Photochromism of Asymmetrical Diarylethenes with a Pyrrole Unit: Effects of Aromatic Stabilization Energies of Aryl Rings

Four novel asymmetrical diarylethenes with a pyrrole and a variable aryl unit have been synthesized. Their crystal structures and photochromic performance were systematically studied to elucidate the effects of the aromatic stabilization energy (ASE) of aryl units. Experimental results showed that their thermal stability as well as cyclization quantum yield, photoconversion ratio, fluorescence modulation efficiency, and fatigue resistance exhibited a strong correlation with ASE.