Cyclohexane photooxidation under visible light irradiation by WO3–TiO2 mixed catalysts

Research on Chemical Intermediates - Cyclohexane photocatalytic oxidation was performed over WO3 photocatalysts under visible light irradiation with molecular oxygen. Cyclohexanone and cyclohexanol...     

Synthesis and Cytotoxic Activity of Macromolecular Prodrug of Cisplatin Using Poly(ethylene glycol) with Galactose Residues or Antennary Galactose Units

To provide a macromolecular prodrug with recognition ability for hepatoma cells, we synthesized new conjugates of cisplatin (CDDP) and poly(ethylene glycol) (PEG) with galactose residues or antennary galactose units (Gal4A, four branched galactose residues) at the chain terminus, Gal‐PEG‐DA/CDDP or Gal4A‐PEG‐DA/CDDP conjugates. An antennary (branched) structure of Gal4A was designed based on the fact that saccharide clusters with branched structures show highly effective binding with saccharide receptors, a phenomenon known as the ‘cluster effect’. The cytotoxic activity of the conjugates was investigated against HepG2 human hepatoma cells in vitro and compared with a control conjugate without galactose, MeO‐PEG‐DA/CDDP. Gal‐PEG‐DA/CDDP and Gal4A‐PEG‐DA/CDDP conjugates showed lower IC₅₀ values (3.1×10^–4 and 2.3×10^–4 M , respectively) than the MeO‐PEG‐DA/CDDP conjugate (10.5×10^–4 M ). The cytotoxic activities of these conjugates with galactose residues or antennary galactose units were inhibited as a result of the addition of galactose and strongly inhibited by the addition of Gal4A, however the inclusion of a methoxy group (the MeO‐PEG‐DA/CDDP conjugate) did not affect the activity. These results suggest that the Gal4A unit introduced to the conjugate has effective recognition ability against HepG2 human hepatoma cells.     

Synthesis of Poly(L‐lactide) with One Terminal D‐Glucose Residue and Wettability of Its Film Surface

To develop the new‐type poly(L ‐lactide)‐based biomedical material having a wettable surface, the synthesis of poly(L ‐lactide) with one terminal D ‐glucose residue was investigated. After the hydroxyl group at 1‐C of α‐tetrabenzyl glucose, α‐Glc(Bzl)₄, was converted to the corresponding potassium alkoxide by using potassium tert‐butoxide, L ‐lactide (L ‐LA) was polymerized in the presence of α‐Glc(Bzl)₄‐OK as an initiator in tetrahydrofuran at room temperature to prepare α‐Glc(Bzl)₄‐polyLA. Subsequently, the removal of O‐protecting benzyl groups in the terminal α‐Glc(Bzl)₄ residue was carried out by hydrogenolysis with Pd/C to obtain the objective D ‐glucose‐end‐capped polyLA, α‐Glc‐polyLA. The wettability of surface of the α‐Glc‐polyLA material is discussed using the difference of the dynamic contact angle between a α‐Glc‐polyLA/homopolyLA blend film and a film of the polyLA homopolymer.     

Investigation of the surface structure of zeolite A

The surface structure of zeolite A was investigated by FE-SEM, AFM, and HRTEM. First, it was shown by FE-SEM and AFM that the surface of zeolite A terminated with the same structure. Then, by combining the results with those of HRTEM, the terminal structure of zeolite A was identified as incomplete sodalite cages.     

Membrane potential across anion-exchange membranes in acidic solution system

The membrane potential across anion-exchange membranes in H2SO4 and Na2SO4 solutions was measured, and the experimental results were fitted to the theory in the 2-1 electrolyte system based on the Donnan equilibrium and the Nernst-Planck flux equations. For the Na2SO4 solution, the Donnan potential makes a significant contribution to the membrane potential, but for the H2SO4 solution, the diffusion potential significantly contributes to the membrane potential. The diffusion potential has a greater contribution to the membrane potential across AEM-2 with a high water content than that across AEM-1. These results suggest that a proton with a high mobility can move without substantial influence of electrostatic interaction in a positively charged membrane.     

Efficient synthesis of substituted quinolines through intramolecular addition of aryl anion to carbonyl carbon

Substituted quinolines were synthesized in three steps from the Boc amides of substituted 2-iodoanilines and alkyl vinyl ketones. This method consists of (1) N-Michael addition of the Boc amide of 2-iodoaniline to alkyl vinyl ketone in the presence of Cs₂CO₃ in MeCN; (2) I-Mg exchange of the adduct with 3.5 equiv of i-PrMgCl·LiCl, and (3) acid-catalyzed reaction (excess AcCl in EtOH) of the resulting alcohol. Six examples are given with good yields.     

Strictly diastereocontrolled photocyclodimerization of 2-anthracenecarboxylates tethered to cyclic tetrasaccharides

Photocyclodimerization of 2-anthracenecarboxylate tethered to a cyclic nigerosylnigerose scaffold gave a single chiral cyclodimer (out of two achiral and two chiral stereoisomers) in 99% optical and 96% chemical yields, achieving the ultimate stereocontrol of the supramolecular photochirogenesis in aqueous solution at 25 °C.     

Synthesis, Stability, and Photoluminescence Properties of PdAu10(PPh3)8Cl2 Clusters

We report on the synthesis, stability, and photoluminescence (PL) properties of triphenylphosphine (PPh₃)-stabilized PdAu₁₀(PPh₃)₈Cl₂ cluster, which is a mono-Pd-doped cluster of the well-studied Au₁₁(PPh₃)₈Cl₂ cluster. The PdAu₁₀(PPh₃)₈Cl₂ cluster was synthesized by simultaneously reducing two different metal complexes; AuCl(PPh₃) and Pd(PPh₃)₄. Experimental evaluation of the stability showed that PdAu₁₀(PPh₃)₈Cl₂ is more stable against degradation in solution than the monometal Au₁₁(PPh₃)₈Cl₂ cluster. PL measurements revealed that PdAu₁₀(PPh₃)₈Cl₂ exhibits PL at 950?nm with a quantum yield of 1.5?×?10^?3, which has not been observed for the monometal Au₁₁(PPh₃)₈Cl₂ cluster. The results indicate that Pd doping is a powerful method to produce clusters with higher stability and different physical properties than the monometal Au:PPh₃ clusters.     

Synthesis and antifungal activity of novel 14-membered benzomacrolides, as galbonolide analogues

Asymmetric total synthesis of benzene analogues of galbonolide, a 14-membered antifungal macrolide, possessing a benzene ring instead of a conjugated diene structure, was achieved starting from chiral 1-aryl-1-propanol obtained by enzyme-catalyzed kinetic resolution with high enantioselectivity. Representatively, a method for the introduction of a methylthio and chloride function at the vinyl position was also established. The resulting analogues unfortunately exhibited very little antifungal potency in comparison with galbonolide A.     

2,6-Bis(benzoxazoyl)pyridine (bzpybox) as a new dialkylammonium cation receptor

2,6-Bis(2-benzoxazoyl)pyridine (bzpybox) ligand is reported as a new artificial receptor for secondary dialkylammonium.