Sulfur-Oxidation of Thiazolinochlorin for Controlling Optical Properties and Structures of Metal Complexes: Expansion to π-Cation Species.

Thiazolinochlorin compounds bearing sulfoxide and sulfone moieties were prepared by selective sulfur-oxidation with m-chloroperoxybenzoic acid. The oxidation state of the sulfur atom directly affected the optical properties of the thiazolinochlorin compounds, which were investigated through computational calculations. The structures of zinc complexes of these compounds were drastically changed by the oxidation state of the sulfur atom. Notably, nonoxidized thiazolinochlorin afforded a π-cation complex with elimination of the alkoxy group. The detailed structure and optical properties of the complexes in solution were investigated and compared with those of neutral zinc complexes derived from sulfoxide and sulfone compounds. Furthermore, the π-cation complex underwent self-aggregation, enabling the absorption of near-infrared light.