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Search Results: 1 - 10 of 21 matches for " Takashiro Akitsu "
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Observation of Long-Range Vicinal Effect in Chiral Cu(II)-Cr(VI) or Cu(II)-W(VI) Bimetallic Coordination Polymers
Naoshi Hayashi,Takashiro Akitsu
Polymers , 2011, DOI: 10.3390/polym3031029
Abstract: We have prepared some diastereomers of [CuL 2][M 2O 7] (L is 1,2-diaminocyclohexane and its derivatives; M = Cr and W) bimetallic coordination polymers and confirmed their structural similarity and inner electronic states by means of XRD and XAS, respectively. For the first time, we have successfully observed distant vicinal effect of which the chiral source is only chiral organic ligands of [CuL 2] 2+ moieties (acting as ligand complex), while probe bands for solid state CD spectra are charge transfer (CT) bands of [M 2O 7] 2? moieties (achiral complex) with the d 0 electronic configuration. The new concept (interpretation) of this observation will be important for supramolecular chirality of coordination polymers built by ligand complexes.
Takashiro Akitsu,Yuki Endo
Acta Crystallographica Section E , 2009, DOI: 10.1107/s160053680900885x
Abstract: The title compound, [CuPd(CN)4(C4H12N2)2]n, consists of one-dimensional chains. The Cu and Pd atoms are both located on centers of symmetry in an alternating array of [Cu(N-Eten)2]2+ (N-Eten = N-ethylethylenediamine) and [Pd(CN)4]2 units. The Pd—C distances of 1.991 (3) and 1.992 (3) are intermediate values compared with the analogous NiII and PtII complexes [Akitsu & Einaga (2007). Inorg. Chim. Acta, 360, 497–505]. Due to Jahn–Teller effects, the axial Cu—N bond distance of 2.548 (2) is noticeably longer than the equatorial distances [Cu—NH2 = 2.007 (2) and Cu—NHC2H5 = 2.050 (2) ]. There are interchain hybrogen bonds, with N(—H)...N = 3.099(4) .
Some Hybrid Systems of Chiral Schiff Base Zn(II) Complexes and Photochromic Spiropyrans for Environmental Ion Sensing  [PDF]
Takatomo Miura, Takashi Onodera, Shinya Endo, Atsuo Yamazaki, Takashiro Akitsu
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.512084
Abstract: This is a review article including our recent results and some previous photo functional hybrid system having potential applications for environmental ion sensing. We have prepared several new and known chiral Schiff base Zn(II) complexes and measured (and also calculated) absorption and fluorescence spectra for sole complexes. After assembling hybrid systems with 1,3,3-trime- thylindolino-6’-nitrobenzopyrylospiran (SP) in methanol solutions, we measured spectral changes before and after alternate irradiation of UV and visible light. Intensity of fluorescence spectra for pale yellow Zn(II) complexes (λem = 450 nm, λex = 270 and 360 nm) was quenched by colorless SP (λem = 533 nm, λex = 612 nm). After UV light irradiation to form purple merocyanine (MC), photoisomerization resulted in changes of the intensity of absorption spectra as well as fluorescence spectra. Thus the hybrid systems could successfully act as molecular logic circuit by input (excitation by light) and output (intensity of fluorescence peaks). Moreover, we investigated concentration dependence of doped Zn(II) and Cu(II) ions to confirm quenching of intensity of fluorescence peaks by Zn(II) and Cu(II) MC complexes for metal ion sensing in solutions.
Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix
Yu Okamoto,Keisuke Nidaira,Takashiro Akitsu
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12106966
Abstract: Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix.
Yoshikazu Aritake,Yoshimasa Watanabe,Takashiro Akitsu
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810007762
Abstract: The title chiral photochromic Schiff base compound, C21H19N3O, was synthesized from (R)-1-phenylethylamine and the salicylaldehyde of an azobenzene derivative. The molecule corresponds to the phenol–imine tautomer, the C=N and N—C bond distances being 1.279 (3) and 1.477 (3) , respectively. An intramolecular O—H...N hydrogen bond occurs. The diazenyl group adopts a trans form with an N=N distance of 1.243 (3) .
Diaquabis(2,4-dichloro-6-formylphenolato)zinc(II)–bis(μ-2,4-dichloro-6-formylphenolato)bis[aqua(2,4-dichloro-6-formylphenolato)zinc(II)] (2/1)
Yoshimasa Watanabe,Yoshikazu Aritake,Takashiro Akitsu
Acta Crystallographica Section E , 2009, DOI: 10.1107/s160053680904896x
Abstract: The crystal of the title compound, [Zn(C7H3Cl2O2)2(H2O)2]2·[Zn2(C7H3Cl2O2)4(H2O)2], consists of monomeric and dimeric ZnII complexes. Both complexes afford a six-coordinated coordination environment about the Zn atoms with cis-configuration ligands. The deprotonated hydroxy groups of the 3,5-dichlorosalicylaldehyde ligands bridge two metal cations, forming a centrosymmetric dimeric complex. Intermolecular O—H...O hydrogen bonding occurs between the coordinated water molecules and deprotonated hydroxy groups in the crystal structure.
A chiral photochromic Schiff base: (R)-4-methoxy-2-[(1-phenylethyl)iminomethyl]phenol
Yukie Miura,Yoshikazu Aritake,Takashiro Akitsu
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809035557
Abstract: The title chiral photochromic Schiff base compound, C16H17NO2, was synthesized from (R)-1-phenylethylamine and 5-methoxysalicylaldehyde. The molecule of the title compound exists in the phenol–imine tautomeric form. The dihedral angle between the two aromatic rings is 62.61 (11)°. An intramolecular O—H...N hydrogen bond with an O...N distance of 2.589 (2) is observed. The crystal packing is stabilized by C—H...π interactions involving the aromatic ring.
Synthesis of Chiral Schiff Base Metal Complex Inducing CD and Elucidation of Structure of Adsorption on Surface of Gold Nanoparticles  [PDF]
Minako Oshima, Minoru Matsuno, Tsutsumi Yuki, Sunaga Nobumitsu, Tomoyuki Haraguchi, Takashiro Akitsu
International Journal of Organic Chemistry (IJOC) , 2017, DOI: 10.4236/ijoc.2017.72013
Abstract: We have prepared supramolecular systems of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes and colloidal gold nanoparticles (AuNP) of 10 nm diameters. They demonstrated that direct adsorption of chiral Schiff base metal complex on the surface of AuNP owing to observation of clear induced CD spectra for the first time. We observed and discussed induced CD bands on AuNP from chiral Schiff base Ni(II), Cu(II), Zn(II) complexes.
The Studies of Conditions for Inducing Chirality to Cu(II) Complexes by Chiral Zn(II) and Ni(II) Complexes with Schiff Base
Takashiro Akitsu,Jun Yamaguchi,Naoki Uchida,Yoshikazu Aritake
Advances in Materials Science and Engineering , 2009, DOI: 10.1155/2009/484172
Abstract: Recently, we have discovered that some chiral Schiff-base nickel(II) complexes induced d-d bands of CD spectra of some achiral copper(II) complexes. However, the novel phenomenon could be observed only a few systems of hybrid materials or limited conditions so far. In order to test conditions about copper(II) ions, we investigated model systems (1) metal-dendrimer (Cu-PAMAM; G4-NH2 terminal) containing relatively small amount of copper(II) ions (4.5 equivalent to PAMAM) for modeling separated systems of achiral copper(II) complex from chiral Schiff-base nickel(II) or zinc(II) complexes, Bis(--1-naphtylethyl-3,5-dichlorosalicydenaminato)nickel(II) or zinc(II) by polymer matrix. (2) equilibrium of copper(II) -ethylethylenediamine complexes to measure absorption spectra of d-d band, pH, and electron conductivity during titration of copper(II) ions. The results showed that (1) 4.5Cu-PAMAM could not be induced their d-d bands by the chiral nickel(II) or zinc(II) complexes, which suggested that separation by polymers prevented from inducing CD peaks. (2) Although 36Cu-PAMAM was known, uncoordinated copper(II) ions excess to ligands mainly attributed to increase electron conductivity by remained ions in methanol solutions, which was not associated with intermolecular interaction or dipole moments being effective for the induced CD mechanism by using molecular recognition between neutral molecules of metal complexes.
Material Conformity and Bactericidal Characteristics of High-Density Ozone Disinfection in Vinyl Polysiloxane Impression and PMMA Dentistry Fillings  [PDF]
Hiroshi Ohkawa, Tetsuya Akitsu
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.67035

Disinfection was investigated in high-density ozone produced by dielectric barrier discharge under atmospheric pressure. Disinfection was studied on three-dimensional carriers made of hydrophilic vinyl-polysiloxane impression material and granular acrylic resin used for oral surgery. Experimental results indicate disinfection of spore-forming bacteria: Geobacillus stearothermophilus and Bacillus atrophaeus, and selected species of opportunistic pathogens: Aspergillus niger, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans.

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