Non-planar core-modified dibenzi expanded isophlorin

Abstract

The role of aromatic subunits is crucial to the structural and electronic properties of isophlorin and its expanded derivatives. Herein we describe the effect of benzene ring substitution in a 32π expanded isophlorin core, which is at the crossroads of hexaphyrin and octaphyrin. Synthesis, structural characterization and electronic properties of a non-planar 32π core-modified expanded isophlorin resembles that of a hexaphyrin like macrocycle. Dibenzi hexaphyrin is known to retain a planar structure; however, the dibenzi expanded isophlorin reported here loses its planarity and is found to adopt a unique V-shaped structure. The non-antiaromatic nature observed from spectroscopic analysis is ably supported by computational studies. Electronic absorption studies and mass spectrometry support a two-electron ring oxidation as expected of antiaromatic macrocycles.