Scrolling in Supramolecular Gels: A Designer’s Guide

Abstract

Gelation by small molecules is a topic of enormous importance in catalysis, nanomaterials, drug delivery, and pharmaceutical crystallization. The mechanism by which gelators self-organize into a fibrous gel network is poorly understood. Herein, we describe the crystal structures and gelation properties of a library of bis(urea) compounds and show, via molecular dynamics simulations, how gelator aggregation progresses from a continuous pattern of supramolecular motifs to a homogeneous fiber network. Our model suggests that lamellae with asymmetric surfaces scroll into uniform unbranched fibrils, while sheets with symmetric surfaces undergo stacking to form crystals. The self-assembly of asymmetric lamellae is associated with specific molecular features, such as the presence of narrow and flexible end groups with high packing densities, and likely represents a general mechanism for the formation of small-molecule gels.

Exploiting Urea-Carboxylate Synthon for Designing Supramolecular Topical Hydrogel via Simple Organic Salt Formation: Synthesis, Crystal Structures, and Anticancer Behavior against Melanoma B16–F10 Cells

“…In fact, LMW hydrogelators − are progressively seeking attention as the gel properties can be easily manipulated by altering factors like pH, temperature, functional groups present on the gelator backbone, solvent systems, − and so forth. However, there still exists limited assurance for a small molecule to be a gelator, − and often the phenomenon of gelation is serendipitous in nature due to the lack of suitable design strategies that correlate the molecular level characteristics with the macroscopic gel-inducing behaviors. For over a decade, our group has actively participated in designing supramolecular gels by utilizing the concept of supramolecular synthons in the context of crystal engineering .…”