Self-Assembly of Bolaamphiphiles into 2D Nanosheets via Synergistic and Meticulous Tailoring of Multiple Noncovalent Interactions.

Abstract

A bolaamphiphile possessing a hydrophobic skeleton and two hydrophilic groups at both ends represents an important class of building blocks toward a rich variety of self-assembled materials for use in ion transport, optoelectronic devices, and drug and gene delivery. Herein, we report a one-step synthesis of an array of rationally designed anionic bolaamphiphiles and unravel the correlation between molecular structure of anionic bolaamphiphiles and their disparate self-assemblies via synergistic and meticulous tailoring of a set of interactions. Intriguingly, by delicately regulating the interactions among these supramolecular interactions, two-dimensional (2D) nanosheets are crafted via self-assembly of anionic bolaamphiphiles. Particularly, single-layered 2D nanosheets are formed through the synergy of aromatic π-π stacking, hydrophobic, hydrogen-bonding, and electrostatic repulsion interactions. In contrast, the selective converting of anionic headgroups of bolaamphiphiles into nonpolar alkyl chain screens the electrostatic repulsion between neighboring bolaamphiphiles while keeping the other segments of bolaamphiphiles intact, thereby allowing them to self-assemble into multilayered 2D nanosheets. Interestingly, the intrinsically charged 2D nanosheets could anchor oppositely charged metal nanoparticles via electrostatic attraction. Conceptually, anionic bolaamphiphile-derived 2D nanosheets may function as a substrate to position a diversity of nanocrystals and conjugated polymers for a broad range of applications in catalysis, optical devices, and photothermal therapy.