RU1063053C - 1-5 (-phenyloxazolyl-2) -4- [5-(x-pyridile) -1,3,4- oxadiazolyl-2]benzol as luminescent additives of organic scintillators - Google Patents

Description

The invention relates to chemical compounds, specifically to the derivatives of 1- (5-phenyloxazolyl-2) -4- 5- (X-pyridyl) -1,3,4-oxadiazolyl-2 benzene of the general formula G,.-GN where Q Compounds of general formula I possess the properties of organic phosphors. They can be used as luminescent additives in liquid and plastic scintilla- tors, in dosimetry of ionizing radiation, in anti-scopic compositions and for other purposes. Carbo- and heterocyclic compounds, which include aromatic polyphenylene hydrocarbons with isolated and condensed aromatic rings, derivatives of aromatic five- and six-membered heterocyclic compounds with one, two, and three heteroatoms in a cycle, are known to be used as organic phosphors. . The disadvantages of the known luminophores are the complexity of the methods for their synthesis. availability of initial compounds, low quantum yields are difficult. In a series of 2-phenyl-5- (X-pyridyl) -1,3.4-oxadiazoles derivatives, compounds are known that possess a very weak violet luminescence in toluene — 2-phenyl-5- (3-pyridyl) -1,3,4- oxadiazole and 2-phenyl-5- (4-pyridyl) -1,3,4-oxadiazole. These compounds, which are colorless under visible light, do not luminesce in a crystalline state when irradiated with UV light. 2-Phenyl-5- {X-pyridyl) -1,3,4-oxadiazoles are obtained by condensation of the corresponding monopyridyl hydrazides with benzoyl chloride and subsequent cyclodehydration of the resulting compounds with dehydrating agents, for example, phosphorus. The disadvantage of these compounds is a weak luminescence in hydrocarbon solvents. This significantly limits their use as luminophores, for example, use in liquid and plastic scintillators. The lack of color in the visible state and the luminescence in the crystalline state upon irradiation with UV light also reduces the possibilities of practical application of these compounds. In connection with this, it is impossible to use them, for example, in daytime fluorescent pigments and paints and in fluorescent dyeing of polymeric materials. The aim of the invention is to expand the range of luminescent additives used in the manufacture of plastic scintillators and possessing intense luminescence in a solid state .; This goal is achieved by 1- (5-phenyloxazolyl-2) -4- {5-X-pyridyl) -1,3,4-okcdiazolyl-2 benzenes of general formula I, which can be used as luminescent additives of organic scintillators. The compounds of general formula I luminesce intensely both in the solid state and in hydrocarbon solvents upon irradiation with UV light. This effect is achieved by combining two structural groups in a single molecular system — a group of 2,5-diphenyloxazole and a group of 2- {X-pyridyl-5-phenyl 1, 3,4-oxadiazole. The grouping of 2,5-diphenyloxazole leads to the formation of a new chemical structure of the phosphor, which, upon irradiation with UV light, has an unexpectedly high luminous intensity. Compounds of general formula I — H5-phenyloxazolyl-2) (X-pyridyl) oxadiazolyl-2 benzenes — are obtained by condensation of 2- (4-carboxyphenyl) -5-phenyloxazole acid chloride with the corresponding hydrides of pyrid Incarboxylic acids, followed by the cyclic hydration of the resulting products in chlorohydroxycarbonyl hydrazides, in the carboxylic acid; PRI me R 1. Preparation of 1- {5-phenyloxazolyl-2} -4K4 pyridyloxadiazolyl-2) benzene. To a mixture of solutions, 4.5 g of 4-pyridylhydrazide in 50 ml of water and 9.3 g of 4- (5-phenyloxazolyl-2) benzoic acid chloride in 75 ml of benzene are added dropwise with vigorous stirring at 20-25 ° C. 10% soda solution until alkaline reaction to litmus. Synthesis is considered complete if after a fifteen minute exposure with vigorous stirring the medium remains alkaline. The precipitate is filtered off, washed with water and dried. The dry precipitate is boiled with five times the amount of phosphorus oxychloride for 1 hour. Then the reaction mass is poured on ice, alkalized with ammonia until neutral reaction, the precipitated at the same time the filter is filtered off, washed with water vi and dried. The resulting precipitate is recrystallized twice from chlorobenzene in the presence of alumina. The product is a yellow-green crystalline powder. Yield 8 g (70%), so pl. 283-284 ° C.

Found,%: C 72.09: H 3.92; N 15.26.

C22H14N402.

Calculated,%: C 72.13; H 3.83; N 15.30,

Amax luminescence in toluene is 415 nm, the absolute quantum yield of luminescence in toluene is 0.76; Amax luminescence in crystals 465 nm.

PRI mme R 2. Preparation of 1- {5-phenyloxazolyl-2) -4- {3-pyridyloxadiazolyl-2) benzene.

To a suspension of 4.2 g of 3-pyridylhydrazide in 100 ml of pyridine with good stirring, 8.4 g of 4- (5-phenyloxazolyl-2) benzoic acid chloride are added in portions. The resulting solution was stirred at room temperature for 2 hours and poured into cold water. The precipitate formed is filtered, washed, washed with water and dried. The dry product is boiled with five times the amount of phosphorus oxychloride for 8 hours. Then the reaction mixture is poured on ice, alkalinized with ammonia until neutral, the precipitated at the same time the filter is filtered, washed with water and dried. The product is recrystallized from chlorobenzene in the presence of alumina. The substance is obtained in the form of yellow-green crystals. Yield 4.5 g (42%), m.p. 331-332C.

Found,%: C 72.18; H 3.79; N 15.37.

C22H13N4023

Calculated,%; C, 72.13; H 3.83; N 15.30.

Dmax of luminescence in toluene 420 nm, the absolute quantum yield of luminescence in toluene 0,64; Dmax luminescence in crystals 465 nm.

Froze Preparation of 145-phenyloxazolyl-2) -4- (2-pyridyloxadiazolyl-2) benzene.

To a mixture of solutions, 4 g of 2-pyridyl-Idrazide in 40 ml of water and 8.3 g of 4- (5-phenyloxazolyl-2) benzoic acid chloride in 50 ml of benzene are added dropwise at room temperature and under vigorous stirring a soda solution alkaline reaction to litmus. The precipitate is filtered off, washed with water and dried. The dry precipitate is boiled with five times the amount of phosphorus oxychloride for 8 hours. Then the reaction mixture is poured onto ice, alkalized with ammonia until neutral, the precipitated precipitate is filtered, washed with water and dried. The precipitate is recrystallized from chlorobenzene in the presence of Oxide.

aluminum. The product is a yellow-green crystalline powder. Yield 8.5 g (80%), m.p. 337338 ° C. .

Found C, 72.10; H 3.88; N 15.28.

C22H14N402.

Calculated,%; C, 72.13; H 3.83; N 15.30.

Amax luminescence in toluene 420 nm. the absolute quantum yield of luminescence in toluene is 0.72; Amax luminescence in crystals 465 nm.

The compounds obtained, in contrast to their closest analogues in the structure of 5-phenyl-2- (X-pyridyl) -1,3,4-oxadiazoles. can be used as blue luminescent phosphors in the solid state (similar in structure does not luminesce in the solid state) and in organic solvents, for example in toluene, alcohol, acetic acid, dimethylformamide, in which, unlike the prototype, have intense luminescence. The proposed 1- (5-phenyloxazolyl-2) (X-pyridyl) -1,3,4-oxadiazolyl -2 benzenes are devoid of the disadvantages inherent in the known analogues in structure. They have a high quantum yield of luminescence (0.6–0.8) and can be used as effective organic phosphors, for example, in the preparation of liquid scintillators in scintillation technology, materials for fluorescent flaw detection, day fluorescent pigments and paints, etc.

Comparison of the luminescent characteristics of real phosphors and their analogues in structure showed that, unlike their analogs. 2- (X-pyridyl) -5-phenyl1, 3.4-oxadiazoles. 1- (5-phenyloxazolyl-2) (X-pyridyl) -1.3,4-oxadiazolyl-2 benzenes intensively luminesce in hydrocarbon solvents, for example in toluene; The absolute luminescence quantum yields of these compounds in toluene range from 0.6–0.8. The results are shown in the table.

Comparison of the luminescence intensity of the claimed luminophores and the known, commercially available and widely used in the scintillation technique of the analog in luminescence (taken as the base object) -1,4-bis- (5-phenyloxazolyl-2) benzene, shows that the luminescence intensity of the claimed luminophores is 1.5 times higher than the luminescence intensity of the known luminophore.

A distinctive feature and an additional advantage of the present compounds, as compared with the prototype, is the presence of intense luminescence in solutions at room temperature, it being found that the color of the luminescence depends on the polarity of the solvent. By changing the polarity of the solvent (chloroform, -heptane, toluene, alcohol, dimethylformamide), the color of the luminescence can be varied in the spectral range from violet to blue-green. Therefore, these compounds, unlike their closest analogs in structure, can be used as phosphors emitting light in different spectral regions.

Using the intense luminescence of the present compounds in solutions, they were tested for suitability as activators in scintillation compositions. The closest analogues in structure due to weak luminescence are not suitable for this purpose. At the same time, the inventive phosphors are effective scintillation activators. Thus, a composition containing 4 g / l of p-terphenyl (main additive) and 0.1 g / l

1- (5-feiiloxazolyl-2) (4-pyridyl) 1 .3,4-oxadiazolyl-2 benzene (secondary additive), has a scintillation efficiency in ditolylmethane 130% with respect to the ethanol commonly used for this purpose - a solution of the mixture -terphenyl (4 g / l) with 1,4-bis- (5-phenyloxazolyl2) benzene (0.1 g / l) in toluene. This gives grounds to propose real phosphors as secondary additives (spectrum mixers) in scintillation compositions.

The use of the inventive luminophores due to their increased luminescence intensity will improve the efficiency and quality of various materials.

(56) Krasrvitsky B.M., Bolotin B.M. Organic phosphors. L .: Chemistry, 1976, p. 200-208.

Grekov A.P., and Nesynov E.P. Synthesis of some heterocyclic 1,3,4-oxadiazole derivatives. JOH, 1960, t.ZO, vol. 10, 25 s. 3240.

Dmax luminescence. Substances in toluene, nm

Claimed compounds

7 r {i JLf5N О

N N N N

OO

M

 About About JT Analogue on structure

 VII

Analogue for the glow

(base object). . -N n-,

T VTiuTUUL /

ABOUT

 The intensity of luminescence, for example, in toluene analogues in the structure is so weak that it cannot be registered by the device.

Lmax luminescence in crystals, nm

0.75

465

0.64

465

0.72

465

Faint glow

0.40

465

Claims (1)

Invention Formula H5-Phenyloxazolyl-2) -4- (5- (X-pyriAI l) -1.3.4-oxadiazolyl-2 benzenes of the general formula NU- -. N Where N- / NAJ as luminescent additives of organic scintillators.