Chemistry of renieramycins. Part 6: Transformation of renieramycin M into jorumycin and renieramycin J including oxidative degradation products, mimosamycin, renierone, and renierol acetate

The transformation of renieramycin M (1m) into renieramycin J (1j) and jorumycin (2) is presented along with the results of antiproliferative assay data. The chemical stability and the oxidative degradation of 2 and renieramycin E (1e) to generate simple isoquinoline alkaloids, such as mimosamycin (7), renierol acetate (12), and renierone (8) are also described.     

Stability of oxygen anions and hydrogen abstraction from methane on reduced SnO2 (110) surface

The stability of oxygen anions and the hydrogen abstraction from methane on a reduced SnO₂ (110) crystal surface have been studied theoretically using a point-charge model. The geometric and electronic structures for the present molecules are calculated by means of a hybrid Hartree–Fock/density functional method at the B3LYP/6-311+G(3df, 3pd) level of theory. The calculations of the energies on the point-charge model are performed using these optimized geometries. It is found that a low concentration of the active oxygen species O⁻ and O₂⁻ is expected on the reduced SnO₂ surface. The activation energies for the abstraction of hydrogen atom from methane on the reduced SnO₂ surface are obtained: 12 kcal/mol for O⁻ species and more than 48 kcal/mol for O₂⁻ species, indicating that O⁻ species on the surface is the main active center for the dissociation of a C(SINGLE BOND)H bond of methane, which is in agreement with the other oxide catalysts. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 669–678, 1998     

Conjugates of a Dinuclear Zinc(II) Complex and DNA Oligomers as Novel Sequence-Selective Artificial Ribonucleases

Even in the presence of a large excess of Zn ^II ions , sequence-selective RNA hydrolysis is achieved by DNA conjugates involving a dinuclear Zn^II complex (shown schematically). This is because the cooperation of two Zn^II ions is essential for the RNA scission.     

Polypeptide-synthetic polymer hybrids, 1. Miscibility of poly(vinyl alcohol) with poly(sodium α,β-D,L-aspartate)

The present paper describes materials of polypeptide-commodity polymer hybrids from poly(vinyl alcohol) (PVA) and poly(sodium α,β-D ,L -aspartate) ( 1 ). Miscible blend films of polypeptide 1 and PVA were prepared by the solvent-cast method from a homogeneous aqueous solution. Differential scanning calorimetry. Fourier transform infrared, and scanning electron microscopy combined with energy dispersive X-ray spectroscopy (EDX) were used to investigate the blends. It was revealed that 1 and PVA are miscible in a wide range of compositions.     

Preparation of CuInGeSe4 thin films by selenization method using the Cu-In-Ge evaporated layer precursors

CuInGeSe₄ quaternary compounds are known to have a chalcopyrite-like structure and have band gaps of about 1.3 eV, suitable for optimum conversion efficiency for solar cells. We have prepared the CuInGeSe₄ thin films by the selenization method using the Cu-In-Ge evaporated layer precursors. The analyses of X-ray diffraction show that the single phase of CuInGeSe₄ is obtained by the selenization of precursors at 450-500 °C. The SEM observation of film surface shows that the grain sizes are in the order of 1-2 μm. The band gaps of selenized films close to 1.6 eV are wider than that of bulk crystals (about 1.3 eV). These films have p-type conduction and higher electrical resistivities than more 10⁵ Ω cm at room temperature.     

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)₃] successfully yielded linear polyesters having hydroxyl functionality (M_n = ca. 1.0 × 10⁴). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009