Study On The Synthesis And Performance Of Bi-Schiff Base Gel Factor Based On O-Phenylenediamine

Small-molecule organic compounds can form gels in certain solvents leads to their unique structures,which makes them of considerable application value in the fields of nanomaterial templates,drug release control,fluorescent sensors,and preparation of sensitive gels.Small molecule organic compounds which can form gels are called organogel factors,and the resulting organic gels are called small molecule organogels.Small molecule organogel factors can aggregate through intermolecular hydrogen bonds,coordination bonds,van der Waals forces,?-?stacking,hydrophobic interactions,etc.,and then they self-assemble into fiber-assembled aggregates at very low concentrations,and further form tangled three-dimensional network structure,so that the solvent molecules are locked to form a gel.In recent years,many responsive gel have been continuously reported.In this paper,a double Schiff base gel factor based on the o-phenylenediamine structure was designed and synthesized,G3 and G4 belong to Salen-type schiff base.Salen schiff bases are usually tetradentate ligands containing N,O coordination atoms obtained by condensation of salicylaldehydes and diamines.They are easy to prepare and have high coordination activity with metal ions,so they have always been the focus of the research.In this paper,the gel properties,microscopic morphology,and self-assembly mechanism of the five gel factors were studied by various methods,and the metal ion responsiveness of G3 and G4was studied.The specific content of the article is as follows:?1?Two long-chain alkyl bis-Schiff base gel factors G1 and G2 based on o-phenylenediamine were synthesized.The synthetic route is based on stearic acid and palmitic acid as raw materials,They were esterified with p-hydroxybenzaldehyde to prepare intermediates,and finally the intermediates were condensed with o-phenylenediamine to obtain gel factors G1 and G2.The structure of the gel factor was confirmed by¹H NMR,¹³C NMR,and ESI-MS.And the gel properties of these two gel factors were studied.It was found that these two gel factors can form thermally stable organic gels in solvents such as ethanol,1,2-dichloroethane and acetone.Through infrared spectroscopy,XRD,scanning electron microscopy,the driving force of self-assembly was analyzed.?2?Two long-chain alkyl-salen-type Schiff base gel factors G3 and G4based on o-phenylenediamine were synthesized.Taking stearic acid and palmitic acid as raw materials,then they were esterified with2,4-dihydroxybenzaldehyde to prepare intermediates,and finally the intermediates were condensed with o-phenylenediamine to prepare gel factors G3 and G4.The structure of the gel factor was confirmed by ¹H NMR,¹³C NMR,and ESI-MS.The gel properties of these two gel factors were also studied.Through infrared spectroscopy,XRD and scanning electron microscopy,the driving force for self-assembly has been studied.Because salen-type Schiff bases are tetradentate ligands,they have better coordination of metal ions.Ultraviolet spectroscopy shows that both gel factors G3 and G4 have good coordination with Zn²⁺.The collapsing of the gel by dropping metal ions into the gel also confirmed the metal ion recognition responsiveness of the two gel factors.Finally,the self-assembly mode of gel factor is speculated.?3?A long-chain alkyl bis-Schiff base gel factor G5 based on o-phenylenediamine was synthesized.The synthetic route is to take oleic acid as the raw material,It was esterified with p-hydroxybenzaldehyde to prepare intermediates,and finally the intermediates was condensed with o-phenylenediamine to obtain the product gel factor G5.Its structure was confirmed by ¹H NMR,¹³C NMR and ESI-MS.And through ultraviolet spectroscopy,infrared spectroscopy,XRD,scanning electron microscopy to analyze the driving force of self-assembly.The Kamlet-Taft parameter analysis explains the gel factor in which solvent can form a thermally stable gel.