Spatial and temporal control over photoresponsive nanoclusters

Although cluster species undergo efficient photoresponsive transformations in dilute solutions, their solid-state materials suffer from severely impeded responsiveness due to insufficient motional freedom. Here, we present a photochemical approach that enables spatial and temporal control over nanocluster structure/size conversions in the crystalline state. The Cu₁₈ nanocluster, whether in solution or in solid form, undergoes a photoinduced transformation when exposed to 365-nm light, resulting in a size-reduced Cu₁₄ nanocluster. The single-atom alloy counterpart, Ag₁Cu₁₇, possesses a remarkably enhanced efficiency towards the photoinduced conversion to form the same cluster product. The comparable photoinduced conversion efficiencies between Cu₁₈ and Ag₁Cu₁₇ are monitored by using time-dependent characterizations and further rationalized by using theoretical calculations. The high photoconversion efficiency of crystalline nanocluster materials allows the precise spatial and temporal control of solid-state transformations at the micrometer scale by using femtosecond cold laser technology or by controlling the irradiation time of ultraviolet light. This study introduces a novel pair of clusters with comparable photoinduced conversion characteristics, allowing atomic-level characterizations and an in-depth understanding of the photochemical behavior of metal nanoclusters. Furthermore, the findings in this work are expected to facilitate the design of cluster-based solid-state nanomaterials for downstream photoresponsive applications.