High performance n- and p-type field-effect transistors based on tetrathiafulvalene derivatives

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.     

Indirect cation pool method. Rapid generation of alkoxycarbenium ion pools from thioacetals

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.     

Circuit resonance energy: a key quantity that links energetic and magnetic criteria of aromaticity

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.     

A novel BEDT-TTF-based purely organic magnetic conductor, α - (BEDT - TTF)2(TEMPO - N(CH3)COCH2SO3) ⋅ 3H2O

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 .     

Terahertz dichroism of MBBA liquid crystal on rubbed substrate

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.     

Killing Magnetic Curves in Sol Space

We determine magnetic curves corresponding to the Killing magnetic fields in the 3-dimensional homogenous Riemannian space Sol₃.     

Synthesis, crystal structures, and properties of 6,12-diaryl-substituted indeno[1,2-b]fluorenes

Fused polycyclic indeno[1,2-b]fluorene derivatives with aryl substituents at the 6,12-positions have been prepared as a potential antiaromatic 20π electronic system. They showed strong absorptions in the visible region and amphoteric redox properties. The quinoid-type molecular structures were revealed by X-ray crystal-structure analysis, which indicated that the bond lengths of the quinoid unit depend on the aryl substituents. Whereas nucleus-independent chemical shift NICS(1) calculations indicate the antiaromatic nature of the s-indacene core, they have higher stability than substituted acene derivatives. The derivatives with difluorophenyl or anthryl groups were stable in solution. Vapor-deposited thin films showed ambipolar carrier transportation in the field-effect transistor devices.     

Molecular weight between entanglements for linear d-glucans

Dynamic viscoelasticity measurements were carried out for concentrated solutions of linear d-glucans in BmimCl to examine the effect of the linkage between repeating units of glucose on the rheological properties. The values of molecular weight between entanglements (M _e) were determined for four d-glucans: curdlan, pullulan, cellulose, and amylose. From the concentration dependence of M _e, the value of M _e in the molten state (M _e,melt) for each d-glucan was estimated as a material constant. The order of M _e,melt became cellulose?<?pullulan?<?curdlan?<?amylose, indicating that the linkage is actually influential in M _e,melt for the linear d-glucans. The relationship between M _e,melt and the molecular structure of the d-glucans were discussed assuming that the values of M _e,melt for the d-glucans primarily reflect the chain stiffness such as the characteristic ratio C _∞ on the analogy of synthetic polymers. Although the trend was not so clear, it was shown that N _unit is a decreasing function of C _∞ .     

Coordination of methyl coenzyme M and coenzyme M at divalent and trivalent nickel cyclams: model studies of methyl coenzyme M reductase active site

Divalent and trivalent nickel complexes of 1,4,8,11-tetraazacyclotetradecane, denoted as cyclam hereafter, coordinated by methyl coenzyme M (MeSCoM(-)) and coenzyme M (HSCoM(-)) have been synthesized in the course our model studies of methyl coenzyme M reductase (MCR). The divalent nickel complexes Ni(cyclam)(RSCoM)(2) (R = Me, H) have two trans-disposed RSCoM(-) ligands at the nickel(II) center as sulfonates, and thus, the nickels have an octahedral coordination. The SCoM(2-) adduct Ni(cyclam)(SCoM) was also synthesized, in which the SCoM(2-) ligand chelates the nickel via the thiolate sulfur and a sulfonate oxygen. The trivalent MeSCoM adduct [Ni(cyclam)(MeSCoM)(2)](OTf) was synthesized by treatment of [Ni(cyclam)(NCCH(3))(2)](OTf)(3) with ((n)Bu(4)N)[MeSCoM]. A similar reaction with ((n)Bu(4)N)[HSCoM] did not afford the corresponding trivalent HSCoM(-) adduct, but rather the divalent nickel complex polymer [-Ni(II)(cyclam)(CoMSSCoM)-](n) was obtained, in which the terminal thiol of HSCoM(-) was oxidized to the disulfide (CoMSSCoM)(2-) by the Ni(III) center.     

Indium(III) triflate-catalyzed reaction of 2-carbomethoxycyclobutanone with nitrones

2-Carbomethoxycyclobutanone reacted with N-phenyl-C-arylnitrones to afford methyl 5-oxo-2-[aryl(phenylamino)methyl]tetrahydrofuran-2-carboxylates by the catalysis of indium(III) triflate in the presence of magnesium sulfate.