Zinc complexes with 1-(1 H -benzimidazol-1-ylmethyl)-1 H -benzotriazole: the structure, quantum chemical calculations, a
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Zinc complexes with 1-(1H-benzimidazol-1-ylmethyl)-1H-benzotriazole: the structure, quantum chemical calculations, and luminescence properties K. S. Smirnova,a E. V. Lider,a,b S. G. Kozlova,a,b T. S. Sukhikh,a,b N. V. Kuratieva,a,b I. P. Pozdniakov,b,c and A. S. Potapova aNikolaev
Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3 prosp. Akad. Lavrentieva, 630090 Novosibirsk, Russian Federation bNovosibirsk State University, 2 ul. Pirogova, 630090 Novosibirsk, Russian Federation. E-mail: [email protected] cVoevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, 3 ul. Institutskaya, 630090 Novosibirsk, Russian Federation. Fax: +7 (383) 330 9489 An organic ligand 1-(1H-benzimidazol-1-ylmethyl)-1H-benzotriazole (bta) and two zinc complexes of the composition [Zn(bta)2Hal2] (Hal = Cl, Br) were synthesized. The crystal structure of the complex [Zn(bta)2Cl2] was determined and its features were discussed. According to X-ray diffraction data, the central atom has a tetrahedral environment composed of two nitrogen atoms from two ligand molecules coordinated in monodentate mode and two terminal chloride ions. Density functional theory (DFT) calculations of the ligand and complex [Zn(bta)2Cl2] were carried out. A study of the luminescence properties of the compounds synthesized suggests that excitation of the zinc complexes gives rise to a dual-band luminescence similar to that of the free ligand. Most probably, the emission originates from π—π* and n—π* intra-ligand transitions. Key words: zinc(II) complexes, benzimidazole, benzotriazole, crystal structure, photoluminescence, DFT calculations.
Heterocyclic compounds, such as benzimidazole or benzotriazole, and their derivatives are of considerable interest since they exhibit various kinds of biological activity1—6 (antibacterial, antifungal, antitumor, etc.), the ability to inhibit corrosion,7,8 as well as the luminescence properties.9—12 These organic compounds contain donor nitrogen atoms and are therefore widely used as mono-, bi-, or tridentate (in the case of benzotriazole) ligands in coordination chemistry. To date, numerous complexes of transition metals (Ni,13—16 Co,14,16—18 Cu,16,19 Ru,20 Mn,16,21—23 Cd,24,25 Zn,14—17,26—29 etc.) with various heterocyclic ligands have been synthesized, including mono-, bi-, oligo-, or polynuclear systems that can be of different dimensionality. The inclusion of benzimidazole and benzotriazole rings in a one ligand leads to a system with three donor nitrogen atoms. According to published data,30—38 the benzimidazole-benzotriazole ligands can be coordinated in two different modes, viz., in bidentate bridging mode via the imidazole and triazole ring nitrogen atoms and in monodentate mode via the imidazole nitrogen atom. An example is provided by 1-[(2-methyl-1Н-benzimidazol1-yl) methyl]-1Н-benzotriazole (L 1 ) that is coordi-
nated to cadmium and zinc ions in the complexes [M(L1)2Cl2]30,31 in monodentate mode via the imidazole nitrogen atom
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