Supramolecular Self-assemblies Of AZO-β-CD Dimer

Supramolecule mainly does research on building various of molecular organizedassemblies by the weak force among two or more molecules, such as hydrophobic,π-π stacking, electrostatic,van der Waals, host-guest, charge transferand hydrogenbonding interactions over their aqueous surroundings. During the past decade,supramolecular nanostructures produced via self-assembly processes were paidconsiderable attention. Supramolecular chemistry has been widely used in materialsscience, biology and physics, as well as forming the supramolecular science andsupramolecular techniques. Supramolecular chemistry plays an immeasurable role inmany fields, and it is considered to be one of the important sources of new conceptionand high technology in the21st century.Molecular recognition and multicomponent assembly based on cyclodextrin (CD)derivatives is an essential part of supramolecular chemistry. Possessing6-8D-glucoseunits linked by-1,4-glucose bonds, CDs can be functionalized to encapsulate variousorganic substrates in their hydrophobic microenvironments through the cooperativecontribution of noncovalent forces, including hydrophobic, π-π stacking, vanderWaals, and hydrogen bonding interactions.In this paper, click chemistry is employed to couple twoβ-cyclodextrins at bothends of azobenzene moiety, yielding dumbbell-shaped amphiphiles (Azo-β-CD dimer)constructed by aromatic rod building blocks as "body" and hydrophilic cyclodextrinsas "heads" with almost quantitative yield and purity.Then a series of researches aredone around the molecules, mainly including the following three aspects:(1)Chemical identification of the dumbbell-shaped amphiphile (AZO-β-CD) isconducted by applying1H NMR and MALDI-TOF-MS and so on. Then we describethe supramolecular assembly behaviors of AZO-β-CD dimer by utilizing thecharacterization methods(such as2D NMR，TEM，Variable Temperature1H NMR)in aqueous solution, and provide the possible aggregation mode of the system. Theresearch indicates that the amphiphilic molecular AZO-β-CD dimer can formuniformed rodlike morphology in aqueous solution by hydrophobic and π-πstacking.By adding epichlorohydrin the CD solution, crosslinked polymerp-AZO-β-CD is synthesized. The self-assembly of crosslinked polymerp-AZO-β-CD morphology is also studied to get the aggregate morphology, whichseems very special.(2) Choosing polyester of AZO-PCL and fullerene as guest molecules throughself-assemble of host-guest, building the AZO-β-CD/AZO-PCL and AZO-β-CD/fullerene assemble system to change the accumulation way of AZO-β-CD and formeda new self-assemble morphology. In the assemble system of AZO-β-CD/AZO-PCL,The facts are found that (1) the light-responsive azobenzene motif is of higherconstant ability with the cavity of β-CD.(2) the aliphatic chains are crucial forconstructing stable organized nanometre-scale assemblies in aqueoussolution.Therefore, a readily available guest molecular polyesters AZO-PCL withcontrollable molecular weights and low polydispersities are successfully synthesizedby ring-opening polymerization of-caprolactone in bulk with p-aminoazobenzene asinitiator. TheAZO-β-CD/AZO-PCL system can undergo light-triggered reversibleunder alternating visible and UV light irradiation. Then we apply the fluorescenceprobe technique to study the release properties of the host-guest amphiphilicassemblies The results clearly verify that pyrene molecules can be effectivelyincluded in the system. AZO-β-CD/Fullerene system was synthesized by using aliquid liquid interfacial precipitation (LLIP) method and find self-assembledaggregates in toluene phase. This system of self-assemble gets a self-assemblemorphology with very special appearance.The innovative points in this paper are:(1) The procedure of preparation for AZO-β-CD dimmer is very convenient.Because the amphiphilic molecular AZO-β-CDhas conjugated group, and caneffectively include some guest molecular, the dimer can be used in varies assemblesystem. The study of the self-assembly process of P-AZO-β-CD proves that theself-assemble morphology of P-AZO-β-CD is very special and the system with greatpotential value for research.(2) We are able to change the accumulation way of AZO-β-CD by addingdifferent molecular. The reversible process of AZO-β-CD/AZO-PCL system can be controlled by ultraviolet-visible. Therefore, this kind of dumbbell super amphiphilicmolecule has great potential application valuein the controlled process system. ByLLIP method, AZO-β-CD/C60system is build successfully and the self-assembledaggregates of this system are found in the toluene phase. Generally speaking,cyclodextrin self-assembly micelles often work in aqueous phase. The report that thecyclodextrin self-assembly micelles are found in toluene phase is rarein theliterature.It also provides a new method for cyclodextrin self-assemble.