Near‐Infrared‐Responsive Hydrocarbons Designed by π‐Extension of Indeno[1,2,3,4‐ pgra ]perylene at the 1,2,12‐Positions

The relationship between the overall electronic structure of π‐conjugated molecules and the arrangement of their constituent elements is of fundamental importance. Establishing rational design guidelines for conjugated hydrocarbons with narrow HOMO‐LUMO gaps is useful to develop near‐infrared (NIR) responsive dyes and redox‐active materials. This study describes the synthesis and properties of three conjugated hydrocarbons, i. e., an indenonaphthoperylene, an indenoterrylene, and a diindenoterrylene. These molecules exhibit NIR absorption despite the absence of significant antiaromaticity and diradical character. Notably, the indenonaphthoperylene exhibits red‐to‐NIR emission in the 620–850 nm region. The indenoterrylene and the diindenoterrylene exhibit NIR absorption tailing to 870 and 940 nm, respectively. Moreover, the effect of the π‐extension of indenoperylene is disclosed in order to propose guidelines for achieving a narrow HOMO‐LUMO gap with negligible antiaromaticity and diradical character.