An exploration of the reactivity of singlet oxygen with biomolecular constituents

Abstract

The thermal reaction between biomolecules and singlet oxygen (¹O₂) is important for rendering the genetic material within toxic cells inactive. Here we present results obtained from state-of-the-art multi-reference computational methods that reveal the mechanistic details of the reaction between ¹O₂ and two exemplary biomolecular systems: guanine (Gua) and histidine (His). The results highlight the splitting of the doubly degenerate ¹Δ_g state of O₂ upon complexation and the essentially barrierless potential energy profile of the thermally allowed cycloaddition reaction when the O₂ molecule is in its lower energy ¹Δ_g state.