Polyimino selenazoline compound as well as synthesis method and application thereof

Abstract

The invention discloses a poly (imino selenazoline) compound as well as a synthesis method and application thereof, and the synthesis method comprises the following steps: synthesizing diselenide from elemental selenium, amine and isonitrile, and polymerizing the diselenide and alpha-bromoacetophenone to synthesize the poly (imino selenazoline) compound. And a one-pot, two-step and four-component series polymerization strategy of elemental selenium, amine, isonitrile and alpha-bromoacetophenone is developed to construct the poly (imino selenazoline) compound in situ. The structures of the amine compound, the isonitrile compound and the alpha-bromoacetophenone compound are adjustable, and the polyimidoselenazoline compounds with different structures can be obtained along with the change of the monomer structures. The synthesis method does not involve a catalyst, has the characteristics of mild reaction conditions and simple process, and solves the problems of harsh reaction conditions, tedious steps, low reaction efficiency, non-specific product structure and the like in the synthesis process of the heterocyclic polymer through a multi-component tandem polymerization method.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer chemistry, and particularly relates to a polyiminoselenazoline compound, a synthesis method thereof, and an application thereof. Background Art

[0002] Selenium-containing polymers are an important class of polymer materials. The synthesis of selenium-containing polymers with novel and diverse structures is of great significance for the development of polymer materials science. However, due to the limitations of their stability and solubility, as well as the lack of safe, economical, efficient, and convenient synthesis methods, the types of reported selenium-containing polymers are very limited at present, mainly including polyselenides, polydiselenides, and polyselenophenes, etc. They usually use small molecule selenium-containing reagents such as selenides, diselenides, selenolactones, selenophene derivatives, and inorganic selenides as monomers to introduce selenium atoms into the polymer chain. The selenium-containing reagents involved in these synthesis methods are usually difficult to synthesize, have poor stability, and are expensive. Therefore, finding a cheap, easily available, and stable selenium source is one of the effective ways to solve the difficulty in synthesizing selenium-containing polymers with diverse structures and functions.

[0003] Elemental selenium, as a by-product of the metal refining industry, has the characteristics of stability, low toxicity, and economy. Moreover, multicomponent polymerization can start from simple monomers and obtain complex and diverse product structures through an economical and efficient synthesis method. In recent years, polymer researchers have found that using elemental selenium as one of the monomers in multicomponent polymerization to synthesize selenium-containing polymers not only promotes the development of selenium chemistry but also will greatly enrich the structures and functions of selenium-containing polymers.

[0004] However, the synthesis process of selenium-containing heterocyclic polymers involves multiple bonding processes, which brings problems such as frequent side reactions and poor product structure specificity. The multicomponent polymerization or multicomponent tandem polymerization involving elemental selenium realizes the precise control of heterocyclic functional motifs at the molecular engineering level through a triple synergistic mechanism of "in-situ activation - spatio-temporal resolution regulation - cascade assembly", effectively overcoming the problems of many side reactions and poor structure specificity in the synthesis of traditional heterocyclic polymers and achieving the precise construction of heterocyclic units. (J. Am. Chem. Soc. 2023, 145, 28204 - 28215; J. Am. Chem. Soc. 2021, 143, 15723 - 15731; CCS Chem. 2020, 2, 191 - 202). Summary of the Invention

[0005] The purpose of the present invention is to provide a polyiminoselenazoline compound, a synthesis method thereof, and an application thereof, and to obtain a series of functional polyiminoselenazoline compounds with simple process, mild conditions, and adjustable product structures.

[0006] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] A method for synthesizing a polyiminoselenazoline compound, comprising the following steps:

[0008] (1) Under a protective atmosphere, elemental selenium, an amine compound, an isocyanide compound, and an organic solvent are mixed to undergo a first reaction to obtain a diselenourea compound;

[0009] (2) The diselenourea compound is mixed with an α-bromoacetophenone compound to undergo a second reaction to obtain a polyiminoselenazoline compound.

[0010] The amine compound includes a monofunctional aromatic amine and a bifunctional aliphatic amine;

[0011] The isocyanide compound includes a bifunctional aliphatic isocyanide and a bifunctional aromatic isocyanide;

[0012] The α-bromoacetophenone compound includes a monofunctional α-bromoacetophenone compound or a bifunctional α-bromoacetophenone compound.

[0013] Optionally, when the amine compound is a monofunctional aromatic amine and the isocyanide compound is a bifunctional aliphatic isocyanide, the molar ratio of the diselenourea compound to the α-bromoacetophenone compound is 1 to 10:1 to 100;

[0014] Or when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide, and the α-bromoacetophenone compound is a bifunctional α-bromoacetophenone compound, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1 to 10:1 to 10;

[0015] Or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide, and the α-bromoacetophenone compound is a monofunctional α-bromoacetophenone, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1 to 10:1 to 20.

[0016] Optionally, the monofunctional aromatic amine includes any one of the following structures:

[0017]

[0018] Wherein, R 1 , R 2 and R 3 are independently H, F, Cl, Br, I, a hydroxyl group, a mercapto group, a trifluoromethyl group, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200;

[0019] The bifunctional aliphatic amine includes any one of the following structures:

[0020]

[0021] Wherein, m is an integer between 0 and 2000;

[0022] The molar ratio of the elemental selenium to the amine compound is 2-20:1-5.

[0023] Optionally, the bifunctional fatty isonitrile compound comprises any one of the following structures:

[0024]

[0025] Wherein, m is an integer between 0 and 2000;

[0026] The bifunctional aromatic isonitrile compound comprises any one of the following structures:

[0027]

[0028] Among them, R 4 is a hydrogen atom or an alkyl group with a carbon chain length of 1 to 200; X is CH2, O or S;

[0029] The molar ratio of the amine compound to the isonitrile compound is 1-10:2-5.

[0030] The protective atmosphere is at least one of nitrogen and rare gas.

[0031] The organic solvent is at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

[0032] Optionally, the temperature of the first reaction is 25-120° C., the time is 3-24 h, and the stirring rate is 100-900 rpm.

[0033] Optionally, the monofunctional α-bromoacetophenone compound comprises any one of the following structures:

[0034]

[0035] Among them, R 5 or R 6 are independently H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200; m is an integer between 0 and 2000;

[0036] The bifunctional α-bromoacetophenone compound comprises any one of the following structures:

[0037]

[0038] Among them, m is an integer between 0 and 2000.

[0039] Optionally, the temperature of the second-step reaction is 25-120 °C, the time is 3-24 h, and the stirring rate is 100-900 rpm.

[0040] The present invention provides a polyiminoselenazoline compound prepared by the said synthesis method.

[0041] The present invention also provides the application of the said polyiminoselenazoline compound in the field of high refractive index materials. As an anti-reflection coating for optical devices and as a potential material for microlenses of complementary metal oxide semiconductor image sensors.

[0042] The present invention uses low-toxic, odorless, and economical elemental selenium as a selenium source, reacts with amine compounds and isocyanide compounds in a solvent to form diselenourea, and then the separated and purified diselenourea intermediate undergoes a polymerization reaction with α-bromoacetophenone compounds to obtain polyiminoselenazoline compounds.

[0043] Furthermore, when the amine compound is a monofunctional aromatic amine and the isocyanide compound is a bifunctional aliphatic isocyanide, they first react with elemental selenium to obtain a diselenourea compound, without separation and purification, and in-situ react with a bifunctional α-bromoacetophenone compound to obtain a polyiminoselenazoline compound with a selenazole ring in the main chain and an imino group in the side chain; when the amine compound is a bifunctional aliphatic amine and the isocyanide compound is a bifunctional aromatic isocyanide compound, they first react with elemental selenium to obtain a diselenourea compound, without separation and purification, and in-situ polymerize with a monofunctional α-bromoacetophenone compound to obtain a polyiminoselenazoline compound with both a selenazole ring and an imino group in the main chain. The polyiminoselenazolines synthesized by this method all have good thermal stability, good film-forming properties, and relatively high refractive indices. In addition, the increase in the content of conjugated groups in the structure helps to increase the thermal stability of the material, and at the same time, is beneficial to improving the refractive index of the material.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] (1) The polymerization conditions of the present invention are mild, the process is simple, the atomic utilization rate is high, the regioselectivity is good, and the structural controllability is extremely strong (different structures of polyiminoselenazoline compounds can be obtained with the change of monomer structures). The present invention uses inexpensive and easily available elemental selenium as a selenium source to in-situ construct a selenium-containing heterocyclic polymer, without involving a catalyst, and has the characteristics of economy and environmental protection.

[0046] (2) The polyiminoselenazoline compounds prepared by the present invention all have good thermal stability, processability, and film-forming properties. The introduction of selenium atoms and conjugated groups endows them with a relatively high refractive index, showing potential application value in the fields of optics and optoelectronics. Description of the Drawings

[0047] Figure 1 It is a reaction equation diagram for preparing polyiminoselenazoline compounds in Examples 1 to 3;

[0048] Figure 2 It is a comparison diagram of 1H NMR and 13C NMR spectra of the polyiminoselenazoline compound prepared in Example 1, its corresponding diselenourea compound, and model compound 6a in deuterated DMSO; among them, A is the 1H NMR spectrum of diselenourea compound 5a, B is the 1H NMR spectrum of model compound 6a, C is the 1H NMR spectrum of polyiminoselenazoline compound P1, D is the 13C NMR spectrum of diselenourea compound 5a, E is the 13C NMR spectrum of model compound 6a, and F is the 13C NMR spectrum of polyiminoselenazoline compound P1;

[0049] Figure 3 It is a comparison diagram of 77Se NMR and X-ray photoelectron spectra of the polyiminoselenazoline compound prepared in Example 1, its corresponding diselenourea compound, and model compound 6a in deuterated DMSO; among them, (A) is the 77Se NMR spectrum of diselenourea compound 5a, model compound 6a, and polyiminoselenazoline compound P1, and (B) is the X-ray photoelectron spectrum of diselenourea compound 5a, model compound 6a, and polyiminoselenazoline compound P1;

[0050] Figure 4 It is an infrared absorption spectrum diagram of raw material 4a (A), diselenourea compound 5a (B), corresponding model compound 6a (C), and synthesized polyiminoselenazoline compound P1 (D) in Example 1;

[0051] Figure 5 It is a thermogravimetric analysis spectrum diagram of the polyiminoselenazoline compound prepared in Example 1;

[0052] Figure 6 It is a refractive index spectrum diagram of the polyiminoselenazoline compound prepared in Example 1;

[0053] Figure 7 It is a thermogravimetric analysis spectrum diagram of the polyiminoselenazoline compound and polyselenourea prepared in Examples 4 and 5. Detailed Embodiments

[0054] The present invention provides a method for synthesizing polyiminoselenazoline compounds, comprising the following steps:

[0055] Under a protective atmosphere, elemental selenium, an amine compound, an isonitrile compound, and an organic solvent are mixed to undergo a first reaction to obtain a diselenourea compound;

[0056] The diselenourea compound is mixed with a bifunctional α-bromoacetophenone compound to undergo a second reaction to obtain a polyiminoselenazoline compound.

[0057] The amine compound includes a monofunctional aromatic amine and a bifunctional aliphatic amine;

[0058] The isonitrile compound includes a bifunctional aliphatic isonitrile and a bifunctional aromatic isonitrile;

[0059] The α-bromoacetophenone compound includes a monofunctional α-bromoacetophenone compound and a bifunctional α-bromo ketone compound.

[0060] In the present invention, the protective atmosphere is preferably at least one of nitrogen or a noble gas, and more preferably nitrogen.

[0061] In the present invention, when the amine compound is a monofunctional aromatic amine and the isonitrile compound is a bifunctional aliphatic isonitrile, the molar ratio of the diselenourea compound to the α-bromoacetophenone compound is 1 to 10: 1 to 100, and more preferably 1 to 10: 1 to 10;

[0062] Or when the amine compound is a monofunctional aromatic amine, the isonitrile compound is a bifunctional aliphatic isonitrile, and the α-bromoacetophenone compound is a bifunctional α-bromoacetophenone, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1 to 10: 1 to 10, and more preferably 5 to 7: 7 to 8;

[0063] Or when the amine compound is a bifunctional aliphatic amine, the isonitrile compound is a bifunctional aliphatic isonitrile, and the α-bromoacetophenone compound is a monofunctional α-bromoacetophenone, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1 to 10: 1 to 20, and more preferably 5 to 7: 7 to 8;

[0064] In the present invention, the monofunctional aromatic amine preferably includes any one of the following structures:

[0065]

[0066] Wherein, R 1 、R 2 and R 3 are independently preferably H, F, Cl, Br, I, a hydroxyl group, a mercapto group, a trifluoromethyl group, an alkyl group or an alkoxy group; the monofunctional aromatic amine is more preferably aniline;

[0067] The bifunctional fatty amine preferably includes any one of the following structures:

[0068]

[0069] Among them, m is preferably an integer between 0 and 2000, and more preferably between 5 and 200; the bifunctional fatty amine is further preferably 1,6-hexanediamine;

[0070] The molar ratio of the elemental selenium to the amine compound is preferably 2-20:1-5, more preferably 3-10:1-4, and even more preferably 4-5:2-4.

[0071] In the present invention, the bifunctional fatty isocyanide compound preferably includes any one of the following structures:

[0072]

[0073] Among them, m is preferably an integer between 0 and 2000, and more preferably between 10 and 500;

[0074] The bifunctional aromatic isocyanide compound preferably includes any one of the following structures:

[0075]

[0076] Among them, R 4 is preferably a hydrogen atom or an alkyl group with a carbon chain length of 1-200, and more preferably an alkyl group with a carbon chain length of 1-10; X is preferably CH2, O or S;

[0077] The isocyanide compound is further preferably 1,6-hexane diisocyanide or 1,6-phenylene diisocyanide;

[0078] The molar ratio of the amine compound to the isocyanide compound is preferably 1-10:2-5, more preferably 2-9:2-4, and even more preferably 4-7.5:3-4.

[0079] In the present invention, the organic solvent preferably includes at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide, and is further preferably N,N-dimethylformamide; when there are two or more of the above organic solvents, there is no special limitation on the ratio of different organic solvents.

[0080] In the present invention, the amount of the organic solvent used in the reaction is not particularly limited and can be adjusted according to the actual situation.

[0081] In the present invention, the temperature of the first step reaction is preferably 25 to 120 °C, more preferably 30 to 100 °C, and even more preferably 50 to 75 °C; the time is preferably 3 to 24 h, more preferably 1 to 8 h, and even more preferably 3 to 6 h; the stirring rate is preferably 100 to 900 rpm, more preferably 200 to 800 rpm, and even more preferably 400 to 600 rpm.

[0082] In the present invention, when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a difunctional aliphatic isocyanide, and the α-bromoacetophenone compound is a difunctional α-bromoacetophenone, after the first step reaction is completed, it is preferred to purify the obtained product;

[0083] In the present invention, the purification is preferably carried out by diluting with a reaction solvent and then adding it to a precipitant, followed by standing, filtering, and drying in sequence to obtain the selenourea compound; when the selenourea compound is mixed with the α-bromo ketone compound, it is preferred to add a part of an organic solvent; the type of the organic solvent used is preferably the same as that in the first step reaction;

[0084] In the present invention, the reaction solvent is preferably at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and water; more preferably a mixed solvent of methanol and water; when the reaction solvent is two or more of the above, there is no special limitation on the ratio of different reaction solvents; the amount of the reaction solvent used in the purification is not particularly limited and can be adjusted according to the actual situation;

[0085] In the present invention, the way of adding the precipitant is preferably dropwise addition; the precipitant is preferably at least one of water, methanol, n-hexane, and ethanol, more preferably methanol or water; when the precipitant is two or more of the above, there is no special limitation on the ratio of different precipitants;

[0086] The drying temperature is preferably 20 to 80 °C, more preferably 30 to 60 °C, and even more preferably 40 to 50 °C.

[0087] In the present invention, the monofunctional α-bromoacetophenone compound preferably includes any one of the following structures:

[0088]

[0089] Wherein, R 5 Or R 6 Independently is preferably H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group with a carbon chain length of 1 to 200, or an alkoxy group with a carbon chain length of 1 to 200, more preferably 1 to 20;

[0090] m is preferably an integer between 0 and 2000, more preferably between 1 and 200;

[0091] The difunctional α-bromoacetophenone compound preferably comprises any one of the following structures:

[0092]

[0093] Wherein, m is preferably an integer between 0 and 2000, more preferably between 1 and 500;

[0094] The α-bromoacetophenone compound is further preferably 1,6-hexanediylbis(4-phenyl)bromoketone, 2-bromoacetophenone, 4,4'-bis(2-bromoacetyl)biphenyl or m-dibromoacetophenone.

[0095] In the present invention, the temperature of the second-step reaction is preferably 25-120 °C, more preferably 50-110 °C, and even more preferably 80-100 °C; the time is preferably 3-24 h, more preferably 1-8 h, and even more preferably 3-6 h; the stirring rate is preferably 100-900 rpm, more preferably 200-800 rpm, and even more preferably 400-600 rpm.

[0096] In the present invention, after the second-step reaction is completed, it preferably comprises mixing the second-step reaction product with a solvent, and then adding it to a precipitant, and successively performing standing, filtration and drying to obtain the polyimine selazoline compound;

[0097] The solvent mixed with the second-step reaction product is preferably at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide; more preferably N,N-dimethylformamide; when there are two or more of the above solvents, there is no special limitation on the ratio of different solvents; the amount of the solvent used in the reaction has no special limitation and can be adjusted according to the actual situation;

[0098] The manner of adding the precipitant is preferably dropwise addition; the precipitant is preferably at least one of water, methanol, n-hexane and ethanol, more preferably a mixed solvent of methanol and water; when there are two or more of the above precipitants, there is no special limitation on the ratio of different precipitants;

[0099] The drying temperature is preferably 20-80 °C, more preferably 40-60 °C.

[0100] The present invention provides the polyimine selazoline compounds prepared by the above synthesis method, preferably comprising any one of the following structures:

[0101]

[0102] The present invention also provides the application of the polyiminoselenazoline compounds in the field of high refractive index materials, preferably as an anti-reflection coating for optical devices and as a potential material for microlenses of complementary metal oxide semiconductor image sensors.

[0103] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0104] Example 1

[0105] Using elemental selenium 1, monofunctional aromatic amine 2a and bifunctional aliphatic isocyanide 3a as raw materials to synthesize diselenourea compound 5a. After separation and purification, the diselenourea compound 5a reacts with bifunctional α-bromoacetophenone 4a to obtain a polyiminoselenazoline compound (P1) with a selazole ring in the main chain and an imino group in the side chain;

[0106] Among them, the monomer elemental selenium is purchased from Aladdin Chemistry Co., Ltd.;

[0107] The monofunctional aromatic amine 2a is aniline, purchased from Aladdin Co., Ltd.;

[0108] The bifunctional aliphatic isocyanide 3a is 1,6-hexanediisocyanide, and its synthesis method is as described in the literature (Preparation of Multi-Functional Polyamide Vitrimers via the Ugi Four-Component Polymerization and Oxime-Promoted Transcarbamoylation Reaction. Polym. Chem. 2021, 12, 2009-2015);

[0109] The bifunctional α-bromoacetophenone 4a is 1,6-hexanedi(4-phenyl)bromo ketone, and its synthesis method is as described in the literature (Ultrasound and Water-Mediated Synthesis of Bis-Thiazoles Catalyzed by Fe(SD)3 as Lewis Acid Surfactant-Combined Catalyst. J. Sulfur Chem. 2018, 39, 140-150;

[0110] Using elemental selenium 1, monofunctional aromatic amine 2a, and bifunctional aliphatic isocyanide 3a as raw materials to synthesize diselenourea compound 5a specifically as follows: In a 10 mL polymerization tube, sequentially add elemental selenium 1 (0.32 g, 4.0 mmol) and 1,6 - hexanediisocyanide 3a (0.14 g, 1.0 mmol). Evacuate and replace with nitrogen 2 - 3 times. Under a nitrogen atmosphere, add 2 mL of a DMSO solution of aniline 2a (0.19 g, 2.0 mmol) through a syringe. React the above reaction mixture at room temperature for 3 hours. After the reaction is completed, add 1 mL of DMSO for dilution. Then filter the reaction solution through cotton, and dropwise add it into 200 mL of tap water. Stir for 3 - 5 minutes and then let it stand to fully precipitate the product. Filter and collect the precipitate. Wash the obtained precipitate 3 times with 50 mL of tap water, and then dry the obtained precipitate in a vacuum oven at 40 °C for 1 day. The obtained white solid is diselenourea 5a, and the yield is 86%.

[0111] The reaction equation is as shown in Equation (1):

[0112]

[0113] Diselenourea 5a reacts with bifunctional α - bromo ketone compound 4a to obtain a polyimine selazoline compound (P1) with a selazole ring in the main chain and an imino group in the side chain, specifically as follows:

[0114] In a 10 mL polymerization tube, sequentially add diselenourea 5a (0.10 g, 0.2 mmol) and dibromo ketone compound 4a (0.10 g, 0.2 mmol). Evacuate and replace with nitrogen 2 - 3 times. Under a nitrogen atmosphere, add 1 mL of DMF as a solvent through a syringe. React the above reaction mixture at 40 °C for 8 hours. After the reaction is completed, add 2 - 3 mL of methanol to completely dissolve the precipitated solid, and dropwise add it into a mixed solvent of methanol and water (10 mL of methanol and 100 mL of tap water). Stir for 5 minutes and then let it stand to fully precipitate the product. If the product fails to fully precipitate, increase the water content in the precipitant or dropwise add saturated NH4Cl solution to completely precipitate the product. Filter and collect the precipitate. Wash the obtained precipitate 3 times with 50 mL of tap water, and then dry the obtained precipitate in a vacuum oven at 40 °C for 1 day. The obtained white solid is polyimine selazoline P1, and the yield is 99%.

[0115] The reaction equation is as shown in Equation (2):

[0116]

[0117] The structural formula of polyimine selazoline compound P1 is:

[0118]

[0119] After determination and analysis, the yield of the polyiminoselenazoline compound P1 was 99%, the weight-average molecular weight was 10700 g / mol, the molecular weight distribution was 1.26, and n was 14.

[0120] Example 2

[0121] Using elemental selenium 1, monofunctional aromatic amine 2a, and bifunctional aliphatic isocyanide 3b as raw materials to synthesize diselenourea compound 5b, and then reacting with bifunctional α-bromoacetophenone 4a to obtain a polyiminoselenazoline compound (P5) with a selazole ring in the main chain and an imino group in the side chain;

[0122] Among them, the synthesis method of the bifunctional aliphatic isocyanide 3b is as described in the literature (Preparation of Multi-Functional Polyamide Vitrimers via the Ugi Four-Component Polymerization and Oxime-Promoted Transcarbamoylation Reaction. Polym. Chem. 2021, 12, 2009-2015);

[0123] The specific synthesis of diselenourea compound 5b from elemental selenium 1, monofunctional aromatic amine 2a, and bifunctional aliphatic isocyanide 3b is as follows: Weigh elemental selenium 1 (0.32 g, 4.0 mmol) and aliphatic diisocyanide 3b (0.17 g, 1.0 mmol) and add them successively to a 10 mL polymerization tube. Evacuate and replace with nitrogen 2-3 times. Under a nitrogen atmosphere, add 2 mL of a DMSO solution of aniline 2a (0.23 g, 2.5 mmol) through a syringe. React the above reaction mixture at room temperature for 3 hours. After the reaction is completed, add 1 mL of DMSO for dilution. Then filter the reaction solution through cotton, dropwise add it to 200 mL of tap water, stir for 3-5 minutes, and then let it stand for the product to fully precipitate. Filter and collect the precipitate. Wash the obtained precipitate 3 times with 50 mL of tap water, and then dry the obtained precipitate in a vacuum oven at 40 °C for 1 day. The obtained off-white solid is diselenourea 5b, and the yield is 69%.

[0124] The reaction equation is as shown in Equation (III):

[0125]

[0126] The reaction of diselenourea 5b with bifunctional α-bromo ketone compound 4a to obtain a polyiminoselenazoline compound (P5) with a selazole ring in the main chain and an imino group in the side chain is specifically as follows:

[0127] In a 10 mL polymerization tube, add bis(selenoureido) 5b (0.10 g, 0.2 mmol) and dibromo ketone compound 4a (0.10 g, 0.2 mmol) in sequence. Evacuate and replace with nitrogen 2 - 3 times. Under a nitrogen atmosphere, add 1 mL of DMF as a solvent through a syringe. The above reaction mixture is reacted at 40 °C for 8 hours. After the reaction is completed, add 2 - 3 mL of methanol to completely dissolve the precipitated solid, and slowly drop it into a mixed solvent of methanol and water (10 mL of methanol and 100 mL of tap water). Stir for 5 minutes and then let it stand to fully precipitate the product. If the product fails to fully precipitate, increase the water content in the precipitating agent or slowly add saturated NH4Cl solution dropwise to fully precipitate the product. Filter and collect the precipitate. After washing it 3 times with 50 mL of tap water, dry the obtained precipitate in a vacuum oven at 40 °C for 1 day. The obtained yellow solid is polyiminoselenazoline P5, and the yield is 92%.

[0128] Its reaction equation is as shown in Equation (IV):

[0129]

[0130] The structural formula of polyiminoselenazoline compound P5 is:

[0131]

[0132] After determination and analysis, the yield of polyiminoselenazoline compound P5 is 92%, the weight - average molecular weight is 13400 g / mol, the molecular weight distribution is 1.65, and n is 17.

[0133] Example 3

[0134] Using elemental selenium 1, monofunctional aromatic amine 2a, and bifunctional aliphatic isocyanide 3a as raw materials for reaction, without separation and purification, directly add bifunctional α - bromoacetophenone 4a for reaction to obtain polyiminoselenazoline compound (P1’) with selenazole rings in the main chain and imino groups in the side chain;

[0135] The specific synthesis steps of the polyiminoselenazoline compound (P1’) are as follows:

[0136] In a 10-mL polymerization tube, elemental selenium (0.03 g, 0.4 mmol) and 1,6-hexanediisocyanide 3a (0.03 g, 0.2 mmol) were successively added to a 10-mL Schlenk tube equipped with a magnetic stir bar. The tube was evacuated and refilled with nitrogen 2-3 times. Under a nitrogen atmosphere, aniline (0.04 g, 0.4 mmol) and 1 mL of DMF as a solvent were added via a syringe. The above reaction mixture was reacted at room temperature for 3 hours. Without separation and purification, bifunctional bromoacetophenone 4a (0.10 g, 0.2 mmol) was added to the above reaction system. At this time, the temperature of the reaction system was raised to 40 °C and the reaction continued for 8 hours. After the reaction was completed, 2-3 mL of methanol was added to completely dissolve the precipitated precipitate. The above reaction solution was gradually dropped into a mixed solvent of methanol and water (10 mL of methanol and 100 mL of tap water). After stirring for 5 minutes, it was left standing to fully precipitate the product. If the product was not completely precipitated, the water content in the precipitant was increased, or saturated NH4Cl solution was added dropwise to completely precipitate the product. The precipitate was filtered and collected, washed 3 times with 50 mL of tap water, and the obtained precipitate was dried in a vacuum oven at 40 °C for 1 day. The obtained white solid was polyiminoselenazoline P1’, and the yield was 71%.

[0137] The reaction equation is as shown in Equation (V):

[0138]

[0139] The structural formula of polyiminoselenazoline compound P1’ is:[[]]

[0140]

[0141] After determination and analysis, the yield of polyiminoselenazoline compound P1’ was 71%, the weight-average molecular weight was 20300 g / mol, and the molecular weight distribution was 1.64. n was 26.[[]]

[0142] Example 4

[0143] Using elemental selenium 1, bifunctional aliphatic amine 2b, and bifunctional aromatic isocyanide compound 3c as raw materials for reaction, without separation and purification, monofunctional α-bromoacetophenone compound 4b was directly added for polymerization to obtain polyiminoselenazoline compound (P9) with selenazole rings and imino groups on the main chain;

[0144] The synthesis steps of the polyiminoselenazoline compound (P9) are as follows: In a 10-milliliter polymerization tube, elemental selenium 1 (0.06 g, 0.8 mmol), aromatic diisocyanide 3c (0.03 g, 0.2 mmol), and 1,6-hexanediamine 2b (0.02 g, 0.2 mmol) are added in sequence. The tube is evacuated and refilled with nitrogen 2 - 3 times. Under a nitrogen atmosphere, 1 mL of DMF is added as a solvent through a syringe, and the above reaction mixture is reacted at room temperature for 3 hours. Without separation and purification, bromoacetophenone 4b (0.08 g, 0.2 mmol) is added to the above reaction system. At this time, the temperature of the reaction system is raised to 40 °C and the reaction continues for 8 hours. After the reaction is completed, 2 - 3 mL of methanol is added to completely dissolve the precipitated solid. The above reaction solution is passed through a cotton filter to remove excess elemental selenium, and then dropped into a mixed solvent of methanol and water (10 mL of methanol and 100 mL of tap water) drop by drop. After stirring for 5 minutes, it is left to stand to fully precipitate the product. If the product fails to fully precipitate, the water content of the precipitant is increased, or saturated NH4Cl solution is added drop by drop to completely precipitate the product. The precipitate is filtered and collected, washed 3 times with 50 mL of tap water, and then the obtained precipitate is dried in a vacuum oven at 40 °C for 1 day. The obtained brown solid is polyiminoselenazoline P9.

[0145] Its reaction equation is as shown in Equation (VI):

[0146]

[0147] The structural formula of the polyiminoselenazoline compound P9 is:

[0148]

[0149] After determination and analysis, the yield of the polyiminoselenazoline compound P9 is 84%.

[0150] Example 5

[0151] Using elemental selenium 1, bifunctional aliphatic amine 2b, and bifunctional aromatic isocyanide compound 3c as raw materials for reaction, poly(selenourea) (P10) is obtained;

[0152] The synthesis steps of the poly(selenourea) (P10) are as follows: In a 10-mL polymerization tube, elemental selenium 1 (0.06 g, 0.8 mmol), aromatic diisocyanide 3c (0.03 g, 0.2 mmol), and 1,6-hexanediamine 2b (0.02 g, 0.2 mmol) are successively added to a 10-mL Schlenk tube equipped with a magnetic stir bar. The tube is evacuated and refilled with nitrogen 2-3 times. Under a nitrogen atmosphere, 1 mL of DMF is added as a solvent through a syringe. The above reaction mixture is reacted at room temperature for 1 hour. After the reaction is completed, 2 mL of DMF is added to dilute the reaction solution. The reaction solution is passed through a cotton filter to remove excess elemental selenium, and then it is slowly dropped into 100 mL of methanol. After stirring for 5 minutes, it is allowed to stand to fully precipitate the product. The precipitate is filtered, collected, washed 3 times with 50 mL of methanol, and the obtained precipitate is naturally dried. The obtained brown solid is poly(selenourea) P10.

[0153] Its reaction equation is as shown in Equation (VII):

[0154]

[0155] The structural formula of poly(selenourea) (P10) is:

[0156]

[0157] After determination and analysis, the yield of poly(selenourea) P10 is 88%.

[0158] The model compound corresponding to the product described in Synthesis Example 1

[0159] In a 10-mL polymerization tube, bis(selenourea) 5a (0.10 g, 0.2 mmol) and α-bromoacetophenone 4b (0.10 g, 0.4 mmol) are successively added. The tube is evacuated and refilled with nitrogen 2-3 times. Under a nitrogen atmosphere, 1 mL of DMF is added as a solvent through a syringe. The above reaction mixture is reacted at 40 °C for 3 hours. After the reaction is completed, 2-3 mL of methanol is added to completely dissolve the precipitated solid. The dissolved and diluted reaction solution is extracted 3 times with CH2Cl2 (80 mL) and water (3 × 50 mL). The organic phase is collected, dried over an appropriate amount of anhydrous MgSO4, filtered, and the filtrate is collected and the organic solvent is removed by a rotary evaporator. The obtained crude product is separated by a silica gel chromatography column. During purification, first, an eluent with low polarity (a mixed solvent of petroleum ether and ethyl acetate with a volume ratio of 5:1) is used to remove impurities, and then the eluent is changed to a mixed solvent of CH2Cl2 and methanol with high polarity (v / v = 10:1). The eluate is collected, and the organic solvent is removed by a rotary evaporator. The obtained yellow solid is iminoselenazoline 6a, and the yield is 96%.

[0160] Its reaction equation is as shown in Equation (VIII):

[0161]

[0162] The reaction equations for preparing polyiminoselenazoline compounds P1, P5, P1', and P9 in Examples 1 to 4 are shown in Figure 1 the figure. Among them, Route A is the general synthesis route for compounds P1 - P8, Route B is the synthesis route for compound P1', and Route C is the synthesis route for compound P9.

[0163] The nuclear magnetic resonance hydrogen spectra and carbon spectra of the polyiminoselenazoline compound P1, diselenourea compound 5a, and model compound 6a prepared in Example 1 were detected, and the results are as Figure 2 shown (* represents the solvent peak);

[0164] Among them, Figure 2 A in it is the nuclear magnetic resonance hydrogen spectrum of diselenourea compound 5a, Figure 2 B in it is the nuclear magnetic resonance hydrogen spectrum of model compound 6a, Figure 2 C in it is the nuclear magnetic resonance hydrogen spectrum of polyiminoselenazoline compound P1, Figure 2 D in it is the nuclear magnetic resonance carbon spectrum of diselenourea compound 5a, Figure 2 E in it is the nuclear magnetic resonance carbon spectrum of model compound 6a, Figure 2 F in it is the nuclear magnetic resonance carbon spectrum of polyiminoselenazoline compound P1;

[0165] Figure 2 The characteristic peak corresponding to the hydrogen atom on the double bond of the selazoline ring of polyiminoselenazoline compound P1 is at a chemical shift of 6.55 ppm, which matches the proton resonance peak of the iminoselenazoline ring double bond at 6.54 ppm in model compound 6a. In addition, the NH proton signal peaks of diselenourea 5a at 9.83 and 8.07 ppm were not observed in the nuclear magnetic resonance hydrogen spectrum of polyiminoselenazoline P1. Furthermore, the characteristic peak of C=N outside the selazoline ring of polyiminoselenazoline compound P1 is at a chemical shift of 159.32 ppm, which matches the C=N carbon resonance peak at 159.31 ppm in model compound 6a. At the same time, the carbon signal peak of C=Se of diselenourea 5a at 178.37 ppm was not observed in the nuclear magnetic resonance carbon spectrum of polyiminoselenazoline P1. Therefore, the structure of the expected polyiminoselenazoline compound can be determined.

[0166] The nuclear magnetic resonance selenium spectra and X-ray photoelectron spectra of raw material 4a (A), diselenourea compound 5a (B), model compound 6a (C), and the prepared polyiminoselenazoline compound P1 (D) in Example 1 were detected, and the results are as Figure 3 shown;

[0167] Figure 3In A, the selenium signal peak of the C=Se of the selenourea group in the nuclear magnetic resonance selenium spectrum of diselenourea 5a appears at 212.75 / 234.52 ppm, while the selenium signal peaks of the iminoselenazoline ring in polyiminoselenazoline P1 and model compound 6a appear at 524.81 ppm (P1) and 527.57 ppm (6a), respectively, indicating that the C=Se in the selenourea group is successfully converted into C-Se in the iminoselenazoline group. In Figure 3 In B, the Se 3d binding energies of polyiminoselenazoline P1 and model compound 6a match, being 56.24 / 57.14 eV (P1) and 56.54 / 57.44 eV (6a) respectively, which are significantly different from the Se 3d binding energy of diselenourea 5a (54.41 / 55.31 eV).

[0168] The raw material 4a (A), diselenourea compound 5a (B), model compound 6a (C), and the prepared polyiminoselenazoline compound P1 (D) in Example 1 were subjected to infrared absorption spectroscopy detection, and the results are as Figure 4 shown;

[0169] Through Figure 4 it can be seen that after the reaction of raw material 4b and diselenourea compound 5b, new stretching vibration peaks of C=N (1608 cm -1 and 1598 cm -1 ) appear in the infrared spectra of model compound 6a and the synthesized polyiminoselenazoline compound P1. At the same time, there are no stretching vibration peaks of C=O (1679 cm -1 ) belonging to α-bromoacetophenone compounds and stretching vibration peaks of C=Se (1545 cm -1 ) belonging to diselenourea compound 5a. This indicates that after the second-step reaction, α-bromoacetophenone compounds and diselenourea compounds are successfully converted into polyiminoselenazoline compounds.

[0170] The polyiminoselenazoline compounds with selenazole rings in the main chain and imino groups in the side chain prepared in Example 1 (P1), Example 2 (P5), and Example 5 (P9) were subjected to thermogravimetric detection, and the obtained thermogravimetric curves are as Figure 5 shown; Figure 5 In it, P2, P3, and P4 are the polymerization products of diselenourea 5a and dibromoacetophenones containing biphenyl, fluorenyl, and meta-substituted phenyl groups; P6, P7, and P8 are the polymerization products of diselenourea 5b and dibromoacetophenones containing biphenyl, fluorenyl, and meta-substituted phenyl groups. From Figure 5 it can be seen that the temperature corresponding to 5% weight loss of this type of selenium-containing heterocyclic polymer is 194 - 307 °C, indicating that this type of selenium-containing heterocyclic polymer has good thermal stability.

[0171] The polyiminoselenazoline compounds (30 mg) with selazole rings in the main chain and imino groups in the side chain prepared in Example 1 (P1), Example 2 (P5), and Example 5 (P9), etc. were dissolved in a mixed solvent of 0.7 mL of N,N-dimethylacetamide (DMAc) and 0.3 mL of chlorobenzene, and then filtered through a 200-μm nylon filter membrane. 30 μL of the filtrate was dropped onto a 2 cm * 2 cm silicon wafer and spin-coated to obtain a thin film.

[0172] The selected spin coater model was KW-41, and the rotation speed was 1000 rpm. After drying the prepared thin film, the refractive index was measured at a wavelength of 400 - 1700 nm using a variable angle spectroscopic ellipsometer (Vertical VASE (V-VASE)); among them, the thicknesses of the prepared polymer thin films were 331 nm (P1), 210 nm (P3), 238 nm (P5), 314 nm (P6), and 321 nm (P7); the results are as Figure 6 shown; Figure 6 P3, P6, and P7 in Figure 5 .

[0173] From Figure 6 it can be seen that the refractive index of this type of polymer at 633 nm can reach 1.8639, which is much higher than that of commercial polymers (the refractive indices of commercial polymer materials are mostly between 1.5 and 1.6), and it has potential applications in the optical and optoelectronic fields.

[0174] Thermogravimetric analysis was performed on the polyiminoselenazoline compound P9 prepared in Example 4 and its corresponding polyselenourea compound P10 (Example 5), and the results are as Figure 7 shown;

[0175] From Figure 7 it can be seen that the temperatures corresponding to a 5% weight loss of the polyiminoselenazoline compound P9 and its corresponding polyselenourea compound P10 are 294 °C and 256 °C, respectively, indicating that this type of selenium-containing heterocyclic polymer has better thermal stability.

[0176] As can be seen from the above embodiments, the present invention provides a method for synthesizing diselenourea from elemental selenium, amine and isocyanide, and polymerizing diselenourea and α-bromoacetophenone to synthesize polyiminoselenazoline compounds. The present invention also provides a method for in-situ constructing polyiminoselenazoline compounds with selenazole rings in the main chain and imino groups in the side chain through tandem polymerization involving elemental selenium, and fully leveraging the great advantage of adjustable multi-component polymerization monomers. By simply swapping monomers, the goal of in-situ constructing polyiminoselenazoline compounds with both selenazole rings and imino groups in the main chain from elemental selenium in one pot is achieved. The polymerization process does not involve any toxic metal catalysts, is simple, efficient, economical and environmentally friendly, and its products have high regioselectivity and adjustable structures. It can be seen through experimental verification that the polyiminoselenazolines synthesized by the present invention all have good thermal stability, good film-forming properties and relatively high refractive indices, and have potential application values in the field of high refractive index materials, and can be used as anti-reflection coatings for optical devices and as microlenses for complementary metal oxide semiconductor image sensors, etc.

[0177] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for synthesizing a polyiminoselenazoline compound, characterized in that, It comprises the following steps: (1) Under a protective atmosphere, elemental selenium, an amine compound, an isocyanide compound and an organic solvent are mixed to carry out the first reaction to obtain a diselenourea compound; (2) The diselenourea compound is mixed with an α-bromoacetophenone compound to carry out the second reaction to obtain a polyiminoselenazoline compound; The amine compound comprises a monofunctional aromatic amine and a bifunctional aliphatic amine; The isocyanide compound comprises a bifunctional aliphatic isocyanide and a bifunctional aromatic isocyanide; The α-bromoacetophenone compound comprises a monofunctional α-bromoacetophenone compound or a bifunctional α-bromoacetophenone compound.

2. The method for synthesizing a polyiminoselenazoline compound according to claim 1, wherein when the amine compound is a monofunctional aromatic amine and the isocyanide compound is a bifunctional aliphatic isocyanide, the molar ratio of the diselenourea compound to the α-bromoacetophenone compound is 1-10:1-100; or when the amine compound is a monofunctional aromatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide and the α-bromoacetophenone compound is a bifunctional α-bromoacetophenone compound, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1-10:1-10; or when the amine compound is a bifunctional aliphatic amine, the isocyanide compound is a bifunctional aliphatic isocyanide and the α-bromoacetophenone compound is a monofunctional α-bromoacetophenone, the molar ratio of the amine compound to the α-bromoacetophenone compound is 1-10:1-20.

3. The synthesis method of the polyiminoselenazoline compound according to claim 1, characterized in that, The monofunctional aromatic amine comprises any one of the following structures: Among them, R 1 , R 2 and R 3 are independently H, F, Cl, Br, I, hydroxyl group, mercapto group, trifluoromethyl group, an alkyl group with a carbon chain length of 1 to 200 or an alkoxy group with a carbon chain length of 1 to 200; The bifunctional aliphatic amine comprises any one of the following structures: wherein, m is an integer between 0 and 2000; The molar ratio of the elemental selenium to the amine compound is 2-20:1-5.

4. The synthesis method of the polyiminoselenazoline compound according to claim 1, characterized in that, The bifunctional aliphatic isocyanide comprises any one of the following structures: wherein, m is an integer between 0 and 2000; The bifunctional aromatic isocyanide compound comprises any one of the following structures: wherein, R 4 is a hydrogen atom or an alkyl group having a carbon chain length of 1 to 200; X is CH2, O or S; The molar ratio of the amine compound to the isocyanide compound is 1-10:2-5.

5. The synthesis method of the polyiminoselenazoline compound according to claim 1, characterized in that, The temperature of the first reaction is 25-120 °C, the time is 3-24 h, and the stirring rate is 100-900 rpm.

6. The synthesis method of the polyiminoselenazoline compound according to claim 1, characterized in that, The monofunctional α-bromoacetophenone compound comprises any one of the following structures: wherein, R 5 or R 6 is independently H, F, Cl, Br, I, trifluoromethyl, phenyl, an alkyl group having a carbon chain length of 1 to 2000, or an alkoxy group having a carbon chain length of 1 to 2000; m is an integer between 0 and 2000; The bifunctional α-bromoacetophenone compound comprises any one of the following structures: wherein, m is an integer between 0 and 2000.

7. The synthesis method of the polyiminoselenazoline compound according to claim 1, wherein The temperature of the second reaction is 25-120 °C, the time is 3-24 h, and the stirring rate is 100-900 rpm.

8. The synthesis method of the polyiminoselenazoline compound according to claim 1, characterized in that, The protective atmosphere is at least one of nitrogen or a noble gas; the organic solvent is at least one of tetrahydrofuran, acetonitrile, ethanol, methanol, toluene, 1,4-dioxane, 1,2-dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide.

9. A polyiminoselenazoline compound synthesized by the synthesis method according to any one of claims 1-8.

10. Use of the polyiminoselenazoline compound according to claim 9 in a high refractive index material, as an anti-reflection coating for optical devices and as a potential material for microlenses of complementary metal oxide semiconductor image sensors.

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