A Highly NIR Emissive Cu₁₆Pd₁ Nanocluster

The construction of stable copper nanoclusters (Cu-NCs) with near-infrared (NIR) emission that can be used for catalysis is highly desired, yet remains a challenge. Herein, an atomically precise bimetallic Cu/Pd NC with a molecular formula of Cu₁₆Pd₁L₁₀(PPh₃)₂(Pz)₆ (Pz = 3,5-(CF₃)₂Pyrazolate, L = 4-CH₃OPhC≡C^-), abbreviated as Cu₁₆Pd₁, is synthesized. Single-crystal X-ray crystallographic analysis of Cu₁₆Pd₁ reveals a Cu₁₀Pd₁ kernel with pseudo-gyroelongated square bipyramid confirmation surrounded by other 6 Cu(I) ions and protected ligands. Interestingly, it exhibits strong NIR emission with the highest photoluminescence quantum yield (PLQY) among all the Cu NCs/Cu alloys (λ_em > 800 nm) in the solid-state, and also displays NIR emission in solution. Experimental results and theoretical calculations suggest that the impressive NIR emission is attributed to abundant supramolecular interactions in the solid-state, including intramolecular metal-metal and intermolecular interactions. Of note, the bimetallic Cu₁₆Pd₁ can catalyze the reduction of 4-nitrophenol. This work provides a novel method for synthesizing Cu/Pd NCs and reminds that the less studied Cu/Pd NC can serve as outstanding luminescent material, which is seldom noticed in atomically precise nanoclusters.