Preparation And Properties Of Supramolecular Polymers Based On Self-assembly Of Cucurbit[n]uril

As an interdisciplinary domain,the research area of supramolecular chemistry crossover several disciplines,including chemistry,physics,biology and material science.Cucurbit[n]urils(CBs)are among the macrocyclic receptor known to date besides,crown ethers,cryptands,cyclodextins and calixaresene.They are a series of macrocyclic host molecules that consisted of methylene bridged glycolurils.Because of their superior molecular recognition properties in aqueous media,CBs have attracted much attention in supramolecular chemistry.These characteristics endow CBs an important role in coordination chemistry and host-guest chemistry,which also provided great convenience for the design of supramolecular assembly.Moreover,the stable chemical structure and good biocompatibility of CBs facilitate their biological application.The most prominent characteristics of CBs are its ion-dipole interaction with metal ions,coordination interaction and host-guest interaction.In the thesis,after studied the interaction between CBs and metal ions,we also studied the host-guest interactions;in addition,a series of polymers based on CBs were constructed,and they were further used in the construction of supramolecular hydrogels.In order to better understand how the temperature and a third species on the coordination and supramolecular assemblies of CB[6],we investigate the interaction of Ln3+(Ln=Gd3+and Dy3+)-CB[6]in different temperature and different structure inducer(hydroquinone or CuCl2).Three new lanthanide complexes with the general formulas{Gd2(H20)10(CB[6])2}·CB[6]·6Cl·112H20(1),{[Gd2(H2O)8 CB[6]2]·(CuCl4)·4Cl·46H2O}n(2),and {Dy2(NO3)2(H2O)10(CB[6]))·4NO3·14H2O(3)were successfully synthesized using cucurbit[6]uril as the ligand.The complexes were further characterized by elemental analysis,infrared spectroscopy,Uv-vis spectroscopy,termogravimetric analysis and magnetic properties.The results indicated that the structures of the complexes can be regulated by changing temperature and a third species.Different structure inducers will lead to distinctly different supramolecular assemblies.Magnetic studies of complex 3 displayed the frequency dependence of the out-of-phase susceptibility(?"),although the weakness of the(?")signal makes the field SMM nature of 3 being questionable.By making use of supramolecular host-guest interactions,a kind of pseudopolyrotaxanes as visualizable nanoscale drug carrier has been constructed by self-assembly of cucurbit[7]uril(CB[7])with methoxy poly(ethylene glycol)-block-quaternized poly(4-vinyl pyridine)(mPEG-b-QP4VP)using 4-(chloromethyl)benzonitrile.Simple addition of CB[7]into an aqueous solution of mPEG-b-QP4VP resulted in noncovalent attachment of CB[7]to 4-cyanobenzyl-containing polymers,transforming the nonemissive mPEG-b-QP4VP micelles into highly fluorescent micelles.These pseudopolyrotaxanes micelles exhibited remarkable supramolecular assembly-induced emission enhancement and excellent biocompatibility,showing great potential for bioimaging applications.In addition,the efficient cellular uptake of the developed pseudopolyrotaxanes micelles loaded with the anticancer drug doxorubicin was a promising platform for simultaneous cell imaging and drug delivery,thereby widening their application in cancer theranostics.A linear cucurbit[6]uril pendent copolymer have been synthesized through radical polymerization,and the aggregation behavior of the copolymer in aqueous solutions was studied.A CB[6]based monomer,4-vinylbenzyloxy CB[6],was synthesized.And then,we chosen acrylamide(AM)as a co-monomer to copolymerize with 4VBOCB[6].The polymerization was conducted using AIBA initiate free radical polymerization.Compositional analysis by H NMR spectroscopy and elementary analysis revealed that copolymers with the mole ratio of CB[6]is 1 mol%.Besides,the self-assembly behavior and morphological properties of this copolymer were characterized by DLS and TEM experiments.A multistimuli-responsive supramolecular hydrogels was fabricated by CB[6]-pendent polymer and n-Hexyl-Poly(allylamine hydrochloride)P(AH-co-AHH).The H NMR spectrum reveals that the driving force of the supramolecular hydrogels is host-guest interactions between CB[6]and the n-Hexyl.By taking advantage of the dynamic nature of the host guest interaction,these gels are self-healable and the gel-sol transition of the supramolecular hydrogels could occur under different pH,ions,and competitive guest bindings.In addition,the hydrogels was also used for the released of anticancer 5-Fu.The release rate of the drug can be controlled by adjusting the pH of the solution.The cytotoxicity of the hydrogel to NIH3T3 cells indicated that the hydrogels have excellent biocompatibility in vitro,can effectively improve the safety of drugs.Such multifunctional gels are exceptional and are promising in fabricating smart multistimuli-responsive gel-based in the future.The injectable supramolecular polymeric hydrogels based on CB[6]-pendent polymer and 1,6-diaminohexane conjugated copolymer were prepared.The gelation kinetics can be controlled with competing guest n-butylamine.Through pre-saturate CB[6]pendent polymer with n-butylamine,the gelling between CB[6]pendent polymer and 1,6-diaminohexane pendent polymer is impeded.By changing the concentrations of the n-butylamine,the gelation rate can be effectively controlled.Moreover,the addition of excess SPM to the hydrogel resulted in a phase transition from gel to sol,which provided some evidence for their application in drug released.