Symmetry Breaking Drives Twisted Prismatic Evolution in Atomically Precise Copper Nanoclusters

Abstract

The stability of the copper nanocluster (Cu NC) has always been a concern owing to its low half-cell reduction potential. It is well documented that anion templates are known to tune the structure and impart stability to the nanocluster. Here, using a simple reduction strategy, we have obtained a dihalide-templated Cu NC for the first time. The Cu NC, namely, [Cu23(μ3-Cl)2(SPh-CF3)18(PPh3)6(CF3COO)3], features a unique double triangular prismatic structure. The structure contained a basic unit with the formula Cu9(μ3-Cl)2 forming an inner triangular prism, which is further wrapped by a second triangular prism with the formula Cu12(SPh-CF3)18(PPh3)6(CF3COO)3, forming a unique twisted triangular double prismatic geometry. Further, we have proposed a plausible growth mechanism that helps us decipher the evolution of the nanocluster, and here we observed a peculiar “twisted concentric growth” of the two prisms, which occurs due to the radial dimerization of the Cu11 base prism to form the dimeric Cu23 nanocluster. The unique growth pattern and structure influence the electronic states of the nanocluster, as evidenced by experimental and theoretical studies, thereby imparting good photoresponse properties to the material. The new insights into this novel dihalide-templated twisted double prismatic Cu NC may pave the way to understanding the unique structural growth and developing photonic materials.