Syntheses, crystal structures, thermal stabilities, CT-DNA, and BSA binding characteristics of a new acylhydrazone and its Co(II), Cu(II), and Zn(II) complexes

A new acylhydrazone (C12H12N4OS, HL) and its three transition metal complexes [M(HL)(2)](NO3)(2) (M = Co, I; Cu, II; Zn, III) have been synthesized. The structures of above four compounds were determined by single-crystal X-ray diffraction analyses. HL belonged to orthorhombic system and Pbca space group. I and II belonged to triclinic system and P-1 space group, whereas III belonged to monoclinic system and P2(1)/C space group. The thermal stabilities of four compounds were investigated by thermogravimetric analyses, and their maximum thermal decomposition peak temperatures were all more than 240 degrees C, showing high thermal stabilities. The binding behaviors of four compounds with CT-DNA were determined by UV-vis absorption spectra, viscosity and microcalorimetric experiments, all presenting intercalative modes. The interactions of four compounds with BSA were determined by fluorescence spectra and microcalorimetric experiments, showing static quenching effects, and the binding constants K-A are (8.32 +/- 0.36) x 10(3) M-1, (1.44 +/- 0.40) x 10(5) M-1, (7.59 +/- 0.09) x 10(4) M-1, and (4.68 +/- 0.45) x 10(5) M-1 for HL, I, II, and III, respectively. Microcalorimetric experiments explored that the interactions of four compounds with CT-DNA or BSA were exothermic processes and the interaction times were all less than 43 min.