Hideki Masuda

Publications of Hideki Masuda

• Synthesis, characterization, and reactivity of a novel μ-η2:η2-diselenidodicopper(II) complex.

  Authors: Jun Matsumoto, Yuji Kajita, Hideki Masuda

  Inorganic chemistry. 02/2012; 51(3):1236-8.

  The first μ-η(2):η(2)-diselenidodicopper(II) complex has been obtained in the reaction of a copper(I) complex with N,N',N″-tribenzyl-cis,cis-1,3,5-triaminocyclohexane and elemental selenium. TheThe first μ-η(2):η(2)-diselenidodicopper(II) complex has been obtained in the reaction of a copper(I) complex with N,N',N″-tribenzyl-cis,cis-1,3,5-triaminocyclohexane and elemental selenium. The structure and reactivity of the complex is described.

• Synthesis and characterization of cobalt(ii) complexes with tripodal polypyridine ligand bearing pivalamide groups. Selective formation of six- and seven-coordinate cobalt(ii) complexes.

  Authors: Jun Matsumoto, Tatsuya Suzuki, Yuji Kajita, Hideki Masuda

  Dalton transactions (Cambridge, England : 2003). 02/2012;

  The reactions of CoX(2) (X = Cl(-), Br(-), I(-) and ClO(4)(-)) with the tripodal polypyridine N(4)O(2)-type ligand bearing pivalamide groups, bis(6-(pivalamide-2-pyridyl)methyl)(2-pyridylmethyl)amineThe reactions of CoX(2) (X = Cl(-), Br(-), I(-) and ClO(4)(-)) with the tripodal polypyridine N(4)O(2)-type ligand bearing pivalamide groups, bis(6-(pivalamide-2-pyridyl)methyl)(2-pyridylmethyl)amine ligand (H(2)BPPA), afforded two types of Co(ii) complexes as follows. One type is purple-coloured Co(ii) complexes, [CoCl(2)(H(2)BPPA)] (1(Cl)) and [CoBr(2)(H(2)BPPA)] (1(Br)) which were prepared when X = Cl(-) and Br(-), respectively. The other type is pale pink-coloured Co(ii) complexes, [Co(MeOH)(H(2)BPPA)](ClO(4)(-))(2) (2·(ClO(4)(-))(2)) and [Co(MeCN)(H(2)BPPA)](I(-))(2) (2·(I(-))(2)), which were obtained when X = I(-) and ClO(4)(-), respectively. From the reaction of 1(Cl) and NaN(3), a purple-coloured complex, [Co(N(3))(2)(H(2)BPPA)] (1(azide)), was obtained. These Co(ii) complexes were characterized by X-ray structural analysis, IR and reflectance spectroscopies, and magnetic susceptibility measurements. All these Co(ii) complexes were shown to be in a d(7) high-spin state based on magnetic susceptibility measurements. The former Co(ii) complexes revealed a six-coordinate octahedron with one amine nitrogen, three pyridyl nitrogens, and two counter anions, and one coordinated anion, Cl(-), Br(-) and N(3)(-), forming intramolecular hydrogen bonds with two pivalamide N-H groups. On the other hand, the latter Co(ii) complexes showed a seven-coordinate face-capped octahedron with one amine nitrogen, three pyridyl nitrogens, two pivalamide carbonyl oxygens and MeCN or MeOH. In these structures, intramolecular hydrogen bonding interaction was not observed, and the metal ion was coordinated by the pivalamide carbonyl oxygens and solvent molecule instead of the counter anions. The difference in coordination geometries might be attributable to the coordination ability and ionic radii of the counteranions; smaller strongly binding anions such as Cl(-), Br(-) and N(3)(-) gave the former complexes, whereas bulky weakly binding anions such as I(-) and ClO(4)(-) afforded the latter ones. In order to demonstrate this hypothesis, the small stronger coordinating ligand, azide, was added to complexes 2·(ClO(4)(-))(2) to obtain the dinuclear cobalt(ii) complex in which two six-coordinate octahedral cobalt(ii) species were bridged with azide, 3·(ClO(4)(-)). Also, the abstraction reaction of halogen anions from complexes 1(Cl) by AgSbF(6) gave a pale pink Co(ii) complex assignable to 2·(SbF(6)(-))(2).

• Adsorption behavior of microbes on a QCM chip modified with an artificial siderophore-Fe3+ complex.

  Authors: Tomohiko Inomata, Hiroshi Eguchi, Yasuhiro Funahashi, Tomohiro Ozawa, Hideki Masuda

  Langmuir : the ACS journal of surfaces and colloids. 12/2011; 28(2):1611-7.

  Three hydroxamate-type artificial siderophores with terminal NH(2) groups, tris[2-{3-(N-acyl-N-hydroxamino)propylamido}propyl]aminomethane (1-3, acyl-R group = Me, Et, and Ph, respectively), andThree hydroxamate-type artificial siderophores with terminal NH(2) groups, tris[2-{3-(N-acyl-N-hydroxamino)propylamido}propyl]aminomethane (1-3, acyl-R group = Me, Et, and Ph, respectively), and their Fe(3+) complexes, 4-6, were prepared. The stability constant (log β) of 4 was estimated to be about 31 by its EDTA titration. The biological activities of 4-6 for Microbacterium flavescens, which is a hydroxamate-type siderophore, auxotrophic gram-positive microbe, clearly indicated that they permeated the cell membrane depending on their terminal bulky acyl-R groups. These artificial siderophore complexes, 4-6, were modified on Au electrode surfaces with the terminal NH(2) group (4-6/Au). The surface modification of 4-6 was confirmed by several electrochemical measurements. The quartz crystal microbalance (QCM) chips were also modified with 4-6. Microbe adsorption measurements using these modified QCM chips for M. flavescens, Pseudomonas putida, and Eschrichia coli were performed. The QCM chips have the ability to adsorb microbes selectively as a result of the differences in the interactions between the structures of Fe(3+)-artificial siderophore complexes and their receptors or binding proteins within the cell membrane.

• Anodization of gold in oxalate solution to form a nanoporous black film.

  Authors: Kazuyuki Nishio, Hideki Masuda

  Angewandte Chemie (International ed. in English). 02/2011; 50(7):1603-7.

• Creation of a type 1 blue copper site within a de novo coiled-coil protein scaffold.

  Authors: Daigo Shiga, Daisuke Nakane, Tomohiko Inomata, Yasuhiro Funahashi, Hideki Masuda, Akihiro Kikuchi, Masayuki Oda, Masanori Noda, Susumu Uchiyama, Kiichi Fukui, Kenji Kanaori, Kunihiko Tajima, Yu Takano, Haruki Nakamura, Toshiki Tanaka

  Journal of the American Chemical Society. 12/2010; 132(51):18191-8.

  Type 1 blue copper proteins uniquely coordinate Cu(2+) in a trigonal planar geometry, formed by three strong equatorial ligands, His, His, and Cys, in the protein. We designed a stable Cu(2+)Type 1 blue copper proteins uniquely coordinate Cu(2+) in a trigonal planar geometry, formed by three strong equatorial ligands, His, His, and Cys, in the protein. We designed a stable Cu(2+) coordination scaffold composed of a four-stranded α-helical coiled-coil structure. Two His residues and one Cys residue were situated to form the trigonal planar geometry and to coordinate the Cu(2+) in the hydrophobic core of the scaffold. The protein bound Cu(2+), displayed a blue color, and exhibited UV-vis spectra with a maximum of 602-616 nm, arising from the thiolate-Cu(2+) ligand to metal charge transfer, depending on the exogenous axial ligand, Cl(-) or HPO(4)(2-). The protein-Cu(2+) complex also showed unresolved small A(∥) values in the electron paramagnetic resonance (EPR) spectral analysis and a 328 mV (vs normal hydrogen electrode, NHE) redox potential with a fast electron reaction rate. The X-ray absorption spectrum revealed that the Cu(2+) coordination environment was identical to that found in natural type 1 blue copper proteins. The extended X-ray absorption fine structure (EXAFS) analysis of the protein showed two typical Cu-N(His) at around 1.9-2.0 Å, Cu-S(Cys) at 2.3 Å, and a long Cu-Cl at a 2.66 Å, which are also characteristic of the natural type 1 blue copper proteins.

• A square-planar Ni(II) complex with an N2S2 donor set similar to the active centre of nickel-containing superoxide dismutase and its reaction with superoxide.

  Authors: Daisuke Nakane, Shin-ich Kuwasako, Michiharu Tsuge, Minoru Kubo, Yasuhiro Funahashi, Tomohiro Ozawa, Takashi Ogura, Hideki Masuda

  Chemical communications (Cambridge, England). 03/2010; 46(12):2142-4.

  The structure around the metal centre of a Ni(II) complex with an N(2)S(2) square-planar geometry, 1, prepared as a model compound of the NiSOD active site was drastically changed upon addition ofThe structure around the metal centre of a Ni(II) complex with an N(2)S(2) square-planar geometry, 1, prepared as a model compound of the NiSOD active site was drastically changed upon addition of potassium superoxide (KO(2)).

• Erratum: Tetra-chlorido[(diphenyl-phosphino)diphenyl-phosphine oxide-κO]zirconium(IV) benzene monosolvate. Corrigendum.

  Authors: Takahiko Ogawa, Yuji Kajita, Hideki Masuda

  Acta crystallographica. Section E, Structure reports online. 01/2010; 66(Pt 2):e16.

  The chemical name of the title compound in the paper by Ogawa, Kajita & Masuda [Acta Cryst. (2009), E65, m1129] is corrected.[This corrects the article DOI: 10.1107/S1600536809031882.].

• Fabrication of Monodisperse Polymer Nanoparticles by Membrane Emulsification Using Ordered Anodic Porous Alumina.

  Authors: Takashi Yanagishita, Ryoko Fujimura, Kazuyuki Nishio, Hideki Masuda

  Langmuir : the ACS journal of surfaces and colloids. 12/2009;

  Uniformly sized droplets of photocurable monomer were obtained through membrane emulsification using highly ordered anodic porous alumina as a membrane. Subsequent polymerization of the monomerUniformly sized droplets of photocurable monomer were obtained through membrane emulsification using highly ordered anodic porous alumina as a membrane. Subsequent polymerization of the monomer generated polymer particles, whose sizes could be controlled by changing the size of the pores in anodic porous alumina. The size distribution was very narrow owing to the uniformity of pore size in the anodic porous alumina used for the emulsification.

• Synthesis and Characterization of a Benzene-Dimolybdenum Complex with a New Bridging Mode.

  Authors: Yuji Kajita, Takahiko Ogawa, Jun Matsumoto, Hideki Masuda

  Inorganic chemistry. 09/2009;

  A novel dimolybdenum complex, [Mo(2)(((i)Pr)L')(2)(C(6)H(6))] (1(C(6)H(6))), has been synthesized and characterized as a benzene-ring-bridged dimolybdenum complex with aA novel dimolybdenum complex, [Mo(2)(((i)Pr)L')(2)(C(6)H(6))] (1(C(6)H(6))), has been synthesized and characterized as a benzene-ring-bridged dimolybdenum complex with a cis-mu-eta(2)(1,2):eta(2)(4,5) binding mode. Complex 1(C(6)H(6)) reacts with MeMgBr to form 2, where mu-benzene is methylated to form mu-xylene.

• The effect of the side chain length of Asp and Glu on coordination structure of Cu(2+) in a de novo designed protein.

  Authors: Daigo Shiga, Daisuke Nakane, Tomohiko Inomata, Hideki Masuda, Masayuki Oda, Masanori Noda, Susumu Uchiyama, Kiichi Fukui, Yu Takano, Haruki Nakamura, Toshihisa Mizuno, Toshiki Tanaka

  Biopolymers. 08/2009;

  Metal ions in proteins are important not only for the formation of the proper structures but also for various biological activities. For biological functions such as hydrolysis and oxidation, metalMetal ions in proteins are important not only for the formation of the proper structures but also for various biological activities. For biological functions such as hydrolysis and oxidation, metal ions often adopt unusual coordination structures. We constructed a stable scaffold for metal binding to create distorted metal coordination structures. A stable four stranded alpha-helical coiled-coil structure was used as the scaffold, and the metal binding site was in the cavity created at the center of the structure. Two His residues and one Asp or Glu residue were used to coordinate the metal ions, AM2D and AM2E, respectively. Cu(2+) bound to AM2D with an equatorial planar coordination structure with two His, one Asp and H(2)O as detected by ESR and UV spectral analyses. On the other hand, Cu(2+) had a slightly distorted square planar structure when it bound two His and Glu in AM2E, due to the longer side-chain of the Glu residue as compared to the Asp residue. Computational analysis also supported the distorted coordination structure of Cu(2+) in AM2E. This construct should be useful to create various coordinations of metal ions for catalytic functions. (c) 2009 Wiley Periodicals, Inc. Biopolymers, 2009.

• Nano-film structures constructed by self-assembly of Co(III) biuretato complexes and long alkyl imidazolium cations.

  Authors: Kazuki Yamada, Yuki Okazaki, Tomohiko Inomata, Keita Kuroiwa, Nobuo Kimizuka, Tomohiro Ozawa, Yasuhiro Funahashi, Hideki Masuda

  Journal of nanoscience and nanotechnology. 02/2009; 9(1):307-12.

  A Co(III) biuretato complex, [Co(III){ph(biu)2}]- (ph(biu)2 = o-phenylenebis(biuretato)) can form layer structures by its self-assembling with a multiply hydrogen bonding network.A Co(III) biuretato complex, [Co(III){ph(biu)2}]- (ph(biu)2 = o-phenylenebis(biuretato)) can form layer structures by its self-assembling with a multiply hydrogen bonding network. PPh4[Co(III)(ph(biu)2}]. 3CHCl3 (PPh4+ = Tetraphenylphosphonium cation) crystallizes in the triclinic, space group P1, with a = 9.740(5) A, b = 13.980(8) A, c = 16.792(9) A, alpha = 103.976(7) degrees, beta = 95.592(8) degrees, gamma = 103.165(8) degrees, V = 2132 A3, and Z=2. In the crystal, counter cations, PPh4+, are inserted between the layer structures of [Co(III){ph(biu)2}]- aggregates, resulting in formation of a multi-layered structure. A treatment of K[Co(III){ph(biu)2}] with C18MelmCl (C18Melm+ = 1-octadecyl-3-methyl-imidazolium cation) in an aqueous solution with a trace amount of PPh4Cl, gave the glaring silver solution containing self-organized nano-film structures. Optical microscopic and AFM studies clearly showed that rectangle-shaped nano-film structures were formed by self-assembly of [Co(III){ph(biu)2}]- and C18Melm+ in the solution, and their sizes were approximately ranged to 6-13 microm in length, 3-7 microm in width and 25.2 +/- 6.2 nm in thickness. Using spectroscopic and XRD data, we concluded that these nano-films have a alternatively accumulated multilayer-structure of [Co(III){ph(biu)2}]- layer and C18Melm+ bilayer structures, the repeating distance being d001 = 2.22 nm.

• Formation of a bridged butterfly-type mu-eta2:eta2-peroxo dicopper core structure with a carboxylate group.

  Authors: Yasuhiro Funahashi, Tomohide Nishikawa, Yuko Wasada-Tsutsui, Yuji Kajita, Syuhei Yamaguchi, Hidekazu Arii, Tomohiro Ozawa, Koichiro Jitsukawa, Takehiko Tosha, Shun Hirota, Teizo Kitagawa, Hideki Masuda

  Journal of the American Chemical Society. 01/2009; 130(49):16444-5.

• {μ-Bis(1-methyl-imidazol-2-yl)methane-κN:N}bis-{[(1-methyl-imidazol-2-yl)methane-κN,N]copper(I)} bis-(tri-fluoro-methane-sulfonate).

  Authors: Jun Matsumoto, Yuji Kajita, Hideki Masuda

  Acta crystallographica. Section E, Structure reports online. 01/2009; 65(Pt 11):m1286-7.

  The title compound, [Cu(2)(C(9)H(12)N(4))(3)](CF(3)SO(3))(2), contains two Cu(I) ions, three bis-(1-methyl-imidazol-2-yl)methane (Me(2)BIM) ligands, and two trifluoromethanesulfonate anions in theThe title compound, [Cu(2)(C(9)H(12)N(4))(3)](CF(3)SO(3))(2), contains two Cu(I) ions, three bis-(1-methyl-imidazol-2-yl)methane (Me(2)BIM) ligands, and two trifluoromethanesulfonate anions in the asymmetric unit. Each Cu(I) ion has a distorted trigonal-planar geometry and is coordinated by two N atoms from the Me(2)BIM ligand and another N atom from the Me(2)BIM that acts as a bridging ligand, another N atom of the bridging Me(2)BIM being linked to the second Cu(I) ion. The imidazole rings of Me(2)BIM form intra-molecular π-π stacking inter-actions [centroid-centroid distances = 3.445 (2) and 3.547 (2) Å].

• Tetra-chlorido[(diphenyl-phosphino)diphenyl-phosphine oxide-κO]zirconium(IV) benzene monosolvate.

  Authors: Takahiko Ogawa, Yuji Kajita, Hideki Masuda

  Acta crystallographica. Section E, Structure reports online. 01/2009; 65(Pt 9):m1129.

  In the title centrosymmetric mononuclear Zr(IV) compound, [ZrCl(4){P(O)(C(6)H(5))(2)P(C(6)H(5))(2)}(2)]·C(6)H(6), the central Zr(IV) ion is coordinated by two O atoms from two symmetry-relatedIn the title centrosymmetric mononuclear Zr(IV) compound, [ZrCl(4){P(O)(C(6)H(5))(2)P(C(6)H(5))(2)}(2)]·C(6)H(6), the central Zr(IV) ion is coordinated by two O atoms from two symmetry-related (diphenyl-phosphino)diphenyl-phosphine ligands and four Cl atoms in a distorted octahedral geometry with the four Cl atoms in the equatorial positions. The mol-ecule lies about a center of inversion and the benzene solvent mol-ecule about another center of inversion. The P=O bond [1.528 (2) Å] is slightly longer than a typical P=O double bond (average 1.500 ).

• Formation of a Bridged Butterfly-Type mu-eta(2):eta(2)-Peroxo Dicopper Core Structure with a Carboxylate Group.

  Authors: Yasuhiro Funahashi, Tomohide Nishikawa, Yuko Wasada-Tsutsui, Yuji Kajita, Syuhei Yamaguchi, Hidekazu Arii, Tomohiro Ozawa, Koichiro Jitsukawa, Takehiko Tosha, Shun Hirota, Teizo Kitagawa, Hideki Masuda

  Journal of the American Chemical Society. 12/2008;

• Self-assembled monolayer electrode of a diiron complex with a phenoxo-based dinucleating ligand: observation of molecular oxygen adsorptionldesorption in aqueous media.

  Authors: Tomohiko Inomata, Kazuma Shinozaki, Yuya Hayashi, Hidekazu Arii, Yasuhiro Funahashi, Tomohiro Ozawa, Hideki Masuda

  Chemical communications (Cambridge, England). 02/2008;

  The phenoxo-based dinucleating ligand, 2,6-bis[bis(6-pivalamido-2-pyridylmethyl)amino-methyl-4-aminophenol (1), and its Fe2(II) complex, [Fe2(II)(1)(PhCOO)2](CF3SO3) (2), were prepared and 2The phenoxo-based dinucleating ligand, 2,6-bis[bis(6-pivalamido-2-pyridylmethyl)amino-methyl-4-aminophenol (1), and its Fe2(II) complex, [Fe2(II)(1)(PhCOO)2](CF3SO3) (2), were prepared and 2 deposited on the Au surface (2/Au) is much more stable than in solution and exhibits redox behavior in aqueous media as well as reversible adsorption/desorption of oxygen at room temperature.

• H-atom abstraction reaction for organic substrates via mononuclear copper(II)-superoxo species as a model for DbetaM and PHM.

  Authors: Tatsuya Fujii, Syuhei Yamaguchi, Shun Hirota, Hideki Masuda

  Dalton transactions (Cambridge, England : 2003). 01/2008;

  Hydrogen atom abstraction reactions have been implicated in oxygenation reactions catalyzed by copper monooxygenases such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamineHydrogen atom abstraction reactions have been implicated in oxygenation reactions catalyzed by copper monooxygenases such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamine beta-monooxygenase (DbetaM). We have investigated mononuclear copper(I) and copper(II) complexes with bis[(6-neopentylamino-2-pyridyl)methyl][(2-pyridyl)methyl]amine (BNPA) as functional models for these enzymes. The reaction of [Cu(II)(bnpa)]2+ with H2O2, affords a quasi-stable mononuclear copper(II)-hydroperoxo complex, [Cu(II)(bnpa)(OOH)]+ (4) which is stabilized by hydrophobic interactions and hydrogen bonds in the vicinity of the copper(II) ion. On the other hand, the reaction of [Cu(I)(bnpa)]+ (1) with O2 generates a trans-mu-1,2-peroxo dicopper(II) complex [Cu(II)2(bnpa)2(O2(2-]2+ (2). Interestingly, the same reactions carried out in the presence of exogenous substrates such as TEMPO-H, produce a mononuclear copper(II)-hydroperoxo complex 4. Under these conditions, the H-atom abstraction reaction proceeds via the mononuclear copper(II)-superoxo intermediate [Cu(II)(bnpa)(O2-)]+ (3), as confirmed from indirect observations using a spin trap reagent. Reactions with several substrates having different bond dissociation energies (BDE) indicate that, under our experimental conditions the H-atom abstraction reaction proceeds for substrates with a weak X-H bond (BDE < 72.6 kcal mol(-1)). These investigations indicate that the copper(II)-hydroperoxo complex is a useful tool for elucidation of H-atom abstraction reaction mechanisms for exogenous substrates. The useful functionality of the complex has been achieved via careful control of experimental conditions and the choice of appropriate ligands for the complex.

• Ordered porous alumina geometries and surface metals for surface-assisted laser desorption/ionization of biomolecules: possible mechanistic implications of metal surface melting.

  Authors: Yoshinao Wada, Takashi Yanagishita, Hideki Masuda

  Analytical chemistry. 01/2008; 79(23):9122-7.

  Platinum- or gold-coated porous alumina with submicrometer structures is a potential substrate for surface-assisted laser desorption/ionization (SALDI) mass spectrometry of biomolecules, notPlatinum- or gold-coated porous alumina with submicrometer structures is a potential substrate for surface-assisted laser desorption/ionization (SALDI) mass spectrometry of biomolecules, not requiring sample matrixes. In this study, a highly ordered porous alumina substrate was fabricated to study the geometric factors allowing good SALDI performance. Evaluation was based on the signal-to-noise ratio of protonated angiotensin I ions in the mass spectrum obtained by 337-nm ultraviolet laser irradiation. Varying the geometries, including pore densities and diameters, revealed the laser intensity required to generate ions to be related to surface porosity. Surface platinum was melted upon laser irradiation at the fluence sufficient to generate peptide ions as confirmed by scanning electron microscopy. Moreover, a thin (5-20 nm) platinum coat requires a low intensity of laser light for desorption/ionization. Considering the size effect on the melting of metals, our findings suggest the surface platinum melting to be involved in ion generation from this SALDI substrate type. Indeed, tantalum, which has a higher melting point, required more laser fluence to generate ions. The porous alumina layer beneath surface metals probably worked as a thermal insulator. This double-layer-type substrate allowed ionization of angiotensin I and verapamil at low femtomole levels. Moreover, small proteins and glycoproteins such as 24-kDa trypsinogen and 15-kDa ribonuclease B could be ionized with sufficient sensitivity on this target. Taking advantage of matrix-free methods, concentrating the sample solution in the target concavity or widening the laser beam focus enhanced the signal-to-noise ratio for analyte ions in the mass spectrum. Activity is maintained for months in air.

• Adsorption of microorganisms onto an artificial siderophore-modified Au substrate.

  Authors: Tomohiko Inomata, Hiroshi Eguchi, Kenji Matsumoto, Yasuhiro Funahashi, Tomohiro Ozawa, Hideki Masuda

  Biosensors & bioelectronics. 01/2008; 23(5):751-5.

  The hydroxamate-type artificial siderophore, tris[2-{3-(N-acetyl-N-hydroxamino)propylamido}propyl]aminomethane (TAPPA) and its Fe(III) complex, Fe(III)-TAPPA were prepared and characterized byThe hydroxamate-type artificial siderophore, tris[2-{3-(N-acetyl-N-hydroxamino)propylamido}propyl]aminomethane (TAPPA) and its Fe(III) complex, Fe(III)-TAPPA were prepared and characterized by several spectroscopic methods. Fe(III)-TAPPA exhibits biological activity for the hydroxamate-type siderophore auxotrophic microorganism, Microbacterium flavescens, suggesting that Fe(III)-TAPPA can permeate the cell membrane of the microorganism. The adsorption of the Fe(III)-siderophore complex onto a deposited Au substrate was achieved by a stepwise self-assembling method. The modification of Fe(III)-TAPPA on the surface was confirmed from the cyclic voltammogram of the resultant Au electrode, Fe(III)-TAPPA/Au. The adsorption experiments of M. flavescens with Fe(III)-TAPPA/Au were monitored by optical, scanning electron, and atomic force microscopy and quartz crystal microbalance (QCM) measurements. These results clearly indicate that Fe(III)-TAPPA/Au can immobilize M. flavescens. This adsorption characteristic is due to the interaction between Fe(III)-TAPPA on an Au electrode and a receptor/binding protein within the cell membrane.

• Syntheses, Characterization, and Reactivities of (μ-η2:η2-Disulfido)dicopper(II) Complexes with N-Alkylated cis,cis-1,3,5-Triaminocyclohexane Derivatives

  Authors: Yuji Kajita, Jun Matsumoto, Isao Takahashi, Shun Hirota, Yasuhiro Funahashi, Tomohiro Ozawa, Hideki Masuda

  European Journal of Inorganic Chemistry. 01/2008; 2008(25):3977-3986.

  Three novel (disulfido)dicopper(II) complexes with N-alkylated cis,cis-1,3,5-triaminocyclohexane derivatives, [Cu2(S2)(R3TACH)]X2 [(R, X) = (Et, CF3SO3) (1), (iBu, SbF6) (2), and (Bn, SbF6) (3)],Three novel (disulfido)dicopper(II) complexes with N-alkylated cis,cis-1,3,5-triaminocyclohexane derivatives, [Cu2(S2)(R3TACH)]X2 [(R, X) = (Et, CF3SO3) (1), (iBu, SbF6) (2), and (Bn, SbF6) (3)], have been synthesized and characterized by elemental, electrochemical, and X-ray structure analyses, and electronic absorption, IR, ESI mass, and resonance Raman spectroscopic methods. The X-ray crystal structures indicate that the two sulfur and two copper atoms of these complexes form a Cu2(S2) structure with slight bending of the two planes defined by the CuS2 plane at angles of 166.12° (the individual bending angles are 175.56° for 1a and 156.67° for 1b), 154.74°, and 180° for 1, 2, and 3, respectively. The UV/Vis absorption spectra of 1, 2, and 3 have a sharp band at ca. 360 nm with a broadened shoulder at 400–480 nm and low intensity d–d bands in the range 666–671 nm. The resonance Raman spectra of the complexes have peaks assignable to a ν(S–S) band at 483–484 cm–1. The complexes have reduction waves at –974 to –946 vs. [Fe(C5H5)2]/[Fe(C5H5)2]+ for 1, –993 to –976 for 2, and –948 to –928 mV for 3. These values are in a low-potential region relative to bis(μ-OH)dicopper complexes with R3TACH. This may be explained by the occurrence of strong π-donation from the disulfide ligands as observed for previously reported (disulfido)Ru complexes. Compounds 1, 2, and 3 react with PPh3 to give S=PPh3 in yields of 65 ± 3.5, 76 ± 1, and 50 ± 2 %, respectively. These results are discussed in terms of the relationship between the dihedral angles in the Cu2(S2) core and the reactivity of S22–. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)