A novel salicylidene aniline-based wholly π-conjugated molecule that could be self-assembled into an organogel was synthesized. The rigid organogel collapsed into fluid solutions with significant changes in UV-vis absorption and fluorescence colors in response to fluoride ions. It was found that the hydroxyl group in the salicylidene aniline moiety played a key role not only in the gelation but also in fluoride ion responses.