Self-assembled nanostructures of 3ph-imi[FeCl₄] as a strong ice recrystallization inhibitor

Ice recrystallization inhibition (IRI) materials are important in both fundamental research and practical applications, but achieving efficient regulation through molecular design remains challenging. Herein, we synthesized a series of imidazole-based ionic liquids with triphenyl groups, 3ph-imi[X], and investigated the influence of various anions on their relationship between self-assembled structures and ice crystal regulation properties. In aqueous solution, 3ph-imi[FeCl₄] was found to form well-defined spindle-shaped nanosheets with crystalline order, whereas the other anions (cl, Br, NO₃, Tb(NO₃)₄, ho(NO₃)₄) yielded conventional spherical micelles. Notably, 3ph-imi[FeCl₄] exhibited strong IRI activity (23.8%) at a rather low concentration (0.32 mM). The mechanism of the high IRI activity was investigated using single crystal X-ray diffraction and molecular dynamics simulations, which indicated that the spacing between its hydrophilic groups (7.07 Å) matched the lattice parameter of hexagonal ice along the c-axis, enabling effective adsorption onto the ice crystal surface thereby inducing interfacial curvature to inhibit ice crystal growth. This study provides new insights for designing high performance IRI materials by optimizing anion selection and molecular assembly to enhance interfacial order and ice matching capability, expanding the potential applications of ionic liquids in low-temperature fields.