Thianthrene-Based Thiapillar[6]Arene Derivatives: Design, Synthesis, and Characterization

Thiapillar[6]arene is a π-electron macrocyclic system with a benzene ring bridged at the 1,4-positions by a sulfur atom to form a hexagonal structure. Further sulfur atoms can be bridged into the molecules of this scaffold to form thianthrene moieties inside the skeleton. This promotes rigidity because of the double bridging, the molecular skeleton is distorted while maintaining the hexagonal structure, and the derivatives begin to show redox and photoluminescence behavior derived from the formed thianthrene. In this study, macrocyclic molecules I–IV, incorporating one to three thianthrene moieties in the thiapillar[6]arene skeleton, were successfully synthesized via a bottom-up approach, and their molecular structures, molecular tiling, unique redox behavior, fluorescence, and phosphorescence properties were elucidated.