Dicyclohepta[ cd, ij]- s-indacene-Based Nonbenzenoid Polycyclic Hydrocarbons: Synthesis and Optoelectronic Properties

Org Lett. 2024 Nov 22. doi: 10.1021/acs.orglett.4c03969. Online ahead of print.

Abstract

Two nonbenzenoid polycyclic hydrocarbons (PHs) bearing one or two dicyclohepta[cd,ij]-s-indacene (DCHI) units were successfully synthesized via palladium-catalyzed intramolecular cyclization. In contrast to the well-known indeno[1,2-b]fluorene skeleton, the as-formed DCHI substructures not only lead to their highly contorted conformations but also significantly contribute to their modulated aromatic structures and optoelectronic properties, such as decreased energy gaps, red-shifted light absorption, and multi-reversible oxidation activity, thus revealing the importance of such nonbenzenoid π extension.