Fluorescent hydrogels formed by CH-π and π-π interactions as the main driving forces: an approach toward understanding the relationship between fluorescence and structure.

Amide-linked tripyridine derivatives 1, with a para-substituent, and 2, with a meta-substituent, were gelated in water or water-DMSO. The gelation capabilities of 1 and 2 were attributed to the cooperative effects of mainly CH-π and π-π stacking or strong intermolecular hydrogen bonding interactions between the amide groups. The fluorescence properties of gels 1 and 2 were dependent on the binding strength of the π-π stacking.