The first stable tetraarylacenaphthenequinodimethanes exhibiting electrochromism with ‘write-protect’ option: preparation, highly deformed structure, and reversible interconversion with acenaphthylene-5,6-diyl dicationic dyes

Severely deformed title quinodimethanes [1,2-bis(diarylmethylene)acenaphthenes] 1 have been designed and prepared as novel electrochromic materials, which can be reversibly interconverted with the deeply colored dicationic dyes 1²⁺ with acenaphthylene-1,2-diyl skeleton. The X-ray analysis of 1 revealed that the inner two aryl groups are forced to overlap in proximity, which can account for the facile electrocyclization process to the isomer. By combination of reversible electrochemical transformation with irreversible isomerization process, the present system provides a prototype for novel molecular response systems equipped with the ‘write-protect’ option.