Self-Assembly Fo Organic-Polyoxometalate Complexes In Solution And Its Charge-Transfer Properties In Solid State

Organic-polyoxometalate complexes as a class of good applicant to preparae advanced functional materials have potential applications in many fields for their diversity in structure and electrical aspects.Three similarly organic cations were designed to encapsulate [SiW12O40]4- anionic to prepared organic-polyoxometalate complexes. These complexes have different aggregates morphology in different organic solution. Methanol, acetone and other solvents play an important role in the formation and stability of complexes aggregates in solution. We tried different combinations, various ratios of organic solution for the self-assembly environment and found concluded that these complexes could obtained stable aggregates in chloroform/methanol (v:v= 4:1) mixed solvent and observed the huge reverse multi-vesicles under the optical which show the spherical morphology looked like beautiful "flowers" in the scanning electron microscope. A imidazole cation with "fan" tail was employed to encapsulate Eu-POMs (EuWn, EUW22 and EuW10) to form fluorescent organic-polyoxometalates. These complexes also have fluorescent properties in solution and solid. Under an optical microscope, these complexes have similar reverse vesicles structure but show different morphology in scanning electron microscope and transmission electron microscope. A new complexe was prepared by Electrostatic interaction between the same imidizole cation and Keplerate {M0132} and can obtained the spherical aggregates in chloroform/methanol mixed solvent. However we unexpectedly get the quasi-crystal of body-centered cubic accumulated by hexagonal structure which was proved by further X-diffraction data. Furthermore, we prepared and characterized two electrostatic self-assemblies of an Anderson-based surfactant (An16) with polyelectrolytes (PMV and POV) and block copolymers (EG193-b-V57 and S480-b-V57) and the latter type complexes showed the regular and reverse vesicular aggregates in aqueous media and organic solutions, respectively.We also prepared four organic-polyoxometalate charge-transfer complexes composed of organic charge donor with polyoxometalate acceptor Keggin [SiM12O40]4- (M=W, Mo) and Lindqvist [M6O19]2- (M=W, Mo). UV diffuse reflectance spectra of the four colorful charge-transfer complexes provided the charge-transfer band edge absorption peaks. Referencing the organic semiconductor band theory and reported reduction potential of polyoxometalate anions, we calculated the level parameters of these charge-transfer complexes as functional organic materials.The experimental results show that we could not change the particular optical properties of polyoxometalate anions in the organic-polyoxometalate complex and the number of organic cations attached on the surface of polyoxometalate anions would impact the self-assembly morphology in solution. We could obtain the various self-assembled thin films of different morphologies by changing the organic cations and polyoxometalate anions. The successful preparation of the organic -polyoxomtalate charge transfer complexes will open a new avenue to develop promising organic electroluminescent materials.