Pyrene-Bridged Tetrathienyles: Synthesis and Photochromism

The integration of a pyrene aromatic core with two photochromic dithienylethene (DTE) units led to the isolation of two distinct atropisomers, each exhibiting markedly different optical properties. One atropisomer displays reversible photoisomerization accompanied by switchable fluorescence, highlighting its potential for optoelectronic applications. Detailed spectroscopic analyses and theoretical calculations provide insight into the structural and electronic differences between the isomers, elucidating the origins of their contrasted photophysical behaviors and the underlying photochromic mechanism of these photoactive species.