Hierarchical Assembly And Performance Research Of Polyoxometalates Functional Matericals Induced By Covalent Modification

Polyoxometalates (POMs) represent a scaled family of metal-oxo clusters built up by transition metals such as V, Mo, W. It has been nearly200years since they were firstly discovered, during which scientific researchers have achieved tremendous accomplishments in structure and function of Polyoxometalates by harnessing advanced scientific instrument and characterization methods. Now it has been emerging as a fast-developing and broad interdisciplinary science, among which functional modification of POMs have risen up to be a hotspot. Based on the acknowledgment of the structure of the classic POMs and multiple scientific methods, researchers have derived and thrived the family of POMs, of which the most important is that more and deeper modification have given birth of huge potential properties and applications to the family of POMs. This dissertation summarizes my and colleagues’ works in synthesis of a series of organic-POMs hybrid systems that have firm structures and unique properties by:1) being based on the subject of functional modification of POMs,2) focusing on modification elements,3) introducing the well-controlled organic chemical reactions,4) inducing hierarchical assembly on the level of molecules. On one hand, by constitutional linking POMs and varied dimensional molecules, we realizes the vista of modification of POMs in different dimensions, on the other hand, based on the POMs molecules and various-dimensional functional materials that contain POMs as skeleton, we systematically investigated their potential functional applications.1. By introducing photo-sensitive organic molecule azobenzene which equipped various alkyl chains to SiW11systems, we have constructed a family of amphiphilic materials that possess POMs as heads and azobenzenes as tails, and the assembly behavior of them in different solvents is systematically investigated. The results have shown that introducing azobenzene helps improve the highly ordered assembly of POMs in mixed solvents. As the polarity increases, the amphiphilic molecules that originally possess the morphology of smooth surface-covered spheres would slowly turn into wrinkled ones and finally develop into defined rods with highly ordered molecular structure inside. Meanwhile, we have acquired the configuration change of the POMs-azobenzene amphiphilic molecules quantitatively along with the change of light exposure under the favor of extreme advanced ion mobility spectrometry-mass spectrometry (IMS-MS).2. By covalently linking SiW11onto one-dimensional nano-material carbon nanotubes, we have obtained greatly homogeneous composite materials with POMs molecules firmly fixed. Besides, we have utilized POMs-carbon nanotubes composite materials as a cathode in Li-ion battery and tested its capacity. The result shows that the POMs-carbon nanotubes composite materials have huge Li-storage and they can remain stable in performance and structure after multiple cyclic testing.3. By referring to the knowledge of polymer chemistry and the structure of POMs that have two spots available for modification, we have prepared a number of polymer systems that bearing one-dimensional main chain contained POMs under the condition of polymerization reaction. In addition, we have also prepared a system of photo-sensitive materials which can be controlled to be either polymerized or dissociated under manipulative light exposure by covalently binding coumarin to POMs system.4. We designed and synthesis two novel bis-imidazole ligands and studied the coordination chemistry about these ligand with copper(Ⅱ) ion, X-Ray measurement was been use to give the compound structures. Which show a very intersting binuclear copper structure. Electron paramagnetic resonance technology(EPR) was use to study the soultion chemistry of comp2in methanl. The next work is to use this type stable binuclear copper compounds as cation part in POMs.In order to bring about a view of brand new structures, properties and further functional applications of polyoxometalates and enrich scientists’ processing and permanent research into polyoxometalates chemistry, we have bridged a number of functional molecules with the fundamental polyoxometalates systems by harnessing both covalent and non-covalent binding.