Novel class of mononuclear 2-methoxy-4-chromanones ligated Cu (II), Zn (II), Ni (II) complexes: synthesis, characterisation and biological studies

Abstract

Abstract Two new 2-methoxy -4-chromanones were synthesized from 3-formylchromone and 2-aminopyridine/2-amino-5-nitropyridine in methanolic media and was characterised using various spectral and analytical techniques. Reactions of these ligands with copper (II), zinc (II) and nickel (II) acetates lead to the formation of a novel class of mononuclear co-ordination complexes. Synthesized complexes were structurally characterised using elemental analysis, IR, UV-Vis, EPR, thermo gravimetric analysis, conductivity studies, magnetic measurements and proton NMR. Spectroscopic analysis reveals that ligand behaves bidendately. The complexes were tested for their binding ability with HS-DNA and found to be intercalative. Complex NiL1 was found to possess the highest Kb value (5.1 × 105). The α-amylase and α-glucosidase inhibition ability of ligands and complexes were also explored. The tested compounds were found to be mild α-amylase inhibitors and strong α-glucosidase inhibitors, characteristically similar to most of the antidiabetic drugs. Among the synthesized compounds, complex CuL2 exhibited highest α-amylase inhibitory activity with IC50 = 0.251 ± 0.2 mM and complex CuL1 exhibited highest α-glucosidase activity with IC50 = 0.060 ± 0.3 mM. In addition, compounds were also screened for their antimicrobial efficacy. All complexes were found significantly potent, among which complex CuL1 the most active with MIC of 15.3 µg/mL against S. aureus (MTCC 96).