Self-assembly of water-soluble silver nanoclusters: superstructure formation and morphological evolution

Abstract

Supramolecular self-assembly, based on non-covalent interactions, has been employed as an efficient approach to obtain various functional materials from nanometer-sized building blocks, in particular, [Ag(mna)], mna = mercaptonicotinate (Ag-NC). A challenging issue is how to modulate the self-assembly process through regulating the relationship between building blocks and solvents. Herein, we report the controlled self-assembly of hexanuclear silver nanoclusters into robust multilayer vesicles in different solvents, DMSO, CHCN, EG and MeOH. Their unique luminescence enables them to be bifunctional probes to sense Fe and dl-dithiothreitol (DTT). By protonating the Ag-NC to Ag-H-NC using hydrochloric acid (HCl), the multilayer vesicles survive in aprotic solvents, DMSO and CHCN, but are transformed to nanowires in protic solvents, water, EG and MeOH. Our results demonstrated that the solvent-bridged H-bond plays a key role in the evolution of the morphologies from vesicles to nanowires. Moreover, the nanowires could further hierarchically self-assemble in water into hydrogels with high water content (99.5%), and with remarkable mechanical strength and self-healing properties. This study introduces a robust cluster-based building block in a supramolecular self-assembly system and reveals the significance of aprotic and protic solvents for the modulation of the morphologies of cluster-based aggregates.

Amphiphilicity Regulation of AgI Nanoclusters: Self‐Assembly and Its Application as a Luminescent Probe

“…It is known that, for amphiphilic molecules, adding a poor solvent to a miscible, good solvent, in which the solute dissolved, could easily trigger the formation of aggregates . As is reported in our previous study, water is a good solvent for Ag 6 ‐NCs as they can not self‐assemble in water, whereas DMSO is a poor solvent for Ag 6 ‐NCs. Thus, firstly, the self‐assembly behaviors of Ag 6 ‐NCs in the mixed solvents were studied.…”

“…Synthesis of Ag 6 -NCs and Ag 6 @C 16 mim-NCs Ag 6 -NCs were synthesized according to our published procedure. [29] Ag 6 @C 16 mim-NCs were synthesized as follows:C 16 mimBr solution (3 mL, c = 20 mmol L À1 )w as added into Ag 6 -NCs solution (10 mL, c = 1mmol L À1 ), which caused precipitates to form. After 1h,t he reaction was nearly complete.…”

Self-Assembly of Metal Nanoclusters for Aggregation-Induced Emission

“…Manipulating the self-assembly of Ag NCs based on non-covalent forces through modulating the interactions between building blocks and solvents. Shen et al reported the controlled assembly of mercaptonicotinate (MNA)-capped Ag NCs into multilayer vesicles or nanowires in different solvents [46]. After protonating the Ag NCs by adding hydrochloric acid, the morphology of self-assembled vesicles kept stable in aprotic solvents, such as DMSO and CH 3 CN, while in protic solvents, such as water, MeOH, and EG, the vesicular morphology would transform into nanowires (Figure 6).…”

Metal–Organic Gels from Silver Nanoclusters with Aggregation‐Induced Emission and Fluorescence‐to‐Phosphorescence Switching

“…Moreover, the MOGs are quite stable without noticeable changes for months at room temperature. This high colloidal stability, together with the regular morphology and high order of the self‐assemblies, make current system an important supplement to existed metal NC‐based AIE systems and metal NC‐based gels . The MOGs are formed solely by Ag 9 NCs without the assistance of any organic gelator, indicating a high content of the metal NCs in MOGs.…”