Electrostatic-driven Self-assembly of Janus-like Monolayer-protected Metal Nanoclusters

TL;DR

This study models zwitterionic Janus-like ligand-protected metal nanoclusters and reveals how electrostatic interactions guide their self-assembly into specific microstructures, providing insights for designing tunable nanostructures.

Contribution

It introduces atomistic simulations of zwitterionic J-MPCs to understand their self-assembly mechanisms driven by electrostatics and hydrogen bonding.

Findings

Oppositely charged ligands induce asymmetric solvation.

Electrostatic interactions guide formation of 1D and ring-like structures.

Hydrogen bonding patterns influence self-assembly behavior.

Abstract

The generation of controlled microstructures of functionalized nanoparticles has been one of the crucial challenges in nanoscience and nanotechnology. Efforts have been made to tune ligand charge states that can affect the aggregation propensity and modulate the self-assembled structures. In this work, we modelled zwitterionic Janus-like monolayer ligand-protected metal nanoclusters (J-MPCs) and studied their self-assembly using atomistic molecular dynamics and advanced enhanced sampling simulations. The oppositely-charged ligands functionalization on two hemispheres of a J-MPC elicits asymmetric solvation, primarily driven by distinctive hydrogen bonding patterns in the ligand-solvent interactions. Electrostatic interactions between the oppositely charged residues in J-MPCs guide the formation of one-dimensional and ring-like self-assembled superstructures with molecular dipoles oriented in specific patterns. The pertinent atomistic insights into the intermolecular interactions governing the self-assembled structures of zwitterionic J-MPCs obtained from this work can be used to design a general strategy to create tunable microstructures of charged MPCs.