Heat-Set Supramolecular Hydrogelation by Regulating the Hydrophilic-Lipophilic Balance for a Tunable Circularly Polarized Luminescent Switch

Small. 2024 Apr;20(16):e2307948. doi: 10.1002/smll.202307948. Epub 2023 Nov 28.

Abstract

Heat-set supramolecular gels exhibited totally opposite phase behaviors of dissolution upon cooling and gelation on heating. They are commonly discovered by chance and their rational design remains a great challenge. Herein, a rational design strategy is proposed to realize heat-set supramolecular hydrogelation through regulation of the hydrophilic-lipophilic balance of the system. A newly synthesized amphiphile hydrogelator with pyrene embedded in its lipophilic terminal can self-assemble into a hydrogel through a heating and cooling cycle. However, the host-guest complex of the gelator and hydrophilic γ-cyclodextrin (γ-CyD) results in a sol at room temperature. Thus, heat-set hydrogelation is realized from the sol state in a controllable manner. Heat-set gelation mechanism is revealed by exploring critical heat-set supramolecular gelation and the related findings provide a general strategy for developing new functional molecular gels with tunable hydrophilic-lipophilic balance.

Keywords: circularly polarized luminescence; heat‐set hydrogels; host‐guest interactions; hydrophilic–lipophilic balance; supramolecular self‐assembly.