Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education and Key Laboratory of Organosilicon Material of Zhejiang Province, Hangzhou Normal University, No. 2318, Yuhangtang Road, Hangzhou, 311121, P. R. China.
State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, China Pharmaceutical University, Nanjing, 211198, P. R. China.
Chem Asian J. 2020 Sep 1;15(17):2724-2730. doi: 10.1002/asia.202000660. Epub 2020 Jul 28.
Si-rhodamine (SiR) is an ideal fluorophore because it possesses bright emission in the NIR region and can be implemented flexibly in living cells. Currently, several promising approaches for synthesizing SiR are being developed. However, challenges remain in the construction of SiR containing functional groups for bioimaging application. Herein, we introduce a general and simple approach by a condensation reaction of diarylsilylether and arylaldehyde in o-dichlorobenzene to synthesize a series of SiRs bearing various functional substituents. These SiRs have moderate to high quantum efficiency, tolerance to photobleaching, and high water solubility as well as NIR emitting, and their NIR fluorescence properties can be controlled through the photoinduced electron transfer (PET) mechanism. Fluorescence OFF-ON switching effect is observed for SiR 9 in the presence of acid, which is rationalized by DFT/TDDFT calculations. Moreover, reversible stimuli response toward temperature is achieved. Since positive charge enables mitochondrial targeting ability and chloromethyl unit can covalently immobilize the dyes onto the mitochondrial via click reaction between the benzyl choride and protein sulfhydryls, SiR 8 is identified as a valuable fluorescent marker to visualize the morphology and monitor the temperature change of mitochondria with high photostability.
硅罗丹明（SiR）是一种理想的荧光团，因为它在近红外区域具有明亮的发射，并且可以在活细胞中灵活地实现。目前，正在开发几种有前途的合成 SiR 的方法。然而，在构建用于生物成像应用的含功能性 SiR 方面仍然存在挑战。在此，我们通过二氯苯中芳基硅醚和芳基醛的缩合反应，介绍了一种通用且简单的方法，来合成一系列带有各种功能取代基的 SiR。这些 SiR 具有中等至高的量子产率、对光漂白的耐受性、高水溶性和近红外发射，并且它们的近红外荧光性质可以通过光诱导电子转移（PET）机制来控制。在存在酸的情况下，观察到 SiR9 的荧光关闭-开启开关效应，这可以通过 DFT/TDDFT 计算来合理化。此外，还实现了对温度的可逆刺激响应。由于正电荷使线粒体靶向能力成为可能，并且氯甲基单元可以通过苄基氯与蛋白质巯基之间的点击反应将染料共价固定在线粒体上，因此 SiR8 被鉴定为一种有价值的荧光标记物，可用于可视化线粒体的形态并监测线粒体的温度变化，具有高的光稳定性。
