WO2020159407A1

WO2020159407A1 - Pigment for protective elements of multi-layered articles based on substituted nickel dithiolene complexes with asymmetrical ligands

Info

Publication number: WO2020159407A1
Application number: PCT/RU2020/050009
Authority: WO
Inventors: Андрей Борисович КУРЯТНИКОВ; Елена Михайловна ФЕДОРОВА; Игорь Васильевич ПАВЛОВ; Ольга Игоревна ВОСКРЕСЕНСКАЯ; Лариса Александровна ПЕВЦОВА; Александра Александровна ТОРГАШОВА; Марина Эдуардовна СНЕГИРЕВА; Ирина Петровна ТАРАНЕЦ; Наталья Леонидовна ЗАЙЧЕНКО; Андрей Иванович ШИЁНОК; Александр Владимирович ЛЮБИМОВ; Любовь Сергеевна КОЛЬЦОВА
Original assignee: Акционерное общество "Гознак" (АО "Гознак")
Priority date: 2019-01-28
Filing date: 2020-01-27
Publication date: 2020-08-06
Also published as: RU2703168C1

Abstract

The invention relates to pigment chemistry, and particularly to the production of variants of pigments based on compounds that are substituted nickel dithiolene complexes with asymmetrical ligands. A method of producing a pigment for protective elements of multi-layered articles that is based on substituted nickel dithiolene complexes with asymmetrical ligands comprises producing 1-R2-3-R1-thiocarbamide, where R1 is aryl, and R2 is alkyl C1-C18, cycloalkyl, allyl, propargyl, aralkyl or aryl, wherein R1 is not equal to R2. Next, it is reacted with oxalyl chloride to form 1-R2-3-R1-2-thioxo-imidazolidine-4,5-dione and introduced into a reaction with metallic nickel in the presence of Lawesson's reagent, and the target product is obtained. A pigment is obtained for protective elements of multi-layered articles that possesses high light resistance and good stability with respect to the effects of the environment and aggressive media.

Description

PIGMENT FOR PROTECTIVE ELEMENTS OF MULTILAYER PRODUCTS BASED ON SUBSTITUTED DITHIOLENE NICKEL COMPLEXES WITH NON-SYMMETRIC LIGANDS

The invention relates to the chemistry of pigments, in particular, to the production of variants of pigments based on compounds - substituted dithiolene complexes of nickel with asymmetric ligands of General formula 1:

where Ri is aryl, including 1 - or 2-naphthyl, or phenyl, unsubstituted or containing at different positions of the benzene ring from 1 to 5 identical or different substituents such as straight or branched alkyl groups Ci-Ci ₈ , including partially or fully fluorinated and / or alkoxy groups, with straight or branched alkyl Ci-Ci ₈ , including partially or completely fluorinated, and / or phenyl, and / or one or more halogen atoms of fluorine, chlorine or bromine;

where R ₂ is a straight or branched alkyl Ci-Ci ₈ , including partially or completely fluorinated, cycloalkyl Cs-C _b , allyl, propargyl or aryl containing from 1 to 5 identical or different substituents at various positions of the benzene ring - normal or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated and / or alkoxy groups, with straight or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated, and / or phenyl, and / or one or several halogen atoms of fluorine, chlorine or bromine; unbranched alkyl containing in the chain one or more oxygen bridges of the type (CO) ^, where n = 1 -4, and R = methyl, ethyl or phenyl; aralkyl, where alkyl - normal alkyl chain C ₁ -C ₄ and the aryl - phenyl unsubstituted or containing the various positions of the benzene ring from 1 to 3 alkyl normal substituents C1-C4, and / or one or more halogen atoms of fluorine, chlorine or bromine, and / or alkoxy groups, with straight or branched C1-C18 alkyls, including partially or completely fluorinated, and / or phenyl, and Ri is not equal to R2, which are IR absorbers, as well as to the method of obtaining them, and can be used to create means of protection against counterfeiting of banknotes, office, accounting and other important business and valuable documents, including such as a valuable document protected from counterfeiting, representing a banknote, passport, security, plastic card, token made of multilayer composite material, certificate, travel document, excise stamp, bill of exchange, diploma, driver's license or other similar products with at least one security element made by printing method.

The claimed pigments-compounds, their properties and production method are not described in the literature.

The claimed compounds have a structure related to dithiolene metal complexes of nickel with alkyl-, cycloalkyl-, aralkyl- or aryl-substituted imide azolidine -2-chalcogenone-4, 5-d itione ligands.

Such metal complexes are known from the prior art, in particular, symmetric substituted dithiolene nickel complexes (EP 3067216 A1, publ. 09/14/2016; US 20114103635 A1, publ. 04/17/2014; US 2013234427 A1, publ. IR regions and practically do not absorb visible light, which makes them invisible to the human eye and is an important advantage, since most of the known IR absorbers of other structures are dyes that intensively absorb in the visible region of the spectrum, which makes them unsuitable for the above-mentioned special application.

For special use, infrared absorbers are required that intensely absorb in the 800-1200 nm range (e> 50,000 L mol Dm ¹ ) and do not absorb or weakly absorb in the visible region (e <10000 L mol ¹ cm ¹ ). In addition to the requirement to be free from absorption in the visible region of the spectrum, IR absorbers for anti-counterfeiting products must meet stringent resistance requirements: thermal stability, lightfastness, and chemical stability with respect to chemicals and solvents.

International patent application WO 2008/086931, 07.24.2008, describes nickel dithiolene complexes with symmetric alkyl-substituted imidazolidine-2-chalcogenone-4,5-dithione ligands, for example, of the following structure:

which practically do not absorb in the visible region of the spectrum, have good light and heat resistance, but are not sufficiently resistant to chemical reagents and boiling water.

In patent RU 2575644 publ. On February 20, 2016, instead of N-alkyl substituents in the ligand, N-aryl substituents are used (all four are the same), which made it possible to increase the stability of symmetric dithiolene nickel complexes with respect to chemical reagents and solvents without losing other advantages.

The structure of compounds belonging to the class of metal-dithiolene complexes, as well as their electronic structure and parameters describing this structure is also known (M. Area et al. Synthesis, X-ray crystal structure and spectroscopic characterization of the new dithiolene [Pd (Et2timdt) 2] and of its adduct with molecular diiodine [Pd (Et2timdt) 2] -I2-CHC13 (Et2timdt = monoanion of l, 3-diethylimidazolidine-2,4,5-trithione) J. Chem. Soc., Dalton Trans., 1998, 0, 3731-3736).

The use of substances to create pigments used in paint to protect products, and techniques for creating anti-counterfeiting pigments to create elements in multilayer products, described in patents RU 2379194, publ. 20.01.2010, and RU 2425757, publ. 08/10/2011

At present, the possibility of creating such a protection with the introduction of pigments, such as dithiolene metal complexes with asymmetric ligands, has not been practically studied.

However, despite the fact that the above proposals to some extent solved the problem of protection against counterfeiting of products, the disadvantage of these known solutions is that rapidly changing requirements for product security determine the need to create and promptly implement new technologies to prevent counterfeiting of products.

The objective of the claimed invention is to develop a high degree of protection against counterfeiting due to the introduction of a new pigment for security elements of multilayer products based on substituted dithiolene nickel complexes with asymmetric imidazolidine ligands, as well as a method for its production.

The technical result of the claimed invention is to obtain a pigment for security elements of multilayer products, which has high lightfastness and good resistance to the external environment and aggressive environments.

The claimed invention ensures that prints of paints with the above-described pigment based on these materials have high lightfastness, good resistance to the action of organic solvents of various types, solutions of acids, alkalis and sodium hypochlorite, hot water, solutions that simulate artificial sweat, as well as solutions of detergents for household and industrial washing.

The solution to this problem is achieved by creating a pigment for security elements of multilayer products based on substituted dithiolene nickel complexes with asymmetric ligands of general formula 1: where Ri is aryl, including 1 - or 2-naphthyl, or phenyl, unsubstituted or containing at different positions of the benzene ring from 1 to 5 identical or different substituents such as straight or branched alkyl groups Ci-Ci ₈ , including partially or fully fluorinated and / or alkoxy groups, with straight or branched alkyl Ci-Ci ₈ , including partially or completely fluorinated, and / or phenyl, and / or one or more halogen atoms of fluorine, chlorine or bromine;

where R ₂ is a straight or branched alkyl Ci-Ci ₈ , including partially or completely fluorinated, cycloalkyl Cs-C _b , allyl, propargyl or aryl containing from 1 to 5 identical or different substituents at various positions of the benzene ring - normal or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated and / or alkoxy groups, with straight or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated, and / or phenyl, and / or one or several halogen atoms of fluorine, chlorine or bromine; unbranched alkyl containing in the chain one or more oxygen bridges of the type (CH ₂ CH ₂ 0) _n R, where n = l-4, and R = methyl, ethyl or phenyl; aralkyl, where alkyl is a normal C1-C4 alkyl chain, and aryl is unsubstituted phenyl or containing from 1 to 3 normal C1-C4 alkyl substituents at various positions on the benzene ring, and / or one or more halogen atoms of fluorine, chlorine or bromine, and / or alkoxy groups, with straight or branched Ci-Cis alkyls, including partially or completely fluorinated, and / or phenyl, where Ri is not equal to R _2.

In addition, the claimed method for obtaining pigment for security elements of multilayer products based on substituted dithiolene complexes of nickel with unsymmetrical ligands of general formula 1 according to and. 1, consisting in the fact that 1 LS-ZLS-thiocarbamide is obtained, where Ri is aryl, and R2 is C1-C18 alkyl, cycloalkyl, aralkyl, aryl, wherein Ri is not equal to R2, reacting it with oxalyl chloride to form 1 - R ₂ -3-R _l -2-thiocoimidazolidine-4,5-dione is reacted with metallic nickel in the presence of Lawesson's reagent and the target product is obtained.

The synthesis of the proposed new dithiolene nickel complexes of general formula 1 is carried out in three stages according to the following scheme:

where Ri is aryl, R2 is Ci-Cis alkyl, cycloalkyl, allyl, propargyl, aralkyl, aryl, and Ri is not equal to R2.

The starting compounds for obtaining new organic IR absorbers of general formula 1 are Ri-isothiocyanate and amine of formula R2NH2, where Ri is aryl, and R2 is C1-C18 alkyl, cycloalkyl, allyl, propargyl, aralkyl, aryl, and Ri is not equal to R2 , which are reacted according to a known method with the formation of 1 L -3 ^ ₁ -thiocarbamide, which is then reacted with oxalyl chloride to form 1 -R ₂ -3-R _I -2-thioxoimidazolidine-4,5-dione (pre-ligand), which, in turn, under the action of Lawesson's reagent in the presence of metallic nickel, makes it possible to obtain the claimed dithiolene nickel complexes with unsymmetrical ligands of general formula 1. The structure of the obtained claimed complexes of nickel of general formula 1 and intermediate compounds is confirmed by the data of elemental analysis and spectral characteristics (examples 1-8).

Example 1.

Obtaining bis (1-n-butyl-3-phenylimidazolidine-2,4,5-trithione) nickel

- connection (1):

Example 1A. Stage 1 - obtaining 1-n-butyl-3-phenylthiocarbamide.

In a 250 ml flask equipped with a magnetic stirrer, a two-horned forstoss and a dropping funnel, 50 ml of dry tetrahydrofuran (THF) and 1.66 g (22.8 mmol) of n-butylamine were added, while stirring, 2.7 ml (3, 08 g, 22.8 mmol) phenyl isothiocyanate, the clear solution was left for several hours, then the solvent was removed, the viscous oil gradually crystallized upon addition of ether. Received a white crystalline substance with T _pl = (62-64) ° C. Yield 4.72 g (99.5%).

NMR spectrum ³ H (300 MHz, CDCh) d, ppm (CSCR, Hz): 0.92 (t, ZN, CH, ³ J = 7.3), 1.33 (m, 2H, CCH ₂ , ³ J = 7.3), 1.56 (m, 2H, CCH ₂ , ³ J = 7.3; 7.0 ), 3.62 (2H, NCH ₂ , ³ J = 7.0).

Example 1B. Stage 2 - preparation of 1-n-butyl-3-phenyl-2-thioxoimidazolidine-4,5-dione.

To a solution of 8.2 g (39.4 mmol) of 1-n-butyl-3-phenylthiocarbamide in 70 ml of dry CH ₂ C1 _{2 was} slowly added dropwise a solution of 8.55 g (39.4 mmol) of oxalyl chloride in 10 ml of dry CH ₂ C1 _{2. It was} boiled for 12 hours, the yellow transparent solution was evaporated and 8.88 g of the product with T _PL = (115-116) ° C was obtained.

Found,%: C 70.69; H 4.21. CsoH ₂₂ 0 _8. Calculated,%: C 70.58; H 4.34;

About 25.07. NMR spectrum * H (300 MHz, CD Cb) d, ppm (CSCR, Hz): 1.00 (tr., ЗН, СНз, ³ J = 7.3), 1.43 (2Н, CCH ₂ , ³ J = 7.3; 7.6), 1.77 (m, 2H, CCH ₂ , ³ J = 7.3; 7.6), 4.06 (t, 2H, NCH ₂ , ³ J = 7.5), 7.33 (d, 2H arom., ³ J = 7.9), 7.56 (t, 2H arom., ³ J = 7.7), 7.58 (t, 1H arom, 7.7).

Example 1B. Stage 3 - obtaining bis (1-n-butyl-3-phenylimidazolidine-2,4,5-trithione) nickel (1).

The reaction flask and solvent were purged with argon. Subsequently, the synthesis was also carried out under argon. 15.28 g (37.8 mmol) of Lawesson's reagent were added to a boiling solution of 8.8 g (34.4 mmol) of 1-n-butyl-3-phenyl-2-thioxoimidazolidine-4,5-dione in 300 ml of dry toluene and boiled for 4-5 minutes, then 1.01 g (17.2 mmol) of metallic nickel powder was quickly added and boiled for another 1 hour. The precipitate of dark brown crystals precipitated in hot toluene. Yield: 3.2 g (29.3% by weight), T _pl about 300 ° C.

The absorption maximum of complex (1) is observed at 1020 nm, e = 50,000 L mol ^ cm ¹ (methylene chloride), in the visible region (400-800 nm) the molar extinction coefficient did not exceed 8000 L mol ^ cm ¹ .

Example 2.

Obtaining bis (1-n-propyl-3-phenylimidazolidine-2,4,5-trithione) nickel - compound (2):

Example 2 A. Step 1 - Preparation of 1-n-propyl-3-phenylthiocarbamide.

Analogously to example 1A at a molar ratio of 1: 1, propylamine was reacted with phenyl isothiocyanate. Received a white crystalline substance with TmH (60-61) ° C. Yield 4.5 g (91.8%).

Example 2B. Stage 2 - preparation of 1-n-propyl-3-phenyl-2-thioxoimidazolidine-4,5-dione. Analogously to example 1B, at a molar ratio of 1: 1, 1-n-propyl-3-phenylthiocarbamide was reacted with oxalyl chloride. Received a yellow crystalline product with T _PL ⁼ (136-138) ° C. Yield 4.9 g (96.0%).

NMR spectrum ³ H (300 MHz, CDCb) d, ppm (CSCR, Hz): 1.03 (t, ZN, CH, ³ J = 7.4), 1.82

4.03 (t, 2H, NCH ₂ , ³ J = 7.5), 7.34 (m, 2H, arom.), 7.51 (m, 3N arom.).

Example 2B. Stage 3 - obtaining bis (1-n-propyl-3-phenylimidazolidine-2,4,5-trithione) nickel (2).

Analogously to example 1B, with a 10% molar excess of Lawesson's reagent and the corresponding amount of metallic nickel, dark brown crystals of the nickel complex (2) were obtained. Yield 1.2 g (48.0%), L _P T 300 ° C. The maximum absorption of complex (2) is observed at 1016 nm, e = 13800 L mol ^ cm ¹ (methylene chloride), in the visible region (400-800 nm) the molar extinction coefficient did not exceed 8000 L mol ^ cm ¹ .

Example 3.

Obtaining bis (1-n-hexyl-3-phenylimidazolidine-2,4,5-trithione) nickel - compound (3):

All three stages of the process of synthesizing the nickel complex (3) were carried out analogously to examples 1-2. Almost black crystals of the nickel complex (3) were obtained. Yield 1.32 g (25.8%), T _PL = (274-277) ° C. The absorption maximum of complex (3) is observed at 1011 nm, e = 90000 L mol ^ cm ¹ (methylene chloride), in the visible region (400-800 nm) the molar extinction coefficient did not exceed 8000 L mol ^ cm ¹ .

Example 4.

Obtaining bis (1-n-octyl-3-phenylimide azolidine-2,4, 5-trithione) nickel - compound (4): All three stages of the synthesis of the nickel complex (4) were carried out analogously to examples 1-3. Almost black dark brown crystals of the nickel complex (4) were obtained. Yield 1.5 g (31.0%), T _PL ⁼ (272-276) ⁰ С.The maximum absorption of complex (4) is observed at 1010 nm, e = 84000 L mol ^ cm ¹ (methylene chloride), in the visible region (400-800 nm) the molar extinction coefficient did not exceed 8000 L mol ^ cm ¹ .

Example 5.

Obtaining bis (1-cyclohexyl-3-phenylimidazolidine-2, 4,5-trithione) nickel - compound (5):

All three stages of the synthesis of the nickel complex (5) were carried out analogously to examples 1-4. Almost black dark brown crystals of the nickel complex (5) were obtained. The yield is about 1%, T _{PL is} more than 300 ° C. The absorption maximum of complex (5) is observed at 1018 nm, e is not determined.

Example 6.

Obtaining bis (1-benzyl-3-phenylimidazolidine-2,4,5-trithione) nickel - compound (6): Example 6 A. Step 1 - Preparation of 1-benzyl-3-phenylthiocarbamide.

In a flat-bottomed flask containing 20 ml of dioxane, 3.0 ml (0.025 mol) of phenyl isothiocyanate, 3.0 ml (0.027 mol) of benzylamine were poured and stirred on a magnetic stirrer at room temperature for 3 hours. It was filtered off, washed with dioxane and then with hexane. The product was dried. In 4, 1 g (67.8% of theory) of a white powder of 1-benzyl-3 -feniltiokarbamida _mp = (192-195) ° C.

Example 6B. Stage 2 - preparation of 1-benzyl-3-phenyl-2-thioxo-imidazolidine-4,5-dione.

3.0 g (12.4 mol) of the obtained 1-benzyl-3-phenylthiocarbamide and 1.57 g (0.012 mol) of oxalyl chloride were boiled for 4 hours in 20 ml of dry toluene. The reaction mixture was cooled, the precipitate was filtered off, the product was dissolved in benzene, precipitated with hexane, and dried in a desiccator over paraffin. 2.2 g (60.0% of theoretical) of an orange-yellow precipitate of the product with

T _pl = (192-195) ° C.

Example 6B. Stage 3 - obtaining bis (1-benzyl-3-phenylimidazolidine-2,4,5-trithione) nickel (6).

3.4 g of Lawesson's reagent (8.4 mmol) was placed in a 250 ml conical flask equipped with a forstoss addition funnel and a reflux condenser with a calcium chloride tube. Added 50 ml of dry toluene, pre-purged with argon, and heated the contents to boiling with stirring on a magnetic stirrer. A solution of 2.2 g (7.5 mmol) of 1-benzyl-3-phenyl-2-thioxoimidazolidine-4,5-dione in 10 ml of dry toluene purged with argon was poured through an addition funnel. After 8 minutes, 0.21 g of Ni powder (3.6 mmol) was added and the mixture was refluxed for another 1 hour. The hot solution was decanted and filtered through a thick filter. Benzene was added to the residue in the flask, the precipitate was filtered off and washed with benzene. Sediment dried in a desiccator over paraffin. Received 1.5 g (56.4% of theoretical) dark brown crystals of the complex of nickel (6). The absorption maximum of complex (6) is observed at 1010 nm, e is not determined due to poor solubility.

Example 7.

Obtaining bis [1- [2- (4-fluorophenyl) ethyl] -3-phenyl-imidazolidine-2,4,5-trithione] nickel - compound (7):

Example 7 A. Step 1 - Preparation of [1- [2- (4-fluorophenyl) ethyl] -3-phenylthiocarbamide.

In a 50 ml flask equipped with a magnetic stirrer, two-horned forstoss and a dropping funnel, 10 ml of dry tetrahydrofuran (TFG) and 2.2 ml (2.33 g, 16.75 mmol) of 2- (4-fluorophenyl) ethylamine were placed, at stirring, a solution of 3 ml (3.30 g, 25 mmol) of phenyl isothiocyanate in 5 ml of dry THF was slowly added dropwise and further stirred at room temperature for 5 hours. The solvent was distilled off on a rotary evaporator, the crystalline white precipitate was washed from the starting materials with light petroleum ether. Received 4.12 g (96.0%) of a white crystalline powder with T _PL = (64-65) ° C. Example 7B. Stage 2 - synthesis of [1- [2- (4-fluorophenyl) ethyl] -3-phenyl-2-thioxoimidazolidine-4,5-dione.

2.7 g (9.9 mmol) of 1- (1-ethyl-4-fluorophenyl) -3-phenyl-thiocarbamide and 20 ml of dry CH2CI2 were placed in a two-necked round-bottom flask equipped with a dropping funnel and a reflux condenser with a calcium chloride tube, a solution of 1 ml (1.455 g, 12 mmol) of oxalyl chloride in 5 ml of dry CH2CI2 and refluxed for 5 hours. The reaction mixture was cooled, the solvent was removed on a rotary evaporator, the residue was washed with light petroleum ether. 2.97 g (91.0%) of a yellow crystalline powder was obtained, luminescent with yellow-green light under UV illumination with T _PL = (136-138) ° C.

Example 7B. Stage 3 - synthesis of bis [1- [2- (4-fluorophenyl) ethyl] -3-phenyl-imidazolidine-2,4,5-trithione] nickel (7).

In a 250 ml flat-bottomed conical flask equipped with a two-horned forstoss with a reflux condenser and a calcium chloride tube, 2.46 g (7.5 mmol) of 1 - [2- (4-fluorophenyl) ethyl] -3-phenyl-2-thioxoimidazolidine 4,5-dione and 80 ml of dry toluene, pre-purged with argon for 20 minutes. Subsequently, the synthesis was also carried out under argon. Brought to a boil with stirring on a magnetic stirrer, and 3.33 g (8.25 mmol) of Lawesson's reagent were poured into the boiling solution. After 6 minutes, a solution of 0.242 g (4.1 mmol) of Ni powder was added and boiled for 1.5 hours. Filtered hot. The precipitate of the complex was dried in a desiccator over paraffin. Received 0.53 g (18.0%) of a brown powder with a _{Tm of} more than 300 ° C. The absorption maximum of complex (7) is observed at 1015 nm, e is not determined due to poor solubility.

Example 8.

Obtaining bis1 - [2- (3,4-dimethoxyphenyl) ethyl] -3-phenyl-imidazolidine-2,4,5-trithione] nickel - compound (8): m

Example 8 A. Step 1 - Synthesis of 1- [2- (3,4-dimethoxyphenyl) ethyl] -3-phenylthiocarbamide.

10 ml of dry tetrahydrofuran (TFG) and 2.9 ml (17.2 mmol) of 2 - (3,4-dimethoxyphenyl) ethylamine were placed in a round-bottom flask equipped with a magnetic stirrer, a two-horned forstoss and a dropping funnel; while stirring, solution 2 was slowly added , 0 ml (2.26 g, 16.7 mmol) of phenyl isothiocyanate in 4 ml of dry THF and then stirred at room temperature for 5 hours. The solvent was distilled off on a rotary evaporator, the crystalline white residue was washed from the starting materials with light petroleum ether. Received 5.04 g (95.4%) white crystalline powder with T _PL = (58-60) ° C.

NMR spectrum * H (300 MHz, CDCh) d, ppm 2.87 (t, 2H, NCH ₂ , ³ J = 6.7), 3.83 (s, 3N, OCH3), 3.90 (t, 2H, ArC, ³ J = 6.6), 6.02 (br.s, 1H, NH), 6.66 (d, 1H arom., ³ J = 8.6), 6.68 (s, 1H arom.), 6.77 (d, 1H arom., ³ J = 8.6), 7.01 (d, 2H arom., ³ J = 7.5), 7.26 (t, 1H arom., ³ J = 7.6), 7.34 (t, 2H arom., ³ J = 7.1), 7.79 (br.s, 1H, NH).

Example 8B. Stage 2 - synthesis of 1- [2- (3,4-dimethoxyphenyl) ethyl] -3-phenyl-2-thioxoimidazolidine-4,5-dione.

In a two-necked round-bottomed flask equipped with a dropping funnel and a reflux condenser with a calcium chloride tube, 2.7 g (8.53 mmol) 1- [2- (3,4-dimethoxyphenyl) ethyl] -3-phenylthiocarbamide and 20 ml of dry CH2CI2, a solution of 1.455 g (11.45 mmol) of oxalyl chloride in 5 ml of dry CH2CI2 was added dropwise and refluxed for 5 hours. The reaction mixture was cooled, the solvent was removed on a rotary evaporator, the residue was washed with light petroleum ether. 2.91 g (85.3%) of a yellow crystalline powder was obtained, luminescent with a yellow-green light under UV-curing with T _PL = (145-146) ° C.

NMR spectrum ³ H (300 MHz CDCI3) d, ppm (CSCR, Hz): 3.04 (t, 2H, CH ₂ , ³ J = 7.9), 3.86 (s, ZN, OCHs), 3.91 (s, ZN, OCHs), 4.28 (t, 2H, CH ₂ , ³ J = 7.7), 6.83 (m, ZN, arom.), 7.30 (m, 2H arom.), 7.56 (m, ZN arom.).

Example 8B. Stage 3 - synthesis of bis [1- [2- (3,4-dimethoxyphenyl) ethyl] -3-phenylimidazolidine-2,4,5-trithione) nickel (8).

In a 250 ml flat-bottomed conical flask equipped with a two-horned forstoss with a reflux condenser and a calcium chloride tube, 4.0 g (10 mmol) of 1 - [2- (3,4-dimethoxyphenyl) ethyl] -3-phenyl-2-thioxo imidazolidine-4,5-dione and 120 ml of dry toluene, previously purged with argon for 20 minutes. Subsequently, the synthesis was also carried out under argon. Brought to a boil while stirring on a magnetic stirrer, and 4.8 g (11.88 mmol) of Lawesson's reagent was poured into the boiling solution. After 5.5 minutes, a solution of 0.35 g (5.94 mmol) of Ni powder was added and boiled for 1 hour and 40 minutes. Filtered hot. The black precipitate of the complex was dried in a desiccator over paraffin. Received 0.7 g (18.0%), which was then stirred on a magnetic stirrer in 30 ml of benzene, filtered and dried in a desiccator over paraffin. Received 0.6 g (13.9%) of a black powder with T _n more than 300 ° C.

The absorption maximum of complex (8) is observed at 1016 nm, e is not determined due to poor solubility.

Example 9. Obtaining bis (1- (1-naphthyl)] - 3-phenyl-imidazolidine-2,4,5-trithione) nickel - compound (9): Example 9 A Step 1 - Preparation of 1- (1-naphthyl) -3-phenylthiocarbamide.

In 50 ml of tert-butanol were dissolved 3.7 g (20 mmol) of 1-naphthyl isothiocyanate and 2.05 g (22 mmol) of aniline and boiled for 7 hours. Gradually, a precipitate formed during boiling, after 7 hours of boiling, the precipitate was transferred to a filter, washed with ether, and dried. Received 5.7 g (94%) of a white crystalline substance, T _pl = (167-168) ° C.

Example 9B. Stage 2 - synthesis of 1- (1-naphthyl) -3-phenyl-2-thioxoimidazolidine-4, 5-dione

In 50 ml of chloroform was dissolved 2.87 g (10 mmol) of 1- (1-naphthyl) -3-phenylthiocarbamide and 1.27 g (10 mmol) of oxalyl chloride was slowly added dropwise. The mixture was refluxed for 9 hours, the red transparent solution was evaporated, and 3.1 g (93%) of a yellow product was obtained (there are no impurities on the chromatogram benzene: acetone = 9: 1), _Tm = (57 - 60) ° C.

Example 9B - Step 3 - Synthesis of bis (1- (1-naphthyl) -3-phenylimidazolidine-

2,4,5-trithione) nickel

The reaction flask and solvent were purged with argon, and further synthesis was also carried out under argon. To a boiling solution of 3.1 g (9.3 mmol) of 1- (1-naphthyl) -3-phenyl-2-thioxo-imidazolidine-4,5-dione in 100 ml of dry toluene was added 4.14 g (10.2 mmol) of Lawesson's reagent and boiled for 3 minutes, then 0.32 g (5.1 mmol) of nickel was quickly added and boiled for 1 hour. Filtered the hot solution while retaining the excess metal with a magnet. Upon cooling, a precipitate formed from the toluene solution, weight 1.5 g. The spectrum in methylene chloride showed the presence of a maximum at 1018 nm.

Example 10. Obtaining bis (1-hexyl-3 - (1-naphthyl) -imidazolidine-2,4,5-trithione) nickel - compound (10): All three stages of the synthesis of the nickel complex (10) were carried out analogously to example 9, using 1-naphthyl isothiocyanate and hexylamine as starting materials. Almost black, dark brown crystals of the nickel complex (10) were obtained.

Example 11. Obtaining bis (1- (1-naphthyl)) - 3- (2-phenylethyl) imidazolidine-2,4,5-trithione) nickel - compound (11):

All three stages of the synthesis of the nickel complex (11) were carried out analogously to example 9, using 2-phenylethyl isothiocyanate and 1-naphthylamine as starting materials. Almost black dark brown crystals of the nickel complex were obtained (11).

Example 12. Obtaining bis (1-benzyl-3 - (3-trifluoromethylphenyl) - imidazolidine-2,4,5-trithione) nickel - compound (9):

Example 12 A Step 1 Preparation of 1-benzyl-3 - (3-trifluoromethylphenyl) thiocarbamide. In 50 ml of tetrahydrofuran were dissolved 2.94 g (20 mmol) of benzyl isothiocyanate and 3.52 g (22 mmol) of 3-trifluoromethylaniline and stirred for 3 hours at room temperature. A precipitate gradually formed, after cooling in a refrigerator, it was transferred to a filter and sucked off. 5.5 g (90%) of a white crystalline solid were obtained.

Example 12B. Stage 2 - synthesis of 1-benzyl-3 - (3-trifluoromethylphenyl) -2-thioxoimidazolidine-4, 5-dione

In 50 ml of dichloromethane was dissolved 3.1 g (10 mmol) of 1-benzyl-3 - (3-trifluoromethylphenyl) thiocarbamide and 1.27 g (10 mmol) of oxalyl chloride was slowly added dropwise. The mixture was refluxed for 6 hours, the solution was evaporated to give 3.1 g (85%) of the product.

Example 12B - Step 3 - Synthesis of bis (1-benzyl-3- (3-trifluoromethylphenyl) imidazolide yn-2,4,5-trithione) nickel

The reaction flask and solvent were purged with argon, and further synthesis was also carried out under argon. To a boiling solution of 3.5 g (9.5 mmol) of 1-benzyl-3 - (3-trifluoromethylphenyl-2-thioxo-imidazolidine-4,5-dione in 100 ml of dry toluene was added 4.14 g (10.2 mmol ) Lawesson's reagent and boiled for 3 minutes, then 0.32 g (5.1 mmol) of nickel was quickly added and boiled for 1 hour.The hot solution was filtered, retaining the excess metal with a magnet. Upon cooling, a precipitate precipitated from the toluene solution, weight 1.1 g ...

As can be seen from the examples, the proposed method for preparing the claimed compounds is quite technological, and the substances used for their synthesis are commercially available compounds.

The absorption spectra of the synthesized complexes and their physicochemical properties were studied.

It was found that the maxima in the absorption spectra of all obtained compounds (1-8) in methylene chloride solutions (CH2CI2) are in the range (1000-1018 nm), and the values of the molar extinction coefficients reach 90,000 L mol ^ cm ¹ in the range (13000-90000 ) l mol ^ cm ¹ . In the visible area, the claimed compounds practically do not absorb. A typical absorption spectrum is shown in FIG. 1. Most of the claimed complexes dissolve in polar organic solvents such as acetone, methanol, ethanol, tetrahydrofuran, chloroform, and do not dissolve in water.

Imprints of paints based on these complexes have high lightfastness, good resistance to the action of organic solvents of various types, solutions of acids, alkalis and sodium hypochlorite, hot water, solutions simulating artificial sweat, as well as solutions of detergents for household and industrial washing.

Thus, as can be seen from the data presented, the claimed compounds intensively absorb in the near infrared region of the spectrum and practically do not absorb in the visible region, which makes it possible to use them as infrared absorbers when creating means of protection against counterfeiting banknotes, office, accounting and other important business and other documentation, which is, for example, a banknote, passport, security, plastic card, token made of multilayer composite material, certificate, travel document, excise stamp, bill of exchange, diploma, driver's license or other similar products with at least one security element made by printing method.

Claims

CLAIM

1. Pigment for security elements of multilayer products based on substituted dithiolenic nickel complexes with asymmetric ligands of general formula 1:

where R ₂ is a straight or branched alkyl Ci-Ci ₈ , including partially or completely fluorinated, cycloalkyl Cs-C _b , allyl, propargyl or aryl containing from 1 to 5 identical or different substituents at various positions of the benzene ring - normal or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated and / or alkoxy groups, with straight or branched Ci-Ci ₈ alkyl groups, including partially or completely fluorinated, and / or phenyl, and / or one or several halogen atoms of fluorine, chlorine or bromine; unbranched alkyl containing in the chain one or more oxygen bridges of the type (CO) ^, where n = l-4, and R = methyl, ethyl or phenyl; aralkyl, where alkyl is a normal C ₁ -C ₄ alkyl chain, and aryl is unsubstituted phenyl or containing from 1 to 3 normal C ₁ -C ₄ alkyl substituents at various positions on the benzene ring, and / or one or more halogen atoms of fluorine, chlorine or bromine, and / or alkoxy groups, straight or branched alkyls Ci-Ci ₈ , including partially or completely fluorinated, and / or phenyl, and Ri is not equal to R2.

2. A method of obtaining a pigment for security elements of multilayer products based on substituted dithiolene complexes of nickel with unsymmetrical ligands of the general formula 1 according to claim 1, consisting in the fact that 1LC-ZLS-thiocarbamide is obtained, where Ri is aryl, and R2 is alkyl C1- C18, cycloalkyl, allyl, propargyl, aralkyl, aryl, and Ri is not equal to R2, reacted with oxalyl chloride to form 1 -R ₂ -3-R _l -2-thiocoimidazolidine-4,5-dione, react with a metal nickel in the presence of Lawesson's reagent and get the target product.