Porous 3 d-4 f Coordination Clusters for Selective Visible-Light Photocatalytic CO₂ Reduction to CO

We report herein two families of porous coordination clusters (PCCs) with 216 nuclearity (M₁₂₀RE₉₆ or PCC-216MR) and 300 nuclearity (Co₁₄₄Gd₁₅₆ or PCC-300CG). For the first family M could be either nickel or cobalt, and RE = Pr, Nd, Sm, Eu, and Gd; while the latter features the highest nuclearity of transition-rare earth metal clusters. Characterized by their cube-like, hollow structures, these clusters exhibit the ability to absorb N₂ and CO₂. Besides, these clusters can be dissolved in both aqueous and acetonitrile/methanol solutions, and capable of acting as homogeneous catalysts for converting CO₂ to CO under visible light. The gadolinium analogues of these clusters all show turnover numbers over 10000 and turnover frequencies over 1 s⁻¹. In particular, the nickel based bimetallic cluster (PCC-216NG) demonstrates nearly 100 % selectivity for the reduction product, which may open a new direction for the design and development of PCCs based catalysts.