Transformation Chemistry of Gold Nanoclusters: From One Stable Size to Another

Abstract

Controlling nanoparticles with atomic precision has long been a major dream of nanochemists. This dream has first been realized in the case of gold nanoparticles. We previously discussed a size-focusing methodology for the syntheses of atomically precise gold nanoclusters protected by thiolate ligands (referred to as Aun(SR)m, where n and m represent the exact numbers of gold atoms and surface ligands). This methodology led to molecularly pure nanoclusters such as Au25(SR)18, Au38(SR)24, Au144(SR)60, and many others in recent work. In this Perspective article, we shall further discuss a new methodology for controlling the size and structure of nanoclusters through ligand-exchange-induced transformation of Aun(SR)m nanoclusters. Notable examples include the transformations of Au25(SR)18 to Au28(SR')20, Au38(SR)24 to Au36(SR')24, and Au144(SR)60 to Au133(SR')52. Total structures of the new nanoclusters have also been attained. The transformation processes are remarkable and resemble the organic transformation chemistry. We have also achieved mechanistic understanding on the transformation process, and a disproportionation mechanism has been for the first time identified. This new methodology (i.e., ligand-exchange-induced size/structure transformation, LEIST for short) has not only demonstrated the important role of thiolate ligand in the transformation chemistry of clusters but also paved the way for creating an expanded "library" of Aun(SR)m nanoclusters for exploration of their magic sizes, structures, properties, and applications.

Thermodynamic stability of ligand-protected metal nanoclusters

“…6). Interestingly, this observation is in agreement with recent work where conversion from Au 38 SR 24 (R=phenylethanethiolate) to Au 36 SR 24 (R=4- tert -butylbenzenethiol) was achieved in solution by swapping the thiolate R groups from phenylethanethiolate to 4- tert -butylbenzenethiol, altering the hydrogen-bond network formed the surface of the NCs49. To further prove that this structural thermodynamic stabilization is a general behaviour and originates solely from the energy balance between the core and the shell of the NCs we analysed (Supplementary Note 5) CE and BE in the presence of the common8 dichloromethane (Supplementary Fig.…”

Ligand-Exchange-Induced Growth of an Atomically Precise Cu29 Nanocluster from a Smaller Cluster

“…[1][2] An emerging method for controlling the size and structure of nanoclusters involves ligand exchange to induce a transformation from one stable cluster to another. 1,[3][4][5][6] Although such ligand exchange reactions are commonly used to introduce new functional groups onto the surface of clusters while preserving the original core size, they can also lead to changes in the shape and/or size of the metal core. [3][4][5]7 24 ].…”

Switching a Nanocluster Core from Hollow to Nonhollow

“…The typical routes for metal NC synthesis are: i) direct reduction of metal precursors in the presence of desired ligands, [22][23][24][25][26][27][28] ii) postsynthetic ligand-exchange (LE), [29][30][31][32][33][34][35] and iii) metal-exchange 15,[36][37][38][39][40][41] . Among these methods, LE has recently been widely adopted for preparing novel gold NCs [42][43][44] .…”