Homogenous catalysis of peroxynitrite conversion to nitrate by diaryl selenide: a theoretical investigation of the reaction mechanism

Quenching peroxynitrite (a reactive oxidant species) is a vital process in biological systems and environmental chemistry as it maintains redox balance and mitigates damaging effects in living cells and the environment. In this study, we report a systematic analysis of the mechanism of transforming peroxynitrite into nitrate using diaryl selenide in water. Through quantum mechanical calculations, we investigate the dynamic isomerization of peroxynitrite in a homogeneous catalytic environment. The mapped potential energy surfaces (PESs) generated using various methods in conjunction with different basis sets suggest that the isomerization mechanism includes four major steps: the reaction of peroxynitrite with diaryl selenide via oxygen-bound selenium; selenium oxidation in the presence of an appropriate oxidant; oxygen transfer; and ultimately, the generation of nitrate. The molecular orbital analysis suggests a substituent effect on the aromatic ring of diaryl selenide in this reaction. Changes in both molecular orbitals and electrostatic potential highlight the significance of the electron transfer step in ensuring the progression of this reaction.