Ligand, platinum complex, preparation method and application

Abstract

The invention relates to a ligand, a platinum complex, a preparation method and application, the platinum complex is selected as a light-emitting core of a light-emitting liquid crystal material, a flexible side chain and / or a liquid crystal unit are / is introduced to the periphery of an auxiliary ligand, and the platinum complex is a multifunctional light-emitting liquid crystal material with high quantum yield, not only has an aggregation-induced emission effect, but also has a light-emitting effect. The characteristics of gasochromism and friction reversibility are also realized.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials, and specifically relates to a ligand, a platinum complex, a preparation method and an application. Background Art

[0002] Liquid crystal is a kind of soft material that has both liquid fluidity and crystal anisotropy. It was discovered by Austrian botanist Reinitzer and German physicist Lehmann in 1888 and is widely used in high-tech fields such as display, smart windows, optical brakes, augmented reality, high-end anti-counterfeiting and high thermal conductivity materials. In addition to the fluidity and order of liquid crystals, luminescent liquid crystals also exhibit luminescent properties, and have broad application prospects in cutting-edge research fields such as liquid crystal displays, light-emitting diodes, field-effect transistors and smart materials. Most luminescent liquid crystals are composed of a rigid core and flexible side groups. Due to the influence of the "aggregation-induced fluorescence quenching" (ACQ) effect, their luminescence quantum yield is usually not high (<50%).

[0003] Among the reported luminescent liquid crystals, transition metal complexes often exhibit different luminescence, conductivity, magnetism and stimulus responsiveness from traditional luminescent liquid crystal systems, and have attracted much attention in recent years. Among them, platinum (II) complexes have long excited state lifetimes, high luminescence quantum yields, and unique planar geometric configurations, which can be assembled through intermolecular Pt…Pt and π-π interactions, and are considered to be the best primitives for constructing luminescent liquid crystals.

[0004] However, there are few reports on the liquid crystalization methods of platinum (II) complexes, and the luminescence quantum yield of these liquid crystals is low. For example, Camerel, Lu et al. reported a series of tridentate platinum (II) complex lyotropic liquid crystals and thermotropic liquid crystals, but did not report their quantum yields (Angewandte Chemie International Edition, 2007, 46 (15): 2659-2662; Angewandte Chemie International Edition, 2009, 48 (41): 7621-7625). Kozhevnikov, Cuerva et al. reported a class of tridentate and bidentate platinum (II) complex liquid crystals with absolute quantum yields of 12% and 20% in powder state, respectively (Chemistry-A European Journal, 2019, 25 (52): 12046-12051; Angewandte Chemie International Edition, 2008, 47 (33): 6286-6289). Santoro et al. introduced acetylacetone derivative ligands into bidentate platinum (II) complexes, weakened the intermolecular interaction, and increased the absolute quantum yield of liquid crystal powder to 50% (Chemistry of Materials, 2009, 21 (16): 3871-3882). Therefore, designing and synthesizing platinum (II) complex liquid crystals with high luminescence quantum yield remains an important challenge. Summary of the invention

[0005] The present invention solves the problem that the luminescent liquid crystal materials in the prior art have low luminescent efficiency and single function. The present invention uses a platinum complex as the luminescent core, introduces flexible side chains or liquid crystal elements, modifies the auxiliary ligand, and specifically designs the structure of the platinum complex, thereby obtaining a high quantum yield and multifunctional platinum complex. The platinum complex is a luminescent liquid crystal material, has the characteristics of aggregation-induced emission effect, gas-induced color change and friction reversibility, and has broad application prospects in the fields of anti-counterfeiting, image display, sensors and electro-optical devices.

[0006] The present invention provides a ligand having a structure shown in formula (I):

[0007]

[0008] In Formula I,

[0009] R1 and R3 are the same, R1 and R2 are the same or different, and R1 and R2 are independently selected from any one of a liquid crystal unit, hydrogen, an alkyl group with or without a substituent, and an alkoxy group with or without a substituent.

[0010] Preferably, the substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy,

[0011] More preferably, the halogen is selected from fluorine, chlorine, bromine and iodine; and / or,

[0012] The C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or,

[0013] The C1-C10 alkoxy group is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentyloxy, n-hexyloxy and n-heptyloxy.

[0014] In some embodiments of the present invention, the ligand is a co-ligand of a platinum complex.

[0015] In some embodiments of the present invention, R1 and R3 are the same, R1 and R2 are the same or different, and R1 and R2 are each independently selected from any one of a mesogen, hydrogen, a C1-20 alkyl group with or without a substituent, and a C1-C20 alkoxy group with or without a substituent;

[0016] Preferably, the C1-20 alkyl group with or without substitution is a flexible chain group of a C1-20 alkyl group with or without substitution, and the flexible chain group of a C1-20 alkyl group with or without substitution is preferably a C6-16 alkyl group with or without substitution; and / or,

[0017] The substituted or unsubstituted C1-C20 alkoxy group is a flexible chain group of the substituted or unsubstituted C1-C20 alkoxy group, and the flexible chain group of the substituted or unsubstituted C1-C20 alkoxy group is preferably a substituted or unsubstituted C6-C16 alkoxy group.

[0018] In some embodiments of the present invention, R1 is a liquid crystal unit, and R2 is any one of hydrogen, a C1-20 alkyl group with or without a substituent, and a C1-C20 alkoxy group with or without a substituent; or

[0019] R1 is a C1-20 alkyl group which may be substituted or not, and a C1-C20 alkoxy group which may be substituted or not, and R2 is hydrogen or a mesogen; or

[0020] R1 is hydrogen, R2 is any one of a liquid crystal unit, a C1-20 alkyl group which may be substituted or not, and a C1-C20 alkoxy group which may be substituted or not;

[0021] In some specific embodiments of the present invention, R1 is a liquid crystal unit, and R2 is a C1-20 alkyl group which may be substituted or unsubstituted, or a C1-C20 alkoxy group which may be substituted or unsubstituted; or

[0022] R1 is a C1-20 alkyl group which may be substituted or not and a C1-C20 alkoxy group which may be substituted or not, and R2 is a liquid crystal unit.

[0023] In some embodiments of the present invention, the structure of the liquid crystal unit is shown in any one of Formula II, Formula III, Formula IV, Formula V and Formula VI:

[0024]

[0025]

[0026] Among them, 1≤m1≤18; 1≤m2≤18;

[0027] Z1 and Z2 are the same or different, and are independently selected from any one of a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkyleneoxy group, and a substituted or unsubstituted imido group;

[0028] R4 to R7 are the same or different and are independently selected from any one of hydrogen, cyano, alkyl with or without substitution and alkoxy with or without substitution;

[0029] The substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy,

[0030] More preferably, the halogen is selected from fluorine, chlorine, bromine and iodine; and / or,

[0031] The C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or,

[0032] The C1-C10 alkoxy group is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentyloxy, n-hexyloxy and n-heptyloxy.

[0033] In some embodiments of the present invention, Z1 is selected from any one of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyleneoxy group, and a substituted or unsubstituted C1-C20 imido group;

[0034] Preferably, Z1 is selected from any one of -CH2-(methylene), -CH2CH2-(ethylene), -CH2CH2CH2-(propylene), -C(CH3)2-(isopropylene), -CH2CH2CH2CH2-(butylene), -CF2CF2CF2CF2-(perfluorosubstituted butylene), -OCH2CF2-(difluorosubstituted ethyleneoxy), and -NHC(=O)CH2-(acetimidyl).

[0035] In some embodiments of the present invention, Z2 is selected from any one of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyleneoxy group, and a substituted or unsubstituted C1-C20 imido group;

[0036] Preferably, Z1 is selected from any one of -CH2-(methylene), -CH2CH2-(ethylene), -CH2CH2CH2-(propylene), -C(CH3)2-(isopropylene), -CH2CH2CH2CH2-(butylene), -CF2CF2CF2CF2-(perfluorosubstituted butylene), -OCH2CF2-(difluorosubstituted ethyleneoxy), and -NHC(=O)CH2-(acetimidyl).

[0037] In some embodiments of the present invention, R4 is cyano.

[0038] In some embodiments of the present invention, R5 is hydrogen.

[0039] In some embodiments of the present invention, R6 is any one of hydrogen, a C1-C20 alkyl group which may be substituted or not substituted, or a C1-C20 alkoxy group which may be substituted or not substituted;

[0040] Preferably, the C1-C20 alkyl group is selected from any one of methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl and 1-ethyl-2-methylpropyl; and / or,

[0041] The C1-C20 alkoxy group is selected from any one of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, 1-methyl-propoxy, 2-methyl-propoxy, tert-butoxy, n-pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy, 1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethyl-propoxy, 1-ethylpropoxy, n-hexyloxy, 1-methylpentoxy, 2-methylpentoxy, 3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy, 1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy, 2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1-ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethyl-1-methylpropoxy and 1-ethyl-2-methylpropoxy;

[0042] R6 is preferably any one of a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 alkoxy group.

[0043] In some embodiments of the present invention, R7 is hydrogen.

[0044] The present invention provides a method for preparing the above ligand, comprising: mixing a compound of formula VII and 4-aminopyridine for reaction;

[0045]

[0046] In Formula VII,

[0047] R1 and R3 are the same, R1 and R2 are the same or different, and R1 and R2 are independently selected from any one of a liquid crystal unit, hydrogen, an alkyl group with or without a substituent, and an alkoxy group with or without a substituent.

[0048] In some embodiments of the present invention, the molar ratio of the compound of formula VII to the 4-aminopyridine is 1:0.5 to 1:1.5.

[0049] In some embodiments of the present invention, the reaction is carried out under the conditions of solvent A and base;

[0050] In some embodiments of the present invention, the preparation method further comprises: removing the solvent and purifying operations after the reaction to obtain the ligand.

[0051] In some embodiments of the present invention, the solvent A is tetrahydrofuran.

[0052] In some embodiments of the invention, the base is potassium tert-butoxide.

[0053] In some embodiments of the present invention, the molar ratio of the compound of formula VII, the 4-aminopyridine and the solvent A is 1:0.5:10 to 1:1.5:50.

[0054] In some embodiments of the present invention, the volume ratio of the compound of formula VII, the 4-aminopyridine and the base is 1:0.5:0.1 to 1:1.5:10.

[0055] In some embodiments of the present invention, the method for preparing the ligand specifically comprises:

[0056] (1) mixing and dissolving the compound of Formula VII, the 4-aminopyridine and the solvent A to obtain a mixed solution A;

[0057] (2) The base, the solvent A and the mixed solution A are mixed and reacted.

[0058] The present invention also provides a platinum complex, which is composed of platinum, a main ligand and an auxiliary ligand, wherein the auxiliary ligand is the above ligand or a ligand prepared by the above method;

[0059] In the present invention, the platinum complex is a platinum (II) complex.

[0060] In some embodiments of the present invention, the platinum complex is a luminescent liquid crystal material.

[0061] In some embodiments of the present invention, the platinum complex has a luminescence quantum yield higher than 80%.

[0062] In some embodiments of the present invention, the platinum complex is a columnar phase liquid crystal.

[0063] In some embodiments of the present invention, the platinum complex has a liquid crystal texture observable under a crossed polarizing microscope, wherein at least one endothermic or exothermic peak appears in DSC.

[0064] In some embodiments of the present invention, the platinum complex is a compound having aggregation-induced emission properties.

[0065] In some embodiments of the present invention, the polarized luminescence of the platinum complex is polarized luminescence based on ultraviolet irradiation.

[0066] In some embodiments of the present invention, the platinum complex is a gas-induced color-changing and friction-reversible compound, specifically a compound that changes color when exposed to dichloromethane and can be restored to its original color by friction.

[0067] In some embodiments of the present invention, the main ligand structure is as shown in Formula VIII,

[0068]

[0069] And / or, the platinum complex has a structure as shown in Formula IX,

[0070]

[0071] in,

[0072] R 11 and R 12 are the same or different, and are independently selected from any one of hydrogen, halogen, cyano, -CF3, -OCF3, alkyl with or without substitution, alkoxy with or without substitution, alkenyl with or without substitution, aryl with or without substitution, heteroaryl with or without substitution, condensed ring aryl with or without substitution, and condensed ring heteroaryl with or without substitution;

[0073] Preferably, the substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy;

[0074] More preferably, the C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or,

[0075] The C1-C10 alkoxy group is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentyloxy, n-hexyloxy and n-heptyloxy.

[0076] In the present invention, the main ligand can only be as shown in Formula VIII. The main ligand is characterized by being a bis(triazole)pyridine derivative and a tridentate ligand, which is beneficial for Pt coordination to form an electrically neutral platinum complex.

[0077] In some embodiments of the present invention, R 11 and R 12 are the same or different, and are independently selected from any one of hydrogen, halogen, cyano, -CF3, -OCF3, C1-C20 alkyl with or without substitution, C1-C20 alkoxy with or without substitution, C2-C20 alkenyl with or without substitution, C6-C30 aryl with or without substitution, C3-C30 heteroaryl with or without substitution, C9-C30 fused ring aryl with or without substitution, and C5-C30 fused ring heteroaryl with or without substitution; the halogen is preferably selected from fluorine, chlorine, bromine and iodine.

[0078] In some embodiments of the present invention, R 11 and R 12 It is -CF3.

[0079] The present invention also provides a method for preparing the platinum complex, comprising: mixing the main ligand, the auxiliary ligand and the platinum salt, and reacting them.

[0080] In some embodiments of the present invention, the molar ratio of the primary ligand, the auxiliary ligand and the platinum salt is 1:0.8:0.8 to 1:1.5:1.5, preferably 1:1:1.

[0081] In some embodiments of the present invention, the platinum salt is PtCl2(DMSO)2.

[0082] In some embodiments of the present invention, the preparation method comprises: mixing the main ligand, the auxiliary ligand, a platinum salt, a solvent B and a catalyst, and reacting them.

[0083] In some embodiments of the present invention, the reaction temperature is 60-120°C, preferably 83°C.

[0084] In some embodiments of the present invention, the reaction is carried out under protective gas conditions, and the protective gas is preferably nitrogen or argon.

[0085] In some embodiments of the present invention, the solvent is removed and purified after the reaction to obtain the platinum complex.

[0086] In some embodiments of the present invention, the solvent B is a mixed solvent of 2-methoxyethanol and water; the volume ratio of 2-methoxyethanol to water is preferably 5:1 to 1:1, more preferably 3:1.

[0087] In some embodiments of the present invention, the amount of solvent B used is such that the volume ratio of solvent B to primary ligand is 20:1 to 50:1;.

[0088] In some embodiments of the present invention, the catalyst is N,N-diisopropylethylamine, and the amount of N,N-diisopropylethylamine is preferably such that the volume ratio of N,N-diisopropylethylamine to the primary ligand is 1:1 to 1:10;

[0089] In some embodiments of the present invention, the method for preparing the platinum complex specifically comprises:

[0090] (a) mixing the primary ligand, the auxiliary ligand, the platinum salt and solvent B to obtain a mixed solution B;

[0091] (b) mixing the B and a catalyst and reacting them.

[0092] The present invention also improves the application of the platinum complex or the platinum complex prepared by the above method in the preparation of anti-counterfeiting, display, sensor and electro-optical devices.

[0093] Compared with the prior art, the present invention provides a ligand, a platinum complex, a preparation method and an application.

[0094] The present invention has the following beneficial effects:

[0095] (1) Platinum complexes are selected as the luminescent core of luminescent liquid crystal materials, and flexible side chains or liquid crystal moieties are introduced on the periphery of the auxiliary ligands. Such platinum complexes have a unique planar geometric configuration and can self-assemble through intermolecular Pt…Pt and π-π interactions to produce metal-metal-ligand charge transfer (MMLCT) excited states, making their quantum yields up to 88%. The luminescent behavior of platinum (II) complexes is highly dependent on intermolecular Pt…Pt and π-π interactions, and can be dynamically regulated by various stimuli such as temperature, mechanical force, and volatile gases. Therefore, such molecules can be used as multifunctional luminescent liquid crystal materials.

[0096] (2) The introduction of different flexible side chains or liquid crystal units will result in different liquid crystal structures and luminescence changes.

[0097] (3) The platinum complex provided by the present invention has good luminescence performance and light-adjustable performance, further expanding the application of luminescent liquid crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 is the mass spectrum of the platinum complex in Example 1 of the present invention;

[0099] Figure 2 is an emission spectrum of the platinum complex in Example 1 of the present invention;

[0100] Figure 3 is a gas-induced color spectrum of the platinum complex in Example 2 of the present invention;

[0101] Figure 4 is the mass spectrum of the platinum complex in Example 3 of the present invention;

[0102] Figure 5 It is a polarizing microscope image of the platinum complex in the comparative example of the present invention. DETAILED DESCRIPTION

[0103] The present invention will be further described below in conjunction with specific implementation methods. The protection scope of the present invention is not limited by the following embodiments but is determined by the claims.

[0104] It should be particularly noted that two or more aspects (or implementation methods) disclosed in the context of this specification can be arbitrarily combined with each other, and the technical solution thus formed is part of the original disclosure of this specification and also falls within the scope of protection of the present invention.

[0105] Example

[0106] Exemplary embodiments of the present invention are described below, including various details of the embodiments of the present invention to aid understanding, which should be considered as merely exemplary. Therefore, it should be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and simplicity, descriptions of known functions and structures are omitted in the following description. The experimental methods used in the following embodiments are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial sources.

[0107] In an exemplary embodiment of the present invention,

[0108] The detection method of the present invention is a conventional technical method in the art.

[0109] Room temperature refers to 15-35°C, and the reaction is at normal pressure (one standard atmosphere).

[0110] In an exemplary embodiment of the present invention, the detection method is a conventional technical method in the art.

[0111] The main ligands are all compounds represented by formula X

[0112]

[0113] Example 1

[0114] Preparation of auxiliary ligands and platinum complexes (liquid crystal luminescent materials)

[0115] (1) Under nitrogen protection, 3.00 g of methyl 3,4,5-trihydroxybenzoate and 22.52 g of anhydrous potassium carbonate were added to a two-necked flask containing 100 mL of butanone, and magnetic stirring was performed. Then, 24.87 g of 1-bromohexane was added, and the mixture was heated to 80°C and refluxed overnight. After the reaction was completed, the system was cooled to room temperature, filtered, and the filtrate was rotary evaporated and purified by column chromatography to obtain a light yellow oily liquid (methyl 3,4,5-trihexyloxybenzoate) with a yield of 91%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and petroleum ether, and the volume ratio of the two was 1:1.

[0116] (2) 2.00 g of methyl 3,4,5-tri(hexyloxy)benzoate and 0.47 g of 4-aminopyridine were added to a single-necked flask containing 20 mL of anhydrous THF, and stirred at room temperature until the solid was completely dissolved. Potassium tert-butoxide was dissolved in anhydrous THF to prepare a 2 mol / L solution, and then added dropwise to the above-mentioned single-necked flask using a constant pressure dropping funnel, with the total amount controlled at 2 mL. After the dropwise addition was completed, stirring was continued at room temperature, and the reaction progress was monitored using thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation, and the sample was purified by column chromatography to obtain a white solid powder (coligand, compound shown in formula XI), with a yield of 73%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, with a volume ratio of 95:5.

[0117] (3) In a nitrogen atmosphere, the main ligand (compound shown in Formula X), the above-mentioned auxiliary ligand and PtCl2(DMSO)2 were added in a molar ratio of 1:1:1 to a total of 5 mol in 20 mL of a mixed solvent consisting of 2-methoxyethanol and water (volume ratio of 3:1), and then 100 μL of N,N-diisopropylethylamine (DIPEA) was added, the temperature was raised to 83°C, and refluxed under stirring overnight. The reaction substrate was tracked by thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation and purified by column chromatography to obtain a yellow solid powder (platinum complex, compound shown in Formula XII) with a yield of 75%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, and the volume ratio of the two was 25:1. ESI-HR-MS (m / z): [MH] - Calculated value 1038.3366, measured value 1038.3347.

[0118]

[0119] Example 2

[0120] (1) Under nitrogen protection, 3.00 g of methyl 3,4,5-trihydroxybenzoate and 22.52 g of anhydrous potassium carbonate were added to a two-necked flask containing 100 mL of butanone, and the mixture was stirred magnetically. Then, 24.87 g of 4-bromo-n-hexyl-4'-cyanobiphenyl was added, and the mixture was heated to 80°C and refluxed overnight. After the reaction was completed, the system was cooled to room temperature, filtered, and the filtrate was rotary evaporated and purified by column chromatography to obtain a light yellow oily liquid (methyl 3,4,5-trihexyloxybenzoate) with a yield of 91%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and petroleum ether, with a volume ratio of 1:1. (2) 2.00 g of methyl 3,4,5-tri(4-n-hexyl-4'-cyanobiphenyl)benzoate and 0.47 g of 4-aminopyridine were added to a single-necked flask containing 20 mL of anhydrous THF and stirred at room temperature until the solid was completely dissolved. Potassium tert-butoxide was dissolved in anhydrous THF to prepare a 2 mol / L solution, and then added dropwise to the above-mentioned single-necked flask using a constant pressure dropping funnel, with the total amount controlled at 2 mL. After the addition was completed, stirring was continued at room temperature, and the reaction progress was monitored using thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation, and the sample was purified by column chromatography to obtain a white solid powder (co-ligand, compound shown in Formula XIII), with a yield of 73%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, with a volume ratio of 95:5.

[0121] (3) In a nitrogen atmosphere, the main ligand (the compound shown in Formula X), the above-mentioned auxiliary ligand and PtCl2(DMSO)2 were added in a molar ratio of 1:1:1 to 10 mol in total into 20 mL of a mixed solvent consisting of 2-methoxyethanol and water (volume ratio of 3:1), and then 100 μL of N,N-diisopropylethylamine (DIPEA) was added, the temperature was raised to 83°C, and the mixture was refluxed under stirring overnight. The reaction substrate was tracked by thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation and purified by column chromatography to obtain a yellow solid powder (platinum complex, compound shown in Formula XIV) with a yield of 75%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and ethanol, and the volume ratio of the two was 25:1.

[0122]

[0123] Example 3

[0124] (1) Under nitrogen protection, 2.97 g of methyl 3,5-trihydroxybenzoate and 1.23 g of anhydrous potassium carbonate were added to a two-necked flask containing 100 mL of butanone, and magnetic stirring was performed. Then 1.43 g of bromocitronellol was added, and the mixture was heated to 90°C and refluxed overnight. After the reaction was completed, the system was cooled to room temperature, filtered, and the filtrate was rotary evaporated and purified by column chromatography to obtain a light yellow oily liquid (methyl 3,5-dicitronellol benzoate) with a yield of 96%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and petroleum ether, and the volume ratio of the two was 1:1.

[0125] (2) 1.09 g of 3,5-dicitronellol methyl benzoate and 0.25 g of 4-aminopyridine were added to a single-necked flask containing 20 mL of anhydrous THF, and stirred at room temperature until the solid was completely dissolved. Potassium tert-butoxide was dissolved in anhydrous THF to prepare a 2 mol / L solution, and then added dropwise to the above-mentioned single-necked flask using a constant pressure dropping funnel, with the total amount controlled at 2 mL. After the dropwise addition was completed, stirring was continued at room temperature, and the reaction progress was monitored using thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation, and the sample was purified by column chromatography to obtain a white solid powder (coligand, compound shown in formula XV), with a yield of 60%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, with a volume ratio of 95:5.

[0126] (3) In a nitrogen atmosphere, the main ligand (compound shown in Formula X), the above auxiliary ligand and PtCl2(DMSO)2 were added in a molar ratio of 1:1:1 to a total of 5 mol in 20 mL of a mixed solvent consisting of 2-methoxyethanol and water (volume ratio of 3:1), and then 100 μL of N,N-diisopropylethylamine (DIPEA) was added, the temperature was raised to 83°C, and refluxed under stirring overnight. The reaction substrate was tracked by thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation and purified by column chromatography to obtain a yellow solid powder (platinum complex, compound shown in Formula XVI) with a yield of 75%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, and the volume ratio of the two was 25:1. ESI-HR-MS (m / z), [MH] - Calculated value 1046.3416, measured value 1046.3408.

[0127]

[0128] Comparative Example

[0129] (1) Under nitrogen protection, 3.00 g of methyl 3,4,5-trihydroxybenzoate and 22.52 g of anhydrous potassium carbonate were added to a two-necked flask containing 100 mL of butanone, and the mixture was stirred magnetically. Then, 24.87 g of 4-bromo-n-hexyl-4'-cyanobiphenyl was added, and the mixture was heated to 80°C and refluxed overnight. After the reaction was completed, the system was cooled to room temperature, filtered, and the filtrate was rotary evaporated and purified by column chromatography to obtain a light yellow oily liquid (methyl 3,4,5-trihexyloxybenzoate) with a yield of 91%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and petroleum ether, with a volume ratio of 1:1. (2) 2.00 g of methyl 3,4,5-tri(4-n-hexyl-4'-cyanobiphenyl)benzoate and 0.47 g of 4-aminopyridine were added to a single-necked flask containing 20 mL of anhydrous THF and stirred at room temperature until the solid was completely dissolved. Potassium tert-butoxide was dissolved in anhydrous THF to prepare a 2 mol / L solution, and then added dropwise to the above-mentioned single-necked flask using a constant pressure dropping funnel, with the total amount controlled at 2 mL. After the addition was completed, stirring was continued at room temperature, and the reaction progress was monitored using thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation, and the sample was purified by column chromatography to obtain a white solid powder (co-ligand, compound shown in Formula XIII), with a yield of 73%. The mobile phase used for column chromatography was a mixed solvent of dichloromethane and ethanol, with a volume ratio of 95:5.

[0130] (3) In a nitrogen atmosphere, the main ligand (compound shown in XVII), the above auxiliary ligand and PtCl2(DMSO)2 were added in a molar ratio of 1:1:1 to 10 mol in total into 20 mL of a mixed solvent consisting of 2-methoxyethanol and water (volume ratio of 3:1), and then 100 μL of N,N-diisopropylethylamine (DIPEA) was added, the temperature was raised to 83°C, and the mixture was refluxed under stirring overnight. The reaction substrate was tracked by thin layer chromatography. After the reaction was complete, the solvent was removed by rotary evaporation and purified by column chromatography to obtain a yellow solid powder (platinum complex, compound shown in XVIII) with a yield of 75%. The mobile phase used in the column chromatography was a mixed solvent of dichloromethane and ethanol, and the volume ratio of the two was 25:1.

[0131]

[0132] Figure 1 is the mass spectrum of the platinum complex (liquid crystal luminescent material) in Example 1 of the present invention; it can be seen from the figure that a platinum complex (liquid crystal luminescent material) is synthesized, and its molecular mass [MH] - The calculated value is 1038.3366, and the measured value is 1038.3347, which is within the allowable error range.

[0133] Figure 2It is the emission spectrum of the platinum complex (liquid crystal luminescent material) in Example 1 of the present invention; it can be seen from the figure that the platinum complex (liquid crystal luminescent material) emits orange-yellow light, and its maximum emission wavelength is 585nm.

[0134] Figure 3 It is the gas-induced color spectrum of the platinum complex (liquid crystal luminescent material) in Example 2 of the present invention; it can be seen from the figure that after being fumigated with dichloromethane gas, the platinum complex (liquid crystal luminescent material) will undergo color change and wavelength red shift.

[0135] Figure 4 is the mass spectrum of the platinum complex (liquid crystal luminescent material) in Example 3 of the present invention; it can be seen from the figure that a platinum complex (liquid crystal luminescent material) is synthesized, and its molecular mass [MH] - The calculated value is 1046.3416, and the measured value is 1046.3408, which is within the allowable error range.

[0136] Figure 5 3 is a polarizing microscope image of the platinum complex in the comparative example of the present invention; it can be seen from the image that the platinum complex does not show a birefringent liquid crystal texture.

[0137] The absolute quantum yield data of the platinum complexes in the solid state in Examples 1, 2, 3 and the comparison of the present invention are measured, and the results are shown in Table 1. It can be seen that the absolute quantum yield of the platinum complex used as the liquid crystal luminescent material of the present invention in the solid state can be as high as 88%.

[0138] Table 1

[0139] sample Luminescence quantum yield Example 1 83％ Example 2 88％ Example 3 86％ Comparative Example 68％

[0140] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A ligand having a structure represented by formula (I), In Formula I, R1 and R3 are the same, R1 and R2 are the same or different, and R1 and R2 are each independently selected from any one of a liquid crystal unit, hydrogen, an alkyl group with or without a substituent, and an alkoxy group with or without a substituent; Preferably, the substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy; More preferably, the halogen is selected from fluorine, chlorine, bromine and iodine; and / or, The C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or, The C1-C10 alkoxy group is selected from methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentoxy, n-hexoxy and n-heptyloxy; Preferably, the ligand is a co-ligand of a platinum complex.

2. The ligand according to claim 1, characterized in that R1 and R3 are the same, R1 and R2 are the same or different, and R1 and R2 are each independently selected from any one of a liquid crystal unit, hydrogen, a C1-20 alkyl group with or without a substituent, and a C1-C20 alkoxy group with or without a substituent; Preferably, the C1-20 alkyl group with or without substitution is a flexible chain group of a C1-20 alkyl group with or without substitution, and the flexible chain group of a C1-20 alkyl group with or without substitution is preferably a C6-16 alkyl group with or without substitution; and / or, The C1-C20 alkoxy group which may be substituted or unsubstituted is a flexible chain group of the C1-C20 alkoxy group which may be substituted or unsubstituted, and the flexible chain group of the C1-C20 alkoxy group which may be substituted or unsubstituted is preferably a C6-C16 alkoxy group which may be substituted or unsubstituted; Preferably, R1 is a liquid crystal unit, and R2 is any one of hydrogen, a C1-20 alkyl group which may be substituted or not, and a C1-C20 alkoxy group which may be substituted or not; or R1 is a C1-20 alkyl group which may be substituted or not, and a C1-C20 alkoxy group which may be substituted or not, and R2 is hydrogen or a mesogen; or R1 is hydrogen, R2 is any one of a liquid crystal unit, a C1-20 alkyl group which may be substituted or not, and a C1-C20 alkoxy group which may be substituted or not; More preferably, R1 is a liquid crystal unit, and R2 is any of a C1-20 alkyl group which may be substituted or not substituted, or a C1-C20 alkoxy group which may be substituted or not substituted; or R1 is a C1-20 alkyl group which may be substituted or not and a C1-C20 alkoxy group which may be substituted or not, and R2 is a liquid crystal unit.

3. The ligand according to claim 1 or 2, characterized in that The structure of the liquid crystal unit is shown in any one of Formula II, Formula III, Formula IV, Formula V and Formula VI: Among them, 1≤m1≤18; 1≤m2≤18; Z1 and Z2 are the same or different, and are independently selected from any one of a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkyleneoxy group, and a substituted or unsubstituted imido group; R4 to R7 are the same or different and are independently selected from any one of hydrogen, cyano, alkyl with or without substitution and alkoxy with or without substitution; Preferably, the substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy, More preferably, the halogen is selected from fluorine, chlorine, bromine and iodine; and / or, The C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or, The C1-C10 alkoxy group is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentyloxy, n-hexyloxy and n-heptyloxy.

4. The ligand according to claim 3, characterized in that Z1 is selected from any one of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyleneoxy group, and a substituted or unsubstituted C1-C20 imido group; Z2 is selected from any one of a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyleneoxy group, and a substituted or unsubstituted C1-C20 imido group; R4 is cyano; and / or, R5 is hydrogen; and / or, R6 is any one of hydrogen, a C1-C20 alkyl group which may be substituted or not, or a C1-C20 alkoxy group which may be substituted or not; and / or, R7 is hydrogen.

5. The method for preparing a ligand according to any one of claims 1 to 4, characterized in that: include: Mixing a compound of formula VII and 4-aminopyridine for reaction; Preferably, the molar ratio of the compound of formula VII to the 4-aminopyridine is 1:0.5 to 1:1.5; and / or, The reaction is carried out under the conditions of solvent A and base; More preferably, the preparation method further comprises: removing the solvent and purifying the ligand after the reaction to obtain the ligand; and / or, The solvent A is selected from any one of tetrahydrofuran, chloroform and acetonitrile; and / or, The base is potassium tert-butoxide or sodium tert-butoxide; and / or, The molar ratio of the compound of formula VII, the 4-aminopyridine and the solvent A is 1:10 to 1:50; and / or, The volume ratio of the compound of formula VII, the 4-aminopyridine and the base is 10:1 to 1:10; and / or, The preparation method of the ligand specifically comprises: (1) mixing and dissolving the compound of Formula VII, the 4-aminopyridine and the solvent A to obtain a mixed solution A; (2) The base, the solvent A and the mixed solution A are mixed and reacted.

6. A platinum complex, characterized in that It is composed of platinum, a main ligand and an auxiliary ligand, wherein the auxiliary ligand is the ligand described in any one of claims 1 to 4 or the ligand prepared by the method described in claim 5; Preferably, the platinum complex is a platinum (II) complex; and / or, The platinum complex is a luminescent liquid crystal material; and / or, The platinum complex has a luminescence quantum yield higher than 80%; and / or, The platinum complex is a columnar phase liquid crystal; and / or, The platinum complex has a liquid crystal texture observable under a crossed polarizing microscope, wherein at least one endothermic or exothermic peak appears in; and / or, The platinum complex is a compound having aggregation-induced emission properties; and / or, The polarized luminescence of the platinum complex is polarized luminescence based on ultraviolet irradiation; and / or, The platinum complex is a compound that changes color in response to gas and is reversible by friction, specifically a compound that changes color when exposed to dichloromethane and can be restored to its original color by friction.

7. The platinum complex according to claim 6, characterized in that The main ligand structure is shown in Formula VIII, And / or, the platinum complex has a structure as shown in Formula IX, in, R 11 and R 12 are the same or different, and are independently selected from any one of hydrogen, halogen, cyano, -CF3, -OCF3, alkyl with or without substitution, alkoxy with or without substitution, alkenyl with or without substitution, aryl with or without substitution, heteroaryl with or without substitution, condensed ring aryl with or without substitution, and condensed ring heteroaryl with or without substitution; Preferably, the substituent is selected from halogen, cyano, phenyl, C1-C10 alkyl and C1-C10 alkoxy; More preferably, the C1-C10 alkyl group is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, n-pentyl, isopentyl, n-hexyl and n-heptyl; and / or, The C1-C10 alkoxy group is selected from the group consisting of methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, isobutoxy, n-pentoxy, isopentyloxy, n-hexyloxy and n-heptyloxy.

8. The platinum complex according to claim 7, characterized in that R 11 and R 12 are the same or different, and are independently selected from any one of hydrogen, halogen, cyano, -CF3, -OCF3, a C1-C20 alkyl group which may be substituted or not, a C1-C20 alkoxy group which may be substituted or not, a C2-C20 alkenyl group which may be substituted or not, a C6-C30 aryl group which may be substituted or not, a C3-C30 heteroaryl group which may be substituted or not, a C9-C30 fused ring aryl group which may be substituted or not, and a C5-C30 fused ring heteroaryl group which may be substituted or not; the halogen is preferably selected from fluorine, chlorine, bromine and iodine; Preferably, R 11 and R 12 It is -CF3.

9. The method for preparing the platinum complex according to claim 7 or 8, characterized in that: include: The main ligand, the auxiliary ligand and the platinum salt are mixed and reacted; Preferably, the molar ratio of the primary ligand, the auxiliary ligand and the platinum salt is 1:0.8:0.8 to 1:1.5:1.5, preferably 1:1:1; and / or, The platinum salt is PtCl2(DMSO)2; and / or, The preparation method comprises: mixing the main ligand, the auxiliary ligand, the platinum salt, the solvent B and the catalyst, and reacting; and / or, The reaction temperature is 60-120°C, preferably 83°C; and / or, Preferably, the reaction is carried out under protective gas conditions, and the protective gas is preferably nitrogen or argon; and / or, After the reaction, the solvent is removed and purified to obtain the platinum complex; More preferably, the solvent B is a mixed solvent of 2-methoxyethanol and water; the volume ratio of 2-methoxyethanol to water is preferably 5:1 to 1:1, more preferably 3:1; and / or, The amount of solvent B used is such that the volume ratio of solvent B to primary ligand is 20:1 to 50:1; and / or, The catalyst is N,N-diisopropylethylamine, and the amount of N,N-diisopropylethylamine used is preferably such that the volume ratio of N,N-diisopropylethylamine to the primary ligand is 1:1 to 1:10; and / or, The preparation method of the platinum complex specifically comprises: (a) mixing the primary ligand, the auxiliary ligand, the platinum salt and solvent B to obtain a mixed solution B; (b) mixing the B and a catalyst and reacting them.

10. Use of the platinum complex according to claim 7 or 8 or the platinum complex prepared by the method according to claim 9 in the preparation of anti-counterfeiting, display, sensor and electro-optical devices.

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