Revisiting indeno[2,1-c]fluorene synthesis while exploring the fully conjugated s-indaceno[2,1-c:6,5-c′]difluorene

Abstract

Described herein is an alternative synthetic approach for conjugated indeno[2,1-c]fluorene, including the experimental and theoretical investigations of a tetraradicaloid s-indaceno[2,1-c:6,5-c′]difluorene that belongs to the rarely explored indacenodifluorene family containing 4n + 2 monocyclic conjugated π-electrons. Expedient synthesis, broad absorption reaching 1150 nm, and small HOMO–LUMO energy gap make [2,1-c:6,5-c′]s-IDF a promising candidate for optoelectronic applications.