Fabrication Of Responsive Ordered Molecular Aggregates Mediated By Supramolecular Interactions

Responsive ordered molecular aggregates based on supramolecular interactions have promising applications in many fields(such as life science,information science,energy and material science)and attracted the interest of researchers in recent years because of their physicochemical and properties could be altered by changing the external conditions.However,there are still many problems to be solved in the current researches,such as the construction of novel structure,the improvement of basic theories and the extension of application scope of responsive organized molecular aggregates.This dissertation is focused on the design and assembly of some novel responsive organized molecular aggregates based on the inclusion of cyclodextrin and dynamic imine bond strategies.In addition,the effects of structural changes on the morphology and responsiveness of aggregates have been studied.It not only broadens the idea of construction responsive organized molecular aggregates and improves its basic theory,but also has guiding significance for expanding its application range.There are four main experimental studies in this dissertation as following.1.A cationic surfactant with a pyridinium head group and adamantane as the end group connected by a hydrophobic alkyl chain(AP)had been synthesized.Its?-cyclodextrin(?-CD)induced hierarchical self-assembling behaviors in aqueous solution were investigated.The dramatic phase transitions occurred when host-guest inclusions between AP and ?-CD were sequentially produced at different host/guest molar ratios(R),corresponding to the supramolecules with different chemical structures(AP@1?-CD?AP@2?-CD).The spherical unilamellar vesicles with the mean diameter about 200 nm were found by DLS and TEM in 1:1(AP:?-CD)system.For 1:2(AP:P-CD)system,the rare multilayer nanotubes with unique"monolayer-like" wall structure were formed in the diluted solution.This work not only constructs the novel organized molecular aggregates,but also provides a new way to regulate the morphology of the organized molecular aggregates.2.The self-assembling behaviors of a-cyclodextrin(a-CD)and a novel anionic surfactant containing a dimethylamino-substituted azobenzene(DAH)in in aqueous solution were investigated.DAH could spontaneously form 2:1 inclusion complexes(DAH@2a-CD)through host-guest interactions with double equivalent amount of?-cyclodextrins(?-CDs),which resulted in the formation of supramolecular lamellar hydrogel.The hydrogen bonds between ?-CDs mainly dominated the formation of hydrogel.The formed hydrogel showed a reversible phase transition in response to both temperature and photo-irradiation.It is worth mentioning that the substituted dimethylamino group red-shifts the responsive wavelength of supramolecular hydrogel,which could be induced by visble light irradiation rather than the traditional ultraviolet(UV)light.The reversible dual-responsive hydrogel obtained here enriches smart aggregation systems and the reversible visble light responsiveness may endow the hydrogel with wide applications without using UV light in biological field.3.Temperature responsive hydrogel with the good biocompatibility and low toxicity was constructed via self-assembly of a-CD and amphiphilic phytosterol ethoxylate(BPS-n)based on the host-guest interaction.The formation mechanism and microstructure of hydrogel were investigated.The oxyethyl chain of BPS-n could spontaneously form the channel-type inclusion complexes with several a-CDs through host-guest interactions,which resulted in the formation of hydrogel with lamellar structure.The hydrogen bonds between a-CDs and the hydrophobic interactions between steroid nuclei of BPS-n mainly dominated the formation of hydrogel.Its mechanical strength,morphology and gel-sol transition temperature could be modulated by varying the length of oxyethyl chain and concentration of a-CD.In addition,the gel-sol transition temperatures(30?45 ?)were close to body temperature.These characteristics make the prepared hydrogel find more potential applications in controlled drug release systems.4.pH-responsive vesicles have been prepared from from the imine bond based supraamphiphiles with two kinds of headgroups,i-FDP or i-FDI.These two kinds of vesicles are stable in alkaline environment but hydrolyzed under acidic conditions.The loading and release studies of a fluorophore,Nile red(NR),demonstrated the capabilities of these vesicles to encapsulate NR and a rapid release at low pH environment.The vesicles from i-FDP behaved relatively more sensitive to acidic environment than those from i-FDI.The dynamic transitions of supra-amphiphiles were characterized by nuclear magnetic resonance or fluorescence emission spectroscopy measurements.This work not only enriches the pH-responsive vesicles systems,but also provides valuable reference for effective design and assembly of organized molecular aggregates with specific structures and responsiveness.