1 Introduction Singlet dioxygen (1O2) is a highly reactive alter ego of the comparatively inert triplet dioxygen (3O2) and a reagent with many facets of efficacy, ranging from organic oxygenation or oxidation reactions[1] to biological processes.[2] In technical terms, ground state 3O2, a diradical with two unpaired electrons in oxygen's antibonding molecular π*-orbitals (3Σg−), can appear in two excited states with spin-paired electrons either in only one of the π∗-orbitals (1Δg) or two...
