Preparation And Properties Of Supramolecular Organogels Formed By Phenylalanine-based Gelators

In recent years,supramolecular hydrogels formed by the self-assembly of gelator have received wide interests because of their potential application.Gel aggregates are formed in solvents through intermolecular hydrogen bonding,π-πstacking and other non-covalent bond interations and turn them into macromolecular gel,then solvent molecules are trapped into three-dimension network.Gelators could be applied on catalyzer, nanomaterials,drug carriers and other fields because of its properties between the liquids and solids.In this paper,several gelators were synthesized,including chrial gelator N-octadecyl-N'-maleoyl-L-phenylalanine(ODMA-L-Phe),polymerizable gelator N-octadecyl maleamic acid(ODMA),gelator N-octadecyl succinic acid(ODSA) and series of gelators based on Phenylalanine or Analine.The mechanism of ODMA-L-Phe self-assembly in organic solvents was investigated using ~1H-NMR and Circular Dichroism (CD).Preparation of cholesteryl-molecular imprinted polymer using ODMA and the adsorption experiments of cholesterol were carded out.The properties of ODSA self-assembly in polymerizable solvents were investigated.The gel properties of the other gelators were characterized also.This paper are consisted of several sections as the following:(1)N-octadecyl-N'-maleoyl-L-phenylalanine(ODMA-L-Phe) was synthesized through the condensation,deprotection and acidylation reaction of BOC-L-phenylalanine, octadecylamine and maleic anhydride.ODMA-L-Phe can self-assemble in some organic solvents and turned them into thermally reversible physical supramolecular organogels. The morphology of ODMA-L-Phe aggregates was characterized by polarized optical microscopy(POM) and field emission scanning electron microscope(FE-SEM).The mechanism of ODMA-L-Phe self-assembly in organic solvents was investigated using ~1H-NMR and Circular Dichroism(CD).The results indicated that hydrogen bonding was one of the main driving forces for the self-assembly of ODMA-L-Phe.(2)Gelator N-octadecyl succinic acid(ODSA) was synthesized from succinic anhydride and octadecylamine by the ring-open reaction.The gel properities of ODSA in several polylymerizable solvents were investigated.The ODSA self-assemble into fibres aggregates in the polymerizable monomer such as styrene,Methyl acrylate,Buthyl acrylate et.al..The morphology of gel aggregates was investigated using POM.(3)Gelators N-octadecyl-N'-succinic-L-alanine(ODSA-L-Ala),N-octadecyl-N' -succinic -L-alanine-p-aminoazobenzene(ODSA-L-Ala-AZ)and N-octadecyl-N'- succinic -L-alanine(ODSA-L-Phe) were synthesized base on BOC-L-phenylalanine and BOC-L-alanine.The gel properities were investigated in some organic solvents. Suprahydrogel aggregrates were characterized using POM.(4)Polymerizable gelator N-octadecyl maleamic acid(ODMA) could self-assemble in polymerizable solvent mixture ofβ-hydroxyethyl methacrylate(HEMA),methylacrylic acid(MAA),polyethylene glycol dimethacrylates-200(PEGDMA-200) in the presence of template molecule 3-Cholesteryloxycarbonylbonylpropanoic Acid(COPA),and turned them into thermally reversible stable polymerizable organogels.Organogels were polymerized by in situ UV irradiation and the molecular-imprinting polymers(MIPs) were obtained after removal of the template molecules from polymer through ethanol extracting. Polarized optical microscopy(POM) and field emission scanning electric microscopy (FE-SEM) indicated the aggregates of ODMA were tree branch-like and sheet-like in organogels.The adsorption experiments of cholesterol exhibited that the adsorption equilibrium amount of cholesterol reached 30.2mg/g.The adsorption efficiency of MIPs was found to be dependent on the concentration of the gelator ODMA and template molecule COPA in organogel.