Containing The Pyridine Small Molecular Organic Gelling Agent Design, Synthesis, And Gelation Behavior Research

Recently,low-molecular-mass gels have attracted considerable attention because of their unique features and potential applications.Low-molecular-mass gels are materials between the solid and the liquid,which consist of a liquid and a small amount of low-molecular-mass gelators(LMGs). Generally speaking,LMGs in a gel exist in a three-dimensional network structure as a result of the gelator molecules assembling into one-dimensional fibrous structures by means of various driving forces,such as hydrogen bonding,π-πstaking,van der Waals forces,coordination interactions,and electrostatic interactions,etc.It is the networks of the gelators immobilize solvent by capillary forces and surface tensions,which leads to the formation of organogels or hydrogels.Unlike conventional chemical gels and polymer gels,low-molecular-mass gels are physical gels in essential and have some remarkable characteristics such as thermo-reversibility,stimuli-responsible to light,sound,pH, host-guest,chemicals,oxidative/reductive reactions,and shearing force,etc.Therefore, low-molecular-mass gels have numerous potential applications in sensors,drug delivery,molecular devices,separation,preparation of advanced materials,and "smart" propellants,etc.In the research of low-molecular-mass gels,pyridine group with special features has been introduced into LMGs,and a series of gel systems have been established.At the same time, cholesterol derivatives have been the subject of attention in the field of low-molecular-mass gels due to their outstanding gelation performances.Based on pyridine-containing cholesterol-appended low molecular mass organic gelators(LMOGs),this dissertation is mainly composed of the following three parts:In the first part,three novel ALS LMOGs beating a 2-,3-,or 4- pyridyl unit which are denoted as 1,2,and 3,respectively,have been synthesized,their corresponding salts(1′,2′,3′) have also been prepared by simply protonating them with HCl.The structures and compositions of all these compounds are characterized by ~1H NMR,FT-IR spectroscopy,elemental analysis,and satisfied results have been obtained.In the second part,the gelation properties of the six new ALS LMOGs in common solvents are studied systematically,and the micro-morphologies of the gels are investigated.The results showed that a slight difference of molecular structure strongly affect both the gelation behaviors of the gelators and the micro-structures of the xerogels.FT-IR and ~1H NMR studies demonstrated clearly that hydrogen bonding between the amide groups of the gelators play an important role on the formation of the organogels.XRD studies showed that the primary assembly of 1 in benzene is similar to that of 1′in the same solvent,and furthermore the assembly is also similar to that of 1 in solid state.The repeat distances of the three aggregates are almost the same,and are very close to the size of molecule 1.Based on these facts,a possible molecular packing model for 1/benzene gel system is proposed.In the third part of this dissertation,a new ALS LMOG containing pyridyl unit has been designed and synthesized using 1,2-diaminoethane as the linker,and its corresponding quaternary pyridinium has also been prepared with the procession of quaternary ammonium using dimethyl sulphate.Then the structures and compositions of the two compounds are characterized by ~1H NMR, FT-IR spectroscopy,and elemental analysis.It is revealed that both the gelation behaviors of the gelators and the micro-structures of the gels strongly depend on the linker structures of the gelators and whether the pyridyl unit is in the state of quaternary ammonium or not.