Functional Nanomaterials And Organic Spintronic Materials Based On Tetrathiafulvalene Derivatives

To date, technologies for building large scale integrated circuit are extremely delicate and complicated. As a result, the silicon-based integrated circuit have reached its integration limitation. Although enhancing the scale of parallel computing could temporarily meets the increasing needs for computers with supercomputing and super information storage capacity, finding a better substitute for silicon-based materials is a long-term solution. The "bottom up" assembling strategy can be controlled with near-atomic-scale precision during the chemical synthesis or growth process which goes beyond that achievable in top-down lithography. Predictable and well-controlled nanostructure growth implies that materials with distinct chemical composition, structure, size and morphology can be assembled by design to build specific functional devices and integrated circuits. This "bottom-up" paradigm could open up new strategies for increasing overall device density by allowing aggressive scaling in three dimensions. This thesis focus on hot spots in further IT storage materials by the advantages of chemical approaches in assembling nanomaterials via "bottom up" strategy. Such as nanowires, spintronic nanomaterials, molecular magnetic materials are developed with multi-sulfur functional molecular materials such as tetrathiafulvalene and dithienylethenes derivatives. By study the relationship between their structures and properities, our knowledge for their application in logical operation and information storage devices, spintronic devices and molecular nanodevices can be expanded.1. Multidimensional nanoassemblies with various morphologies such as nanosheets, nanorods, and nanofibers are developed via charge-transfer interaction and supra-amphiphile self-assembling in aqueous phase. The charge-transfer interactions between tetrathiafulvalene derivatives (TTFs:TTFA-TTFD) and methyl viologen derivatives (MVs:MV, DMV and HDMV) have been confirmed by the characteristic charger-transfer absorption.1H NMR and ESI-MS analyses also indicate supra-amphiphiles are formed by the combination of TTFs and MVs head group through charge-transfer interaction and Coulombic force. X-ray single crystal structural studies, TEM, and SEM reveal that both linkage pattern of TTFs in hydrophilic part and alkane chain structure in hydrophobic part have significant influence on nanoassemblies morphology and microstructure. Moreover, gold nanoparticles (AuNPs) are introduced in the above supramolecular nanoassemblies to construct a supra-amphiphile-driven organic-AuNPs assembly system. AuNPs could be assembled into 1D-3D structures by adding different amount of MVs.2. A strategy to coat Fe3O4 nanoparticles (NPs) with tetrathiafulvalene-fused carboxylic ligands (L1-3 and Li’) and to control electron conduction and magnetoresistance (MR) within the NP molecular junction spin-valves (MJSVs) assemblies is designed. The TTF-COO-Fe3O4 NPs are prepared by replacing oleylamine (OA) from OA-coated 5.7 nm Fe3O4 NPs. In the TTF-COO-Fe3O4 NPs, the ligand binding density is controlled by the ligand size, and spin polarization on the Fe3O4 NPs is greatly improved. As a result, the inter-particle spacing within the TTF-COO-Fe3O4 NP assemblies are readily controlled by the geometric length of TTF-based ligand. The shorter the distance and the better the conjugation between the TTF’s HOMO and LUMO, the higher the conductivity and MR of the assembly. The TTF-coating further stabilize the Fe3O4 NPs against deep oxidation and allowed 12-doping to increase electron conduction, making it possible to measure MR of the NP assembly at low temperature (<100 K). The TTF-COO-coating provides a viable way for producing stable magnetic Fe3O4 NP assemblies with controlled electron transport and MR for spintronics applications.3. Magnetoresistance of tetrathiafulvalene-fused carboxylic ligands coated NP molecular junction spin-valves (MJSVs) assemblies is enhanced via modification of TTF-COO-building blocks and changing assembling process. First, the surface spin-polarization of NPs is enhanced by altering surface ligands from monocarboxylic acids (L1) to dicarboxylic acids (bL1). Therefore, MR in NP assemblies is tuned separately without changing any another physical or chemical properties. This fine tuning of MR by building blocks structure could hardly achieved through conventional coating manner such as aliphatic acids;, polymers, organic semiconductors, or SiO2. Secondly, Fe3O4 NPs can be assembled into different topology pattern in colloidal solution and normal solution of amphiphilic TTF-COO-ligands (L1’).The spin scattering of NP MJSVs assembled in colloidal solution is highly decreased in tunneling process. As a result, the MR is greatly improved while coulomb blockade at room temperature is also vanished. The method of changing NP topology pattern for tuning electronic conduction and MR in NP assemblies expand our knowledge in organic spintronic materials, and enrich our approaches for tuning NP MJSVs properties.4. Using tetrathiafulvalene-phenanthroline (TTF-phen:L4 and L5) as the first ligand and potassium dihydrobis(pyrazol-l-yl)borate (K[H2B(pz)2]) as the second ligand, two spin crossover (SCO) FeⅡ complexes, namely [Fe(L4)(H2B(bz)2)2] (I) and [Fe(L5)(H2B(bz)2)2] (II), are successfully synthesized. The corresponding characterization has been performed by TOF-MALDI, IR, X-ray powder/single crystals diffraction analysis, magnetic measurements and electrochemical measurement. Owing to the structural difference between L4 and L5, the properties, especially magnetic properties, of I and II are remarkably distinct. The noncoincidence of the heating and cooling xMT-T curves in I leads to an obvious hysteresis loop. However, II has typical mutant type spin crossover XMT-T curves, and the transition point is T1/2↑=T1/2=141 K. Meanwhile, this result can provide an effective approach and theoretical basis to the construction of redox activity SCO complexes and molecular materials with ferromagnetic and conductive properties.5. Four eight-coordinate single lanthanide complexes with photoactive diarylethene-containing 1,10-phenanthroline ligand (L6) and Ln(acac)3, [Dy(L6)(acac)3] (III), [Tb(L6)(acac)3] (IV), [Ho(L6)(acac)3] (V) and [Er(L6)(acac)3] (VI) are synthesized and structurally characterized. The diarylethene groups in these complexes undergo reversible open-close process by UV and visible light irradiation in both solution and crystal phase.Complex III exhibits the zero-field slow relaxation of magnetization with an energy barrier of 65.8 K.Unfortunately, no obvious change in the magnetic properties of III is observed before and after UV irradiation.