug of choice for the treatment of multi-drug / pan-drug resistant Salmonella infections. Figure 5 C shows that at concentrations > 96 pg / mL, growth is completely inhibited, as indicated by cell debris. Ciprofloxacin inhibits DNA gyrase, an enzyme essential for chromosome replication and function. Inhibition of DNA gyrase inhibits bacterial cell division. Although intact cells are rare in the scanning electron micrographs, we observed impaired cell division in pan-drug resistant S. Typhi CL15, as indicated by the apparent changes in ultrastructure and the few cells with division septa, when incubated with MIC 90 concentrations of ciprofloxacin ( Figure 5 D). Figure 6 The scanning electron micrographs in D illustrate the effect of ruthenium complexes (including 15 and 17) on the growth and morphology of S. Typhi CL15. The scanning micrographs show extensive cellular damage in pan-drug resistant S. Typhi CL15 cells at lower MIC 90 doses compared to standard antibacterial agents, including azithromycin. Clearly, ruthenium complex 15 exhibits a pronounced cell surface damaging effect on S. Typhi CL15 at > 2.5 pg / mL, as indicated by the enhanced degree of cell swelling and subsequent lysis Figure 6 E and F). Most of the rod-shaped bacilli are transformed into elongated cells, with a visibly reduced cell thickness, however, a few dividing cells show cell septa, and the cell shape is visibly irregular, with reduced electron density on the cell surface. In addition, a large number of cells are damaged, with cell debris visible everywhere Figure 6 E and F). Figure 6G and H show that 17 inhibited cell division at concentrations > 8.0 μg / mL. Interestingly, the cell wall was locally thickened, followed by deformation of the entire wall surface, uneven swelling of the cell wall, and unclear contours, with multiple pores on the cell surface. Thus, these observations emphasize that 17 strongly interferes with the synthesis of the cell wall.

[0357] Method

[0358] The effects of the active complexes and antibiotics on the ultrastructure and cell cycle of the resistant bacterial strain at the MIC90were observed by scanning electron microscopy (SEM). After the 24 h log phase of killing, the adherent resistant bacterial strain cells were analyzed by SEM. Different morphological groups were prepared, including untreated control cells, cells treated with the arene ruthenium complexes, and cells treated with antibiotics. The cells treated with the arene ruthenium complexes and antibiotics were fixed with 2.5% glutaraldehyde buffered with 0.1 M phosphate buffer (pH 7.2) for 18 h, and then washed with the same buffer. Subsequently, the cells were fixed with 2% osmium tetroxide at room temperature for 2 h, and then dehydrated with gradient concentrations of ethanol. The samples were coated with gold using a vacuum sputter coater, and examined by scanning electron microscopy at a range of 1-2 microns, using an accelerating electron beam of 7.0 KV at a magnification of 4-10 million times to obtain uniform scanning.

[0359] (IV) Effects of 15 and 17 on the ultrastructure and cell cycle of the cells (atomic force microscopy)

[0360] Figure 7 Normal cell morphology in (A and B), and MIC in (C and D) 90 Effects of ampicillin and azithromycin at concentrations on pan-resistant S. Typhi CL15. Figure 7 The high-resolution atomic force microscopy images in A show uniform colonization of pan-resistant S. Typhi CL15, while in the heat map, intact cells with uniform wall structure can be clearly seen Figure 7 B). The estimated cell size of the normal cells is 2.5 μM in length and 0.8 μM in diameter Figure 7 B). Figure 7 In C and 7D, pan-resistant S. Typhi CL15 is resistant to ampicillin and azithromycin at MIC90concentrations, showing distorted cell morphology, thickened cell walls, and possible aggregation of cell debris and reduced population density. Figure 7 B demonstrates the effects of ciprofloxacin, ruthenium complexes, including 15 and 17, by atomic force microscopy. Pan-resistant S. Typhi CL15 is resistant to ciprofloxacin; however, the cell morphology is disrupted, and intact cells are rare. Figure 8 MIC in (E) 90(F) and (G) are vanillyl acid derived arene ruthenium complexes 15 and 17. Figure 8 F shows that when treated with 2.5 μg of 15, S. Typhi CL15 growth was arrested and completely destroyed, as indicated by the accumulation of cell scars. Similarly, at the MIC 90 A significant decrease in the estimated cell size was observed at Figure 8 G, while

[0361] Methods

[0362] The effect of ampicillin, azithromycin, ciprofloxacin and arene ruthenium complexes (15 and 17) at MIC90concentrations on pan-resistant S. Typhi CL15 cells was evaluated by high resolution atomic force microscopy imaging, using untreated cells as positive control. Briefly, pan-resistant S. Typhi CL15 was grown overnight in Mueller-Hinton broth (MHB) and cell suspension was adjusted according to the 0.5 McFarland standard. After the time kill log lag phase, cells were treated with MIC 90 of 15, 17 and control antibiotics. Treated and control cells were harvested after high speed centrifugation and dispersed in sterile pure grade water. For immobilization, cell suspension was dropped on poly-L-lysine coated mica slides and air-dried at room temperature before atomic force microscopy analysis. Atomic force microscopy (Agilent 5500) was used to study morphological changes using tapping mode. Images were captured at the optimal scan speed of 1-5 μm / s and 512 x 512 line resolution and processed by PicoView 1.2 imaging software.

[0363] V. Hemolytic toxicity of 15 and 17

[0364] Results are shown in Figure 9 Ruthenium arene complexes 15 and 17 did not show red blood cell membrane lysis during the assay, even at concentrations much higher than their 2X MIC values (i.e. 32 μg / mL), compared to triton X-100, and thus, are considered safe for pharmacological applications. Similarly, standard antibacterial agents including azithromycin, ciprofloxacin and ampicillin did not lyse red blood cells.

[0365] Methods

[0366] 5.0 mL of venous blood was drawn from healthy individuals using vacuum blood collection tubes. The hemolytic toxicity of arene ruthenium complexes was observed by hemolysis test. Red blood cells (RBCs) were washed twice and then resuspended in phosphate buffered saline (PBS) at a ratio of 1 : 10. Stock solution of arene ruthenium complexes was prepared at a concentration of 1 mg / 500 μL and filtered through 0.22 μm micropore filter. Standard solutions of ampicillin, azithromycin and ciprofloxacin were prepared in sterile water (2 mg / 1000 μL). Before performing the hemolysis test, the stock solutions of antibiotics, arene ruthenium complexes, red blood cells, DMSO (5%), PBS (negative control), triton X100 (1%, positive control) were pre-incubated at 37 °C. Aliquots of blood diluted in 190 μL of PBS were dispensed in triplicate into microtiter plates at 37 °C. Red blood cells were treated with arene ruthenium complexes and antibiotics at increasing concentrations (4 - 128 μg) for 30 min at physiological temperature. Blood cells incubated with 1% (w / v) triton X-100, DMSO (5%) and physiological saline were considered as positive and negative controls, respectively. The amount of hemoglobin released from the ruptured red blood cells was estimated at 576 nm and converted into percentage of hemolysis.

[0367] While embodiments of the application have been disclosed in connection with the specified embodiments, as above, it should be understood that it can be adapted in a variety of arrangements, applications and uses without departing from the spirit and scope of the present application, and that other modifications are possible within the scope of the claims and their equivalents, and that the scope of the claims should not be limited to the specific details presented herein but should be given the broadest interpretation of the general concepts underlying the application.

Claims

1. A method for preparing vanillic acid-derived ruthenium aromatic hydrocarbon complexes, characterized in that, Includes the following steps: Step 1: Synthesize vanillic acid esterified derivatives or vanillic acid etherified derivatives using vanillic acid as a raw material; Step 2: The vanillic acid esterified derivative synthesized in Step 1 is coupled with 3-pyridinecarboxylic acid or 4-pyridinecarboxylic acid via a carboxylic acid ester bond to prepare an esterified ligand; the vanillic acid etherified derivative synthesized in Step 1 is coupled with 4-hydroxyphenol, and then reacted with 3-pyridinecarboxylic acid or 4-pyridinecarboxylic acid to prepare an etherified ligand. Step 3: In an inert atmosphere, react the esterified ligand and etherified ligand generated in Step 2 with the ruthenium dimer precursor [Ru2(η]). 6 The reaction of [-Ar)2(μ-Cl)2Cl2] in chloroform or dichloromethane produces a product with the general formula [Ru(η] 6 Vanillic acid-derived ruthenium aromatic complexes of [-Ar)Cl2(ligand)]; Ar is selected from one of benzene, p-methylisopropylbenzene, and hexamethylbenzene.

2. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 1, characterized in that, In step one, the specific method for synthesizing the vanillic acid ester derivative is as follows: Vanillic acid is mixed with C1-C4 straight-chain or branched alkyl alcohols, wherein the mass concentration of vanillic acid in the mixed solution is 18-22 g / L, and Brønsted acid catalyst with a molar amount of 9-11% of vanillic acid is added. The reaction was refluxed at 65-85℃ for 18-24 hours. After the reaction was completed, the mixture was neutralized to pH 7-8 with a 10% sodium bicarbonate aqueous solution. The organic phase was collected by dichloromethane extraction and the solvent was removed by vacuum distillation to obtain the crude product. The crude product was purified by silica gel column chromatography with hexane and ethyl acetate in a volume ratio of 8-10:1 to obtain various vanillyl esterified derivatives.

3. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 2, characterized in that, In step two, the specific method for synthesizing the esterified ligand is as follows: The vanillic acid ester derivative is mixed with 3-pyridinecarboxylic acid or 4-pyridinecarboxylic acid at a molar ratio of 0.8-1.2:1 and dissolved in anhydrous dichloromethane or anhydrous DMF; Under nitrogen protection, the reaction system was cooled to 0°C, and then dicyclohexylcarbodiimide and 4-dimethylaminopyridine, with a molar amount of 0.8-1.2 times that of the vanillic acid ester derivative, were added sequentially. Heat the reaction mixture to room temperature, stir for 12-24 hours, filter and collect the filtrate, concentrate the filtrate under reduced pressure to obtain the crude product; The crude product was purified by silica gel column chromatography using hexane and ethyl acetate in a volume ratio of 8-10:1 to obtain nicotinic acid esterified ligands or isonicotinic acid esterified ligands.

4. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 2, characterized in that, In step one, the specific method for synthesizing the vanillic acid etherified derivative is as follows: The vanillic acid ester derivative was dissolved in acetone at a concentration of 18-22 g / L. Potassium carbonate was added at a molar ratio of 1.8-2.2:1 to the vanillic acid ester derivative. Alkyl bromide was added dropwise, and the mixture was refluxed at 65-85°C for 16-30 hours. The reaction was monitored by TLC until the substrate was completely reacted. The molar ratio of alkyl bromide to vanillic acid ester derivative was 1.05-1.15:

1. After the reaction was completed, the reaction mixture was neutralized and the organic phase was collected by extraction with ethyl acetate. The solvent was evaporated to dryness under reduced pressure and purified by silica gel column chromatography with hexane and ethyl acetate in a volume ratio of 8-10:1 to obtain the purified product. The purified product was cooled to 0°C, and 1M NaOH was added for alkaline hydrolysis of the ester. After neutralization with 1M hydrochloric acid, the vanillic acid etherified derivative was obtained.

5. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 4, characterized in that, The specific process of TLC monitoring is as follows: Thin-layer chromatography (TLC) plates were used, with silica gel as the stationary phase and n-hexane and ethyl acetate as the developing solvent in a volume ratio of 5:1 to 7:

1. Samples were taken every 2 hours, spotted, and developed. The substrate spots were observed under a 254nm UV lamp. At the same time, 10% phosphomolybdic acid ethanol solution was sprayed and heated for color development. The reaction endpoint is determined when the substrate spot disappears and only a single product spot remains. If the substrate is not completely consumed after 24 hours of reaction, add alkyl bromide or coupling reagent and continue the reaction until TLC shows that the reaction is complete.

6. The method for preparing the vanillic acid-derived aromatic ruthenium complex as described in claim 5, characterized in that, The amount of alkyl bromide or coupling reagent added is achieved through dynamic adjustment, and the specific steps include: If the substrate is not completely consumed after 24 hours of reaction, the residual substrate ratio is quantitatively analyzed by TLC, and reagents are added according to the following rules: If the substrate residue is 10%-20%, add 5%-8% of the initial feed amount; If the substrate residue is 20%-40%, add 8%-12% of the initial feed amount; If the substrate residue is >40%, add 12%-15% of the initial feed amount; After adding the additive, raise the temperature to 70-80℃ and continue the reaction for 2-4 hours. Take samples every hour for TLC monitoring. If the substrate residue is still >5%, add the corresponding amount twice according to the above substrate residue range, but the total amount added shall not exceed 20% of the initial feed amount. If the substrate is not completely consumed after the total supplementation reaches 20%, the reaction is terminated and purification is performed.

7. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 1, characterized in that, In step two, the specific method for synthesizing the etherified ligand is as follows: Step a: Under an inert atmosphere, the vanillic acid etherified derivative and 4-benzyloxyphenol are mixed at a molar ratio of 0.8-1.2:1 and dissolved in anhydrous dichloromethane; Step b: Cool the reaction system to 0°C, and add 4-dimethylaminopyridine in a molar amount of 0.08-0.12 times that of the vanillic acid ester derivative and dicyclohexylcarbodiimide in a molar amount of 0.8-1.2 times that of the vanillic acid ester derivative; Step c: Heat the reaction mixture to room temperature, stir for 18-24 hours, filter and collect the filtrate, concentrate the filtrate under reduced pressure to obtain the crude product; Step d: The crude product was purified by silica gel column chromatography using a mixed solvent of hexane / ethyl acetate / chloroform with a volume ratio of (4.8-5.0):0.1:(0.8-1.2) to obtain intermediate one; Step e: Dissolve intermediate one in a mixed solvent of ethanol and dichloromethane with a volume ratio of 8-10:1, add 8-12% by mass of palladium on carbon catalyst of intermediate one, stir at room temperature for 12-16 hours under hydrogen atmosphere, filter and collect the filtrate, concentrate under reduced pressure to obtain intermediate two. Step f: Mix intermediate 2 with 3-pyridinecarboxylic acid or 4-pyridinecarboxylic acid at a molar ratio of 0.8-1.2:1, dissolve in dichloromethane under an inert atmosphere, add 0.08-0.12 times the molar amount of 4-dimethylaminopyridine and 0.8-1.2 times the molar amount of 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride at 0°C, stir the reaction mixture at room temperature for 12-16 hours, extract with dichloromethane, collect the filtrate, evaporate to dryness under reduced pressure, and purify by silica gel column chromatography to obtain nicotinic acid ester etherified ligand or isonicotinic acid ester etherified ligand.

8. The method for preparing vanillic acid-derived aromatic ruthenium complexes as described in claim 1, characterized in that, The specific method for synthesizing the vanillic acid-derived aromatic ruthenium complex in step three is as follows: Under nitrogen protection, the esterified or etherified ligands are dissolved in anhydrous chloroform or dichloromethane, and a ruthenium dimer precursor is added. The molar ratio of the esterified or etherified ligands to the ruthenium dimer precursor is 1.8-2.2:

1. The mixture is stirred at room temperature for 12-24 hours, and the solvent is removed under reduced pressure to obtain a crude product. The crude product is washed with dichloromethane and dried under vacuum to obtain a vanillic acid-derived aromatic ruthenium complex.

9. Vanillic acid-derived ruthenium aromatic hydrocarbon complexes, characterized in that, It is prepared by the method for preparing vanillic acid-derived aromatic ruthenium complex according to any one of claims 1-8.

10. The use of the vanillic acid-derived aromatic ruthenium complex as described in claim 9 in the preparation of drugs against drug-resistant Salmonella typhi.

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