Synthesis and two-electron redox behavior of diazuleno[2,1-a:1,2-c]naphthalenes

The Diels-Alder reaction of di-2-azulenylacetylene with tetraphenylcyclopentadienone afforded 7,8,9,10-tetraphenyldiazuleno[2,1-a:1,2-c]naphthalene in one pot via autoxidation of the presumed 1,2-di-2-azulenylbenzene derivative. In contrast, a similar reaction of bis(1-methoxycarbonyl-2-azulenyl)acetylene with tetraphenylcyclopentadienone gave the 1,2-di-2-azulenylbenzene derivative. The following cyclodehydrogenation reaction of the benzene derivative with iron(III) chloride afforded diazuleno[2,1-a:1,2-c]naphthalene 6,11-bismethoxycarbonyl derivative. The redox behavior of these novel diazuleno[2,1-a:1,2-c]naphthalenes was examined by cyclic voltammetry (CV). These compounds exhibited two-step oxidation waves at +0.22 to +0.71 V upon CV, which revealed the formation of a radical cation and dication stabilized by the fused two azulene rings under the electrochemical oxidation conditions. Since the 1,2-di-2-azulenylbenzene derivative was oxidized at higher oxidation potentials (+0.83 and +1.86 V), the fusion of the two azulene rings to naphthalene increased electron-donating properties because of the formation of a closed-shell dicationic structure. Formation of the radical cation was characterized by UV-vis spectroscopy under the electrochemical oxidation conditions, although no evidence was obtained for the presumed dication under the conditions of the UV-vis spectroscopy measurement.     

Synthesis of 5H-pyrido[2,3-a]phenoxazin-5-one and 5H-pyrido[3,2-a]phenoxazin-5-one derivatives

The 5H-pyrido[2,3-a]phenoxazin-5-one derivatives and 5H-pyrido[3,2-a]phenoxazin-5-one derivatives were prepared by the condensation of substituted 2-aminophenols with 6,7-dibromo-5,8-quinolinequinone followed by dehalogenation in the presence of sodium hydrosulfite dissolved in aqueous pyridine under a nitrogen atmosphere.     

Degradation of hydroxymaleimide in 2-propanol by irradiation of energetic heavy ions (II)—N2-saturated system

Hydroxymaleimide was irradiated in N₂-saturated 2-propanol solutions by high-energy heavy ions over a wide range of LET values. The differential G-values of the degradation of hydroxymaleimide by irradiation with the heavier ions were lower than those of the lighter ions for the same LET value. An opposite result obtained in the air-saturated system. The degradation efficiency was 1.5 times higher, when the dose rate was 1/10 times lower. When irradiated at an LET value lower than 8 eV/nm, the G-values converged to a value less than that obtained by γ-irradiation.     

Conformational behavior of styrene–p-chlorostyrene triblock copolymers in dilute solutions. I. Composition dependence of conformational behavior

Dilute solution properties of (styrene-p-chlorostyrene) triblock copolymers in various solvents were studied over a wide range of molecular weight and composition. Viscosity and osmotic pressure results indicate that the conformational behavior of the B_mA_nB_m and A_mB_nA_m copolymers (A = styrene; B = p-chlorostyrene; m and n denote the number of units) are similar in nonselective solvents such as toluene and 2-butanone, but different in selective solvents such as carbon tetrachloride and cumene. Short-range and long-range interaction parameters of the block copolymers were determined by applying the Stockmayer–Fixman method to viscosity data and also by application of the equation relating the osmotic virial coefficient and the excluded volume. The results show that the unperturbed dimensions of the block copolymers vary linearly with composition, and long-range interaction parameters in nonselective solvents can be expressed by those of the parent homopolymers, the chemical composition, and values of the interaction parameter β_AB between styrene and p-chlorostyrene monomeric units.     

Size-exclusion SPR sensor chip: application to detection of aggregation and disaggregation of biological particles

We propose a novel surface plasmon resonance (SPR) sensor chip with a microfabricated slit array. The microslit excludes micrometre-size objects larger than its slit size from the SPR sensing area, so that it functions as an in situ filter. We demonstrated the sensing of microparticles of different diameters using the chip, and the results show a successful size-exclusion effect. As a demonstration of the biological application, we performed the detection of aggregation and disaggregation of biological particles using sugar-chain-immobilized gold nanoparticles as a test sample.     

Determination of Easy Axis in a Chemical Ferromagnet, 4-(p-Chlorobenzylideneamino)–TEMPO (TEMPO=2,2,6,6-Tetramethylpiperidin-1-Oxyl)

The trapping sites for muon and muonium in ferromagnetic p-Cl–Ph–CH=N–TEMPO [(4-(p-chlorobenzylideneamino)–TEMPO (TEMPO = 2,6,6-tetramethyl-piperidin-1-yloxyl)] and the hyperfine interaction tensors for these sites are obtained using first-principles Unrestricted Hartree–Fock theory. The calculated hyperfine interactions are used to compare the calculated zero field muon spin rotation (μSR) frequencies for different choices for the easy axis and the observed frequency. It has been concluded that the two trapping centers that can best explain the observed μSR frequency are a trapped singlet muonium near the radical oxygen and a trapped muon site near the chlorine. The direction of the easy axis also is determined to be the b-axis of the monoclinic lattice. This direction for the easy axis is confirmed by determining the direction of the distributed magnetization in the molecular solid which leads to a minimum dipole–dipole interaction energy. The consequences of this agreement for the easy axis direction by two independent procedures are discussed. This revised version was published online in September 2006 with corrections to the Cover Date.     

Isoindole derivatives from o-diacylbenzenes and aromatic amines

o-Acetylbenzophenone produced yellow 1,2-diaryl-3-(aryliminomethyl)isoindole by the reaction with aromatic amines in the absence of acid. On the reaction of o-diacetylbenzene under the similar condition, three types of yellow products were obtained. The structures of these isoindole derivatives were determined and their formation mechanism was proposed.     

Formation of isoindoline derivatives from o-bromoacetylbenzophenones

o-Dibromoacetylbenzophenone, 2 or o-bromoacetylbenzophenone 3 reacted with aqueous ammonia to produce 3-phenylisoindolin-1-one 5. The reaction of 3 with methylamine afforded 3-hydroxy-2-methyl-3-phenyl-isoindolin-1-one 4 and 2-methyl-3-phenylisoindolin-1-one 5. Whereas from 2 with methylamine only 5 was obtained.     

The condensation products of 2,3,6-trisubstituted-1,4-naphthoquinones with 2-aminothiophenol

The 2,6-disubstituted-, 3,6-disubstituted-5H-benzo[a]phenothiazin-5-one derivatives and 7-substituted-benzo[a] [1,4]benzothiazino[3,2-a]phenothiazine derivatives were prepared by the condensation of 2,3,6-trisubstituted-1,4-naphthoquinones with 2-aminothiophenol. The resulting compounds were subjected to reduction, dehalogenation and condensation with aniline. Some of the condensation intermediates were isolated and the reaction mechanism was also investigated.