The Synthesis, Self-assembly And Properties Of Novel Low-Molecular-Mass Organogelators

In recent years, as novel self-assembled materials, low-molecular-mass organic gelators(LMOGs) have received considerable attention. They can assemble into networks by means of various noncovalent interactions, such as hydrogen bonds, coordination interactions,hydrophobic interactions, π-π interactions and van der Waals forces, etc. Then the networks with solutions form gels. As the gels have the properties of thermally reversible, self-healing,relatively low cytotoxicity and rapid response to external environmental stimulation. And so they have developed into functional materials which have numerous potential applications. In this thesis, we designed and synthesized novel LMOGs. We characterized the compounds and studied the properties of gels and the process of self-assembly through advanced technologies.Besides, we also explored the potential applications of the gels. The whole paper mainly contains the following two parts:1、Vesicle-tube-fibre evolution via spontaneous fusion and its applicationswe introduced 4-aminoantipyrine, which has been extensively applied in dyes,biomedicine, pesticides and environmental fields, into the ALS system for the first time.Here,4-amino-2,3-dimethyl-pyrazolone was used as the linker to construct a new kind of gelator. A real-time reversible fusion pathway from vesicles to fibres, passing through several types of intermediates such as fused vesicles and short and long tubes, was monitored in the assembly. The mechanism of the structural evolution via a gelation process was studied by means of electronic microscopy, small-angle X-ray scattering and powder X-ray diffraction.The fibres of the gel tissue could be switched by sonication and mechanical shaking to tubes and broken fibres, respectively, the destroyed fibres could match with each other in the healing process, showing the self-healing and self-correcting character of the self-assembly.We also studied the reversed process by thermal treatment. This complete investigation of the reversible vesicle-tube-fibre transition is of great significance in the design and synthesis of new nano/microstructures, especially stimulus-responsive aggregates.2、Sugar functionalized naphthalimide based hydrogels and its application in drug release systemIn addition to the mechanism of the “vesicle-tube-fibre” structural evolution in the firstpart. In this part, we found another “sphere-ring-tube” self-assembling process. We designed and synthesized sugar functionalized naphthalimide derivatives including H1 and H2, they can form hydrogels. H1 self-assembles into supramolecular nanotubes by the reaction of4-N-ethylaminenaphthalimide-N-propinyl and deltagluconolactone in refluxed ethanol.The suspension of the tube assembly in water can directly form hydrogels when triggered by sonication, without change in morphology or molecular aggregates in the pH range of 5-8.And the direct and instant suspension-to-gel phase transformation bypasses the sol intermediate. The gelation mechanism was studied in detail. Modified with aminocarproic acid, H2 with more hydrogen bonding sites can form pH tolerant hydrogels in the widest range of pH values from 1-14 accelerated by sonication. Finally, the potential of the hydrogel as a drug delivery and release system for hydrophilic medicine was explored.