The Metacyclophanediene-Dihydropyrene Photochromic π Switch

This Microreview highlights the chemistry of the metacyclophanediene-dihydropyrene system, which is a reversible photochromic π switch. Although most studies have been carried out on systems with a single dihydropyrene, recently multiple dihydropyrenes have been fused to conjugated spacers to give multi-state switches.