Thanetchaiyakup Adisak, Sadek Mansour, Chan Wei Xin, Qian Yuqing, Yang Jingcheng, Bati Gabor, Xiao Yonghao, Soo Han Sen
School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371, Singapore.
School of Marine Science and Engineering, Hainan University, Haikou 570228, China.
JACS Au. 2025 Jun 16;5(7):3189-3202. doi: 10.1021/jacsau.5c00366. eCollection 2025 Jul 28.
Photoelectrocatalysis offers a powerful method for driving organic transformations by combining light and electrical energy to access more extreme potentials to generate reactive intermediates under milder conditions. Herein, we report the first application of a metal halide perovskite photoelectrocatalytic system for C-(sp)-H activation, leading to C-C and C-N bond formation via alkylation. A lead-free, alloyed double perovskite, CsAgNaBiBr, was engineered as a relatively stable photoanode and used catalytically (0.5-1 mol %) under visible-light irradiation and ambient conditions with 9,10-diphenylanthracene as a cocatalyst to facilitate cross-coupling organic syntheses. Extensive characterization of the photoanode by electrochemical analyses, powder X-ray diffraction, ultraviolet photoelectron spectroscopy, and scanning electron microscopy confirmed the structural integrity and photoelectrocatalytic activity of the CsAgNaBiBr anode. Under optimal conditions, aliphatic substrates underwent C-H activation and coupling with electron-deficient SOMOphiles to afford C-C coupled products in up to 94% yield and C-N coupled products in up to 99% yield. Mechanistic studies, including isotope labeling, kinetic isotope effect competition experiments, and density functional theory calculations, reveal that the reaction proceeds via photogenerated •Br radicals that induce hydrogen atom transfer from the solvent molecules to generate nucleophilic alkyl radicals. These nucleophilic alkyl radicals then underwent polarity-matched addition to electron-deficient alkenes or azo compounds to form the desired products, with C-H activation of the substrate identified as the rate-determining step. This work demonstrates C-H functionalization and cross-coupling reactions under remarkably mild ambient conditions and establishes a new frontier for the application of metal halide perovskites in the photoelectrocatalytic activation and tandem transformation of small organic molecules.
光电催化提供了一种强大的方法，通过结合光能和电能来驱动有机转化，从而在更温和的条件下获得更极端的电位以产生活性中间体。在此，我们报道了金属卤化物钙钛矿光电催化体系在C-(sp)-H活化中的首次应用，该体系通过烷基化反应实现了C-C和C-N键的形成。一种无铅的合金双钙钛矿CsAgNaBiBr被设计成相对稳定的光阳极，并在可见光照射和环境条件下，以9,10-二苯基蒽作为助催化剂，催化用量为0.5-1 mol%，用于促进交叉偶联有机合成。通过电化学分析、粉末X射线衍射分析、紫外光电子能谱分析和扫描电子显微镜对光阳极进行了广泛表征，证实了CsAgNaBiBr阳极的结构完整性和光电催化活性。在最佳条件下，脂肪族底物发生C-H活化，并与缺电子的亲SOMO体偶联，得到产率高达94%的C-C偶联产物和产率高达99%的C-N偶联产物。机理研究包括同位素标记、动力学同位素效应竞争实验和密度泛函理论计算，结果表明该反应通过光生•Br自由基进行，该自由基诱导氢原子从溶剂分子转移以产生活性亲核烷基自由基。然后，这些亲核烷基自由基与缺电子烯烃或偶氮化合物进行极性匹配加成，形成所需产物，底物的C-H活化被确定为速率决定步骤。这项工作展示了在非常温和的环境条件下的C-H官能团化和交叉偶联反应，并为金属卤化物钙钛矿在光催化活化和小分子有机化合物串联转化中的应用开辟了新的领域。
