Thermal properties of polyamides containing 1,3–cyclohexane rings

The effect of the 1,3–cyclohexane rings in the chain backbone on thermal properties of polyamides, especially the glass-transition temperature, has been studied using polyamides based on 1,3–cyclohexanebis(methylamine). The increase in glass-transition temperature was far greater than that obtained with the analogous polymers containing m–benzene rings. However, the effects of 1,4–cyclohexane and p-benzene rings are nearly equal. Several possible causes for this difference are examined. It is concluded that restricted chain mobility due to steric hindrance of the cis-1,3–cyclohexane ring, the predominant isomer, is the most likely cause of the difference.     

Binding enhancement of antigen-functionalized PEGylated gold nanoparticles onto antibody-immobilized surface by increasing the functionalized antigen using alpha-sulfanyl-omega-amino-PEG

We established a technique for constructing PEGylated gold nanoparticles (GNP) that have small compounds with almost complete functionalities on their surfaces using a newly synthesized hetero-telechelic poly(ethylene glycol) (PEG), and their association/dissociation behavior on an antibody-immobilized surface was evaluated using a surface plasmon resonance (SPR) sensor.     

Biosynthesis of a novel cyclic C35-terpene via the cyclisation of a Z-type C35-polyprenyl diphosphate obtained from a nonpathogenic Mycobacterium species

Lipid components from 12 nonpathogenic Mycobacterium species were analysed. A novel cyclic C(35)-terpene, named heptaprenylcycline , was obtained from 3 species, while octahydroheptaprenol , which has 3 Z-double bonds, was obtained from 6 species. The amounts of and in the cultured cells increased after the 4- to 6-d stationary phase. The yield of was considerably greater at a higher temperature of 37 degrees C than at an optimal temperature of 28 degrees C, while that of remained unchanged at all temperatures. A feeding experiment with d-[1-(13)C]glucose revealed that was produced via isopentenyl diphosphate, which is a metabolite of glycolysis and the methylerythritol phosphate pathway. The conversion of octahydroheptaprenyl diphosphate to was successful by using the cell-free extracts of M. chlorophenolicum, demonstrating that is the biosynthetic intermediate of . This is the first example of the biosynthesis of a natural terpene via the cyclisation of a linear C(35)-isoprenoid. The substrate for C(35)-terpene cyclase has Z-type prenyl moieties; however, terpene cyclases usually employ E-type isoprenoids. The gene encoding the terpene cyclase that cyclises prenyl diphosphate containing Z-double bonds as the natural substrate has not yet been detected. Despite a careful search using the FASTA3 program, we could not detect any gene that is homologous to the known diphosphate-triggered type of mono-, sesqui- and diterpene cyclases in the genome of M. vanbaalenii, the DNA sequence of which has recently been elucidated. This suggests that a novel type of terpene cyclase might exist in the nonpathogenic Mycobacterium species.     

Induction and structural control of chiral nematic phases by the use of photoresponsive tris(beta-diketonato) Co(III) and Ru(III) complexes

Two kinds of tris(beta-diketonato) metal(III) complexes denoted as [M(acac)2(LC12)] and [M(acac)2(Lazo)] (M=Ru(III) and Co(III); acac=acetylacetonato; LC12=1,3-didodecyloxyphenyl-1,3-propanedionato; Lazo=3-[4'-(4'-(butoxy)phenylazo)phenyl]-pentane-2,4-dionato) were synthesized and optically resolved into Delta, Lambda isomers. Here, LC12 and Lazo were designed to be elongated perpendicular to and in parallel with the molecular C 2 axis, respectively. The metal complexes were doped into three kinds of nematic liquid crystals (MBBA, EBBA, and ZLI-1132). Both dopants induced chiral nematic phases with relatively high helical twisting powers. With a purpose to clarify the mechanisms of helical induction, order parameters (S) were determined by means of polarized UV-vis measurements on nematic samples doped with racemic Co(III) complexes. As a result, the long axes of the elongated ligands in both [Co(acac)2(LC 12)] and [Co(acac)2(trans-Lazo)] were found to align in the direction of the director vector with S=0.50+/-0.05 and 0.60+/-0.05, respectively. Based on the results, the photoresponsive behavior of Delta- or Lambda-[Ru(acac)2(Lazo)] was interpreted in terms of the variation of S accompanied with the cis-trans isomerization of the azobenzene moiety in Lazo.     

Diels-alder reaction of 2(1H)-pyridones acting as dienes

Diels-Alder reactions between N-phenylmaleimide, acting as the dienophile, and 2(1H)-pyridones having a methoxy or a chloro substituent, were carried out, under atmospheric and high pressure conditions, to give the corresponding isoquinuclidine derivatives. Stereoselectivity of the Diels-Alder reactions was studied using molecular orbital calculations.     

Functional evaluation of iron oxypyriporphyrin in protein heme pocket

The iron complex of oxypyriporphyrin, a porphyrinoid containing a keto-substituted pyridine, was coupled with apomyoglobin. The reconstituted ferric myoglobin was found to be five-coordinate without iron-bound water molecules. The anionic ligands such as CN (-) and N 3 (-) bound the myoglobin with high affinities, while neutral imidazole did not. The IR observation indicated that the azide complex was pure high-spin, although the corresponding native protein was in the spin-state equilibrium. The reduced myoglobin was five-coordinate but exhibited no measurable affinity for O 2. The affinity for CO was lowered down to 1/2400 as compared with native myoglobin. These anomalies were ascribed to the deformation in the iron coordination core after the replacement of one of the four pyrroles with a larger pyridine ring. The ligand binding analyses for the ferric and ferrous myoglobin suggest that the proximal histidine pulls the iron atom from the deformed core to reduce the interaction between the iron and exogenous ligands. Similarity of the reconstituted myoglobin with guanylate cyclase, a NO-responsive signaling hemoprotein, was pointed out.     

Photophysical properties of highly luminescent copper(I) halide complexes chelated with 1,2-bis(diphenylphosphino)benzene

Studies on synthesis, structures, and photophysics have been carried out for a series of luminescent copper(I) halide complexes with the chelating ligand, 1,2-bis[diphenylphosphino]benzene (dppb). The complexes studied are halogen-bridged dinuclear complexes, [Cu(mu-X)dppb]2 (X = I (1), Br (2), Cl (3)), and a mononuclear complex, CuI(dppb)(PPh3) (4). These complexes in the solid state exhibit intense blue-green photoluminescence with microsecond lifetimes (emission peaks, lambdamax = 492-533 nm; quantum yields, Phi = 0.6-0.8; and lifetimes, tau = 4.0-10.4 mus) at 298 K. In 2-methyltetrahydrofuran (2mTHF) solutions at 298 K, only 1 and 4 show weaker emission (Phi = 0.009) with shorter lifetimes (tau = 0.35 and 0.23 mus) and red-shifted spectra (lambdamax = 543 and 546 nm). The emission in the solid state originates from the (M + X)LCT excited state with a distorted-tetrahedral conformation, in which emissive excited states, 1(M + X)LCT and 3(M + X)LCT, are in equilibrium with an energy difference of approximately 2 kcal/mol. On the other hand, the complexes in the 2mTHF solutions emit from the MLCT excited state with an energetically favorable flattened conformation in the temperature range of 298-130 K. The flattened geometry with equilibrated 1MLCT and 3MLCT states has a nonradiative rate at least 2 orders of magnitude larger than that of the distorted-tetrahedral geometry, leading to a much smaller emission quantum yield (Phi = 0.009) at 298 K. Since the flattening motion is markedly suppressed below 130 K, the emission observed in 2mTHF below 130 K is considered to occur principally from the (M + X)LCT state with a distorted-tetrahedral geometry. To interpret the photophysics of 1 and 4 in both the solid and solution states, we have proposed the "2-conformations with 2-spin-states model (2C x 2S model)". The electroluminescence device using (1) as a green emissive dopant showed a moderate EL efficiency; luminous efficiency = 10.4 cd/A, power efficiency = 4.2 lm/W at 93 cd/m(2), and maximum external quantum efficiency = 4.8%.     

Space-time analytic smoothing effect for a system of nonlinear Schrödinger equations with non pseudo-conformally invariant interactions

In this study, we consider the local Cauchy problem for a system of nonlinear Schrödinger equations with non pseudo-conformally invariant interactions in the framework of space of charge and in the framework of space of energy. The main purpose of this study is to construct local solutions in function spaces of analytic vectors for the Galilei generator and the pseudo-conformal generator with data which satisfy exponentially decaying condition at spatial infinity. In particular, we improve the nonlinear estimates have been proved by Hayashi and Kato and Ozawa et al. involving the pseudo-conformal generator with coe?cient which depends on time of local existence of solutions and has singularity at finite value.