Abstract
<jats:p> Supramolecular hydrogels are promising sensing materials, but rapid drying under ambient conditions limits their long-term operation. Replacing water with ionic liquids enables airstable ionogels, although design strategies remain unclear. Here, we introduce peptide ionogels using a choline phosphate ionic liquid buffer mimicking aqueous phosphate media. Using C-terminally amidated tripeptide isomers YFD and DFY as a model system, we investigate how sequence governs assembly in ionic versus aqueous environments. While both tripeptides form hydrogels, only DFY undergoes ionogelation, forming hierarchical assemblies distinct from those in water, whereas YFD remains soluble. These observations suggest that ionogelation requires strong aromatic interactions (through central F and neighboring Y) along with spatial separation of charged and aromatic regions, enabling interfacial ion stabilization of peripheral charges, particularly at the N-terminus. DFY ionogels exhibit air stability for over 100 days and ionic conductivities of ≈10 <jats:sup>-3</jats:sup> Scm <jats:sup>-1</jats:sup> at high frequencies. They function as chemoresistive sensors for humidity and volatile organic compounds under ambient conditions. Notably, they discriminate between ethanol and methanol, highlighting their potential for detecting adulteration in spirit beverages. These findings establish a foundation for the rational design of peptide ionogels, showing how sequence-informed approaches combined with tailored ionic environments enable functional soft materials beyond aqueous systems. </jats:p>