Spontaneous Resolution of Chiral Multi-Thiolate-Protected Ag₃₀ Nanoclusters

Abstract

Despite significant progress achieved in the preparation of chiral nanoparticles, the enantioseparation of racemates still presents a big challenge in nanomaterial research. Herein, we report the synthesis and structural characterization of racemic anisotropic nanocluster Ag 30 (C 2 B 10 H 9 S 3 ) 8 Dppm 6 ( Ag 30 - rac ), which is protected by mixed carboranetrithiolate and phosphine ligands. Spontaneous self-resolution of the racemates was realized through conglomerate crystallization in dimethylacetamide (DMAc). The homochiral nanoclusters in the racemic conglomerates adopt enantiomeric helical self-assemblies ( R / L - Ag 30 ). Diverse noncovalent interactions as the driving force in directing superstructure packing were elucidated in detail. Furthermore, the nanoclusters show red luminescence in both solid and solution states, and the racemic conglomerates display a mirror-image CPL response. This work provides atom-precise helical nanoparticle superstructures that facilitate an in-depth understanding of the helical-assembly mechanism.

Circularly polarized luminescence of agglomerate emitters

“…Very recently, one racemate of silver clusters, composed of chiral Ag 30 (C 2 B 10 H 9 S 3 ) 8 Dppm 6 (abbreviated as Ag 30rac; 8,9,12-trimercapto-1,2-closo-carborane, C 2 B 10 H 9 S 3 ; bis(diphenylphosphino)methane, Dppm), was prepared and characterized by their group. [215] More interestingly, spontaneous resolution driven conglomerate crystallization of the racemate could be realized by a facile approach of only dissolving in dimethylacetamide (DMAc), resulting in racemic conglomerates (R/L-Ag 30 ), where each single crystal was homochiral (Figure 11B). Moreover, due to their red-emitting, CPL of single crystal was carried out (g lum , ±7 × 10 −4 ).…”

Self‐Assembly of Precision Noble Metal Nanoclusters: Hierarchical Structural Complexity, Colloidal Superstructures, and Applications

“…reported the synthesis and structural characterization of racemic anisotropic [Ag 30 (C 2 B 10 H 9 S 3 ) 8 (DPPM) 6 ] NCs, (Ag 30 ‐ rac ) protected with a mixture of achiral carboranetrithiolate and phosphine ligands (C 2 B 10 H 9 S 3 = 8,9,12‐trimercapto‐1,2‐ closo ‐carborane and DPPM = bis(diphenylphosphino)methane) via one‐pot reduction method using hydrazine. [ 248 ] The spiral arrangement of the ligands directed by unusual BH···π and CH···π bonding interactions between the carborane cages and benzene rings could induce chirality for Ag 30 ‐ rac . During the crystallization of Ag 30 ‐ rac in dimethylacetamide, the racemates ( R ‐Ag 30 and L ‐Ag 30 ) were self‐resolved into the racemic conglomerates and the enantiomeric NCs self‐assembled into helical structures.…”

Atom-Precise Fluorescent Copper Cluster for Tumor Microenvironment Targeting and Transient Chemodynamic Cancer Therapy

“…[30] By far, our group have designed and synthesized dozens of metal NCs with atomically precise assembly. [31][32][33][34][35][36][37] Bene ting from the precise formulas, both the structure and the physicochemical properties of atomically precise metal NCs are controllable. [38,39] Thus, one could reasonably hypothesize that with rationale design, the additional introduction of the organic ligand could modulate targeting properties while the functional modi cation may generate sustained releasement of NCs in particular position.…”