Design,Synthesis And Application Of Acylhydrazone-based Supramolecular Gels

Supramolecular gel is a kind of soft material assembled by noncovalent interactions（hydrogen bond,coordination,Van der Waals force,π-πstacking,etc.）between low molecular weight gels（LMWGs）.Its architecture is similar to a solid nano-network,which can transform the information of molecular scale into the properties of materials.As a special Schiff base,acyl hydrazone has a unique structure.Compared with common Schiff base,it is more stable and less prone to hydrolysis,which makes it have special physical and chemical properties.In this thesis,a new type of acyl hydrazone gel factor N,N’,N’’-tris（4-pyridyl）tribenzoylhydrazone（BTTN4）with small molecular weight was designed and synthesized by dehydration condensation of mesitylhydrazine and 4-pyridine formaldehyde.The gel properties,self-assembly morphology and self-assembly mechanism in different solvents were studied in detail,its application in dye wastewater treatment was further explored.The main contents are as follows:（1）The obtained compounds have poor solubility in organic solvents,but have good solubility in acidic aqueous solutions and can form gels.It is found that the formed gel not only has good thermal reversibility,but also has sensitive p H response.In addition,with the change of p H,the color of gel system also changed.When the p H of the system was small,white gel was formed,and with the increase of p H,the gel gradually collapsed until it became yellow solution.Rheological properties show that the gel exhibits good mechanical and self-repairing properties.XRD and FT-IR results show that hydrogen bonding between adjacent molecules,van der waals force andπ-πstacking are the main driving forces for gel formation.（2）On the basis of ligand BTTN4,supramolecular metal gel was constructed by coordination with Fe³⁺（Fe Cl₃,Fe（NO₃）₃）.We investigated the effects of p H,concentration,anion and cation and solvent on gel formation.SEM results show that the microstructure of metal gel system is mostly flaky or blocky aggregates.XRD and FTIR show that the coordination of Fe³⁺in BTTN4molecule and the hydrogen bond between adjacent molecules are the main driving forces for gel formation.（3）Fe（NO₃）₃-BBTN4 was used as precursor to prepare Fe₃C/C magnetic composites by high temperature nitrogen protection firing,and the adsorption properties of cationic dye Rhodamine B（Rh B）and anionic dye Congo Red（CR）were tested.The adsorption experiment results show that Fe₃C/C has adsorption effect on both dyes and the adsorption process of both dyes accords with Langmuir isothermal adsorption model and pseudo-second-order kinetic model,and the adsorption process belongs to an exothermic process.The maximum adsorption capacity of Rh B and CR was 49.43 mg·g^-1 and 859.75 mg·g^-1,respectively.In addition,the adsorbent can be reused many times.