Benziporphyrins, a unique platform for exploring the aromatic characteristics of porphyrinoid systems

Abstract

Benziporphyrins were first discovered over 20 years ago. Although initially they were considered to be a chemical curiosity, a wide range of benzene-containing porphyrinoid systems are now known that exhibit intriguing spectroscopic, structural and chemical properties. These systems can often generate stable organometallic derivatives, and have been shown to have applications in the development of chemical sensors and in molecular recognition studies. The characteristics of these porphyrinoid macrocycles vary from nonaromatic to highly aromatic systems, and in a few cases antiaromatic structures are formed. The variations in aromatic character are insightful and provide a deeper understanding of aromaticity and conjugation in porphyrinoid structures. In this review, the synthesis and properties of benziporphyrinoid systems is presented with a particular emphasis on the variations in aromatic characteristics.