The Study On Synthesis, Self-assembly And Catalytic Properties Of Low-Molecular-Weight Gels Derived By Trimesic Acid And Melamine

Supramolecular gels have extensive properties, such as dispersible structure, thermo-reversible, sensitivity on chemical solvent, and specificity of the aggregate structure. Therefore, they have wide potential applications in soft organic materials, drug-delivery system, template of nanomaterials, biofilm simulation, organic transistors, catalysis and other fields. In the present work, low-molecular-weight gels derived by trimesic acid and melamine were synthesized. The micro-structures and mechanism of formation were investigated systematically by Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM), Scanning tunneling microscope(STM), nuclear magnetic resonance (NMR) spectroscopy, rheological methods, Differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). Then polymer films containing iron compound were synthesized using template effect of supramolecular gels under UV-irradiation and the catalytic properties on the reduction of nitrobenzene with hydrazine hydrate were investigated.1、A series of monochain 4-aminopyridine derivatives 1-5 were synthesized. The experimental results reveal that 1-5 and various aliphatic dicarboxylic acids 1’-4’ have no gelation abilities, respectively. However, they can form stable two-component systems with the molar ratio of 2:1 in various organic liquids. This kind of two-component organogels can self-assemble into fibrous or banded aggregates through intermolecular hydrogen bonding and van der Waals interactions of long alkyl chains. Finally, the forming mechanism of organogels was obtained.2、Melamine and Vc have no gelation abilities, respectively. But two-component systems consisting of them can form hydrogel in water. The results suggest that intermolecular hydrogen bonding and van der Waals interactions of long alkyl chains are the driving force of formation of gel, which is useful to understand not only the mechanism of melamine calculus, but also understand the recognition and self-assembly of food law. Thus, the results have certain theoretical and practical significance.3、Metallogels have been successfully fabricated from N,N’,N"-tris (4-pyridyl) trimesic amide and N,N’,N"-tris(3-pyridyl) trimesic amide in aqueous solution induced by Fe(Ⅲ)/Fe(Ⅱ) ions. The experimental results reveal that the xerogels of metallogels are possessed fibrous/banded micro-morphologies and the ligand molecules in the two dimensional molecular layer was connected by coordination and the intermolecular hydrogen bonds between N-H of amide and N of pyridine. The two dimensional molecular layer was further connected by inter-layer hydrogen bonds between part adjacent amide gruops and n-n stacking interactions to form a hydrogen bond network and then develop a three dimensional network superstructure. The driving forces are intermolecular hydrogen bonding, π-π stacking interactions and metal-ligand coordination interactions between Fe3+/Fe2+ and N-py.4、Metal complex catalysts (Cat.1、Cat.2、Cat.3、Cat.4) were synthesized based on metallogels induced by Fe3+/Fe2+ and catalytic properties on the reduction of nitrobenzene with hydrazine hydrate were investaged. The yield of aniline depends strongly on n(ligand):n(Fe3+), reaction temperatue, amount of catalyst, reaction time and n(hydrazine):n(nitrobenzene). The results suggest that Cat.3 and Cat.4 exhibit high catalytic activities for reduction of nitrobenzene and the optimal reaction conditions were also obtained. In the case of Cat.3, the yield of aniline could reach up to 100% under the experimental conditions:n(ligand):n(Fe3+)=1:3,40 mg catalyst, n(hydrazine):n(nitrobenzene)=2.5,80℃ for 3 h. In the case of Cat.4, the yield of aniline could reach up to 100% under the conditions:n(ligand):n(Fe3+)=1:3,40 mg catalyst, n(hydrazine):n(nitrobenzene)=2.5,80℃ for 4 h.5、Polymer films (PF.1, PF.2, PF.3, PF.4) were synthesized using template effect of metallogels under UV-irradiation and catalytic properties on the reduction of nitrobenzene with hydrazine hydrate were studied. The yield of aniline depends strongly on n(ligand):n(Fe3+), reaction temperatue, reaction time and n(hydrazine): n(nitrobenzene). The results suggest that PF.3 and PF.4 exhibit high catalytic activities for reduction of nitrobenzene and the optimal reaction conditions were also obtained. For PF.3, the yield of aniline could reach up to 100% under the conditions: n(ligand):n(Fe3+)=1:3, n(hydrazine):n(nitrobenzene)=2.5,90℃ for 12 h. For PF.4, the yield of aniline could also reach up to 100% under the conditions: n(ligand):n(Fe3+)=1:3, n(hydrazine):n(nitrobenzene)=2.5,90℃ for 18 h. Easy separability and recycling are the greatest feature for using polymer films to catalyze reactions, which can reduce the costs and renvironmental pollution.