Heterotriangulenes π-Expanded at Bridging Positions

A series of nitrogen-containing heterotriangulenes expanded at the bridging positions has been synthesized. Among them, a dibenzo[c,g]fluorenylidene-substituted derivative has a highly twisted conformation for the overcrowded alkene moieties, which impart a highly electron-accepting character to the electron-donating heterotriangulene skeleton and thereby an NIR absorption as well as multiredox properties with a low reduction potential.