Exploration of synthesis, structural aspects, DFT studies and bio-efficacy of some new DHA-benzohydrazide based copper(II) complexes

Abstract A copper (II) complex with ligand obtained by the dehydrative condensation of 3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione (DHA) and benzohydrazide has been synthesized. The complex species are additionally coordinated by various solvent molecules, namely ethanolamine, methanol, DMF, dimethyl amine, isopropyl amine, diisobutylamine, and ethylenediamine (5a-5g) have been synthesized. All the complexes were characterized by single crystal X-ray diffraction analysis and other analytical techniques. In each case, the copper atom is tetra-coordinated by chelating carbohydrazide ligand through O, N, O donor atoms and the N/O heteroatom from the coordinated solvent (except for ethylenediamine, where Cu is pentacoordinated). The intermolecular interactions present in each complex have been quantified using Hirshfeld surface analysis, and the electrostatic properties associated with these complexes were calculated using DFT studies. Considering the expected bioactivity of carbohydrazide derivatives, the antibacterial activity of ligand and copper complexes was tested against pathogenic Gram-positive and Gram-negative bacteria using ciprofloxacin as positive control. Compound 4 and 5f shows potent antibacterial activity against B. subtilis with MIC and MBC value of 32 μM