Construction And Characterization Of Hierarchical Aggregates Based On Ferrocene-containing Surfactant Encapsulated Polyoxometalate

Stimuli-responsive organic/inorganic hybrid complexes composed of stimuli-responsive surfactants and polyoxomatalate clusters are exhibiting potential application in the fields like biological recognition,drug delivery,novelly smart materials and so on.Various aggregates,like micllars,vesicles and gels,can be self-assemblied by these amphiphilic complexe.By applying external stimuli and adjusting the environment of self-assembly(temperature,pH,solvent,etc.),the control of the assembly behaviors can be achieved,which provide a method to find more smart soft-matericals and develop self-assemble chemistry.Based on non-covalent modification,we chosen ferrocene-containing surfactant to encapsulate a Keggin-type polyoxometalate(POM),and the redox-responsive organic/inorganic hybrid complex was finally synthesizd.There are three main contents in our dissertation as follows:Chapter 1,we first synthesized ferrocene-containg surfactant(BFDMA)and characterized its structure.the surfactant-encapsulated polyoxometalate complex(SEC)was obtained through a single-phase method.1H NMR spectrum and Fourier-transformed infrared(FTIR)spectrum confirm the electrostatic interaction between BFDMA and POM.and elemental analysis date ascertain the final molecular formula(BFDMA)3PW12O40.Chapter 2,we systematically investigated the assemble behaviors of SEC in DMF/butanol(3:7,v/v)mixed solvent.The hollow spherical aggregates with multilayered shells were initially observed with their diameter about 55 ± 9 nm;As aging time increases,these spherical aggregates were found to gradually fuse together into aggregates with flower-like and finally compartment-like morphologies with the average size of 120-150 nm after aged 1 h.Bsed on HR-TEM(High-Resolution Transmission Electron Microscope)and XRD(X-ray Diffraction)results,the layered spacing was confirmed about 2.87 nm.Owing to the redox-responsive character of SEC,the assemble behavior of these aggregates were able to be modulated bypotentiostatic method.Appling an anodic potential(+ 0.81 V)for 4 h,the ferrocene groups in SEC have been oxidized because the UV-vis spectrum at 440 nm belonging to the characterized peak of ferrocene group was disappeared.TEM image showed that the compartment-like aggregates disassembled into irregular spheres.The compartment-like aggregates could be turned back after applying a cathodic reduction potential(-0.81 V).In summary,the assembly behaviors of SEC in solution can be reversibly controlled by using electrochemical methods.Chapter 3,we investigated the assembly behaviors of SEC in solution by additive agent and solvent properties.First,DMF/butanol(3:7,v/v)mixed solvent was chosen in the process of adding β-CD.Considering the inclusion between β-CD and ferrocene groups,β-CD was used as host molecule.However,UV-vis spectrum and CV curve confirmed that there has no inclusion reaction between p-CD and SEC.Spherical aggregates with 60 nm in size formed by these β-CD～SEC complexes were observed.Second,solvent properties which have crucial influences on assembly behaviors of SEC were also be investigated.Based on experimental results,we found that SEC assemblied into incompact even defective aggregates with increasing the proportion DMF.While,spherical aggregates were formed in the solution that butanol was in the majority.It is interesting that fusion was also existent and final short-rod aggregates were formed with butanol in majority.These two factors of inclusion reaction and solvent properties will be another method to module assembly behaviors of organic/inorganic complexes.