N. I. Vikrishchuk

Synthesis, structure, and spectral luminescent properties of novel 1,2,4-triazole derivatives containing benzthiazole group

Novel derivatives of 1,2,4-triazol with benzthiazole fragment have been prepared, including Cu(II) and Be complexes. Their structure and spectral luminescent properties have been investigated. With ohydroxyphenylbenzthiazolyl-1,2,4-triazole as an example, the density functional theory has been applied to find the stable conformers with different structures of coordination nodes, stabilized by intramolecular hydrogen bonds between hydroxyl group hydrogen and either triazole of benzthiazole nitrogen.

Synthesis and luminescence properties of 2-(2-benzoyloxyphenyl)-5-aryl-1,3,4-oxadiazoles

Bidentate ligand systems based on 2-hydroxyphenyloxadiazole attract strong interest due to application of metal complexes derived therefrom in photoand electroluminescent devices as blue-emitting chromophores, as well as electron-transporting materials that improve charge transfer balance in organic light-emitting diodes (OLEDs) [1, 2]. In addition, organic luminophores based on diphenyloxadiazoles exhibit an anomalously high Stokes shift (ASS), which favors increase in the light yield as a result of reduced self-absorption and minimizes liminophore photodegradation [3].

Synthesis and luminescent properties of 2-[2′-acyl(benzoyl)oxyphenyl]-5-(4″-nonylphenyl)-1,3,4-oxadiazole

a Southern Scientific Center, Russian Academy of Sciences, ul. Chekhova 41, Rostov-on-Don, 344006 Russia e-mail: mikhail@ipoc.rsu.ru b Southern Federal University, Rostov-on-Don, Russia c Institute of Arid Zones, Southern Scientific Centre, Russian Academy of Sciences, Rostov-on-Don, Russia d Scientific Research Institute of Physical and Organic Chemistry, Southern Federal University, Rostov-on-Don, Russia

Absorption and luminescence spectra of 5-aryl-3-methyl-1,2,4-oxadiazoles and their chelate complexes with Zinc(II) and copper(II)

Abstract5-(2-Hydroxyphenyl)-3-methyl-1,2,4-oxadiazole and its O-methyl and O-acyl derivatives, as well as zinc(II) and copper(II) chelates, were synthesized. All these compounds showed luminescence with the emission maxima ranging from λ = 332 to 490 nm, but only 5-(2-methoxyphenyl)- and 5-(2-acetoxyphenyl)-3-methyl-1,2,4-oxadiazoles and zinc(II) complex of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole were characterized by high luminescence quantum yield (φ = 0.308–0.452, 0.089–0.153, and 0.115–0.334, respectively). Stable conformers of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole with different structures of the coordination entity were identified by DFT quantum chemical calculations.

Synthesis of 1-(benzothiazol-2-yl)-5-(o-hydroxyphenyl)-1H-1,2,4-triazoles

Recyclization of 4-oxo-1,3-benzoxazinium perchlorates by the action of benzothiazolylhydrazine gave previously unknown benzothiazolyl-substituted 1,2,4-triazoles that attract interest as potential biologically active substances. The structure of the isolated compounds was determined on the basis of their IR and 1H and 13C NMR spectra.

Synthesis of derivatives of 1,2,4-oxadiazole, 1,2,4-triazole, and 1,3,5-triazine

Diuretics [1], analgesics, and antispasmolytics [2], as well as herbicides [3], fungicides [4], and nematocides [5], have been found among 1,2,4-oxadiazoles, 1,2,4-triazoles, and 1,3,5-triazines. For the purpose of synthesizing similar heterocycles conraining the pharmacophoric 3-chloropropyl group, the previously unknown synthon 2-(3-chloropropyl)-4-oxo-l,3benzoxazinium perchlorate (VIII) was synthesized, and its reactions with 1,2and 1,3-dinucleophiles [hydroxylamine (I), hydrazine hydrate (II), phenylhydrazine (III), guanidine (IV), and S-methylisothiourea (V)] were investigated. The compounds synthesized I X XIII have promise not only as biologically active substances, but also as starting substances for the synthesis ofoxadiazoles, triazoles, and triazines with other pharmacophoric fragments by means of the exchange of the chlorine in the 3-chloropropyl substituent for amino, hydroxy, and other functional groups. The acylation of salicylamide (VI) with y-chlorobutyryl chloride in the solution in chloroform in the presence of pyridine as a catalyst and an acid-binding agent led to the synthesis of N-(3-chlorobutyryl)salicylamide VII. It can be seen that the reaction proceeds analogously to [2] by the O-N rearrangement o f t he initially formed O-acyl derivative of salicylamide VI. The acid cyclization of the amide VII using 70% HCI04 in the solution of acetic anhydride and glacial acetic acid [6]

New Acylhydrazones of Indole Series and Their Metal Complexes

By the reaction of 2-chloroindole-3-carbaldehyde with acylhydrazones new acylhydrazones of the indole series have been synthesized, and their structure, the possibility of cyclization to pyrazoloindoles, and complexing properties have been studied. By means of quantum chemical DFT calculations taking into account the solvent effect it was shown that the reaction of 2-chloroindole-3-carbaldehyde and the corresponding acylhydrazine is an exothermic process, irrespective of which final product is formed, indolemethylenehydrazide or pyrazoloindole. Therefore, both possible transformations in the studied reacting system are controlled kinetically and not thermodynamically.

New functionalized amino derivatives of 2-hydroxyphenyl-1,3,5-triazines

Abstract4-(2-Hydroxyphenyl)-1,3,5-triazin-2-ylcyanamides reacted with sodium azide to give N-(tetrazol-5-yl)-1,3,5-triazin-2-amines, and their reaction with allyl bromide afforded allyl(1,3,5-triazin-2-yl)cyanamides. Acetylation of 4-(2-hydroxyphenyl)-1,3,5-triazin-2-amines involved only the amino group with formation of diacetylamino derivatives, whereas the phenolic hydroxy group remained intact. The reaction of triazinamines with 2,5-dimethoxytetrahydrofuran in the presence of P2O5 gave pyrrolyl-substituted triazines.

5-(2-hydroxyphenyl)-1,2-dimethyl(1-methyl-2-vinylaryl)-1H-1,3,4-triazoles and their complexes with Zn(II)

The interaction of 2,3-dimethyl-4-oxo-1,3-benzoxazinium and 2-[β-(4-bromophenylvinyl)]-3-methyl-4-oxo-1,3-benzoxazinium perchlorates with hydrazine hydrate has afforded the corresponding triazoles that have been used as ligands for the synthesis of zinc complexes L2Zn. Luminescent properties of the prepared complexes have been studied.

Synthesis of 3-(2-hydroxyphenyl)-1,5-dialkyl-1H-1,2,4-triazoles and their Zn(II) complexes

It has been demonstrated by 13C NMR and quantum-chemical calculations that alkylation of 5-(2-hydroxyphenyl)-3-methyl(vinylphenyl)-1H-1,2,4-triazoles with dialkyl sulfates in aqueous DMSO in the presence of alkali occurs exclusively in the 2-position of the triazole ring to give 3-(2-hydroxyphenyl)-1,5-dialkyl(alkylvinylphenyl)-1H-1,2,4-triazoles. Emission spectra of these compounds show two weak bands (λmaxfl = 317–346 and 430–447 nm, φ = 0.002–0.007), whereas their zinc complexes emit in the violet range of the visible spectrum (λmaxfl= 373–377 nm, φ = 0.20–0.25).