Cutting-edge Results on Energies and Catalysts at SPring-8

What is an industrial researcher expecting from the use of synchrotron radiation at SPring-8? It seems that there are two answers. One expectation is that he is able to explain convincingly to his customers a distinctive advantage of the developed product in a visible manner, and the other is that he investigates essential quality of materials by returning to the starting point when he is at a loss what to do in the process of his R&D; thus he can gain the opportunity of making a technical breakthrough in his R&D. This is because SPring-8 provides the most powerful synchrotron radiation currently available. As a result, a researcher can understand the chemical-bonding states of the material structure at the atomic and electronic levels by utilizing new analytical tools such as XAFS (X-ray Absorption Fine Structure) and XRD (X-ray Diffraction), etc.     

Formation of a Pentacoordinate 1,2-Oxastannetanide by Novel Base-Induced Rearrangement of a Bis(β-Hydroxyalkyl)Stannane

Treatment of a bis(β-hydroxyalkyl)diphenylstannane with potassium hydride in THF in the presence of 18-crown-6 gave the corresponding pentacoordinate t-alkoxy-l,2-oxastannetanide as stable crystals instead of a hexacoordinate stannate with two oxetane rings. This compound is considered to be formed by novel tin-1,3-migration reaction from carbon to oxygen reaction involving the formation of an oxetane ring and the subsequent tin-carbon bond cleavage.     

Mechanical Properties and Intermolecular Interactions in Molecular Composites Composed of Wholly Aromatic Polyamide and Poly-(Amide-Imide)

Poly(p-phenylene-3,4′-oxydiphenylene terephthalamide) (PPOT) and poly(4,4′-oxydiphenylene-4-carbonamidephthalimide-N-yl) (PAI) are compatible. Molecular composites were prepared by solution blending and subsequently solvent casting. The glass transition temperature of the composite increased with increasing fraction of PPOT. Intermolecular interactions between the two components increase due to formation of hydrogen bonds between the amide linkages of the component polymers. The elastic modulus of the composite was always higher than the modulus predicted on the basis of the additivity. Similar deviations from additivity were observed for the bulk density. These desirable results arise from an increase of the packing density of molecules due to the additional hydrogen bonding also shown by the infrared spectra.     

Hydrogen-bonded network and enforced supramolecular cavities in molecular crystals: An orthogonal aromatic-triad strategy. Guest binding,molecular recognition,and molecular alignment properties of a bisresorcinol derivative of anthracene in the crystalline state

Abstract

Crystallization of an orthogonal resorcinol-anthracene-resorcinol compound 1a (host) from an ester solvent such as alkyl benzoate (guest) affords a 1:2 host-guest adduct 1a·2(ester). An essential aspect of the crystal structures of ethyl, propyl, and isobutyl benzoate adducts (space group, P2₁/n) and also that of methyl benzoate adduct (C2/c) is an extensive hydrogen-bonded network of host 1a, leading to a molecular sheet composed of hydrogen-bonded polyresorcinol chains and anthracene columns. This network generates well-defined, cyclophane-like supramolecular cavities, which incorporate two alkyl benzoate molecules in a highly selective manner via a combination of essential host-guest hydrogen-bonding and what may be called the cavity-packing effect. The selectivity factor between methyl benzoate (the lowest-affinity guest) and isobutyl benzoate (the highest-affinity guest) is 1:70 under competitive conditions. The actual geometry of the cavity is somehow dependent on and hence induced-fit adjustable to the guest structures by manipulating the intramolecular (anthracene-resorcinol dihedral angle) and intermolecular conformation (tilt angle between two hydrogen-bonded resorcinol rings) of compound 1a as well as the sheet-to-sheet distance. The adducts 1a·2(guest) can also be obtained by solid-state guest-exchange or guest-binding, respectively, using a preformed adduct or guest-free apohost dipped in an appropriate guest solvent. The methyl benzoate adducts obtained in these ways exhibit the same X-ray powder diffraction pattern as the genuine single-crystal obtained by direct crystallization of host 1a from methyl benzoate. Thus, even internal supramolecular cavities maintained by the hydrogen-bonded network are readily accessible to molecules in bulk solution. In addition, they undergo an induced-fit adjustment to a guest molecule newly added by the guest-exchange or the guest-binding process, during which the crystallinity is maintained. The potential use of symmetrical and divergent multiple hydrogen-bonding sites with an orthogonal aromatic spacer (orthogonal aromatic-triad strategy) is discussed in terms of a tool to construct a new class of porous organic crystals that show novel molecular recognition, crystalline-state guest-binding, and crystalline-phase molecular alignment properties.     

Swern Oxidation of α-Ketols to α-Diketones1

The Swern oxidation of acyclic and cyclic α-ketols delivered α-diketones or the tautomeric diosphenols in good yield.     

Quinolone Analogues 12: Synthesis and Tautomers of 2‐Substituted 4‐Quinolones and Related Compounds

The 4‐quinolone‐2‐carboxylates 4a,b were converted into the 4‐quinolone‐2‐carbohydrazides 5a,b , hydrazones 6,7,10 , and related compounds 8,9,11 . The 4‐methoxyquinoline‐2‐carboxylate 12 was also transformed into the 4‐methoxyquinoline‐2‐carbohydrazide 13 , which was modified to the hydrazone 14 and related compound 15 . The antimicrobial activities of compounds 6b and 14 are described together with the 4‐oxo and 4‐hydroxy tautomers of compounds 4‐11 in deuteriodimethyl sulfoxide and deuteriotrifluoroacetic acid.     

Hysteresis properties for local magnetic sites distribution on grain boundary

Magnetic hysteresis curves were calculated using the Monte Carlo method to study the dependence of magnetic properties on the distribution of local magnetic sites on the grain boundaries of sensitized Alloy 600. The simulated curves illustrate that the total number of the magnetic sites and the standard deviation of the site distribution on grain boundary influence strongly the magnetic remanence and coercivity. The magnetic system can, therefore, be regarded as a magnetic granular structure with a distribution, and the results suggest a possibility of new method to control magnetic hysteresis.