Spectroscopic, X-ray structure, radical scavenging and in vitro antifungal activities and catalytic degradation of methyl orange dye investigation of the Meso-tetrakis(p-tolyl) diprotonated porphyrin

Abstract

With the aim to fully characterize the diprotonated porphyrin: meso‑tetrakis(p-tolyl)porphyrindi-ium dichloride chloroform trisolvate with the formula [H4TTP]Cl2·3CHCl3 (2) this porphyrinic diacid species was first prepared by protonation of the meso‑tetrakis(p-tolyl)porphyrin (H2TTP, (1)). Compound 2 was studied by UV/Vis, fluorescence, IR, 1H NMR spectroscopy as well as by MALDI-TOF mass spectroscopy. The single crystal X-ray structure of 2 was a very useful technique to show the very important deformation of the porphyrin core of the diprotonated [H4TTP]2+ porphyrinic species (2) which is considered the principal cause of the important redshift of the UV/Vis and fluorescence spectra of compound 2. We used computational studies at B3LYP/6-311+G(d,p) level of theory to investigate the HOMO and LUMO molecular orbitals characteristics and calculate the global reactive parameters of compound 2 such as the electrophilicity index ψ, the chemical potential (μ), the hardness (η) and the chemical softness (S). The diacid porphyrin species (2) was tested as adsorbent of the Methyl Orange dye (MO) and also as catalyst of the degradation of this organic dye in presence of hydrogen peroxide. Biological studies on the H2TTP free base porphyrin (1) and the corresponding [H4TTP]2+ diacid species (2) were carried out in vitro in order to test their inhibitory effect against some fungal strings and the ability of these two porphyrinic compounds to scavenge 1,1-diphenyl-picrylhydrazyl DPPH radical.