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Synthesis And Properties Study Of EDO-TTF Derivatives

Posted on:2016-02-24Degree:MasterType:Thesis
Country:ChinaCandidate:Y L ZhaoFull Text:PDF
GTID:2271330461973837Subject:Organic Chemistry
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Tetrathiafulvalene is an excellent electron donor molecule as it can be reversibly and stepwisely oxidized to the radical and dication forms with good thermal stability. The charge transfer complex of TTF and its derivatives are mostly created to prepareorganic conductors and/or superconductors. Very recently, TTF framework has been widely applied in the organic supramolecular structures and multifunctional organic materials, for example, exploration of conduction-magnetism dual functional system from the TTF derivatives bearing coordination unit. In the present thesis, we reported the design and synthesis of a series of TTF derivatives bearing pyridyl and other types of aromatic substituents. The chemical reactivity, electrochemical and optical properties of these TTFs have been thoroughly investigated. Meanwhile, we reported the preparation, solid state structure, band structure, and physical properties of the cation radical salts of EDO-TTF derivatives. The followings are the main contents of the present thesis:In Chapter 1, we made a brief introduction of the characteristics of TTF unit. Then, we summarized TTF derivatives bearing coordinating functional groups, and their application in the preparation of supramolecular structures showing multiple functionalities such as sensors, metal ions recognition, and so on. We also summarize the recent progress on the structures and physical properties of the organic conductors based on the TTF charge transfer complexes. Finally, we introduce the hypothesis of the present thesis including molecule design rationale, expected supramolecular structure and their physical properties.In Chapter 2, we designed new type of TTF derivatives bearing a-pyridoin groups as the coordination unit. These compounds can coordinate with metal ions, which consequently result in the intramolecular charge transfer of "TTF→ metal ion" to perform the dual functionalities of conduction and magnetism. To synthesize such compounds, we proposed two synthetic approaches and had completed the synthesis of their precursors. In the first approach, we firstly synthesized the 5-(2-bromo-pyridyl)-substituted 1,3-dithiole-2-one, which was then coupled to form 5-(2-bromo-pyridyl)-substituted TTF in the presence of P(OEt)3. The resulting TTF was then converted to 5-(2-aldehyde-pyridyl)-substituted TTF by means of functional group transformation. This synthetic approach is tedious and of low production yield. In the second approach, the Pd-catalyzed C-C coupling between EDO-TTF/EDT-TTF and aryl iodide was employed to synthesize 5-(2-aldehyde-aryl)-substituted TTFs, and the aryls are 2-aldehyde-pyridyl, 2-aldehyde-phenyl, and 2-aldehyde-thienyl. The further benzoin reaction of the aldehyde in the presence of NaCN/CH3OH didn’t afford the expected pyridoin unit, but the aldehyde group was converted to the methyl ester. We have evaluated the spectroscopic and electrochemical properties of the newly obtained TTF derivatives, and clarified their potential application on the metal ion (Ni2+, Zn24) recognition.In Chapter 3, we reported the preparation, crystal structure, band structure, and physical properties of the cation radical salts of TTF derivatives bearing ethylenedioxy groups, EDO-TTT, MeEDO-TTF, and MeSEDO-TTF. The cation radical salts of these three donor molecules with [Cu(SCN)]- ion were prepared by electrochemical oxidation. Crystallographic investigation indicates that the donor molecules form the typical K-type stacks in the cation radical salts of EDO-TTF and MeSEDO-TTF. In this packing mode, the donor molecules are dimerized, and the donor dimers form the pseudo-orthogonal arrangement. In the crystal structure of these two salts, the counter anions are severely disordered which makes it very difficult to define the structure of the anion layer. On the other hand, MeEDO-TTF form the 2:1 salts with [Cu(SCN)]" ion. In the crystal structure of this salt, the donor molecule and the dimer of the anions form the mixed columnar stacks. The physical properties and electronic ground states wof these salts were evaluated by means of optical spectroscopy, conduction and magnetism measurement, and band structure calculation. EDO-TTF and MeSEDO-TTF salts showed almost constant conductivities in the temperature range of 300-200 K which is consistent with their two-dimensional Fermi surface, and they exhibited the thermo-activited contucting behavior below 200 K. The MeEDO-TTF salt is an insulator due to the mixed stacking of donor and counter anion.
Keywords/Search Tags:Tetrathiafulvalene, bidentate ligand, ion recognition, cation radical salts, conduting behavior
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