Synthesis and structure of charge transfer salts of tetrathiafulvalene (TTF) and tetramethyl-TTF with 2,4,7-trinitro and 2,4,5,7-tetranitro-9-fluorenone

Charge transfer salts of tetrathiafulvalene (TTF) and tetramethyltetrathiafulvalene (TMTTF) with the organic acceptors 2,4,7-trinitro-9-fluorenone and 2,4,5,7-tetranitro-9-fluorenone have been prepared and characterized. The compounds (TTF)[TENF] (1), (TTF)₃[TRNF]₂ (2) and (TMTTF)[TRNF] (3) contain mixed stacks of alternating TTF and nitrofluorenone units. Surprisingly, the degree of charge transfer that occurs in these salts is not controlled solely by the redox potentials of the building blocks, but apparently also by the most effective intermolecular interactions in the solid, as determined from the crystal structures obtained. These three compounds exhibit poor electron delocalization and therefore they behave as diamagnetic insulators.     

Tris-fused tetrathiafulvalenes (TTF): highly conducting single-component organics and metallic charge-transfer salt

Tris-fused tetrathiafulvalene (TTF) derivatives, TTC_n-TTPY, 2,2′-bis[4,5-alkylthio-(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalenylidene] with four alkylthio chains [C_nH_2n+1S: n=3–5] are prepared and the structural and conducting properties are investigated. Crystals of the neutral molecules show very low electrical resistivity (400 Ω cm) as single-component pure organic materials. Irrespective of the alkylthio chain length, the crystal structures are so-called β″-type consisting of uniform stacks of the tris-fused TTF parts. Iodine-doped TTC₃-TTPY exhibits metallic conductivity down to liquid helium temperature.     

Proton magnetic relaxation in tetrathiafulvalene (TTF) complexes of copper halides, (TTF)2CuCl2 and (TTF)6CuBr4

The proton magnetic relaxation time (¹HT₁) was determined for (TTF)₂CuCl₂ and (TTF)₆CuBr₄ as a function of temperature (T). The ¹HT₁ of the compounds can be explained by the Korringa relation at high temperatures: the electrical conduction is metallic in their high-temperature phases. The ¹H relaxation is strongly enhanced by the electron-electron interaction. In the vicinity of the metal-insulator transition, the T₁versusT⁻¹ curves of the two compounds were quite different from each other, reflecting the difference in the mechanism of the phase transition.     

A new type of molecular packing in the conducting complex of tetrathiofulvalene C6H4S4 (TTF) with pyromellitic dianhydride C10H2O6 (PMDA)

The structure of the tetrathiofulvalene-pyromellitic dianhydride complex, TTF-PMDA (C₆H₄S₄?C₁₀H₂O₆), has been determined (a = 0.72550, b = 0.76317, c = 1.71905 nm, α = 106.226, β = 108.580, γ = 70.493°, $\text{space group}\text{, P}\text{I}\text{, N}{}_{\mathrm{I}}\text{= 1538, Z = 2, R}{}_{\mathrm{<mtext>F</mtext>}}\text{= 8.5\%)}$. The 1:1 TTF-PMDA complex is the first compound where TTF molecules do not form stacks. Instead, the structure contains quasi-one-dimensional strips of donor molecules where π-orbitals overlap π-like. With the actual degree of charge transfer, the donor strips are conducting (the conductivity of pellet samples is about 0.1 $\text{Ω}{}^{\mathrm{?1}}$ m^?1). The TTF strips showing no Peierls distortions are stabilized by close contact with PMDA strips.     

Conductive complexes of [Ni(dmid)2] with TTF,TMTTF, and ET

Three charge-transfer salts of [Ni(dmid)₂]⁻ (dmid: 1,3-dithiol-2-one-4,5-dithiolate)—TMTTF[Ni(dmid)₂], TTF_x[Ni(dmid)₂] and ET_x[Ni(dmid)₂] (TMTTF: tetramethyl-tetrathifulvalene, TTF: tetrathifulvalene, ET: bis(ethylenedithio)-tetrathiafulvalene) are prepared and characterized. The TMTTF[Ni(dmid)₂] complex has a structure with mixed packs is formed by cations and anions, which alternate each other with subsequent shift. This compound is semiconductor with the room-temperature conductivity of 2.2 × 10⁻³ Ω⁻¹ cm⁻¹. The TTF_x[Ni(dmid)₂] and ET_x[Ni(dmid)₂] complexes have a highest conductivity: σ_RT 1.86 and 0.54 Ω⁻¹ cm⁻¹, respectively.     

Synthesis of tetra-silylated tetrathiafulvalene derivatives TTF(SiR2H)4 (R = Me,Ph): Novel assembling ligands for the construction of bimetallic transition metal complexes

The HR₂Si-functionalized tetrathiafulvalene (TTF) ligand TTF(SiR₂H)₄ (R = Me 2a; R = Ph 2b) have been synthesized and the molecular structure of 2a determined. The reactivity of the four Si–H bonds for oxidative addition reactions has been exploited. Thus, the bimetallic platinum–silicon complex [(PPh₃)₂Pt{(Me₂Si)₂TTF(SiMe₂)₂}Pt(PPh₃)₂] 3 incorporating TTF(SiMe₂H)₄ as bridging unit has been assembled by oxidative addition across [Pt(PPh₃)₂(CH₂CH₂)]. Electrochemical investigations by means of cyclic voltammetry reveals, for the complex 3, a strong cathodic shift of the two redox processes of the TTF core compared with those of 2a.     

New TTF and bis-TTF containing thiophene units: Electrical properties of the resulting salts

Series of new TTF and bis-TTF containing a thiophene ring as a substituent or as a spacer group were prepared by using a palladium-catalyzed cross-coupling reaction from tributylstannyl–trimethyltetrathiafulvalene (tMeTTF–SnBu₃) and different halogeno and dihalogenothiophene derivatives. The reducing power of each new precursor was determined by cyclic voltammetry. Radical cations salts and charge transfer complexes of the donors with TCNQ were prepared and characterized. The electrical conductivity of these materials was measured and discussed in terms of (electronic) structure.     

Organic single crystalline micro- and nanowires field-effect transistors of a tetrathiafulvalene (TTF) derivative with strong π–π orbits and S⋯S interactions

Tetrathiafulvalene (TTF) was one of the most widely studied heterocyclic systems. However, TTF itself was easily oxidized, which induced the low stability and limited its potential applications. Here, a TTF derivative, 2,3,6,7-tetrakis(2-cyanoethylthio)tetrathiafulvalene (TCE-TTF), was synthesized. It was found that single crystalline micro- and nanowires of TCE-TTF were easily obtained by simple casting due to the enhanced π–π overlapping and S?S interaction. The thermal and vacuum stability analyses revealed TCE-TTF was much better than TTF. Single crystalline micro- and nanowires field-effect transistors were also fabricated by in situ dropping method. The typical mobility and on/off ratio were ～0.02 cm²/V s and ～10³, which predicted great potential applications of organic nanowires electronics.     

Hot corrosion of a novel (Ni,Co)O/(Ni,Co)Fe2O4 composite coating thermally converted from an electrodeposited Ni–Co–Fe2O3 composite coating

Ni–Co–Fe₂O₃ composite coatings were successfully developed by sediment co-deposition. In order to improve their hot corrosion resistance, a pre-oxidation treatment was conducted at 1000 °C for 6 h. The corrosion behaviour of the oxidised composite coating was investigated at 960 °C in an atmosphere consisting of a mixture of Na₃AlF₆–AlF₃–CaF molten salts and air. They exhibited good hot corrosion resistance due to not only the pre-formed oxide scale with (Ni,Co)O and (Ni,Co)Fe₂O₄ phases after pre-oxidation, but also the formation of (Ni,Co,Fe)Al₂O₄ phases in the outer layer and a well-distributed NiFe₂O₄-enriched phase along the grain boundaries in the subscale area during the corrosion process.     

Synthesis and electrochemical behaviors of novel TTF derivatives bearing thiazole groups

At present work, five new tetrathiafulvalene (TTF) derivatives bearing two or four thiazole groups are prepared, which have been characterized by ¹H NMR, IR, MS spectra, elemental analysis and X-ray analysis for 6. The preliminary electrochemical properties of them are investigated by cyclic voltammetry (CV) and two one-electron quasi-reversible waves with redox potentials are observed.     

Single-component organic conductors based on neutral betainic radicals of N-methyl substituted dioxo- and aminooxo-pyrimido-fused TTFs

New dioxo- and aminooxo-pyrimido-fused tetrathiafulvalene (TTF) derivatives, whose pyrimido-rings are substituted by methyl group, were synthesized. In the crystal structures of their tetrabutylammonium salts, complementary hydrogen-bonds inherent in pyrimido-fused TTF derivatives were inhibited by the methyl substitution, and the crystals were constructed by the segregated motifs of cations and anions. Betainic radicals prepared by one-electron oxidation of tetrabutylammonium salts exhibited relatively high conductivities (ca. 10⁻⁴ S cm⁻¹ at room temperature) as single-component organic molecules. The optical measurement of betainic radicals showed considerably low-energy charge-transfer absorption between radical molecules compared to those of conventional TTF systems, indicating the reduction of on-site Coulomb repulsion.     

In the search of an electron transfer between π-donors and C60: the bis-linking of tetrathiafulvalene (TTF) to C60

In order to realize the bis-linking of tetrathiafulvalene (TTF) to one or two C₆₀, and to reach the dyad compounds 1 and 2, the [4 + 2] Diels-Alder reactions of C₆₀ with orthoquinodimethanic derivatives of 1,3-dithioles 5a,b or TTF 9 are studied.     

On the mechanism of current-transport in Cu/CdS/SnO2/In-Ga structures

The structural and optical properties of CdS films deposited by evaporation were investigated. X-ray diffraction study showed that CdS films were polycrystalline in nature with zinc-blende structure and a strong (1 1 1) texture. The study has been made on the behavior of Cu/n-CdS thin film junction on SnO₂ coated glass substrate grown using thermal evaporation method. The forward bias current-voltage (I-V) characteristics of Cu/CdS/SnO₂/In-Ga structures have been investigated in the temperature range of 130-325 K. The semi-logarithmic lnI-V characteristics based on the Thermionic emission (TE) mechanism showed a decrease in the ideality factor (n) and an increase in the zero-bias barrier height (Φ_Bo) with the increasing temperature. The values of n and Φ_Bo change from 8.98 and 0.29 eV (at 130 K) to 3.42 and 0.72 eV (at 325 K), respectively. The conventional Richardson plot of the ln(I_o/T²) vs q/kT shows nonlinear behavior. The forward bias current I is found to be proportional to I_o(T)exp(AV), where A is the slope of ln(I)-V plot and almost independent of the applied bias voltage and temperature, and I_o(T) is relatively a weak function of temperature. These results indicate that the mechanism of charge transport in the SnO₂/CdS/Cu structure in the whole temperature range is performed by tunneling among interface states/traps or dislocations intersecting the space-charge region. In addition, voltage dependent values of resistance (R_i) were obtained from forward and reverse bias I-V characteristics by using Ohm's law for each temperature level.     

Hot corrosion of a novel NiO/NiFe2O4 composite coating thermally converted from the electroplated Ni–Fe alloy

A novel NiO/NiFe₂O₄ composite coating thermally converted from an electroplated Ni–Fe alloy was successfully fabricated. The composite coating consisted of a NiO matrix and homogeneously distributed criss-cross intragranular and intergranular NiFe₂O₄ precipitates, with a very dense and flat structure. The composite, compared to bare Ni metal, exhibited increased hot corrosion resistance under an atmosphere of Na₃AlF₆–AlF₃–CaF molten salts and air at 960 °C, mainly because of the dense structure and well-adhered, homogeneously dispersed intragranular and intergranular NiFe₂O₄ precipitates.     

The influence of CO2, AlCl3 · 6H2O, MgCl2 · 6H2O, Na2SO4 and NaCl on the atmospheric corrosion of aluminum

The influence of salt deposits on the atmospheric corrosion of high purity Al (99.999%) was studied in the laboratory. Four chloride and sulfate-containing salts, NaCl, Na₂SO₄, AlCl₃ · 6H₂O and MgCl₂ · 6H₂O were investigated. The samples were exposed to purified humid air with careful control of the relative humidity (95%), temperature (22.0 °C), and air flow. The concentration of CO₂ was 350 ppm or <1 ppm and the exposure time was four weeks. Under the experimental conditions all four salts formed aqueous solutions on the metal surface. Mass gain and metal loss results are reported. The corroded surfaces were studied by ESEM, OM, AES and FEG/SEM equipped with EDX. The corrosion products were analyzed by gravimetry, IC and grazing incidence XRD. In the absence of CO₂, the corrosivity of the chloride salts studied increases in the order MgCl₂ · 6H₂O < AlCl₃ · 6H₂O < NaCl. Sodium chloride is very corrosive in this environment because the sodium ion supports the development of high pH in the cathodic areas, resulting in alkaline dissolution of the alumina passive film and rapid general corrosion. The low corrosivity of MgCl₂ · 6H₂O is explained by the inability of Mg²⁺ to support high pH values in the cathodic areas. In the presence of carbon dioxide, the corrosion induced by the salts studied exhibit similar rates. Carbon dioxide strongly inhibits aluminum corrosion in the presence of AlCl₃ · 6H₂O and especially, NaCl, while it is slightly corrosive in the presence of MgCl₂ · 6H₂O. The corrosion effects of CO₂ are explained in terms of its acidic properties and by the precipitation of carbonates. In the absence of CO₂, Na₂SO₄ is less corrosive than NaCl. This is explained by the lower solubility of aluminum hydroxy sulfates in comparison to the chlorides. The average corrosion rate in the presence of CO₂ is the same for both salts. The main difference is that sulfate is less efficient than chloride in causing pitting of aluminum in neutral or acidic media.     

Effect of substituent groups for formation of organic-metal hybrid nanowires by charge-transfer of tetrathiafulvalene derivatives with metal ion

Effect of substituent groups on a tetrathiafulvalene (TTF) unit for formation of organic-metal hybrid nanowires was studied. Depend on the substituent groups, the nanowires were obtained as a precipitate just by mixing TTF derivatives and HAuCl₄ in CH₃CN solution at room temperature via electron transfer reaction between the TTF derivatives and a gold ion. To precede favorably hybrid nanowire formation, increase planarity and introduction of strong interaction on the TTF derivatives are required.     

Preparation and properties of some new extended tetrathiafulvalene (TTF) derivatives

The synthesis of extended tetrathiafulvalene (TTF) derivatives with naphthalene as spacer is reported. The electron donor properties have been studied by cyclic voltammetry.     

Two-dimensional X-shaped organic dyes bearing two anchoring groups to TiO2 photoanode for efficient dye-sensitized solar cells

Novel two-dimensional X-shaped donor–π–acceptor (D–π–A)-type dyes were designed and successfully synthesized for use in a dye-sensitized solar cell (DSSC). Two triphenylamine units in these dyes act as electron donor units, while two cyanoacrylic acid groups act as electron acceptor units and anchoring groups to the TiO₂ photoanode. The photovoltaic properties of the newly synthesized dye-containing DSSCs were investigated to identify the effects of conjugation length between the electron donors and acceptors, and the molecular energy levels of the dyes. Among the three dyes we synthesized, (2E,2′E)-3,3′-(5′,5″-(4,5-bis(4-(bis(4-tert-butylphenyl)amino)styryl)-1,2-phenylene)bis(2,2′-bithiophene-5′,5-diyl))bis(2-cyanoacrylic acid) (11) showed the highest power conversion efficiency of 3.14% (η_max = 4.06% with TiCl₄ treatment) under AM 1.5G illumination (100 mW cm⁻²) in a photoactive area of 0.418 cm² with short circuit current density of 7.27 mA cm⁻², open circuit photovoltage of 612 mV, and a fill factor of 70.6%.     

Synthesis, structure, and properties of Li2Pb2CuB4O10 with isolated [CuB4O10] units

The copper borate Li₂Pb₂CuB₄O₁₀ has been synthesized in air by the standard solid-state reaction at temperature in the range 550-650 °C and the structure of Li₂Pb₂CuB₄O₁₀ was determined by single-crystal X-ray diffraction. Li₂Pb₂CuB₄O₁₀ crystallizes in the monoclinic space group C2/c (no. 15) with a = 16.8419(12), b = 4.7895(4), c = 13.8976(10) Å, and β = 125.3620(10)°, V = 914.22(12) Å³, and Z = 4, as determined by single-crystal X-ray diffraction. The Li₂Pb₂CuB₄O₁₀ structure exhibits isolated units of stoichiometry [CuB₄O₁₀]⁶⁻ that are built from CuO₄ distorted square planes and triangular BO₃ groups. The IR spectroscopy and thermal analysis investigations of Li₂Pb₂CuB₄O₁₀ are also presented.     

载体中ZrO2/Al2O3比对Pt/ZrO2-Al2O3催化剂性能的影响

相比汽油车而言,柴油车具有高效、低油耗的优势已得到广泛应用。本实验以ZrO₂作为改性剂,探究了ZrO₂与Al₂O₃的质量比对催化剂的影响。研究结果表明：随着ZrO₂的加入,Pt粒子先减小后增大;Pt粒子与载体的交互作用先增大后减小。活性实验数据分析表明,ZrO₂的最佳添加量为40 wt%,CO和C₃H₆完全氧化温度分别降低20 _oC 、25 _oC。贵金属在催化剂的分散度以及贵金属与载体的相互作用随着ZrO₂与Al₂O₃质量比的变化而变化。Pt粒子越小,其与载体的交互作用越强,这表明催化剂性能越强。