Advanced Materials Research Vols. 11-12

Abstract: With a view to understanding the reactivity of the μ-peroxo diiron(III) complexes in biological oxidation enzymes, such as soluble methane monooxygenase (sMMO) and ribonucleotide reductase (RNR), cis-μ-1,2- and trans-μ-1,2-peroxo diiron complexes were theroretically treated by the use of DFT calculation. Full-optimizations of the structures were carried out using the initial structures of (μ-O2-)(μ-CH3COO-)(μ-O2 2-)[FeIII(A3CY)]2 + and (μ-O2 2- )[FeIII(A3CY)Cl2]2 (A3CY = cis,cis-1,3,5-tris-amino-cyclohexane) for cis- and trans-forms, respectively, by minimizing their total energies. The O-O stretching vibrations were estimated for both isomers; the 16O-16O stretching frequencies for peroxo diiron complexes with cis- and transforms were 840 and 769 cm-1, respectively, which showed an isotope shift to 791 and 724 cm-1, respectively, by the use of 18O2 2- in the place of 16O2 2-. The structure/function relationship for them was discussed.

Abstract: As a basic study to search a molecular recognition site in electron transfer proteins, optically-active ruthenium complexes, [RuII/III(bcmaa)(bpy)] (BCMAA: N,Nbis( carboxymethyl)amino acid, BPY: 2,2’-bipyridine), were designed and prepared. The electron transfer reaction with cytochrome c553 (Alcaligenes xylosoxidans GIFU1051) was kinetically investigated, and its enantio-selectivity was detected. Based on the results of enantio-selective behavior for cytochrome c553, the local structure of molecular recognition site of cytochrome c553 was discussed.

Abstract: A distorted square-pyramidal N2S3-type Co(III) complex with a vacant site was previously synthesized as an active site model of Nitrile hydratase (NHase), and the coordination behavior of a water molecule to the vacant site was discussed. In this paper, the coordination of other monodentate ligands (CN-, tBuNC) to the complex was studied using UV-vis and IR spectral measurements. The UV-vis spectra changed with isosbestic points at ca. 300 nm and 370 nm by addition of CN- or tBuNC. The IR spectra showed C≡N stretching vibrations at 2112 and 2197 cm-1, respectively, both of which are different from those of the respective metal-free ligands, CN- (2069 cm-1) and tBuNC (2135 cm-1). These results indicate that CN- and tBuNC can coordinate to the vacant site of the Co(III) complex. Furthermore, we tried the adsorption experiments of the complex into FSM (folded-sheet mesoporous metarial) with hydrophobic mesopores. The adsorption amount of PPh4[Co(L1-O4)] for FSM exhibited a high value of ∼40 w/w% in CH2Cl2, although such an adsorption behavior was not observed in MeOH.

Abstract: In order to analyze the polarization of Poly(vinyl alcohol) (PVA) film, both the polarizing film and polarizing film exposed to UV light were prepared and investigated by X-ray diffractometer (XRD) and polarized UV-Visible Spectrometer. Through a series of experiments, it was found that the crystallization degree of the unirradiated PVA film was higher than that of the UV-irradiated PVA film. Furthermore, the transmittance of both unirradiated PVA film and UV-irradiated PVA film was selective, different wavelength and different polarizing angles parallelism different light transmittance.

Abstract: One-dimensional multiplexed anisotropic gratings were fabricated in photoreactive polymer liquid crystals (PPLCs), and the diffraction properties were characterized. Based on the holographic technique, the overwriting process is combined with the highly-stable and –controllable molecular alignment of the PPLCs. As a result, 1st- and 2nd-order diffraction intensities variable gratings dependent on the polarization direction of probe beam were obtained without significant changing their total diffraction intensity. The multiplexed gratings can be used as polarization-selective diffractive optical elements.

Abstract: Lithium acrylate (LiAA) was applied as a functional monomer to modify the surface properties of polypropylene films via photografting polymerization in a precipitation reaction system. Two-step photografting polymerization technique was adopted with benzophenone (BP) as the photoinitiator and methanol as the solvent. ATR-FITR spectra proved the occurrence of grafting polymerization of LiAA on the substrate. Gravimetric analysis was performed to investigate the influences of some important factors on the photografting polymerization of LiAA. SEM was utilized to investigate the topography of the grafted film. The experimental results indicated that elongation of the irradiation time could increase the grafting yield (Yg) and Yg performed a maximum at a certain concentration of LiAA. SEM images showed that regular particles evenly dispersed on the surface of the grafted film.

Abstract: Polystyrene (PS), polyethylene (PE), polypropylene (PP), glass and stainless steel were exposed to aqueous solutions of a series amphiphilic polymers at room temperature, including N-isopropylacrylamide (NIPAM)-based polymers, polyvinylpyrrolidone (PVP), polypropylene oxide (PPO)-polyethylene oxide (PEO) block copolymers and PEO. Dynamic contact angle measurements of the material surfaces before and after the treatment indicate that only NIPAM-based polymers can adsorb on both hydrophobic and hydrophilic surfaces. The surface morphologies of the materials before and after polymer adsorption were investigated by profilometry. Protein adsorption on the surfaces pre-adsorbed NIPAM-based polymers was investigated by dual polarisation interferometry (DPI) and profilometry using lysozyme as the model protein. The results obtained indicate that NIPAM-based polymers can significantly improve the biofouling resistance of synthetic surfaces.

Abstract: The linear random isoprene-styrene copolymer (L-SIR) was prepared by solution polymerization with cyclohexane—n-hexane mixture as solvent and n-BuLi as initiator in the presence of the polar regulator—tetrahydrofuran (THF). Microstructures of L-SIR have been studied by 1H-NMR.

Abstract: One novel fluorene-based amphiphilic copolymers has been synthesized by Suzuki polycondensation (SPC) with monomer 2,7-dibromo-9,9-bis-(3,6-dioxahepyl)fluorene and 9,9-dioctylfluorene-2,7-bis-(trimethyleneboronate). The copolyfluorenes’ molecular structure is characterized by 1H and 13C NMR as well as elemental analysis. The copolyfluorenes have high molecular weight and narrow molecular weight distribution, at the same time, are found to have good solubility and thermal stabilities. The copolyfluorenes exhibit a UV-visible absorption band in the range of 389-393 nm in both toluene solution and the film state. Upon photo-excitation around the absorption maximum wavelength, their PL spectra show a maximum peaks around at 415-427 nm.

Abstract: Rh-Ru bimetallic complex is a novel catalyst used to hydrogenate nitrile rubber, which has high activity and high selectivity. Hydrogenated nitrile rubber with a degree of hydrogenation over 99% and gel-free was obtained using this homogeneous catalyst. In this paper, relative molecular weight and mechanical properties of three types of HNBR, including HNBR hydrogenated by Rh-Ru bimetallic catalyst, Therban A3406 and Zetpol 2000L, were analyzed and compared. The results showed that the relative molecular weight of HNBR increased a little after hydrogenation compared to NBR, its mechanical properties were superior to those of Therban A3406 and Zetpol 2000L, and their oil resistant and rheological curves at 130°C and 140°C in the range of shear rate 0∼100s-1 were similar.