Dithienylethene-functionalized difluoroboron β-diketonate complexes: Synthesis, photophysical properties and NIR photochromism

The development of photoresponsive organoboron materials, especially visible light-responsive luminescent materials, has drawn much attention for their potential application in optoelectronics and functional biomaterials. In this study, we described a series of difluoroboron beta-diketonate complexes 1a-1e based on dithienylethene unit. Their structures have been confirmed by H-1 NMR, C-13 NMR and HRMS (ESI). And they exhibited solvent-dependent photophysical and visible light-triggered NIR photochromic properties in the solution. Simultaneously, excellent fluorescence switching behavior and photochromism were also observed in the PMMA film upon irradiation. Moreover, it was found that different substituent on the benzene ring in these complexes have a noteworthy effect on the photochromic properties and fluorescence switching behavior in the solution or PMMA film. Density functional theory (DFT) calculations were performed to provide further insight into the effect of the substituents on the photophysical and photochromic properties. Accordingly, they may be acted as novel visible light-responsive luminescent dyes for optoelectronics and functional biomaterials.