Developing dithienylethene (DTE)-based fluorescence switches triggered by biocompatible visible light has always been a long-term goal in view of their potential in numerous biological scenarios. However, their practical availability is severely limited by the short visible light (generally less than 500 nm) required for photocyclization, their inability to achieve red or near-infrared emission, and their short fluorescence lifetimes. Herein, we present a novel DTE derivative featuring a dimethylamine-functionalized BF2-curcuminoid moiety (NBDC) by using an “acceptor synergistic conjugation system” strategy. The dimethylamine group not only enables a red shift in the absorption and emission wavelengths of the open isomer but also endows NBDC with unique acid/base-gated photochromism. As expected, as-prepared NBDC presents 570 nm-/770 nm light-driven photochromic properties, red-emissive fluorescence, and thermally activated delayed fluorescence (TADF) switching in toluene. To our knowledge, this represents the first instance of a yellow-green- and NIR light-controlled red fluorescence DTE switch with the longer fluorescence lifetime. Specifically, NBDC, which shows almost no photochromic activity in CHCl3, demonstrates enhanced photochromic performance when gated by TFA/TEA. Ultimately, this non-toxic deep-red fluorescence switch has been successfully applied for photoswitchable imaging in vivo of living cells and zebrafish, further proving its versatility in life sciences.

中文翻译：

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基于 BF2-姜黄素衍生的二噻吩乙烯的 570 nm-/770 nm 光激发深红荧光开关


鉴于它们在众多生物场景中的潜力，开发由生物相容性可见光触发的基于二噻傔烯 （DTE） 的荧光开关一直是一个长期目标。然而，由于光环化所需的短可见光（通常小于 500 nm）、无法实现红光或近红外发射以及荧光寿命短，它们的实际可用性受到严重限制。在此，我们通过使用“受体协同偶联系统”策略提出了一种新型的 DTE 衍生物，其特点是二甲胺官能化的 BF2-姜黄素部分 （NBDC）。二甲胺基团不仅使开放异构体的吸收和发射波长发生红移，而且还赋予 NBDC 独特的酸/碱门控光致变色。正如预期的那样，制备的 NBDC 在甲苯中呈现 570 nm-/770 nm 光驱动的光致变色特性、红光发射荧光和热激活延迟荧光 （TADF） 切换。据我们所知，这代表了具有更长荧光寿命的黄-绿和近红外光控红色荧光 DTE 开关的第一个实例。具体来说，NBDC 在 CHCl3 中几乎没有光致变色活性，当被 TFA/TEA 设门时表现出增强的光致变色性能。最终，这种无毒的深红色荧光开关已成功应用于活细胞和斑马鱼的体内光开关成像，进一步证明了其在生命科学中的多功能性。