Metallic behavior down to low temperature is shown by charge transfer salts of BDH-TTP ( 1 ), a structural isomer of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF). In the case of (BDH-TTP)2PF6 this behavior is attributed to the structure, which is made up of κ-type sheets of BDH-TTP donor molecules and sheets of PF6− anions. 相似文献
Entanglement network of carboxymethyl cellulose (CMC) was characterized based on the dynamic viscoelasticity of the concentrated solutions in an ionic liquid. According to the concentration dependence of the molecular weight between entanglements (Me), Me for the molten state (Me,melt) for CMC was estimated to be 3.9 × 103 as a chain variable reflecting the chemical structure of the polysaccharide. Furthermore, relations between Me,melt and other chain variables were examined to elucidate the specificity in the entanglement properties of CMC and related polysaccharides. It was shown that the number of entanglement strands (Pe), the ratio of the cube of the tube diameter, and the volume occupied by the entanglement strand, for CMC was 72 being significantly larger than the universal value of ca. 20 recognized for flexible polymers. Anomalous values of Pe > 20 were also obtained for related polysaccharides such as cellulose and amylose.
We report on measurements of a mode-locking resonance in amorphous MoxGe1?x films at different temperatures T down to 0.8 K, which is well below the superconducting transition (6 K). We observe dynamic ordering of driven vortex matter for all the temperatures studied. As the field exceeds a certain critical field Bc,dyn at fixed T, moving vortices do not exhibit dynamic ordering. At high T, this field Bc,dyn(T), so-called dynamic melting, nearly coincides with a characteristic field Bc(T) where the linear resistivity vanishes. At low T, however, Bc,dyn(T) is significantly suppressed compared to Bc(T), suggesting intrinsic quantum melting in the absence of pinning. 相似文献
p-Polyphenyl-α,ω-quinododimethides were predicted to be moderately aromatic and diatropic, although they exist only in a single
classical resonance structure with no aromatic conjugated circuits. Such a dichotomy was resolved using our graph theory of
aromaticity and ring-current diamagnetism. Six-site non-conjugated circuits were found to contribute appreciably to aromaticity
and ring-current diamagnetism. Within each quinododimethide molecule, local aromaticity increases on going from the outermost
to inner phenylene rings. 相似文献
Thioacetals were found to be effective precursors to generate and accumulate alkoxycarbenium ions based on direct and indirect cation pool methods. Alkoxycarbenium ions thus generated reacted with carbon nucleophiles such as allylsilanes and enol silyl ethers to give C-C bond formation products in good yields. 相似文献
The first n-type FET based on TTF derivatives was prepared. TTF derivatives with halogeno-substituted quinoxaline rings showed excellent n- or p-type performances with high carrier mobilities. Introduction of halogen groups determined the FET polarity by controlling the HOMO and LUMO levels of the molecules. The pi-stacking structures were observed in the single crystals of tetrahalogeno-TTFs. 相似文献
A sequential one-pot indirect cation pool method has been developed. The method involves the electrochemical generation and accumulation of ArS(ArSSAr)+ at low temperature (step 1) and the follow-up reaction with a thioacetal to generate an alkoxycarbenium ion pool (step 2), which reacts with various carbon nucleophiles (step 3). Steps 2 and 3 are extremely fast. The electrogenerated ArS(ArSSAr)+ was well-characterized by 1H NMR and CSI-MS. The alkoxycarbenium ion pool generated by the present indirect method exhibited 1H and 13C NMR spectra and thermal stability similar to those of the alkoxycarbenium ion pool generated by the direct electrochemical method. 相似文献
Energetic and magnetic criteria of aromaticity are different in nature and sometimes make different predictions as to the aromaticity of a polycyclic pi-system. Thus, some charged polycyclic pi-systems are aromatic but paratropic. We derived the individual circuit contributions to aromaticity from the magnetic response of a polycyclic pi-system and named them circuit resonance energies (CREs). Each CRE has the same sign and essentially the same magnitude as the corresponding cyclic conjugation energy (CCE) defined by Bosanac and Gutman. Such CREs were found to play a crucial role in associating the energetic criteria for determining the degree of aromaticity with the magnetic ones. We can now interpret both energetic and magnetic criteria of aromaticity consistently in terms of CREs. Ring-current diamagnetism proved to be the tendency of a cyclic pi-system to retain aromatic stabilization energy (ASE) at the level of individual circuits. 相似文献
A new BEDT-TTF-based salt with an organic free radical TEMPO has been prepared. The salt consists of alternate layers of conducting and magnetic sheets, between which are short S(BEDT-TTF) …O(TEMPO) contacts. The magnetic susceptibility is well modelled by the combination of a 2D Heisenberg and a Curie-Weiss model with and . 相似文献
Terahertz (THz) dichroism of a nematic liquid N-(p-methoxybenzylidene)-p-butylaniline (MBBA) was measured using a GaP Raman THz spectrometer. MBBA on a rubbed plastic substrate generates a band at around 4.0 THz: its liquid crystal phase shows strong dichroism, which well corresponds to that of the IR absorption caused by π(CH) of MBBA molecule reported in the literature. Based on inferences drawn from the present THz and the published IR dichroic results, the 4.0 THz band probably stems from lateral intermolecular or intramolecular interactions of MBBA molecules aligned to the rubbing direction. The results clearly demonstrate that THz spectroscopy is powerful for discussing of phase transition and dichroism of liquid crystals. 相似文献