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.     

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.     

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.     

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.     

Angular heterocycles. A convenient synthesis of azabenzophenothiazines

The acid-catalysed reaction of substituted 1,4-naphthoquinones with o-aminoheterocyclic thiones in alcoholic solution afforded substituted monoazabenzo[a]phenothiazin-5-ones 4,5 and substituted benzo[a][1,4]diazabenzothiazino[3,2-c]phenothiazin-5-one ( 6 ). Some of the resulting compounds were subjected to dehalogenation. The structures of the products were assigned by elemental analysis, ¹H-nmr, and other spectral analysis.     

Reliable and fast allele-specific extension of 3'-LNA modified oligonucleotides covalently immobilized on a plastic base, combined with biotin-dUTP mediated optical detection.

In the present work, a convenient microarray SNP typing system has been developed using a plastic base that covalently immobilizes amino-modified oligonucleotides. Reliable SNP allele discrimination was achieved by using allelic specificity-enhanced enzymatic extension of immobilized oligonucleotide primer, with a locked nucleic acid (LNA) modification at the SNP-discriminating 3'-end nucleotide. Incorporation of multiple biotin-dUTP molecules during primer extension, followed by binding of alkaline phosphatase-conjugated streptavidin, allowed optical detection of the genotyping results through precipitation of colored alkaline phosphatase substrates onto the surface of the plastic base. Notably, rapid primer extension was demonstrated without a preliminary annealing step of double-stranded template DNA, allowing overall processes to be performed within a couple of hours. Simultaneous evaluation of three SNPs in the genes TGFB1, SOD2 and APEX1, previously investigated for association with radiation sensitivity, in 25 individuals has shown perfect assignment with data obtained by another established technique (MassARRAY system).