Synthesis of a new benzoate bridged NNO tethered copper(ii) complex: exploration of its bio, catalytic and anticancer activities

Abstract

Considering the pervasive and multifarious impact of copper ions in different biological processes, this research effort covers the one-pot easy synthesis, characterization details (spectroscopic, X-ray structure and quantum calculation including DFT and TD DFT), Hirshfeld surface computation, and bio, catalytic and anticancer activities of a benzoate bridging NNO tethered homo-binuclear copper complex of the formulation [(CuL)₂(PhCOO)](ClO₄) (1). The bio-catalytic activities of 1 have been evaluated spectrophotometrically during the aerial oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) and 2-aminophenol (OAPH) in acetonitrile. Using spectro-photo and fluorometric titration, it has been found that complex 1 binds avidly to CT DNA and BSA protein (binding propensities of ∼10⁵ M⁻¹). The data from circular dichroism (CD) and viscosity testing indicate that it binds to DNA intercalatively. The static quenching of BSA's endogenous fluorescence is demonstrated by fluorescence life time titration using 1, which is further verified by a temperature-dependent quenching analysis. Synchronous spectroscopic tests combined with CD and 3D fluorescence spectra of BSA in the presence of 1 support the protein's structural modifications around the Trp-residue. Relevant thermodynamic parameters (ΔH, ΔS and ΔG) and FRET distances between the pair (BSA and 1) were also estimated. Finally, the MTT colorimetric technique was used to measure 1's cytotoxic activities against a range of malignant and non-cancerous cell lines. 1 exhibits specific cytotoxicity against MCF-7 (human breast cancer) exclusively (IC₅₀ = 9.53 ± 2.5 μM at 24 h) with an apoptotic mechanism of cell death, as validated by Hoechst and AO/EB staining.