Availability of π–Cation Radical in the Oxidative Products of Oxidovanadium Porphyrin: Significance for DNA Binding and Antibacterial Activity

Abstract

Oxidovanadium meso-tetrakis(3,4,5-trimethoxyphenyl) porphyrin [VO(T(OMe)3PP)] (Complex 1) was prepared. The oxidation product of Complex 1 has been characterized by cyclic voltammetry (CV), UV–visible spectrophotometer, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) by the addition of SbCl₅ to Complex 1. There is a one-electron oxidation product in Complex 1 that creates π–cation radicals in CV data. This is supported by an IR spectrophotometer. Subsequent EPR spectra verified the initiation of the π–cation monoradical, which subsequently transforms into a triplet state where S = 1. DNA binding and antibacterial analysis with Complex 1 have also been analysed. In the DNA-binding analysis, the CV data confirm the interaction between Complex 1 and DNA. Furthermore, the fact that Complex 1 is more effective at killing bacteria shows that the metal ion's chelation with the porphyrin ligand makes it more lipophilic.