Synthesis, structure elucidation, DNA binding and molecular docking studies of novel copper (II) complexes of two 1,3,4-thiadiazolethiosemicarbazone derivatives

Four novel Cu (II) chelates were synthesized by reacting hydrated CuCl(2)and Cu (CH3COO)(2)with two derivatives of 1,3,4-thiadiazolethiosemicarbazone. The structures and geometries of the synthesized complexes were deduced applying the alternative analytical and spectral tools confirming the complexes to have the formulae [(LH)Cu (Cl)]center dot 0.5H(2)O, [(LH)Cu (OAc)(H2O)(2)]center dot 0.5H(2)O, [(LCl)Cu (Cl)(H2O)(2)]center dot H2O and [(LCl)Cu (OAc)]; whereLHandLClare phenyl and p-chlorophenyl derivatives of 1,3,4-thiadiazolethiosemicarbazone ligands, respectively (deprotonated form). IR spectral data confirmed the coordination of the ligands to the copper center as monobasic tridentate in the thiol form. Thermal analysis, UV-Vis spectra and magnetic moment assured the geometry around the copper center to be square planar, trigonal bipyramid and octahedral which have been confirmed by the computational studies. The two ligand derivatives and their copper complexes were applied to evaluate their binding modes with SS-DNAviaUV-Vis spectral titration and viscosity measurements. The DNA-binding constant (k(b)) values of the investigated derivatives were calculated and compared with ethidium bromide in order to assess their mode of binding with DNA. Moreover, docking study of these complexes was carried out to recognize the drug-DNA interactions and to calculate their binding energies.