Utilization and Modification of Perovskite-Type Layered Structures as Inorganic-Organic Hybrid Materials

Abstract

The aromatic ammonium-based layered halide compounds were obtained of bis(4-nitroanilinium)tetrachlorocadmate and bis(2-methyl-4-nitroanilinium) tetrachlorocadmate, aiming at a new type of inorganic-organic hybrid layered material. X-ray diffraction analyses of the single crystals revealed that both of the crystals take an alternate layered structure of the organic bilayer and the inorganic sheet. Cadmium ion and chloride anions form six-coordinated octahedra whose corner anions are shared with the neighboring octahedra for the crystal of bis(4-nitroanilinium)tetrachlorocadmate. In the case of bis(2-methyl-4-nitroanilinium) tetrachlorocadmate crystal the inorganic portion takes distorted four-coordinated tetrahedra. The structure of the inorganic portion for the latter crystal can be considered to be caused by the distortion of a perovskite-type octahedron due to the introduction of a bulky organic molecule.     

A new resin glycoside from Ipomoea maxima

A new resin glycoside (1) was isolated from the aerial part of Ipomoea maxima, together with three known compounds, pescaprein XX (2), stoloniferin X (3), and stoloniferin IX (4). The structure of 1 was elucidated on the basis of 1D NMR spectroscopy, a fragmentation study by APCIMS, and HRESIMS analysis.     

Protein C-Mannosylation and C-Mannosyl Tryptophan in Chemical Biology and Medicine

C-Mannosylation is a post-translational modification of proteins in the endoplasmic reticulum. Monomeric α-mannose is attached to specific Trp residues at the first Trp in the Trp-x-x-Trp/Cys (W-x-x-W/C) motif of substrate proteins, by the action of C-mannosyltransferases, DPY19-related gene products. The acceptor substrate proteins are included in the thrombospondin type I repeat (TSR) superfamily, cytokine receptor type I family, and others. Previous studies demonstrated that C-mannosylation plays critical roles in the folding, sorting, and/or secretion of substrate proteins. A C-mannosylation-defective gene mutation was identified in humans as the disease-associated variant affecting a C-mannosylation motif of W-x-x-W of ADAMTSL1, which suggests the involvement of defects in protein C-mannosylation in human diseases such as developmental glaucoma, myopia, and/or retinal defects. On the other hand, monomeric C-mannosyl Trp (C-Man-Trp), a deduced degradation product of C-mannosylated proteins, occurs in cells and extracellular fluids. Several studies showed that the level of C-Man-Trp is upregulated in blood of patients with renal dysfunction, suggesting that the metabolism of C-Man-Trp may be involved in human kidney diseases. Together, protein C-mannosylation is considered to play important roles in the biosynthesis and functions of substrate proteins, and the altered regulation of protein C-manosylation may be involved in the pathophysiology of human diseases. In this review, we consider the biochemical and biomedical knowledge of protein C-mannosylation and C-Man-Trp, and introduce recent studies concerning their significance in biology and medicine.     

Spontaneous chiral resolution of N,N′-diarylsquaramides: Formation of various types of one-handed helical networks during crystallization

N,N′-Bis(ortho-substituted phenyl)squaramides afforded chiral crystals, in which squaramide molecules are arranged in one-handed helical networks, upon simple recrystallization. Three types of crystals with different helices were obtained, depending on the substituents or recrystallization solvent. Folded-type intermolecular hydrogen-bonding interactions of squaramides play a key role in forming the helical networks.     

Influence of substrate temperature on nitridation of (0 0 1) GaAs using RF-radical source

The mechanism of nitridation of (0 0 1) GaAs surface using RF-radical source was systematically studied with changing substrate temperature, nitridation time and supplying As molecular beam. It was found from atomic forth microscopy (AFM) measurements that supplying As is very important to suppress the re-evaporation of As atoms and to keep the surface smooth. Reflection high-energy electron diffraction (RHEED) measurements shows that surface lattice constant (SLC) of GaAs of 0.565 nm decreases with increasing the substrate temperature and that it finally relaxes to the value of c-GaN of 0.452 nm, at 570 °C in both [1 1 0] and [1¯ 1 0] directions without concerning with the supply of As molecular beam. But, in the medium temperature range (between 350 and 520 °C), SLC of [1 1 0] direction was smaller than that of [1¯ 1 0] direction. This suggests a relation between the surface structure and the relaxing mechanism of the lattice. The valence band discontinuity between the nitridated layer and the GaAs layer was estimated by using X-ray photoemission spectroscopy (XPS). It was between 1.7 and 2.0 eV, which coincides well with the reported value of c-GaN of 1.84 eV. This suggests that the fabricated GaN layer was in cubic structure.     

Double coverings of 2‐paths by Hamilton cycles*

A double Dudeney set in K_n is a multiset of Hamilton cycles in K_n having the property that each 2‐path in K_n lies in exactly two of the cycles. A double Dudeney set in K_n has been constructed when n ≥ 4 is even. In this paper, we construct a double Dudeney set in K_n when n ≥ 3 is odd. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 195–206, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/jcd.10003     

Effect of carrier concentration on the facilitated oxygen transport in a polymer membrane

Facilitated transport of oxygen in a solid Polymer membrane containing cobaltporphyrin (CoP) which carries oxygen specifically and reversibly, leads to permselectivity of oxygen against nitrogen in the membrane. The increase in concentration of the CoP carrier is expected to enhance the oxygen transport. The membranes of poly(octylmethacrylate-co-vinylimidazole) containing 0.8 ～ 10 wt% CoP were prepared, and the effects of the CoP-concentration on the transport and the diffusion constants of oxygen are studied. Although the induction period before the steady state of oxygen permeation was prolonged with the CoP concentration in the polymer membrane, the glass transition temperature (T_g) of the membrane was increased and the diffusion constants of oxygen were decreased with the CoP concentration to yield unexpected reduction of the oxygen permeation in the highly CoP loaded membrane.