Octahedral Copper(II) Carboxylates with 1,10-Phenanthroline: Synthesis, Structural Characterization, DNA-Binding and Anti-Fungal Properties

Abstract

Two mono-nuclear axially distorted octahedral copper(II) complexes have been prepared and characterized via FT-IR, UV–Visible, elctrochemical, electron spin resonance and powder and single crystal XRD techniques. The complexes consist of a phenanthroline and two carboxylate ligands each bonded in bidentate fashion. Carboxylates are ortho-nitro-2-phenyl acetate (L1) and para-chloro-2-phenyl acetate (L2). Structural study showed that both complexes possess Jahn–Teller distorted octahedral geometry. The bulk purity was assessed from the matching experimental and simulated powder XRD spectra. The results of spectroscopic techniques are consistent with each other. ESR data revealed single electron occupancy of dx2 − y2 orbital with 2B1g as ground state typical of tetragonally distorted octahedral geometry. Electrochemical solution study showed diffusion controlled electron transfer processes with diffusion co-efficient values of 10.323 × 10–8 cm2s–1 and 0.972 × 10–8 cm2s–1 for 1 and 2. Complexes exhibited excellent DNA-binding activity studied via UV–Visible spectroscopy, cyclic voltammetry, florescence spectroscopy and viscometry yielding Kb values of 1.871 × 104 M–1 (1) and 1.577 × 104 M–1 (2), 0.38 × 104 M–1 (1) and 6.39 × 104 M–1 (2) and 2.1 × 106 M–1 (1) and 2.0 × 06 M–1 (2), respectively, for the first three techniques. Complexes possess good antifungal activity against three fungal strains.