Construction And Optical Properties Of Low Molecular Weight Organogelator With Fluorescence Emission Enhancement Induced By Aggregation

Low-molecular-weight organogelators can self-assemble into various dimensional and morphologic superstructures in organc solvents directed by noncovalent interactions, such as H-bonding, van der Walls,π-πstacking ect. We may introduce functional units into LMMGs, which possessed specific applications in light harvesting, energy and charge transfer, switches, and chiral or molecular-shape selection.We have synthesized functional organogelators and constructed low-molecular-weight organogels with aggregation-induced emission enhancement. The obtained results were outlined as follows:(1) In the first chapter, we have desigened a series of organogelators consisting of coumarin with different alkoxy chains and studied their gelation property in organic solvents. It was found that the compounds with three alkoxy chains could gel organic solvents. The longer of the alkoxy chains, the stronger of the ability of gel. This would help us to design functional LMWG. It was found that the organogelators packed into biomolecular lamellar structure. In addition, the optical properties can be tunned by the [2+2] cycloaddition of coumarin.(2) A series of dicholesterol derivatives consisting of salicylideneaniline moieties were synthesized and their gelation properties were studied in organic solvents. It was found that only one compound was a good gelator. The fluorescence emission intensity of the organogel was more than 1000 times higher than that of the solution at the same concentration as a result of the formation of J-aggregations and the restricted molecular motion in the gel state. Strong fluorescence emission and photochromism could be involved in such a gel system, indicating that the expected optical properties may be realized through tuning the self-assembly process of the functional gelator.(3) We synthesized a series of salicylideneaniline derivatives with didodecyloxy chains and studied their gelation properties in organic solvents. It was found that the ability of salicylideneaniline derivative with didodecyloxy chains gel solvents was weaker than that of dicholesterol derivative consisting of salicylideneaniline moieties. We found that the organogelator formed rodlike fibers in the gel. The fluorescence emission intensity of the organogel was higher than that of the solution at the same concentration.(4) A new functional Stilbazole compound was synthesized and functional binary gels based on benzoic acid with different alkoxy chains and stilbazole were prepared. H-bonding andπ-πstacking were the driving forces for the formation of the gel based on the results of UV-vis and FT-IR. The fluorescence emission intensity of the organogel was more than 10 times higher than that of the solution at the same concentration. It provides an extensive way to prepare functional gels via non-covalent interactions.