Synthesis, Optical, and Mesomorphic Properties of Self-Assembled Organogels Featuring Phenylethynyl Framework with Elaborated Long-Chain Pyridine-2,6-Dicarboxamides

A series of new orgailogelators with pi-conjugated phenylethynyl framework featuring long-chain carboxamides have been synthesized. These organgelators have shown great ability to gel a variety of organic solvents to form stable organogels with the minimum gelation concentration as low as 0.1 wt %. Gelation is completely thermoreversible, and it occurs due to the aggregation of the organogelators resulting in the formation of a fibrous network via a combination of intermolecular hydrogen bonding, pi-pi stacking, and van der Waals interactions that is observed for the xerogels by TEM. The influence of sol-to-gel transition has been explored in detail by variable-temperature H-1 NMR, UV-vis absorption, and fluorescence spectroscopy. Aggregation-induced enhanced emission has been observed in these organogelator molecules with ail order of higher fluorescence quantum yields from solution to gels. In addition, Some Molecules also exhibit unique liquid crystalline properties over a large temperature range as revealed by DSC and POM studies.