New coordination compounds of Co(II), Ni(II), and Cu(II) halides with 2-methyl-1,2,4-triazolo[1,5-a]benzimidazole (L), [Co(L) 2 Cl 2 ] ( Ia ), [Ni(L) 2 (H 2 O) 4 ]Cl 2 · 4H 2 O ( II ), and [Сu 2 (L) 4 (µ-Br) 2 Br 2 ] ( IIIa ), are synthesized. The complexes are studied by X-ray structure analysis (СIF files CCDC nos. 1825006–1825008), electronic (diffuse reflectance) spectroscopy, and IR spectroscopy. In compounds Ia , II , and IIIa , ligand L is coordinated to the metal by the N 4 atom of the triazole fragment. The study of the cytotoxic effect of the ligand and synthesized complexes on the Hep-2 line (laryngeal cancer cells) shows a considerably higher activity of the copper(II) complex than that of the ligand.

Coordination compounds based on cobalt(II) and copper(II) halides with 2,4-dimethyl-1,2,4-triazolo[1,5-a]benzimidazole (L) of composition [ML2Cl2] (where M = Co2+ (I) or Cu2+ (II)) and [CuL2Br2] (III) were synthesised. The compounds were characterised by single-crystal X-ray diffraction (XRD) analysis, UV-Vis spectroscopy (diffuse reflectance spectra, DRS) and infrared (IR) spectroscopy. Via XRD structural analysis, crystal structures were determined for [CoL2Cl2] (I), [CuL2Cl2] (II) and [Cu2L2(mu-Cl)(2)Cl-2(H2O)(2)] (IIa). Cytotoxic effects of the complexes and ligand on cell line Hep-2 were studied, and it was found that the formation of a copper(II) complex with L considerably enhances cytotoxicity.

The complex salt {[CuL2][Cu4I6]•MeCN}n (1) and the compound [Cu4L3I4]•3 MeCN (2) (L is a chiral ligand bearing a natural monoterpene (+)-3-carene moiety) were synthesized. The crystal structures of compounds 1 and 2 were determined by X-ray diffraction. The structure of compound 1 consists of complex cations [CuL2]2+ (N3O2 polyhedron is a trigonal bipyramid) and CuI coordination polymers (CuI4 polyhedron is a tetrahedron) as anions. The experimental magnetic moment μeff at 300 K is 1.90 μB, which is consistent with the X-ray diffraction data and the assumption that compound 1 is mixed-valence. The structure of compound 2 comprises a tetranuclear CuI complex, in which three Cu atoms are coordinated by two N atoms of the ligand L and two I atoms, and the fourth Cu atom is coordinated by four I atoms (coordination polyhedra are distorted tetrahedra). Compounds L and 2 were found to influence the viability of human laryngeal carcinoma cells (Hep2). The IC50 value for complex 2 (13.0±1.7 μM) is substantially smaller than IC50 for compound L (30.5±0.5 μM).

Fluorinated benzo-fused 1,3-diazoles, 1,2,3-triazoles, 1,2,5-thia/selenadiazoles and 1,4-diazines were synthesized and tried for cytotoxicity towards the Hep2 (laryngeal epidermoid carcinoma) cells. The diazoles, triazoles and selenadiazoles were cytotoxic with IC50 = 2.2-26.4 mu M and induced the cells apoptosis at concentrations C = 1-25 mu M. At the same time, they were nontoxic towards normal cells. Due to this, these scaffolds were used in the computer-aided molecular design of new antitumor agents. Particularly, novel 1,2,3-triazole and 1,3-diazole derivatives for the binding site of the PAS domain of the transcription factor HIF were designed and some of them synthesized for further study. Overall, new anticancer agents featuring apoptotic activity are suggested.

CuLCl, CuL1Cl, PdLCl2, and PdL1Cl2 complexes [L and L1 being (+)-camphor and (–)-carvone thiosemicarbazones, respectively] have been synthesized. The structure of binuclear [Pd2L22Cl4] complex has been determined by means of X-ray diffraction. The L2 ligand (dehydrogenated (–)-carvone thiosemicarbazone) is coordinated via the bridging S atom to two Pd atoms. The complexes of Cu(I) and Pd(II) presumably have polynuclear and binuclear structure, respectively. These facts are in good agreement with IR and NMR spectroscopy as well as mass spectrometry data which indicate the coordination of L and L1 ligands via the S atom. The influence of L1 and PdL1Cl2 on viability of the Hep2 cell line has been studied. The PdL1Cl2 complex is more cytotoxic than L1 ligand.

Coordination compounds based on copper(ii) halides with 4H-1,2,4-triazolo[1,5-a]benzimidazole (L) and its derivatives with the compositions [CuL2Hal2]·nH2O.