Hofmeister Effect Steers the Self‐Assembly Pathway of Supramolecular Hydrogels

ABSTRACT Because of the feature of noncovalent interactions, supramolecular assemblies show intrinsic dynamics, whose structures and functions usually depend on their self‐assembly pathways. However, the Hofmeister effect, an important factor capable of modulating intermolecular interactions, is underexplored in its potential of controlling the self‐assembly pathway. Here, on the basis of a hydrazone‐based supramolecular gelation system, we show that the Hofmeister effect can accelerate the self‐assembly of gelators into a hydrogel that cannot be achieved under thermodynamic conditions. By decreasing the concentration of gelators to the corresponding critical gelation level, gelation fails to occur under standard conditions. However, with the addition of sufficient kosmotropic anions that can strengthen intermolecular interactions via the disruption of solvation, we surprisingly find that the gelator solution is rapidly converted into a hydrogel state. More importantly, the resultant hydrogel network remains sustained even after a subsequent removal of the kosmotropic anions, indicating that the addition of kosmotropic anions enables a gelation pathway that is inaccessible by the standard approach. Our findings suggest that the Hofmeister effect can serve as an effective approach to interfere with the self‐assembly pathway, and therefore, it should be considered in future studies of supramolecular chemistry.