Comparative spectroscopic and DFT calculations of binary and ternary complexes derived from 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L1) and 2,2′-dipyridyl

•4-Allyl-1-(2-hydroxybenzoyl) thiosemicarbazide complexes.•Binary and ternary complexes.•Spectral and biological studies of Co2+, Cu2+ and Zn2+ complexes.•DFT calculations.

Five metal complexes derived the reactions of 4-allyl-1-(2-hydroxybenzoyl) thiosemicarbazide (L1) with MX2 (M = Co2+, Cu2+ and Zn2+ ions; X = Cl− in case of Co2+ and Cu2+ ions and Cl− and Ac− in case of Zn2+ ion) in EtOH were synthesized and characterized. The results suggested that the binary and ternary complexes have the general formulae, [Cu(L1-2H)(EtOH)], [Co(L1-2H)(H2O)2]⋅H2O and [Zn(L1-2H) (H2O)1/2]⋅½EtOH, [Cu2(dipy)(L1-2H)(OH)2(H2O)], [Co(dipy)(L1-2H)]⋅4H2O and [Zn(dipy)(L1-2H)]. The binary and ternary complexes were characterized by elemental analyses, molar conductivities, spectral (IR, UV–vis; 1H NMR, mass), thermal (TGA, DTG) and magnetic moments measurements. The mode of chelation is suggested using spectral data. The existence of OH group in the ternary complexes is confirmed from the results of IR, mass and 1H NMR spectra. All the geometries of the ligands and the complexes are confirmed using DFT method from DMOL3. The biological activity for the L1 and two metal complexes were tested against DNA.

Graphical abstractStructure of [Cu2(dipy)(L1-2H)(OH)2(H2O)].Figure optionsDownload full-size imageDownload as PowerPoint slide