Modulating Decarboxylative\nOxidation Photocatalysis\nby Ligand Engineering of Atomically Precise Copper Nanoclusters

Copper nanoclusters (Cu NCs) characterized by their well-defined\nelectronic and optical properties are an ideal platform for organic\nphotocatalysis and exploring atomic-level behaviors. However, their\npotential as greener, efficient catalysts for challenging reactions\nlike decarboxylative oxygenation under mild conditions remains unexplored.\nHerein, we present Cu<sub>13</sub>(Nap)<sub>3</sub>(PPh<sub>3</sub>)<sub>7</sub>H<sub>10</sub> (hereafter Cu<sub>13</sub>Nap), protected\nby 1-naphthalene thiolate (Nap), which performs well in decarboxylative\noxidation (90% yield) under photochemical conditions. In comparison,\nthe isostructural Cu<sub>13</sub>(DCBT)<sub>3</sub>(PPh<sub>3</sub>)<sub>7</sub>H<sub>10</sub> (hereafter Cu<sub>13</sub>DCBT), stabilized\nby 2,4-dichlorobenzenethiolate (DCBT), yields only 28%, and other\npreviously reported Cu NCs (Cu<sub>28</sub>, Cu<sub>29</sub>, Cu<sub>45</sub>, Cu<sub>57</sub>, and Cu<sub>61</sub>) yield in the range\nof 6–18%. The introduction of naphthalene thiolate to the surface\nof Cu<sub>13</sub> NCs influences their electronic structure and charge\ntransfer in the ligand shell, enhancing visible light absorption and\ncatalytic performance. Density functional theory (DFT) and experimental\nevidence suggest that the reaction proceeds primarily through an energy\ntransfer mechanism. The energy transfer pathway is uncommon in the\ncontext of previous reports for decarboxylative oxidation reactions.\nOur findings suggest that strategically manipulating ligands holds\nsignificant potential for creating composite active sites on atomically\nprecise copper NCs, resulting in enhanced catalytic efficacy and selectivity\nacross various challenging reactions.