Our study proposes an approach to semiheterogeneous photocatalysis, focusing on recyclability challenges. We developed a method employing visible light with photoinert anhydrous CeCl₃, rendering it into a reusable semiheterogeneous photocatalyst. Despite being photoinert and insoluble in organic solvents, anhydrous CeCl₃ formed a transient charge transfer complex in acetonitrile, denoted as CeCl₃ - NXS (NBS or NCS), due to the strong oxophilicity of trivalent cerium toward oxygen. This complex facilitated visible-light absorption, leading to the photoexcitation of the Ce(III) complexes and conversion of Ce(III) centers into potent reductants, donating electrons to NXS. As a proof of concept, we demonstrated organic reactions where NXS, upon accepting electrons, generated halide radicals, allowing the synthesis of gem-dihaloketones under sunlight from terminal aromatic alkynes via C–X cross-coupling reactions. Significantly, CeCl₃ exhibited recyclability without notable decomposition, demonstrated by its regeneration and isolation through simple filtration postreaction, underscoring its potential for prolonged use.

中文翻译：

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利用光惰性 CeCl3 实现可回收半非均相光催化


我们的研究提出了一种半异相光催化方法，重点关注可回收性挑战。我们开发了一种利用可见光和光惰性无水 CeCl ₃ 的方法，将其变成可重复使用的半异质光催化剂。尽管具有光惰性且不溶于有机溶剂，但由于强亲氧性，无水 CeCl ₃ 在乙腈中形成瞬态电荷转移络合物，表示为 CeCl ₃ - NXS（NBS 或 NCS）三价铈与氧的反应。该配合物促进可见光吸收，导致 Ce(III) 配合物的光激发，并将 Ce(III) 中心转化为有效的还原剂，向 NXS 提供电子。作为概念证明，我们演示了有机反应，其中 NXS 在接受电子后产生卤化物自由基，从而允许在阳光下通过 C-X 交叉偶联反应从末端芳族炔烃合成偕二卤酮。值得注意的是，CeCl ₃ 表现出可回收性，没有明显的分解，通过简单的过滤后反应进行再生和分离证明了这一点，强调了其长期使用的潜力。