Photoconversion of Ag₃₁ to Ag₄₂ Initiated by Solvated Electrons

Abstract

Light-matter interactions, especially in atomically precise nanomaterials, belong to an unexplored realm of research with potential benefits for the synthesis of materials. Here, we present an interesting light-activated expansion process of an Ag 31 nanocluster to an Ag 42 analogue, both clusters being protected with 6-(dibutylamino)-1,3,5-triazine-2, 4-dithiol (shortly, TRZ-H 2 ) ligands. The conversion process was initially monitored through UV−vis, revealing that the violet-colored Ag 31 got converted to greenish Ag 42 , exhibiting their characteristic absorption features. High-resolution mass spectrometric studies confirmed that the assynthesized [Ag 31 (TRZ) 10 ] with coexisting di-and monoanionic charged species in dichloromethane solution got converted to [Ag 42 (TRZ) 13 ] with a dipositive charge state. Electrochemical studies revealed the photoresponsive nature of Ag 31 , and light illumination resulted in transient intermediate clusters covered with solvated electrons, which contributed to the core expansion. Ag 31 is NIR-emitting, while Ag 42 is red-emitting. The ultrafast transient absorption studies reveal that Ag 42 has strikingly short excited-state carrier dynamics than Ag 31 . The stable excited-state carriers for Ag 31 upon photoexcitation also underline the unique electronic characteristics responsible for such light-activated structural evolution.

Chemical Flexibility of Atomically Precise Metal Clusters

“…Physical stimuli, including light irradiation, temperature, electricity, and pressure, play a role in activating the chemical flexibility of metal clusters . Light irradiation easily excites electron transitions in metal clusters, especially when combined with other factors in a solution, thereby initiating reactions of the metal clusters. ,− Elevated temperatures can modify bond lengths, affecting the overall thermodynamics of cluster formation, and increase the kinetic energy of molecules, inducing phase transitions that potentially lead to complete reconstruction. − The application of an electric field or current can drive electrochemical reactions involving metal clusters. − Under high-pressure conditions, there can be changes in bond lengths, coordination environments, and even phase transitions. Understanding the pressure dependence of cluster stability is crucial for applications in extreme environments. − In section , this Review will explore the structural changes and associated properties of metal clusters under various physical conditions, closely aligning with potential future application environments.…”

Recent advances in synthesis and properties of silver nanoclusters

“…In a recent study, the same group observed a light-activated size-expansion process, wherein the [Ag 31 (TRZ) 10 ] 2−/1− cluster transformed into the [Ag 42 (TRZ) 13 ] 2+ cluster (TRZ: 6-(dibutylamino)-1,3,5-triazine-2,4-dithiolate). 87 The size conversion was demonstrated using absorption spectroscopy of NCs with fingerprint absorption features, as well as a clear color change from violet to greenish. The Ag 31 cluster exhibits photoresponsive behavior, and the resulting intermediate species are covered with solvated electrons, contributing to the expansion of the cluster size.…”