Bis(DMAP) cobalt(II) porphyrin complexes: Dielectric properties and visible light irradiated photocatalytic degradation of toluidine blue studies

Abstract

Two novel cobalt(II) tetraphenylporphyrin-based six-coordinate complexes; bis(4-Dimethylaminopyridine)(5,10,15,20-tetrakis[4-bromophenyl]porphinato) cobalt(II) (1) and bis(4-Dimethylaminopyridine) (5,10,15,20-tetrakis[4-chlorophenyl]porphinato)cobalt(II) (2) were synthesised in good qualitative and quantitative yields. The chemical structures of these synthesized compounds were confirmed by elemental analysis, infrared, proton nuclear magnetic resonance and mass spectrometry, UV–vis absorption, and fluorescence spectroscopies. Their photophysical properties, namely their molar extinction coefficients (ε), fluorescence quantum yields (Φf) and lifetimes (τf), were determined and compared with those of meso-tetraphenylporphyrin. The dielectric properties such as dielectric constant (ε′), dielectric loss (ε″), and conductivity (σ) were investigated as a function of temperature and frequency. Impedance analysis was carried out using Cole-Cole plots to understand the electrical conduction mechanism. As an application of our two cobaltous complexes, an investigation involving complexes 1–2 in the photocatalytic performance was carried out by decomposing the TB dye under visible light irradiation at room temperature.