New cationic and neutral copper(II) complexes containing 7-hydroxy-4-oxo-4[H]-chromene derived ONO pincer ligands: Synthesis, characterization and in vitro biological evaluations.

New Schiff base ligands are prepared by the condensation of 7-hydroxy-3-formylchromone with semicarbazone and phenyl semicarbazone. The complexation of these ligands with Cu(II) ion is proposed in the light of spectral studies (IR, UV-Vis, 1H NMR, 13C NMR, Mass and ESR). In the complexes 1 and 2, the ligands coordinate to the Cu(II) ion in a neutral fashion via ONO donor atoms. The single crystal XRD studies reveal a slightly distorted square-pyramidal geometry for cationic complex (1) and an octahedral geometry for neutral complex (2). Preliminary biological studies such as DNA and Protein binding are carried out by using absorption and emission titration methods. Observation of intercalative mode of binding with Calf Thymus DNA (CT-DNA) is confirmed by means of viscosity measurements. The micro-environmental changes occurring in Bovine Serum Albumin (BSA) and Human Serum Albumin (HSA) are monitored via three dimensional (3D) fluorescence studies. The compounds ability in inhibiting microbial growth is tested against different pathogens. MCF-7 (human breast cancer) and A549 (human lung carcinoma) cell lines are utilized to check the anticancer potential of the synthesized compounds by using MTT, LDH and NO assays. The results show that complexes 1 and 2 exhibited potent cytotoxic activity over standard drug cisplatin.