Abstract：
Photoclick reactions combine the advantages offered by light-driven processes and classical click chemistry and have found applications ranging from surface functionalization, polymer conjugation, photo-crosslinking, and protein labeling. Despite these advances, the dependency of most of the photoclick reactions on UV light poses a severe obstacle for their general implementation, as this light can be absorbed by other molecules in the system resulting in their degradation or unwanted reactivity. However, the development of a simple and efficient system to achieve bathochromically shifted photoclick transformations remains challenging. Here, we introduce triplet-triplet energy transfer as a fast and selective way to enable visible light-induced photoclick reactions. Specifically, we show that 9,10-phenanthrenequinones (PQs) can efficiently react with electron-rich alkenes (ERAs) in the presence of a catalytic amount (as little as 5 mol %) of photosensitizers. The photocycloaddition reaction can be achieved under green (530 nm) or orange (590 nm) light irradiation, representing a bathochromic shift of over 100 nm as compared to the classical PQ-ERAs system. Furthermore, by combining appropriate reactants, we establish an orthogonal, blue and green light-induced photoclick reaction system in which the product distribution can be precisely controlled by the choice of the color of light.
摘要：
光点击反应结合了光驱动过程和经典点击化学提供的优势，并发现了从表面功能化，聚合物共轭，光交联，和蛋白质标记。尽管取得了这些进展,大多数光点击反应对紫外光的依赖性对它们的一般实施构成了严重的障碍，因为这种光可以被系统中的其他分子吸收，导致它们的降解或不需要的反应性。然而,开发一个简单而有效的系统来实现向变色的光点击转换仍然具有挑战性。这里,我们引入三重态-三重态能量转移作为一种快速和选择性的方式来实现可见光诱导的光点击反应。具体来说,我们表明，在催化量（少至5mol％）的光敏剂存在下，9,10-菲醌（PQs）可以有效地与富电子烯烃（ERAs）反应。光环加成反应可以在绿色（530nm）或橙色（590nm）光照射下实现，表示与经典PQ-ERA系统相比超过100nm的红移。此外，通过结合适当的反应物，我们建立一个正交的，蓝光和绿光诱导的光点击反应系统，其中产物分布可以通过选择光的颜色来精确控制。
