Solvent-dependent and visible light-activated NIR photochromic dithienylethene modified by difluoroboron β-diketonates as fluorescent turn-on pH sensor

Abstract The development of near-infrared (NIR) photochromic materials, particularly activated by visible light, are of increasing interest for their potential application in photoresponsive optoelectronics and functional bio-materials. Here, a novel D-DTE-A type dithienylethene NDB , which was modified by difluoroboron β-diketonate (BF 2 bdk) and dimethylphenylamine (DMPA) moieties, has been developed. It exhibited solvent-dependent photophysical properties before irradiation, and the visible light-triggered NIR photochromic behavior with solvent-dependent features was only observed in Toluene. Moreover, it displayed intense fluorescent turn-on acid-sensing properties in less polar solvent [Toluene, Dichloromethane (DCM) and Ethyl acetate (EA)] through the blockage of photoinduced electron transfer (PET) effect. Specially, NDB with photochromic inactivity in DCM could perform a unique gated photochromism in the presence of TFA/TEA.