Photosensitive ruthenium carbene complex as well as preparation method and application thereof

Abstract

The invention relates to a photosensitive ruthenium carbene complex as well as a preparation method and application thereof, the chemical structural formula of the complex is # imgabs0, and R1, R2, R3 and R4 are respectively and independently hydrogen, amino, cyano, ester group, C1-C20 straight chain and branched chain alkyl, C7-C30 mono-or polyaryl substituted alkyl, C6-C18 aryl or halogen. Compared with the prior art, the complex catalyst provided by the invention can avoid the defect of lower activity of a temperature control type catalyst, and also meets the requirement of a latent catalyst which can be mixed with feed liquid in advance, so that the ring-opening metathesis polymerization reaction of photocatalytic cyclic olefin feed liquid is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of organometallic catalysts, and relates to a photosensitive ruthenium carbene complex, a preparation method thereof and an application thereof. Background Art

[0002] In recent decades, olefin metathesis reactions have received numerous studies and attentions due to their wide applications in fields such as pharmaceutical intermediates, construction, polymer chemistry, and lightweight transportation. Among them, ring-opening metathesis polymerization is a very characteristic reaction type, and this reaction can polymerize cyclic olefins into polymer materials under the action of highly active catalysts. The most influential factor on the ring-opening metathesis polymerization reaction is the catalyst. In the ring-opening metathesis polymerization catalyst system, the most widely used and practical one is the Grubbs catalyst, a ruthenium carbene complex, which has been increasingly widely used in the pharmaceutical and materials industries due to its stability to oxygen and protic solvents.

[0003] Most commercial ruthenium carbene catalysts have very high initiation activities, but these catalysts can only be stored for a long time at low temperatures and in solid states, and degrade at a relatively fast rate in solutions or during reactions, and cannot be stored in solution states for a long time. Therefore, ruthenium carbene catalysts can only be prepared immediately before use, which is very inconvenient to use, greatly limiting their application scenarios. To address these challenges, researchers have designed various latent ruthenium carbene catalysts, and latent catalysts can exhibit activities through external stimuli. Among them, heat (Organometallics, 1998, 17(16): 3460-3465.), acidity and alkalinity (Journal of organometallic chemistry, 2006, 691(24-25): 5482-5486.), mechanical force (Nature chemistry, 2009, 1(2): 133-137.) and light (Organometallics, 2009, 28(16): 4652-4655.) are the most common external stimuli. Among these different external stimuli, activation by light is particularly attractive. First, it allows the catalyst to be activated at ambient temperature, and the catalyst and monomer can be combined to form a storable and ready-to-use formulation. Second, as a photopolymerization product, polymers based on ring-opening metathesis polymerization enable the development of new ultraviolet curable coatings or adhesives. Third, different from other catalysts, photosensitive catalysts can achieve spatial control of the reaction by light, opening up the way for applications in additive manufacturing.

[0004] Therefore, it is of great significance to prepare a photosensitive catalyst with high catalytic activity that can achieve the ring-opening metathesis polymerization of cyclic olefins under light irradiation. Wang D et al. [Angewandte Chemie International Edition, 2008, 47(17): 3267-3270.] developed a UV-light-initiated cationic ruthenium-based complex. This catalyst did not react with cyclic olefin monomers at room temperature for 24 h. Under the irradiation of 308 nm and 254 nm light, the polymerization yield of cyclic olefins was relatively high, but the initiation efficiency of the catalyst was very low. In subsequent research [Angewandte Chemie, 2015, 127(42): 12561-12565.], the authors grafted photolabile silyl protecting groups with different wavelengths to further control the results of olefin metathesis reactions. Ginzburg Y et al. [Organometallics, 2011, 30(12): 3430-3437.] reported a ruthenium complex with a tridentate ligand. The catalytic activity of this catalyst was very low both at room temperature and under light irradiation, but it showed obvious catalytic activity under the combined action of high temperature and light. Teator A J et al. [Organometallics, 2017, 36(2): 490-497.] synthesized a dithienylethene-functionalized ruthenium-based complex, which undergoes reversible photoisomerization, thus affecting its inherent catalytic activity. This catalyst is reactive towards both ring-opening metathesis polymerization and ring-closing metathesis, so it does not meet the requirements of a latent catalyst.

[0005] So far, the available photosensitive catalysts all have obvious disadvantages. The low catalytic activity of the catalyst results in a low polymer yield (less than 30%) during the photochemical reaction process; the poor thermal stability of the catalyst makes it not suitable for applications in photocatalytic ring-opening metathesis polymerization; it is impossible to achieve photochemical reactions under normal temperature conditions and requires additional external stimuli.

[0006] The Grubbs 3rd generation catalyst is a catalyst that replaces the PCy3 phosphorus ligand with a pyridine-based ligand on the basis of the Grubbs 2nd generation catalyst. Because the pyridine ligand is more likely to leave to form an active transition state, it has a faster initiation speed and higher activity. Among them, the general formula of the Grubbs 3rd generation catalyst is as follows:

[0007]

[0008] The advantages of the faster initiation speed and higher activity of the catalyst are actually a disadvantage in industrial applications, which is likely to cause local over-fast polymerization and is difficult to premix with the feed liquid. Therefore, temperature-controlled catalysts have become a research hotspot for many scholars.

[0009] The pyridine ligand unit and the alkylene structural unit are chemically bonded to form a binary chelate. In this way, the pyridine ligand requires higher energy to leave, so the reaction can only be initiated when heated to a certain temperature. It can be pre-mixed with the feed liquid as a latent catalyst. However, after the pyridine ligand leaves, it can re-coordinate with the Ru metal center at a certain rate, which is actually a dynamic equilibrium process. This affects the activity of this type of catalyst, resulting in medium activity, high dosage during the catalytic reaction, and poor economy.

[0010]

[0011] In addition, the ruthenium-based catalyst developed by Wang D et al. (Angew. Chem. Int. Ed., 2008) has a high yield under light irradiation, but a low initiation efficiency; the tridentate ligand ruthenium complex developed by Ginzburg Y et al. (Organometallics, 2011) shows activity only under the combined action of high temperature and light irradiation, and it is difficult to meet the requirements of a latent catalyst. Summary of the Invention

[0012] The purpose of the present invention is to provide a photosensitive ruthenium carbene complex, its preparation method and application. When the provided photosensitive complex is used as a catalyst, it can avoid the disadvantage of low activity of the temperature-controlled catalyst and meet the requirements of a latent catalyst that can be pre-mixed with the feed liquid, so as to realize the ring-opening metathesis polymerization reaction of the cyclic olefin feed liquid by photocatalysis.

[0013] The purpose of the present invention can be achieved by the following technical solutions:

[0014] In the first aspect, the present invention provides a photosensitive ruthenium carbene complex, and its chemical structural formula is:

[0015]

[0016] Wherein, R1, R2, R3 and R4 are each independently hydrogen, amino group, cyano group, ester group, C1-C 20 linear or branched alkyl group, C7-C 30 alkyl group substituted with single or multiple aryl groups, C6-C 18 aryl group or halogen.

[0017] Exemplarily, the selection of R1, R2, R3, and R4 can make Specifically, they are 3-hydroxypyridine, 2,6-dimethyl-3-hydroxypyridine, 4-amino-3-hydroxypyridine, 2-amino-3-hydroxypyridine, 6-(3-methylphenethyl)-3-hydroxypyridine, 2-fluoro-3-hydroxypyridine, 2-sec-butyl-3-hydroxypyridine, 2-iodo-3-hydroxypyridine, 4-bromo-3-hydroxypyridine, 5-m-tolyl-3-hydroxypyridine, 4-nonyl-3-hydroxypyridine, 2-chloro-5-fluoro-3-hydroxypyridine, 2-ethyl-3-hydroxypyridine, 2,6-dibromo-3-hydroxypyridine, 4-iodo-3-hydroxypyridine, 5,6-dimethyl-3-hydroxypyridine, 2-chloro-3-hydroxypyridine, 6-iodo-3-hydroxypyridine, 2-cyano-3-hydroxypyridine, 6-chloro-2-iodo-3-hydroxypyridine, methyl 3-hydroxypicolinate, 2-amino-5-bromo-3-hydroxypyridine, etc.

[0018] The present invention discovers through research that since o-nitrobenzyl ether derivatives can be rapidly cleaved into o-nitroso benzaldehyde and the corresponding alcohol under ultraviolet light irradiation.

[0019]

[0020] Based on the above principle, the photosensitive ruthenium carbene complex of the present invention connects the pyridine ligand and the alkylidene structure in the form of an unstable chemical bond to form a novel catalyst in a chelated form with relatively low activity and a latent state (when not irradiated). When irradiated with light, the connection between the two breaks, becoming a highly active structure similar to the Grubbs third-generation catalyst. In this way, the disadvantage of the relatively low activity of the temperature-controlled catalyst can be avoided, and the requirement for a latent catalyst that can be pre-mixed with the feed liquid is satisfied, thereby realizing the ring-opening metathesis polymerization reaction of the cyclic olefin feed liquid by photocatalysis.

[0021] In the second aspect, the present invention also provides a preparation method of the photosensitive ruthenium carbene complex of the first aspect above. Weigh the o-nitrobenzyl ether ligand and the ruthenium metal complex precursor, and carry out an exchange reaction in a solvent system. After separating and purifying the obtained reaction product, the photosensitive ruthenium carbene complex is obtained, which is the target product;

[0022] The chemical structural formula of the o-nitrobenzyl ether ligand is:

[0023]

[0024] Furthermore, the ruthenium metal complex precursor is 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)(tricyclohexylphosphine)ruthenium or 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)bis(3-bromopyridine)ruthenium.

[0025] Furthermore, the molar ratio of the o-nitrobenzyl ether ligand to the ruthenium metal complex precursor is 1 to 5:1.

[0026] Furthermore, the exchange reaction temperature is 40-80°C, illustratively 50°C, 40°C, 60°C, 80°C, etc., and the reaction time is 6-24 hours. The organic medium used in this reaction can be selected from one or a mixture of dichloromethane, dichloroethane, dioxane, diethyl ether, tetrahydrofuran, benzene, toluene, and n-hexane.

[0027] Furthermore, the o-nitrobenzyl ether ligand is prepared by the following steps:

[0028] S1. Weigh methyl 3-methyl-4-nitrobenzoate and an initiator, add a brominating agent to carry out bromination reaction under solvent conditions, the reaction temperature is 50-120° C., the reaction time is 3-15 h, and after the reaction is completed, extract and recrystallize to obtain product A;

[0029] S2. Using product A and 3-hydroxypyridine compounds as raw materials, adding a base under solvent conditions to carry out etherification reaction at a reaction temperature of 0 to 80° C. for a reaction time of 1 to 12 hours. After the reaction is completed, extraction is performed to obtain product B;

[0030] S3, using product B as a raw material, adding a reducing agent under solvent conditions to carry out a reduction reaction at a temperature of -20 to 80°C for 3 to 14 hours. After the reaction is completed, extract and collect product C;

[0031] S4. Using product C as a raw material, an oxidant is added under solvent conditions to carry out an oxidation reaction at a temperature of 20 to 80° C. for 6 to 24 hours. After the reaction is completed, extraction is performed to collect product D;

[0032] S5. Using product D as a raw material, adding a quaternary phosphonium salt and a strong base under solvent conditions to carry out a nucleophilic addition reaction at a temperature of -78 to 50° C. for 1 to 12 hours. After the reaction is completed, extracting and collecting product E, i.e., the o-nitrobenzyl ether ligand;

[0033] The chemical structural formula of the product A is:

[0034]

[0035] The chemical structural formula of the 3-hydroxypyridine compound is:

[0036] For example, it can be 3-hydroxypyridine, 2,6-dimethyl-3-hydroxypyridine, 4-amino-3-hydroxypyridine, 2-amino-3-hydroxypyridine, 6-(3-methylphenethyl)-3-hydroxypyridine, 2-fluoro-3-hydroxypyridine, 2-sec-butyl-3-hydroxypyridine, 2-iodo-3-hydroxypyridine, 4-bromo-3-hydroxypyridine, 5-m-toluene-3-hydroxypyridine, 4-nonyl-3-hydroxypyridine , 2-chloro-5-fluoro-3-hydroxypyridine, 2-ethyl-3-hydroxypyridine, 2,6-dibromo-3-hydroxypyridine, 4-iodo-3-hydroxypyridine, 5,6-dimethyl-3-hydroxypyridine, 2-chloro-3-hydroxypyridine, 6-iodo-3-hydroxypyridine, 2-cyano-3-hydroxypyridine, 6-chloro-2-iodo-3-hydroxypyridine, methyl 3-hydroxypicolinate, 2-amino-5-bromo-3-hydroxypyridine, etc. Preferred are 3-hydroxypyridine, 2,6-dimethyl-3-hydroxypyridine, 4-amino-3-hydroxypyridine, etc.

[0037] The chemical structural formula of the product B is:

[0038]

[0039] The chemical structural formula of the product C is:

[0040]

[0041] The chemical structural formula of the product D is:

[0042]

[0043] Furthermore, in S1, the brominating agent is one or a mixture of elemental bromine, hydrobromic acid, sodium bromide, N-bromosuccinimide (NBS), dibromohydantoin (DBDMH), perbromide pyridinium (PHBP), tetrabromocyclopentane (TBCO), and phenyltrimethylammonium tribromide (TBAB); the initiator is one or a mixture of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, diisopropylbenzene peroxide, cyclohexanone peroxide, 2-butyl ketone peroxide, and tert-butyl benzoyl peroxide; the molar ratio of methyl 3-methyl-4-nitrobenzoate to the brominating agent is 1:1~5, and the molar ratio of methyl 3-methyl-4-nitrobenzoate to the initiator is 1:0.01~1. In addition, the organic medium used is selected from one of carbon tetrachloride, chloroform, dichloromethane, dichloroethane, benzene, toluene, xylene, chlorobenzene, p-dichlorobenzene, benzonitrile, acetonitrile, cyclohexane, trifluorotoluene, or a mixture of several thereof.

[0044] Further, in S2, the base used is one or a mixture of sodium hydride, potassium hydride, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, potassium tert-butoxide, lithium bis(trimethylsilyl)amide, and lithium diisopropylamide. The molar ratio of product A to the 3-hydroxypyridine compound is 1:1 to 5; the molar ratio of product A to the base is 1:0.5 to 10. Additionally, the organic medium used can be selected from one or a mixture of dimethyl sulfoxide, ethyl acetate, dichloromethane, N,N-dimethylformamide, tetrahydrofuran, acetonitrile, and tetrahydrofuran.

[0045] Further, in S3, the reducing agent is one or a mixture of diisobutylaluminum hydride, lithium aluminum hydride, sodium borohydride, sodium cyanoborohydride, lithium borohydride, lithium triethylborohydride, and zinc borohydride; the molar ratio of product B to the reducing agent is 1:2 to 10. Additionally, the organic medium used can be selected from one or a mixture of dichloromethane, dichloroethane, chloroform, ether, tetrahydrofuran, acetonitrile, methanol, and ethanol.

[0046] Further, in S4, the oxidizing agent is one or a mixture of pyridinium chlorochromate (PCC), pyridinium dichromate (PDC), Dess-Martin periodinane, 2-iodoxybenzoic acid, potassium permanganate, manganese dioxide, ruthenium tetroxide, sodium hypochlorite, sodium dichromate, and chromium trioxide; the molar ratio of product C to the oxidizing agent is 1:1 to 10. Additionally, the organic medium used is selected from one or a mixture of dichloromethane, dichloroethane, tetrahydrofuran, chloroform, carbon tetrachloride, ethyl acetate, sulfuric acid solution, and glacial acetic acid solution.

[0047] Further, in S5, the quaternary phosphonium salt is one or a mixture of methyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, and methyltriphenylphosphonium iodide; the strong base used is one or a mixture of phenyllithium, n-butyllithium, potassium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, sodium hydride, lithium hydride, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide, and potassium ethoxide; the molar ratio of product D to the quaternary phosphonium salt is 1:1 to 5; the molar ratio of the quaternary phosphonium salt to the strong base is 1:1 to 5. Additionally, the organic medium used can be selected from one or a mixture of acetone, dichloromethane, carbon tetrachloride, ether, tetrahydrofuran, dimethyl sulfoxide, benzene, toluene, dimethyl ether, N,N-dimethylformamide, and methyl tert-butyl ether.

[0048] Generally speaking, the synthetic process route of the photosensitive ruthenium carbene complex provided by the present invention is as follows:

[0049]

[0050] In the third aspect, the present invention also provides an application of the photosensitive ruthenium carbene complex in catalyzing the ring-opening metathesis polymerization of cyclic olefins.

[0051] Furthermore, during use, the cyclic olefin is mixed with the photosensitive ruthenium carbene complex. In the dark, the cyclic olefin cannot undergo ring-opening metathesis polymerization; under a light source, the cyclic olefin can undergo ring-opening metathesis polymerization. Here, when the cyclic olefin undergoes ring-opening metathesis polymerization, it only needs to be under a light source and does not require heating, that is, it can be carried out at room temperature.

[0052] Specifically, the cleavage reaction of the novel photosensitive catalyst under light is as follows:

[0053]

[0054] Furthermore, the cyclic olefin is selected from one or more mixtures of dicyclopentadiene, cyclopentene, cyclohexene, cyclopentadiene, norbornene, cyclooctene, 1,4-cyclooctadiene, or derivatives of any of the above cyclic olefins

[0055] The molar ratio of the photosensitive ruthenium carbene complex to the cyclic olefin polymerization monomer is 1:200 - 30000;

[0056] The reaction time of the polymerization reaction is 60 - 300 seconds;

[0057] The wavelength of the light source is 254 - 420 nm.

[0058] Compared with the prior art, the present invention has the following advantages:

[0059] (1) The photosensitive ruthenium carbene complex prepared by the present invention has photosensitive properties. This metal complex can achieve photo-controlled polymerization of cyclic olefins, that is, it does not cause polymerization of cyclic olefins in the absence of light, while when the system with the catalyst is under a light source of a certain wavelength, rapid polymerization of cyclic olefins can be achieved.

[0060] (2) The photosensitive ruthenium carbene complex prepared by the present invention has easily available raw materials, mild preparation conditions, and a relatively high yield.

[0061] (3) The photosensitive ruthenium carbene complex prepared by the present invention has good light responsiveness, requires less catalyst, and has a short reaction time.

[0062] (4) The photosensitive ruthenium carbene complex prepared by the present invention can achieve 3D printing and forming of the stereolithography technology of cyclic olefins, and can process complex and high-resolution parts that cannot be achieved by traditional technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 1H NMR spectrum of A prepared in Example 1 1 1H NMR spectrum;

[0064] Figure 2 1H NMR spectrum of B1 prepared in Example 11 1H NMR spectrum;

[0065] Figure 3 1H NMR spectrum of C1 prepared in Example 1; 1 1H NMR spectrum;

[0066] Figure 4 1H NMR spectrum of D1 prepared in Example 1; 1 1H NMR spectrum;

[0067] Figure 5 1H NMR spectrum of E1 prepared in Example 1; 1 1H NMR spectrum;

[0068] Figure 6 1H NMR spectrum of Ru1 prepared in Example 1; 1 1H NMR spectrum;

[0069] Figure 7 Liquid solution prepared in Example 4;

[0070] Figure 8 Solid polymer obtained after light irradiation in Example 4. Detailed implementation manners

[0071] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0073] The term "and / or", "or / and", "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The said any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items. It should be noted that when at least two conjunctions selected from "and / or", "or / and", "and / or" are used to connect at least three items, it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR".

[0074] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0075] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0076] This document specifically discloses only some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly recited; and any lower limit can be combined with other lower limits to form a range not explicitly recited, and similarly any upper limit can be combined with any other upper limit to form a range not explicitly recited. In addition, each individually disclosed point or single numerical value itself can be used as a lower limit or upper limit and combined with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recited.

[0077] For the temperature parameters in this application, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are allowed. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0078] In this document, the "suitable combination method", "suitable method", "any suitable method", etc., the "suitable" described therein shall be subject to being able to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0079] In this application, "further", "even further", "especially", etc. are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the protection scope of this application.

[0080] In this application, "optionally", "optional", "option", mean that it can be either present or absent, that is, it refers to any one of the two alternative schemes of "present" or "absent". If "optional" appears multiple times in a technical solution, unless otherwise specified and there are no contradictions or mutual restrictions, each "optional" is independent of each other.

[0081] In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0082] Unless otherwise specified, all formulations and tests in this document occur in an environment of 25°C.

[0083] As used herein, the terms "comprise," "include," "contain," "have," "have," or other variations thereof are intended to encompass non-exclusive inclusions, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients that do not affect the end result may be added. The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. As used herein, no distinction is made between the terms "efficacy," "performance," "effect," and "efficacy."

[0084] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0085] Unless otherwise specified, all steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0086] In the following examples, unless otherwise specified, the rest of the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0087] Example 1

[0088] (1) Bromination reaction

[0089] To a 250ml three-necked flask, add 5g of methyl 3-methyl-4-nitrobenzoate, 1.64g of azobisisobutyronitrile, 7.44g of NBS, and 100ml of carbon tetrachloride. React at 100°C for 8h. After extraction, product A is collected from the reaction product. After purification, the calculated yield is 74.5%.

[0090] like Figure 1 As shown, A 1 H NMR spectrum, 1 H NMR (CDCl3, 500MHz, 298K): δ8.13(1H,dd,J=8.6,0.5Hz), 7.99(1H,dd,J=1.7,0.5Hz), 7.83(1H,dd,J=8.6,1.7Hz), 4.51(2H,s), 3.78(3H,s).

[0091] (2) Etherification reaction

[0092] To a 100 ml three-necked flask, add 2 g of A, 1.32 g of 3-hydroxypyridine, 9.77 g of lithium bis(trimethylsilyl)amide, and 50 ml of dimethyl sulfoxide. React at 70°C for 6 h. After extraction, product B1 is collected from the reaction product. After purification, the calculated yield is 82.2%.

[0093] As Figure 2 shown, the 1 1H NMR spectrum of B1 1 1H NMR (CDCl3, 500 MHz, 298 K): δ 8.54 (1H, ddd, J = 1.7, 1.6, 0.6 Hz), 8.42 (1H, ddd, J = 4.7, 1.9, 1.6 Hz), 8.20 - 8.06 (2H, 8.14 (dd, J = 8.6, 0.5 Hz), 8.12 (dd, J = 1.7, 0.5 Hz)), 7.83 (1H, dd, J = 8.6, 1.7 Hz), 7.61 - 7.38 (2H, 7.54 (ddd, J = 7.9, 4.7, 0.6 Hz), 7.44 (ddd, J = 7.9, 1.9, 1.7 Hz)), 5.10 (2H, s), δ 3.78 (3H, s).

[0094] (3) Reduction reaction

[0095] 2 g of B1, 3.66 g of sodium cyanoborohydride and 30 ml of dichloromethane were added to a 100 ml three-necked flask, and the reaction was carried out at 60 °C for 13 h. After extraction, product C1 was collected from the reaction product. After purification, the yield was calculated to be 94.9%.

[0096] As Figure 3 shown, the 1 1H NMR spectrum of C1 1 1H NMR (CDCl3, 500 MHz, 298 K): δ 8.54 (1H, ddd, J = 1.7, 1.6, 0.6 Hz), 8.42 (1H, ddd, J = 4.7, 1.9, 1.6 Hz), 8.10 (1H, dd, J = 8.5, 0.5 Hz), 7.62 - 7.38 (4H, 7.56 (dd, J = 2.4, 0.5 Hz), 7.54 (ddd, J = 7.9, 4.7, 0.6 Hz), 7.51 (dd, J = 8.5, 2.4 Hz), 7.44 (ddd, J = 7.9, 1.9, 1.7 Hz)), 5.04 (2H, s), 4.55 (2H, s).

[0097] (4) Oxidation reaction

[0098] 2 g of C1, 13.25 g of PCC and 50 ml of dichloromethane were added to a 100 ml three-necked flask, and the reaction was carried out at 20 °C for 7 h. After extraction, product D1 was collected from the reaction product. After purification, the yield was calculated to be 83.7%.

[0099] As Figure 4 shown, the 1 1H NMR spectrum of D1 1H NMR(CDCl3,500MHz,298K): δ10.08(1H,s),8.54(1H,ddd,J=1.7,1.6,0.6Hz),8.42(1H,ddd,J=4.7,1.9,1.6Hz),8.10(1H,dd,J=8.5,0.4Hz) ,8.07(1H,dd,J=1.8,0.4Hz),7.77(1H,dd,J=8.5,1.8Hz),7.54(1H,ddd,J=7.9,4.7,0.6Hz),7.44(1H,ddd,J=7.9,1.9,1.7Hz),5.12(2H,s).

[0100] (5) Nucleophilic addition reaction

[0101] Using standard Schlenk techniques, the bottles and solvents used in the experiment were prepared. 2 g of D1, 6.92 g of methyltriphenylphosphonium bromide, 3.48 g of potassium tert-butoxide, and 50 ml of acetone were added to a 100 ml three-necked flask and reacted at 30°C for 7 h. After extraction, the product E1 was collected from the reaction mixture. After purification, the calculated yield was 74.2%.

[0102] like Figure 5 As shown, E1 1 H NMR spectrum, 1 H NMR (CDCl3, 500MHz, 298K): δ8.54 (1H,ddd,J=1.7,1.6,0.6Hz), 8.42 (1H,ddd,J=4.7,1.9, 1.6Hz),8.02(1H,dd,J=8.7,0.5Hz),7.83(1H,dd,J=8.7,1.9Hz),7.64(1H,dd,J=1.9,0.5 Hz)),7.54(1H,ddd,J=7.9,4.7,0.6Hz),7.44(1H,ddd,J=7.9,1.9,1.7Hz),6.88(1H,dd,J =18.2,11.1Hz),6.14(1H,dd,J=18.2,1.2Hz),5.46(1H,dd,J=11.1,1.2Hz),5.14(2H,s).

[0103] (6) Ligand exchange reaction

[0104] The bottles and solvents used in the experiment were treated with standard Schlenk techniques. 1.97 g of E1, 2 g of 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)bis(3-bromopyridine)ruthenium and 50 ml of dichloromethane were added to a 100 ml three-necked flask, and the reaction was carried out at 50 °C for 22 h. After extraction, the photosensitive ruthenium carbene complex Ru1 was collected from the reaction product. After purification, the yield was calculated to be 74.7%.

[0105] As Figure 6 shown, the 1 1H NMR spectrum of Ru1, 1 1H NMR (CD2CB, 500 MHz, 298 K): δ 19.89 (s, 1H), 8.32 (1H, ddd, J = 1.7, 1.6, 0.6 Hz), 8.26 (1H, ddd, J = 4.7, 1.9, 1.6 Hz), 8.02 (1H, dd, J = 8.7, 0.5 Hz), 7.71 (1H, dd, J = 8.7, 1.9 Hz), 7.64 (1H, dd, J = 1.9, 0.5 Hz)), 7.54 (1H, ddd, J = 7.9, 4.7, 0.6 Hz), 7.44 (1H, ddd, J = 7.9, 1.9, 1.7 Hz), 6.68 (4H, d, J = 2.3 Hz), 5.14 (2H, s), 3.45 (4H, ddd, J = 14.0, 7.3, 4.4 Hz), 2.23 - 2.08 (18H, 2.18 (s), 2.13 (s)).

[0106] Example 2

[0107] (1) Bromination reaction

[0108] 5 g of methyl 3-methyl-4-nitrobenzoate, 0.25 g of benzoyl peroxide, 5.23 g of sodium bromide and 100 ml of chloroform were added to a 250 ml three-necked flask, and the reaction was carried out at 60 °C for 10 h. After extraction, the product A was collected from the reaction product. After purification, the yield was calculated to be 82.7%.

[0109] 1 1H NMR (CDCl3, 500 MHz, 298 K): δ 3.78 (3H, s), 4.51 (2H, s), 7.83 (1H, dd, J = 8.6, 1.7 Hz), 7.99 (1H, dd, J = 1.7, 0.5 Hz), 8.13 (1H, dd, J = 8.6, 0.5 Hz).

[0110] (2) Etherification reaction

[0111] Add 2 g of A, 2.61 g of 2,6-dimethyl-3-hydroxypyridine, 2.25 g of potassium hydroxide and 50 ml of ethyl acetate to a 100-ml three-necked flask, and react at 10 °C for 8 h. After extraction, collect product B2 from the reaction product. After purification, the yield is calculated to be 70.3%.

[0112] 1 H NMR(CDCl3, 500 MHz, 298 K): δ 8.20 - 8.07(2H, 8.14(dd, J = 8.6, 0.5 Hz), 8.12(dd, J = 1.5, 0.5 Hz)), 7.83(1H, dd, J = 8.6, 1.5 Hz), 7.08(1H, d, J = 8.6 Hz), 6.50(1H, d, J = 8.6 Hz), 5.17(2H, s), 3.78(3H, s), 2.23(3H, s), 2.06(3H, s).

[0113] (3) Reduction reaction

[0114] Add 2 g of B2, 6.83 g of diisobutylaluminum hydride and 50 ml of dichloroethane to a 100-ml three-necked flask, and react at 50 °C for 9 h. After extraction, collect product C2 from the reaction product. After purification, the yield is calculated to be 94.4%.

[0115] 1 H NMR(CDCl3, 500 MHz, 298 K): δ 8.10(1H, dd, J = 8.5, 0.5 Hz), 7.62 - 7.45(2H, 7.57(dd, J = 2.4, 0.5 Hz), 7.51(dd, J = 8.5, 2.4 Hz)), 7.08(1H, d, J = 8.6 Hz), 6.50(1H, d, J = 8.6 Hz), 5.13(2H, s), 4.55(2H, s), 2.23(3H, s), 2.06(3H, s).

[0116] (4) Oxidation reaction

[0117] Add 2 g of C2, 4.49 g of PCC and 50 ml of dichloroethane to a 100-ml three-necked flask, and react at 80 °C for 13 h. After extraction, collect product D2 from the reaction product. After purification, the yield is calculated to be 69.5%.

[0118] 11H NMR (CDCl3, 500 MHz, 298 K): δ 10.08 (1H, s), 8.16 - 8.02 (2H, 8.10 (dd, J = 8.5, 0.4 Hz), 8.07 (dd, J = 1.8, 0.4 Hz)), 7.77 (1H, dd, J = 8.5, 1.8 Hz), 7.08 (1H, d, J = 8.6 Hz), 6.50 (1H, d, J = 8.6 Hz), 5.12 (2H, s), 2.23 (3H, s), 2.06 (3H, s).

[0119] (5) Nucleophilic addition reaction

[0120] The bottles and solvents used in the experiment were treated with standard Schlenk techniques. 2 g of D2, 3.99 g of methyltriphenylphosphonium bromide, 2.58 g of sodium tert - butoxide and 50 ml of dichloromethane were added to a 100 ml three - necked flask, and the reaction was carried out at - 10 °C for 3 h. After extraction, product E2 was collected from the reaction product. After purification, the yield was calculated to be 71.3%.

[0121] 1 1H NMR (CDCl3, 500 MHz, 298 K): δ 8.02 (1H, dd, J = 8.7, 0.5 Hz), 7.83 (1H, dd, J = 8.7, 1.9 Hz), 7.64 (1H, dd, J = 1.9, 0.5 Hz), 7.08 (1H, d, J = 8.6 Hz), 6.88 (1H, dd, J = 18.2, 11.1 Hz), 6.51 (1H, d, J = 8.6 Hz), 6.14 (1H, dd, J = 18.2, 1.2 Hz), 5.46 (1H, dd, J = 11.1, 1.2 Hz), 5.14 (2H, s), 2.23 (3H, s), 2.06 (3H, s).

[0122] (6) Ligand exchange reaction

[0123] The bottles and solvents used in the experiment were treated with standard Schlenk techniques. 1 g of E2, 1.08 g of 1,3 - bis(2,4,6 - trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)(tricyclohexylphosphine)ruthenium and 50 ml of dichloroethane were added to a 250 ml three - necked flask, and the reaction was carried out at 40 °C for 21 h. After extraction, the photosensitive ruthenium carbene complex Ru2 was collected from the reaction product. After purification, the yield was calculated to be 72.4%.

[0124] 11H NMR (CD2CB, 500 MHz, 298 K): δ 19.78 (s, 1H), 8.21 (1H, dd, J = 8.7, 0.5 Hz), 7.58 (1H, dd, J = 8.7, 1.9 Hz), 7.37 (1H, dd, J = 1.9, 0.5 Hz), 7.08 (1H, d, J = 8.6 Hz), 6.68 (4H, d, J = 2.3 Hz), 6.51 (1H, d, J = 8.6 Hz), 5.14 (2H, s), 4.43 (2H, d, J = 14.0 Hz), 3.45 (4H, ddd, J = 14.0, 7.3, 4.4 Hz), 2.23 (3H, s), 2.18 (6H, s), 2.13 (12H, s), 2.06 (3H, s).

[0125] Example 3

[0126] (1) Bromination reaction

[0127] Add 5 g of methyl 3-methyl-4-nitrobenzoate, 2.15 g of 2,2'-azobis(2-methylbutyronitrile), 8.24 g of elemental bromine and 100 ml of dichloromethane to a 250 ml three-necked flask, and react at 50 °C for 8 h. After extraction, collect product A from the reaction product. After purification, the yield is calculated to be 93.5%.

[0128] (2) Etherification reaction

[0129] Add 2 g of A, 3.78 g of 4-amino-3-hydroxypyridine, 4.49 g of sodium carbonate and 50 ml of dichloromethane to a 100 ml three-necked flask, and react at 0 °C for 7 h. After extraction, collect product B3 from the reaction product. After purification, the yield is calculated to be 76.3%.

[0130] (3) Reduction reaction

[0131] Add 2 g of B3, 0.82 g of lithium borohydride and 50 ml of chloroform to a 100 ml three-necked flask, and react at -20 °C for 7 h. After extraction, collect product C3 from the reaction product. After purification, the yield is calculated to be 95.0%.

[0132] (4) Oxidation reaction

[0133] Add 2 g of C3, 1.20 g of ruthenium tetroxide and 50 ml of carbon tetrachloride to a 100 ml three-necked flask, and react at 50 °C for 13 h. After extraction, collect product D3 from the reaction product. After purification, the yield is calculated to be 76.2%.

[0134] (5) Nucleophilic addition reaction

[0135] The bottles and solvents used in the experiment were treated with standard Schlenk techniques. 2 g of D3, 7.99 g of methyltriphenylphosphonium iodide, 6.48 g of phenyllithium and 50 ml of carbon tetrachloride were added to a 100 ml three-necked flask, and the reaction was carried out at -78 °C for 2 h. After extraction, product E3 was collected from the reaction product. After purification, the yield was calculated to be 82.6%.

[0136] (6) Ligand exchange reaction

[0137] The bottles and solvents used in the experiment were treated with standard Schlenk techniques. 1.28 g of E3, 2 g of 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)(tricyclohexylphosphine)ruthenium and 50 ml of dioxane were added to a 250 ml three-necked flask, and the reaction was carried out at 80 °C for 9 h. After extraction, the photosensitive ruthenium carbene complex Ru3 was collected from the reaction product. After purification, the yield was calculated to be 36.7%.

[0138] Example 4

[0139] Dicyclopentadiene (40 g, 302.6 mmol) was added to a polymerization flask, and complex Ru1 (0.008 g, 0.011 mmol) was weighed. After reacting under 420 nm light for 180 s, the liquid solution (as shown) turned into a solid polymer (as shown), and the conversion rate of dicyclopentadiene was 99%. Figure 7 as shown Figure 8 as shown

[0140] In the literature [European Journal of Inorganic Chemistry, 2013, 2013(31):5462 - 5468.], under the same light conditions with the photosensitive ruthenium carbene catalyst prepared therein for 2 h of illumination, the conversion rate of dicyclopentadiene was still only 10%.

[0141] It can be seen from this that the photo-responsive catalytic activity of the photosensitive ruthenium carbene catalyst complex Ru1 provided by the present invention is much better than that of this conventional photosensitive ruthenium carbene catalyst.

[0142] In addition, in the experiment, the Ru1 catalyst and dicyclopentadiene were stored at room temperature in the dark for 48 h, and no polymerization phenomenon occurred.

[0143] Example 5

[0144] Norbornene (40 g, 424.9 mmol) was added to a polymerization flask, and complex Ru2 (0.018 g, 0.024 mmol) was weighed. After reacting under 254 nm light for 120 s, the liquid solution turned into a solid polymer, and the conversion rate of norbornene was 98%.

[0145] Example 6

[0146] Add cyclopentadiene (40 g, 605.1 mmol) to the polymerization flask, and weigh the complex Ru3 (1.183 g, 1.398 mmol). After reacting for 180 s under 365 nm light irradiation, the polymer becomes an elastomer, and the conversion rate of cyclopentadiene is 94%.

[0147] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A photosensitive ruthenium carbene complex, characterized in that, Its chemical structural formula is as follows: Among them, R1, R2, R3 and R4 are each independently hydrogen, amino group, cyano group, ester group, C1-C 20 linear or branched alkyl group, C7-C 30 alkyl group substituted by mono- or poly-aryl group, C6-C 18 aryl group or halogen.

2. A photosensitive ruthenium carbene complex according to claim 1, characterized in that, The selection of R1, R2, R3, and R4 can be such that is 3-hydroxypyridine, 2,6-dimethyl-3-hydroxypyridine, 4-amino-3-hydroxypyridine, 2-amino-3-hydroxypyridine, 6-(3-methylphenethyl)-3-hydroxypyridine, 2-fluoro-3-hydroxypyridine, 2-sec-butyl-3-hydroxypyridine, 2-iodo-3-hydroxypyridine, 4-bromo-3-hydroxypyridine, 5-m-tolyl-3-hydroxypyridine, 4-nonyl-3-hydroxypyridine, 2-chloro-5-fluoro-3-hydroxypyridine, 2-ethyl-3-hydroxypyridine, 2,6-dibromo-3-hydroxypyridine, 4-iodo-3-hydroxypyridine, 5,6-dimethyl-3-hydroxypyridine, 2-chloro-3-hydroxypyridine, 6-iodo-3-hydroxypyridine, 2-cyano-3-hydroxypyridine, 6-chloro-2-iodo-3-hydroxypyridine, or methyl 3-hydroxypicolinate, 2-amino-5-bromo-3-hydroxypyridine.

3. The preparation method of a photosensitive ruthenium carbene complex according to claim 1 or 2, characterized in that, Weigh an o-nitrobenzyl ether ligand and a ruthenium metal complex precursor, and carry out an exchange reaction in a solvent system. After separating and purifying the obtained reaction product, a photosensitive ruthenium carbene complex is obtained, which is the target product. The chemical structural formula of the o-nitrobenzyl ether ligand is as follows: The ruthenium metal complex precursor is 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)(tricyclohexylphosphine)ruthenium or 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorobenzylidene)bis(3-bromopyridine)ruthenium.

4. The preparation method of a photosensitive ruthenium carbene complex according to claim 3, characterized in that, The molar ratio of the o-nitrobenzyl ether ligand to the ruthenium metal complex precursor is 1-5:

1.

5. The preparation method of a photosensitive ruthenium carbene complex according to claim 3, characterized in that, The temperature of the exchange reaction is 0-80 °C.

6. The preparation method of a photosensitive ruthenium carbene complex according to claim 3, characterized in that, The o-nitrobenzyl ether ligand is prepared through the following steps: S1. Weigh methyl 3-methyl-4-nitrobenzoate and an initiator, mix them, and add a brominating agent for bromination reaction under solvent conditions. The reaction temperature is 50-120 °C, the reaction time is 3-15 h. After the reaction, extract and recrystallize to obtain product A. S2. Use product A and a 3-hydroxypyridine compound as raw materials, add a base for etherification reaction under solvent conditions. The reaction temperature is 0-80 °C, the reaction time is 1-12 h. After the reaction, extract to obtain product B. S3. Use product B as a raw material, add a reducing agent for reduction reaction under solvent conditions. The reaction temperature is -20-80 °C, the reaction time is 3-14 h. After the reaction, extract and collect product C. S4. Use product C as a raw material, add an oxidizing agent for oxidation reaction under solvent conditions. The reaction temperature is 20-80 °C, the reaction time is 6-24 h. After the reaction, extract and collect product D. S5. Use product D as a raw material, add a quaternary phosphonium salt and a strong base for nucleophilic addition reaction under solvent conditions. The reaction temperature is -78-50 °C, the reaction time is 1-12 h. After the reaction, extract and collect product E, which is the o-nitrobenzyl ether ligand. The chemical structural formula of product A is as follows: The chemical structural formula of the 3-hydroxypyridine compound is as follows: The chemical structural formula of product B is as follows: The chemical structural formula of product C is as follows: The chemical structural formula of product D is as follows:

7. The preparation method of a photosensitive ruthenium carbene complex according to claim 6, wherein, In S1, the brominating agent is one or a mixture of bromine, hydrobromic acid, sodium bromide, N-bromosuccinimide, dibromohydantoin, pyridinium perbromide, tetrabromocyclohexanone, phenyltrimethylammonium tribromide, etc.; the initiator is one or a mixture of azobisisobutyronitrile, azobisisoheptonitrile, benzoyl peroxide, diisopropylbenzene peroxide, cyclohexanone peroxide, 2-butanone peroxide, tert-butyl benzoyl peroxide, etc.; the molar ratio of methyl 3-methyl-4-nitrobenzoate to the brominating agent is 1:1-5, and the molar ratio of methyl 3-methyl-4-nitrobenzoate to the initiator is 1:0.01-1. In S2, the base used is one or a mixture of sodium hydride, potassium hydride, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, potassium tert-butoxide, lithium bis(trimethylsilyl)amide, and lithium diisopropylamide. The molar ratio of product A to the 3-hydroxypyridine compound is 1:1 to 5; the molar ratio of product A to the base is 1:0.5 to 10; In S3, the reducing agent is one or a mixture of diisobutylaluminum hydride, lithium aluminum hydride, sodium borohydride, sodium cyanoborohydride, lithium borohydride, lithium triethylborohydride, and zinc borohydride; the molar ratio of product B to the reducing agent is 1:2 to 10; In S4, the oxidizing agent is one or a mixture of pyridinium chlorochromate, pyridinium dichromate, Dess-Martin periodinane, 2-iodoxybenzoic acid, potassium permanganate, manganese dioxide, ruthenium tetroxide, sodium hypochlorite, sodium dichromate, and chromium trioxide; the molar ratio of product C to the oxidizing agent is 1:1 to 10; In S5, the quaternary phosphonium salt is one or a mixture of methyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, and methyltriphenylphosphonium iodide; the strong base used is one or a mixture of phenyllithium, n-butyllithium, potassium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, sodium hydride, lithium hydride, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide, and potassium ethoxide; the molar ratio of product D to the quaternary phosphonium salt is 1:1 to 5; the molar ratio of the quaternary phosphonium salt to the strong base is 1:1 to 5.

8. Use of a photosensitive ruthenium carbene complex as claimed in claim 1 or 2 in the catalytic ring-opening metathesis polymerization of cyclic olefins.

9. Use of the photosensitive ruthenium carbene complex according to claim 8, characterized in that, In use, the cyclic olefin is mixed with the photosensitive ruthenium carbene complex. In the dark, the cyclic olefin cannot undergo ring-opening metathesis polymerization; under a light source, the cyclic olefin can undergo ring-opening metathesis polymerization.

10. Use of the photosensitive ruthenium carbene complex according to claim 9, characterized in that, The cyclic olefin is selected from one or a mixture of dicyclopentadiene, cyclopentene, cyclohexene, cyclopentadiene, norbornene, cyclooctene, 1,4-cyclooctadiene, or derivatives of any of the above cyclic olefins The molar ratio of the photosensitive ruthenium carbene complex to the cyclic olefin polymerization monomer is 1:200 to 30000; The reaction time of the polymerization reaction is 60 to 300 seconds; The wavelength of the light source is 254 - 420 nm.

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