Synthesis and Photocatalytic Property of Hectorite/(Pt,TiO2) and H4Nb6O17/(Pt,TiO2) Nanocomposites

Abstract

TiO₂ and Pt have been intercalated in hectorite and H₄Nb₆O₁₇. The height of TiO₂ and Pt pillars was less than 0.8 nm and the band gap energy of TiO₂ pillars was ca. 3.3 eV. Both hectorite/TiO₂ and H₄Nb₆O₁₇(Pt, TiO₂) were capable of hydrogen evolution following irradiation from a high pressure mercury are (λ > 290 nm) in the presence of methanol as a sacrificial hole acceptor and the hydrogen evolution was enhanced by co-incorporation of Pt, although hectorite and hectorite/Pt did not show photocatalytic activity. Incorporation of Pt or Pt and TiO₂ in the interlayer of H₄Nb₆O₁₇ has resulted in enhanced photo evolution of hydrogen, however, TiO₂ alone in the interlayer of H₄Nb₆O₁₇ showed adverse photocatalytic activity.     

SYNTHESIS AND CHARACTERIZATION OF KINETICALLY STABILIZED 1,3-DIPHOSPHACYCLOBUTENE DERIVATIVES

1-(2,4,6-Tri-tert-butylphenyl)-2-phosphaethyne (1) was allowed to react with 0.5 equiv of an alkyllithium and subsequently with an alcohol to afford a bulky 1,3-diphosphacyclobutene, and its structure and coordination properties on transition metals were investigated. On the other hand, 1 was allowed to react with an alkyllithium and iodomethane to form a stable biradical, 1,3-diphosphacyclobutane-2,4-diyl.     

Synthesis and Hydrolysis of Polymers Having Anesthetic or Amantadine Residues in Sidechains

The polymerizable derivatives of chemotherapeutic agents such as benzocaine, procaine, and amantadine were prepared and free-radical copolymerized with styrene or methyl methacrylate in order to obtain polymers with pharmacological activity and increased duration of action of the drugs. The monomeric and polymeric derivatives were subjected to hydrolysis in vitro in order to measure the release of the active ingredient.     

Mechanistic Investigation of Catalyst‐Transfer Suzuki–Miyaura Condensation Polymerization of Thiophene–Pyridine Biaryl Monomers with the Aid of Model Reactions

We have investigated the requirements for efficient Pd‐catalyzed Suzuki–Miyaura catalyst‐transfer condensation polymerization (Pd‐CTCP) reactions of 2‐alkoxypropyl‐6‐(5‐bromothiophen‐2‐yl)‐3‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)pyridine ( 12 ) as a donor–acceptor (D –A) biaryl monomer. As model reactions, we first carried out the Suzuki–Miyaura coupling reaction of X–Py–Th–X′ (Th=thiophene, Py=pyridine, X, X′=Br or I) 1 with phenylboronic acid ester 2 by using tBu₃PPd⁰ as the catalyst. Monosubstitution with a phenyl group at Th‐I mainly took place in the reaction of Br–Py–Th–I ( 1 b ) with 2 , whereas disubstitution selectively occurred in the reaction of I–Py–Th–Br ( 1 c ) with 2 , indicating that the Pd catalyst is intramolecularly transferred from acceptor Py to donor Th. Therefore, we synthesized monomer 12 by introduction of a boronate moiety and bromine into Py and Th, respectively. However, examination of the relationship between monomer conversion and the M_n of the obtained polymer, as well as the matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectra, indicated that Suzuki–Miyaura coupling polymerization of 12 with (o‐tolyl)tBu₃PPdBr initiator 13 proceeded in a step‐growth polymerization manner through intermolecular transfer of the Pd catalyst. To understand the discrepancy between the model reactions and polymerization reaction, Suzuki–Miyaura coupling reactions of 1 c with thiopheneboronic acid ester instead of 2 were carried out. This resulted in a decrease of the disubstitution product. Therefore, step‐growth polymerization appears to be due to intermolecular transfer of the Pd catalyst from Th after reductive elimination of the Th‐Pd‐Py complex formed by transmetalation of polymer Th–Br with (Pin)B–Py–Th–Br monomer 12 (Pin=pinacol). Catalysts with similar stabilization energies of metal–arene η²‐coordination for D and A monomers may be needed for CTCP reactions of biaryl D–A monomers.     

Ligand Design to Acquire Specificity to Intended G-Quadruplex Structures

A G-quadruplex is a nucleic acid secondary structure that is adopted by guanine-rich sequences, and is considered to be relevant in various pharmacological and biological contexts. G-Quadruplexes have also attracted great attention in the field of DNA nanotechnology because of their extremely high thermal stability and the availability of many defined structures. To date, a large repertory of DNA/RNA G-quadruplex-interactive ligands has been developed by numerous laboratories. Several relevant reviews have also been published that have helped researchers to grasp the full scope of G-quadruplex research from its outset to the present. This review focuses on the G-quadruplex ligands that allow targeting of specific G-quadruplexes. Moreover, unique ligands, successful methodologies, and future perspectives in relation to specific G-quadruplex recognition are also addressed.     

The role of the dynamic pressure in stationary heat conduction of a rarefied polyatomic gas

The effect of the dynamic pressure (non-equilibrium pressure) on stationary heat conduction in a rarefied polyatomic gas at rest is elucidated by the theory of extended thermodynamics. It is shown that this effect is observable in a non-polytropic gas. Numerical studies are presented for a para-hydrogen gas as a typical example.     

NMR‐based analysis of the chemical composition of Japanese persimmon aqueous extracts

Japanese persimmon (Diospyros kaki L.) is recognized as an outstanding source of biologically active compounds relating to many health benefits. In the present study, NMR spectroscopy provided a comprehensive metabolic overview of Japanese persimmon juice. Detailed signal assignments of Japanese persimmon juice were carried out using various 2D NMR techniques incorporated with broadband water suppression enhanced through T₁ effects (BB‐WET) or WET sequences, and 26 components, including minor components, were identified. In addition, most components were quantitatively evaluated by the integration of signals using conventional ¹H NMR and BB‐WET NMR. This is the first detailed analysis combined with quantitative characterization of chemical components using NMR for Japanese persimmon. Copyright © 2015 John Wiley & Sons, Ltd.