A Visible-Light-Driven Dithienylethene Derivative Exhibiting Rapid Photocyclization with Near-Quantitative Conversion Efficiency

Achieving high efficiency in visible-light-driven dithienylethene (DTE) derivatives remains a significant challenge due to inherent limitations such as low ring-closing reactivity and poor conversion efficiency. In this work, a novel DTE derivative (<b>3</b>) was rationally designed and successfully prepared in which the <i>N</i>,<i>N</i>-dimethylaniline units are covalently linked to the DTE core via an alkene group as a π-bridge, thereby extending the π-conjugated system. As expected, the resulting DTE structure <b>3</b> displays efficient photochromism in different solvents when alternately irradiated with purple (λ = 420 nm) and red (λ = 600 nm) light. Remarkably, ring-open isomer <b>3(o)</b> reaches the photostationary state (PSS) within 3 s under 420 nm irradiation and achieves near-quantitative conversion efficiency. Importantly, DTE derivative <b>3</b> maintains excellent photoswitching properties even in DMSO and nano-aqueous solution, with only a minor attenuation. Furthermore, the DTE <b>3</b>-loaded poly(methyl methacrylate) (PMMA) film also exhibits enhanced photoswitching performance upon irradiation with purple light. The experimental findings are in agreement with time-dependent density functional theory (TD-DFT) calculations. Consequently, taking the advantages of excellent photochromism and fluorescence emission of this novel DTE derivative, it may be a promising candidate applied as functional optical materials.