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Electrochemical oxidation of oxalic acid has been investigated at bare, highly boron-doped diamond electrodes. Cyclic voltammetry and flow injection analysis with amperometric detection were used to study the electrochemical reaction. Hydrogen-terminated diamonds exhibited well-defined peaks of oxalic acid oxidation in a wide pH range. A good linear response was observed for a concentration range from 50 nM to 10 microM, with an estimated detection limit of approximately 0.5 nM (S/N = 3). In contrast, oxygen-terminated diamonds showed no response for oxalic acid oxidation inside the potential window, indicating that surface termination contributed highly to the control of the oxidation reaction. An investigation with glassy carbon electrodes was conducted to confirm the surface termination effect on oxalic acid oxidation. Although a hydrogen-terminated glassy carbon electrode showed an enhancement of signal-to-background ratio in comparison with untreated glassy carbon, less stability of the current responses was observed than that at hydrogen-terminated diamond.

Highly boron-doped diamond (BDD) electrode, have been examined for simultaneous detection of purine and pyrimidine bases in mild acidic media by using HPLC with amperometric detection. Cyclic voltammetry at as-deposited (AD) and anodically oxidized (AO) BDD were used to study the electrochemistry and to optimize the condition for HPLC applications. At AO BDD electrode, due to its higher overpotential of oxygen evolution reaction, well-defined anodic peaks were observed for the oxidation of purine and pyrimidine bases in acid medium, whereas at AD BDD the oxidation peak of thymine was overlapped with the anodic current of oxygen evolution. The chromatograms of adenine, guanine, cytosine, thymine and 5-methylcytosine mixture were well resolved by using a silica-based column and a solution of 5% acetonitrile in 100mM ammonium acetate buffer (pH 4.25) as the mobile phase. The detection was carried out at AO BDD electrode at an applied potential of 1.6V versus Ag/AgCl. Linear calibration curves were obtained within the concentration range from 0.1 to 10microM with the limits of detection (S/N=3) ranging from 26.3 to 162.1nM, resulting in an order of magnitude higher sensitivities than those at conventional electrodes. HPLC analysis with diamond amperometric detector was successfully applied for determination of 5-methylcytosine in real DNA samples with high reproducibility. No deactivation of the electrode was found during cyclic voltammetric and HPLC measurements, indicating the high stability for analysis of biological samples.

The electronic structure of a cobalt iron cyanide thin film, Na0.4Co1.3[Fe(CN)6]5H2O, was switched from FeIII(low spin)−CN−CoII(high spin) to FeII(low spin)−CN−CoIII(low spin) by exchanging cations in interstitial sites from Na+ to K+. The reverse process was also induced by replacing Na+ with K+. That is, the alkali cations in the interstitial sites dominate the electronic and spin states of the host compound. This type of switching phenomenon can be achieved by choosing a compound with both electronic degeneracy and zeolitic properties.

Reversible photoinduced magnetization was observed in a cobalt iron cyanide thin film. Magnetic properties of the prussian blue analog, K 0.4 Co 1.3 [Fe(CN) 5 ].5H 2 O, can be switched between ferrimagnetic and paramagnetic by visible and near-IR light illumination. The critical temperature after illumination was about 26 K. This material, obtained via an electrochemical route in the form of thin films on an electrode, provides a new system whose magnetic properties can be controlled by both photochemical and electrochemical redox reactions.

The electrochemical analysis of tetracycline was investigated using nickel-implanted boron-doped diamond thin film electrode by cyclic voltammetry and amperometry with a flow injection system. Cyclic voltammetry was used to study the electrochemical oxidation of tetracycline. Comparison experiments were carried out using as-deposited boron-doped diamond thin film electrode (BDD). Nickel-implanted boron-doped diamond thin film electrode (Ni-DIA) provided well-resolved oxidation irreversible cyclic voltammograms. The current signals were higher than those obtained using the as-deposited BDD electrode. Results using nickel-implanted boron-doped diamond thin film electrode in flow injection system coupled with amperometric detection are presented. The optimum potential for tetracycline was 1.55 V versus Ag/AgCl. The linear range of 1.0 to 100 microM and the detection limit of 10 nM were obtained. In addition, the application for drug formulation was also investigated.

The title compounds, a hydrogen-bonded linear chain, [Mn(C18H18N2O4)(H2O)2]ClO4, (I), a hydrogen-bonded pseudo-dimer, [Mn(C16H10Cl4N2O2)(CH4O)(H2O)]ClO4, (II), and a dimer, [Mn2(C18H18N2O4)2(CH4O)2](ClO4)2, (III), respectively, have been structurally characterized. The three complexes are completely different in their structural features, despite identical counter-anions and only slight modification of the substituents in the ligands. Complex (I) affords an elongated octahedral coordination environment, with axial Mn-O(water) distances of 2.259 (3) and 2.313 (3) A, which forms hydrogen-bonded linear chains along the crystallographic c axis. Hydrogen-bonded pseudo-dimeric compound (II) also affords an elongated octahedral coordination environment, with axial Mn-O(CH3OH) = 2.222 (3) A and Mn-O(water) = 2.266 (3) A. Dimeric complex (III) is centrosymmetric and consists of distorted octahedral Mn atoms, with axial Mn-O(CH3OH) = 2.242 (2) A and Mn-O(phenolate) = 2.348 (1) A, connected via bridging O atoms from one of the ligands. The magnetic properties of the three complexes are described.

X-ray absorption (XAS) and emission (XES) spectroscopy near B K and C K edges have been performed on metallic ($\ensuremath{\sim}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ B, B-diamond) and semiconducting ($\ensuremath{\sim}0.03\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ B and N, BN-diamond) doped diamond films. Both B K XAS and XES spectra show a metallic partial density of states (PDOS) with the Fermi energy of $185.3\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, and there is no apparent boron-concentration dependence in contrast to the different electric property. In C K XAS spectrum of B-diamond, the impurity state ascribed to boron is clearly observed near the Fermi level. The Fermi energy is found to be almost same with the top of the valence band of nondoped diamond: ${E}_{V}=283.9\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. C K XAS of BN-diamond shows both the B-induced shallow level and N-induced deep and broad levels as the in-gap states, in which the shallow level is in good agreement with the activation energy $({E}_{a}=0.37\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ estimated from the temperature dependence of the conductivity; namely, the change in $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ PDOS of impurity-induced metallization is directly observed. The electric property of this diamond is ascribed mainly to the electronic structure of $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ near the Fermi level. The observed XES spectra are compared with the discrete variational $\mathrm{X}\ensuremath{\alpha}$ ($\mathrm{DVX}\ensuremath{\alpha}$) cluster calculation. The $\mathrm{DVX}\ensuremath{\alpha}$ result supports the strong hybridization between $\mathrm{B}\phantom{\rule{0.2em}{0ex}}2p$ and $\mathrm{C}\phantom{\rule{0.2em}{0ex}}2p$ observed in XAS and XES spectra, and suggests that the small amount of boron $(\ensuremath{\leqslant}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%)$ in diamond occupies the substitutional site rather than interstitial site.

FeCo Prussian blue analogues, which are known as typical molecule-based magnets, exhibited abrupt conductance switching by applying a high electric field as well as by varying the temperature. The current density versus electric field (J−E) curves of FeCo Prussian blue with Rb cations in interstitial sites shows so-called negative resistance effects at electric fields higher than the threshold voltage. This means that the FeCo Prussian blue analogues are multiproperty materials in the sense that their conducting, magnetic, and optical properties can be reversibly controlled by certain external stimuli.

The title compounds, [Cu(C(15)H(12)Cl(2)NO)(2)], (I), and [Cu(C(17)H(18)NO(2))(2)], (II), both adopt a compressed tetrahedral trans-[CuN(2)O(2)] coordination geometry, the molecules having an umbrella conformation overall. These complexes differ from one another with respect to the 1-phenylethylamine moieties, the direction of the benzene rings being either inside [in (I)] or inside and outside [in (II)] of the molecules. The crystals of (I) and (II) have Delta(R,R) and Lambda(R,R) absolute configurations, respectively.

The crystal structures of the title compounds, [Cu(C 15 H 11 N 2 -O 2 ) 2 (C 14 H 15 N) 2 ] and [Cu(C 15 H 11 N 2 O 2 ) 2 (C 14 H 15 N) 2 ].2CHCl 3 , respectively, have been determined. The red disolvate complex affords a square-planar CuN 4 coordination environment in which the Cult atom lies on a centre of symmetry. The blue solvent-free complex affords a distorted square-pyramidal CuN 4 O coordination environment and adjacent molecules form centrosymmetric dimers. A comparison of the different crystal structures focuses on the role of the solvent molecules in supramolecular assemblies of the copper(II) complexes.

The title compound, [Cu(C(4)H(12)N(2))(2)(C(3)H(6)O)(2)](ClO(4))(2), is the first structurally characterized Cu(II) complex having acetone as axial ligands. The complex adopts an elongated octahedral trans-[CuN(4)O(2)] coordination geometry, with the Cu atom having 222 site symmetry. The axial Cu-O(acetone) and in-plane Cu-N bond lengths are 2.507 (5) and 2.041 (3) A, respectively.

Photoinduced magnetization of the cyano-bridged 3d-4f hetero-bimetallic assembly Nd (DMF)4(H2O)3(µ-CN)Fe(CN)5 • H2O (1) (DMF = N,N-dimethylformamide) is described in this paper. The XMT values are enhanced by about 45% after UV light illumination in the temperature range of 5–50 K. We propose that UV light illumination induces a structural distortion in 1. This small structural change is propagated by molecular interactions in the inorganic network. Furthermore, the cooperativity resulting from the molecular interaction functions to increase the activation energy of the relaxation processes, which makes observation of the photoexcited state possible. The flexible network structure through the hydrogen bonds in 1 plays an essential role for the photoinduced phenomenon. This finding may open up a new domain for developing molecule-based magnetic materials.

Photoinduced magnetization of the cyano-bridged 3d-4f heterobimetallic assembly Nd(DMF)4(H2O)3(mu-CN)Fe(CN)5.H2O (1) (DMF = N,N-dimethylformamide) is described in this paper. The chiMT values are enhanced by about 45% after UV light illumination in the temperature range of 5-50 K. We propose that UV light illumination induces a structural distortion in 1. This small structural change is propagated by molecular interactions in the inorganic network. Furthermore, the cooperativity resulting from the molecular interaction functions to increase the activation energy of the relaxation processes, which makes observation of the photoexcited state possible. The flexible network structure through the hydrogen bonds in 1 plays an essential role for the photoinduced phenomenon. This finding may open up a new domain for developing the molecule-based magnetic materials.

The first preparation of an Fe(II) spin-crossover complex including a 1,3-dithiole ligand is reported. Crystal analyses of both the low- and the high-temperature phases reveal that short S...S contacts play a key role in an abrupt spin transition.

Back ground: CD44 is an adhesion molecule expressed in cancer stem-like cells (CSCs). Our group recently reported that CD44 splice variant (CD44v) is expressed in CSCs and interacts with xCT, a glutamate-cystine transporter, keeping high levels of the intracellular reduced glutathione (GSH). Thus, CSCs with a high expression of CD44v have an enhanced capacity for GSH synthesis and defense against reactive oxygen species (ROS), resulting in resistance to various therapeutic stresses (Cancer Cell 2011; Cancer Res 2013). Sulfasalazine (SSZ) as an xCT inhibitor suppressed CD44v-dependent tumor growth and increased sensitivity to cytotoxic drugs in vivo study. Methods: A phase 1 dose escalation study in patients with advanced gastric cancer who had received one or more standard chemotherapies was conducted to determine the optimal dose, change in CD44v expression and intra-tumor level of GSH pre- and post SSZ exposure and pharmacokinetics. SSZ was given fourth-daily oral administration with 2 weeks as one cycle, which were continued until progression of disease, unacceptable toxicity, or other discontinuation criteria were met. A 3+3 escalation was used to evaluate a MTD. Tumor tissues were obtained pre- and post SSZ administration to evaluate expression of CD44v and intra-tumor level of GSH by immunohistochemistry and boron doped diamond microelectrode (Sci Rep 2012), respectively. Results: Eleven patients were dosed from 8 g to 12 g/day; median age: 71 years (61-78); median number of prior chemotherapies: 3 (1-4). There was two DLT of grade 3 anorexia and nausea among patients who were treated with 12 g/day. One additional patients required frequent dose interruption with grade 2 anorexia and nausea. Therefore 12g/day was judged as MTD. No DLT was observed among patients with 8g/day. Among the 5 patients with high CD44v expression, 4 patients achieved reduced expression of CD44v after the administration of SSZ for 2 weeks. GSH was also apparently decreased in 2 of 5 patients. Further exploratory biomarker analyses are still ongoing. The individual variability of SSZ exposure was explainable in terms of the genotypes of ABCG2 and NAT2 which influence SSZ pharmacokinetics. Conclusions: Optimal dose of SSZ was considered as 8g/day. Down regulation of CD44v expression and decreased level of GSH is confirmed as a pharmacodynamic marker of drug-on-target effect and mode of action of SSZ for CSCs, which warrants further investigation for combination with chemotherapy or other targeting agents. Clinical trial information: UMIN000010254 Citation Format: Kohei Shitara, Shunji Takahashi, Takako Nakajima, Hironaka Shuichi, Osamu Nagano, Chiyo Imamura, Taisei Mushiroda, Yasuaki Einaga, Miki Fukunani, Akihiro Sato, Atsushi Ohtsu, Hideyuki Saya, Toshihiko Doi. Sulfasalazine (SSZ) works cancer stem-like cells (CSCs) via inhibiting xCT signal pathway: Phase 1 study in patients with gastric cancer (EPOC 1205). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 211. doi:10.1158/1538-7445.AM2014-211

The spin-crossover iron(II) complex [Fe(L)(CN)2]·H2O (1) has been investigated. Complex 1 has a pentagonal bipyramidal structure which is seven-coordinated, containing an N3O2 macrocycle and two CN- ligands. Water molecules bind the complex by means of hydrogen bonding. It was found that the complex 1 exhibited a light-induced excited spin state trapping (LIESST) effect. The relaxation temperature is above 130 K, which is the highest temperature for LIESST compounds reported so far.

We show experimentally that room-temperature ferromagnetism can be induced in ZnO/ZnS core/shell nanoparticles without any magnetic components. This ferromagnetism could be attributed to p―p coupling interactions between S 3p and 0 2p electrons arising from the redistribution of charges between Zn and 0 or S atoms. Our present findings possibly open up a new way for introducing magnetism in semiconductor-based "spintronics" devices.

Ultrathin films composed of titania nanosheets and Prussian Blue were prepared by using the modified Langmuir-Blodgett technique. The ultrathin films could be deposited in a layer-by-layer manner with lamellar structure. Upon band gap excitation of titania nanosheets, the generated electrons were injected into ferromagnetic Prussian Blue, resulting in reduction to paramagnetic Prussian White. It was revealed that the reaction could proceed only in the presence of hole-scavenging interlayer water molecules.

Nanosized e-Fe 2 O 3 crystals with a diameter below 20nm were successfully prepared at 600°C in a mesoporous silica matrix. The formation of the metastable iron oxide occurred through nanoscale segregation in an immiscible SiO 2 -Fe 2 O 3 system having a mesoporous structure. The nanocrystals incorporated into ca. 50nm-size particles of the mesoporous silica exhibited a coercive field up to 8 kOe.

A novel spin-crossover molecular conductor, [Fe(qnal)2][Pd(dmit)2]5.acetone, was prepared and characterized. The crystal structural analyses of both the low- and high-temperature phases revealed that the supramolecular pi-pi interactions between the spin-crossover Fe(qnal)2 cations as well as the cation contraction play an important role in the uniaxial lattice deformation which will modulate the electrical conductivity of the conducting Pd(dmit)2 layer.

The Ni(dmit) 2 salt with an Fe(III) spin-crossover cation, Fe(qsal) 2 , was prepared and showed a cooperative spin transition based on π-π interactions between π-ligands. The light-induced excited spin state trapping effect on this complex was also observed.

Electrochemical behavior of gold-nanoparticle-dispersed diamond electrodes have been studied for the oxidation of oxalic acid in phosphate buffer solution. Comparison is made with gold, as-deposite...

The photoswitchable magnetic thin films have been designed by alternate depositions of bipolar amphiphilic azobenzene and Fe 3 O 4 nanoparticles by using the layer-by-layer adsorption technique. In these films, reversible photoisomerizations of the azobenzene chromophore affected the electrostatic interaction between the azobenzene chromophore and the surface of Fe 3 O 4 nanoparticles. As a result, we have succeeded in controlling the magnetization of these films by photoillumination at room temperature.

As a prototype for a “highly sensitive electrochemical detection system for single drop analysis using boron-doped diamond (BDD) electrodes”, a three-electrode system for the measurement of samples consisting of a single drop was fabricated. An Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) system, employing the Bosch process in order to realize high-aspect-ratio near vertical structures, was used to etch the BDD. A single drop (10 μL) was analyzed using the resulting fabricated ‘BDD chip electrode’ which exhibited the typical superior electrochemical properties of BDD electrodes.

The title compound, (RS)-3,5-dichloro-2-[[(1-phenylethyl)imino]methyl]phenol, C(15)H(13)Cl(2)NO, was synthesized from racemic 1-phenylethylamine and 3,5-dichlorosalicylaldehyde. The pi-conjugate system around the imine group is essentially planar in the phenol-imine tautomer. Intramolecular O...N hydrogen-bond and intermolecular C-H...pi interactions are present in the crystal structure.

Pt-modified diamond electrodes were fabricated for electroanalytical applications by implantation method with a dose of 5 × 1014 cm−2. The electrochemical behavior has been studied for oxidation of...

Co–Fe Prussian blue thin films have been prepared by means of a modified Langmuir–Blodgett technique, in which the hybrid monolayer composed of amphiphiles and clay platelets plays a template role ...

The thermal and photo-responsibility of the axial semi-coordination Cu–O bonds in [Cu(en)2](ClO4)2 (1) (en = ethylenediamine) have been investigated. We discovered a new photoresponsive behavior th...

The title compound, [Co(C14H18N2O6)], is the first structurally characterized example of a β-ketoiminato CoII complex without axial ligands. It adopts a square-planar cis-[CoN2O2] coordination geometry, and lies on a mirror plane. The planar complexes are stacked along 21 screw axes parallel to b to form columns, the Co⋯Co distance in the column being 3.5213 (2) A.

The initial rough, faceted surfaces of boron-doped conductive polycrystalline diamond electrodes were smoothed by Ar+ ion sputtering at very low energy (50 eV). A lower background current was measured at the modified electrodes with a mirror-like appearance than at the initial polycrystalline electrodes. The electrochemical responses to several redox systems also showed a morphological-dependence in some cases. Here, we discuss the electrochemical properties of the diamond electrodes with the smoothed surfaces from the point of view of a novel electrode material.

A polymer matrix isolation technique was examined as a potentially novel strategy for realizing optically switchable materials. Not only was a ferricinium ion ([Cp2FeIII]+) produced, but also was produced an isomer of ferrocene (Cp2Fe) with high spin FeII in a poly(methyl methacrylate) (PMMA) matrix film containing CCl4 by the photoillumination of ferrocene at low temperature. The high spin state could be maintained for an extended period when the sample was kept below ≈130 K. This is the first observation of a photoinduced spin transition for ferrocene. The strategy that we used to achieve the spin transition using optical stimuli may open up many possibilities for the development of new magneto-optical devices.

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Microdisc array (MDA) electrodes of boron-doped diamond (BDD) were fabricated on structured silicon substrates. The BDD-MDA electrodes exhibited sigmoidal voltammetric curves, which show that they function as assemblies of single microelectrodes. The microelectrode behavior was also confirmed with biologically important species such as ascorbic acid and 3,4-dihydroxyphenylacetic acid, indicating its applicability in electroanalysis.

The boron doped diamond (BDD) electrode is presented as an appropriate candidate for next generation glass-free, highly stable and accurate pH sensors. The method used in this study is based on the potential change related to the hydrogen evolution reaction following a current step, which is pH dependent. Alkali cations in the solution have no influence on the accuracy of the pH calibration curve, which provides an advantage with respect to the conventional pH glass electrode. The unwanted influence of electrochemically active compounds in solution can be avoided by adjusting the current density applied during chronopotentiometric measurements. The accuracy of the pH measurements is due to the excellent stability as well as the wide potential window and low background current of BDD electrodes. This faculty was not observed when using conventional electrode materials. The efficacy of this new type of pH sensor has been tested using tap water as a typical real sample.

A one-dimensional iron(II) spin-crossover compound [Fe(3py-im)(2)(NCS)(2)].7H(2)O (1) (3py-im = 2,4,5-tris(4-pyridly)-imidazole) has been solvothermally synthesized and structurally characterized. Compound 1 crystallizes in the monoclinic space group P2/c with a = 11.9078(2), b = 9.9474(1), c = 17.7290(3) and beta = 102.361(2) degrees at 105 K. Studies on the variable-temperature magnetic susceptibilities and Mössbauer spectra suggest that compound undergoes incomplete spin transition behaviour. Pressure effects on the transition behaviour have also been investigated, the thermal-induced spin transition becomes more gradual and the critical temperature shifts towards slightly higher temperature range when external pressure increases. However, the spin transition can not be completed by applying external pressure even as high as 0.79 GPa.