Syntheses And Properties Of Functional Metal Complexes Based On Conjugated Tetrathiafulvalene Ligands

Tetrathiafulvalene (TTF) and its derivatives have been intensively studied for long time, due to their unique ?-electron donor and redox properties. They have been used as versatile building blocks in supramolecular and material chemistry. One of the research trends in new TTF derivatives for functional materials is to search for molecules with more ?-extended systems. It has been demonstrated that the extension of the TTF core not only leads to stabilized oxidized states and can enhance the dimensionality in materials by increasing ?…? or S…S interactions. In this dissertation, we report the syntheses and characterization of new N-heterocycle or carboxylate substituted ?-conjugated TTF ligands and related metal complexes. The photophysical and electrochemical properties of the new compounds are also discussed.1. The ?-conjugated tetrathiafulvene-based donors with mono amine moiety, 2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)benzo[d][1,3]dithiol-5-amine (La), 2-(4,5-ethylenethio-1,3-dithiol-2-ylidene)benzo [d] [1,3] dithiol-5-amine (Lb) are synthesized. Further condensation of these TTF amine with different pyridylaldehyde affords new tetrathiafulvene-fused ?-extended Schiff base ligands, La-Imine-4-Pyridyl (L1), La-Imine-3-Pyridyl (L2) and Lb-Imine-2-Pyridyl (L3). Four metal complexes based on these Schiff-base pyridine ligands, M(hfac)2(L)2 (M= Cu?, L=L1,4; M=Mn?, L=L1 5; M= Cu?, L=L2,6; hfac= hexafluoroacetylacetonato) and [Re(CO)4(L3)][Re2(CO)6Cl3] (7), have been synthesized and structurally characterized. The structures of all new complexes have been determined by X-ray crystallography. The ligands in all complexes show near planar structure, while the different coordination modes of the metal ions and relative orientation of the terminal N donors result in different crystalline organization in the solid state. The absorption spectra and redox behaviors of these new compounds have been studied. The absorption spectral changes of 1-4 upon addition of NOPF6 have been studied. The results suggest that the oxidized compounds can be obtained via chemical approach in the present system.2. A series of tetrathiafulvalene annulated phenanthroline ligands, 4'5'-dimethyldithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L4), 4',5'-ethylenedithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L5) and 4',5'-bis(methyloxycarbonyl)dithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline (L6), have been prepared by a facile and efficient synthetic procedure under mild conditions. Further coordination reactions of these ligands with Re(CO)sCl afford new rhenium tricarbonyl complexes, ClRe(CO)3(L) (L=L4,5;L=L5,6;L=L6,7), respectively. X-ray crystal structure determinations on 5 and 7 reveal that the ligands are nearly planar and they show unique packing mode in the solid state. The electrochemical and spectroscopic behaviors of these compounds have been studied. The UV absorption studies of these new compounds demonstrate that the TTF unit interacts with the electron accepting group-phen, thus leading to the intramolecular charge transfer (ILCT). Meanwhile the effect of the substituents on electrochemical and spectroscopic behaviors of these compounds have also been discussed.3. The TTF-fused terminal ligand with mono pyridine (4',5'-dimethyldithiotetrathiafulvenyl-4-pyridine, Lp) and the chelating ligands (4',5'-dimethyldithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline, L4; 4',5'-bis(methyloxycarbonyl)dithiotetrathiafulvenyl[4,5-f][1,10]phenanthroline, L.6) are specially chosen to annulate the triruthenium cluster to TTF skeleton. By using the triruthenium precursor [Ru3O(OAc)6(py)2(CH3OH)](PF6), a series of triruthenium derivatives, [Ru3O(OAc)6(py)2(Lp)](PF6) (8), [Ru3O(OAc)5{?-?1(C), ?2(N,N)-L}(py)2](PF6) (L=L4,9, L=L6,10), are successfully synthesized. These new compounds are characterized by UV-Vis, IR,1H NMR, ESI-MS spectroscopic methods and elemental analysis. No significant electronic interaction between the TTF unit and the triruthenium cluster core is observed. These new complexes afford rich electrochemical behaviour and exhibit multistep one-electron redox processes. The results from cyclic voltammetry characterization demonstrate that different substitution modes result in the changes in redox potentials for both TTF and oxo-centered triruthenium subunits.4. Tetrathiafulvalene annulated phenanthroline ligand L4 is chosen to act as N^N ancillary ligand to prepare novel Iridium(?) cationic complex 11. The new compound is characterized by elemental analysis, IR,1H NMR and ESI-MS spectroscopic methods. The electrochemical and spectroscopic behaviors including UV-Vis absorption spectra, photoluminescence and electrochemiluminescence of 11 have been studied. The ground state structures and spin-allowed electronic transitions of 11 has been studied by using density functional theory (DFT) and time-dependent DFT (TDDFT), and the calculated transitions (???*, ILCT, LLCT and MLCT) agree well with the experimental ones.5 A well-soluble TTF-carboxylate ligand L7 derived from four methoxycarbonyl groups substituted TTF derivative II has been prepared and characterized by IR, ESI-MS and X-ray crystallography. Further cation exchange reaction of the ligand with Mn(GlO4)2·6H2O affords novel compound 12. X-ray crystal structure determinations on 12 reveasl that it is a 3D supramolecular network driven by hydrogen bonds. Because of the strong electron-withdrawing effect of the carboxylate group, the intramolecular charge transfer (ILCT) ransition bands for L7 and 12 are red shifted about 100 nm compared with the N-heterocycle substituted TTF ligands L1-L6. The cyclic voltammetry of L7 and 12 in solution exhibit two characteristic oxidation waves of the TTF core, nevertheless, only the first ones were found to be reversible, which could be related to the decarboxylation of the TTF bones in their dioxidized form.