  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.
