Papers - Einaga, Yasuaki

Photo-control of the electronic states of Iron coordinated to photo-responsive polyaniline

Oshida Kazuyoshi, Einaga Yasuaki

Thin Solid Films 515 ( 13 ) 5484 - 5489 2007.05

ISSN  0040-6090

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<p>Fe³⁺ doped polyaniline (PANI) films containing azobenzene derivatives in the side chain have been prepared. Photoisomerization of the azobenzene derivative in the PANI films was observed at room temperature. Furthermore, ⁵⁷Fe Mössbauer measurements showed that the ligand-metal bond distance and the symmetry around the Fe³⁺ were influenced by the photoisomerization. © 2007 Elsevier B.V. All rights reserved.</p>

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Reversible photoswitching of ferromagnetic FePt nanoparticles at room temperature

Suda Masayuki, Nakagawa Masaru, Iyoda Tomokazu, Einaga Yasuaki

Journal of the American Chemical Society 129 ( 17 ) 5538 - 5543 2007.05

ISSN  0002-7863

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<p>There has been a great interest in developing photoswitchable magnetic materials because of their possible applications for future high-density information storage media. In fact, however, the examples reported so far did not show ferromagnetic behavior at room temperature. From the viewpoint of their practical application to magnetic recording systems, the ability to fix their magnetic moments such that they still exhibit room-temperature ferromagnetism is an absolute requirement. Here, we have designed reversible photoswitchable ferromagnetic FePt nanoparticles whose surfaces were coated with azobenzene-derivatized ligands. On the surfaces of core particles, reversible photoisomerization of azobenzene in the solid state was realized by using spacer ligands that provide sufficient free volume. These photoisomerizations brought about changes in the electrostatic field around the core-FePt nanoparticles. As a result, we have succeeded in controlling the magnetic properties of these ferromagnetic composite nanoparticles by alternating the photoillumination in the solid state at room temperature. © 2007 American Chemical Society.</p>

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Plasma etching treatment for surface modification of boron-doped diamond electrodes

Kondo Takeshi, Ito Hiroyuki, Kusakabe Kazuhide, Ohkawa Kazuhiro, Einaga Yasuaki, Fujishima Akira, Kawai Takeshi

Electrochimica Acta 52 ( 11 ) 3841 - 3848 2007.03

ISSN  0013-4686

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<p>Boron-doped diamond (BDD) thin film surfaces were modified by brief plasma treatment using various source gases such as Cl₂, CF₄, Ar and CH₄, and the electrochemical properties of the surfaces were subsequently investigated. From X-ray photoelectron spectroscopy analysis, Cl and F atoms were detected on the BDD surfaces after 3 min of Cl₂ and CF₄ plasma treatments, respectively. From the results of cyclic voltammetry and electrochemical AC impedance measurements, the electron-transfer rate for Fe(CN)₆^3-/4- and Fe^2+/3+ at the BDD electrodes was found to decrease after Cl₂ and CF₄ plasma treatments. However, the electron-transfer rate for Ru(NH₃)₆^2+/3+ showed almost no change after these treatments. This may have been related to the specific interactions of surface halogen (C-Cl and C-F) moieties with the redox species because no electrical passivation was observed after the treatments. In addition, Raman spectroscopy showed that CH₄ plasma treatment of diamond surfaces formed an insulating diamond-like carbon thin layer on the surfaces. Thus, by an appropriate choice of plasma source, short-duration plasma treatments can be an effective way to functionalize diamond surfaces in various ways while maintaining a wide potential window and a low background current. © 2006 Elsevier Ltd. All rights reserved.</p>

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Simultaneous detection of purine and pyrimidine at highly boron-doped diamond electrodes by using liquid chromatography

Ivandini Tribidasari A., Honda Kensuke, Rao Tata N., Fujishima Akira, Einaga Yasuaki

Talanta 71 ( 2 ) 648 - 655 2007.02

ISSN  0039-9140

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<p>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 100 mM ammonium acetate buffer (pH 4.25) as the mobile phase. The detection was carried out at AO BDD electrode at an applied potential of 1.6 V versus Ag/AgCl. Linear calibration curves were obtained within the concentration range from 0.1 to 10 μM with the limits of detection (S/N = 3) ranging from 26.3 to 162.1 nM, 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. © 2006 Elsevier B.V. All rights reserved.</p>

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Structures, magnetic properties, and XPS of one-dimensional cyanide-bridged Cu^II-Ni^II/Pt^II bimetallic assembly complexes

Akitsu Takashiro, Einaga Yasuaki

Inorganica Chimica Acta 360 ( 2 ) 497 - 505 2007.02

ISSN  0020-1693

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<p>Synthesis, crystal structures, and spectroscopic and magnetic properties of new one-dimensional cyano-bridged bimetallic complexes, [Cu^II(N-Eten)₂][M^II(CN)₄] (N-Eten = N-ethylethylenediamine; M^II = Ni^II (1) and Pt^II (2)), have been reported. Both complexes consist of one-dimensional alternate chains of Cu^II and M^II moieties. The Pt-C bond distances of 1.997(3) and 2.001(3) Å for 2 are considerably longer than the Ni-C bond lengths of 1.866(3) and 1.872(3) Å for 1. Because of pseudo Jahn-Teller distortion, the axial Cu-N bond distances of 2.554(2) and 2.550(3) Å for 1 and 2 are longer than those of equatorial ones of 2.008(2) and 2.056(2) Å for 1 and 2.010(2) and 2.054(2) Å for 2. In contrast to M^II-C bond distances, the Cu-N ones of 1 are similar to those of 2 regardless of element-substitution. These complexes indicate weak antiferromagnetic interactions with Weiss constants = - 4.68 and -3.95 K for 1 and 2, respectively. The emission spectrum of 2 (λ_ex = 360 nm) exhibits a broad band with peaks at 22 800 and 24 000 cm^-1 at 298 K. The Cu 2p_1/2 and 2p_3/2 peaks of XPS spectra are compared systematically to various copper(II) complexes showing different bridging features or distorted coordination geometries as models for excited structures induced by external physical conditions. The spectroscopic properties are discussed from the viewpoint of magneto-optical properties. © 2006 Elsevier B.V. All rights reserved.</p>

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Direct electrochemical detection of sodium azide in physiological saline buffers using highly boron-doped diamond electrodes

Suzuki Akane, Ivandini Tribidasari A., Kamiya Akihide, Nomura Satoshi, Yamanuki Mikito, Matsumoto Koichi, Fujishima Akira, Einaga Yasuaki

Sensors and Actuators, B: Chemical 120 ( 2 ) 500 - 507 2007.01

ISSN  0925-4005

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<p>Direct detection of sodium azide was examined by using highly boron-doped diamond (BDD) electrodes in some physiological saline buffer solutions. Three important saline buffers, ADA buffer (N-(2-acetamido) iminodiacetic acid), sodium EDTA and imidazole, were investigated. Hydrogen-terminated BDD was fixed for the investigation since it showed much better sensitivity for azide oxidation in comparison with the oxygen-terminated one. Wide range of buffer concentration was examined. A well-separated peak of sodium azide was observed in its mixture with the buffers, resulting in selective sodium azide detection. The current responses were exactly total addition of sodium azide and buffer current responses. The present method was evidenced to be available for direct detection of sodium azide in two samples of commercial diluents for cell counting. A standard addition method was applied. Sodium azide concentrations of 502 and 1355 μg mL^-1 were detected in both samples with the R.S.D.s of 0.07 and 2.37%, respectively. Validation was achieved by the comparison with the sample concentrations given by the manufacturer. Simple, selective, good sensitivity and excellent reproducible detection make the diamond electrodes very attractive for numerous electroanalytical applications. © 2006 Elsevier B.V. All rights reserved.</p>

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Heterometal assembly in dendritic polyphenylazomethines

Takanashi Kensaku, Fujii Atsunobu, Nakajima Reina, Chiba Hiroshi, Higuchi Masayoshi, Einaga Yasuaki, Yamamoto Kimihisa

Bulletin of the Chemical Society of Japan 80 ( 8 ) 1563 - 1572 2007

ISSN  0009-2673

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<p>Fine-controlled metal-organic hybridization is strongly desired for advanced nano-materials. Dendrimers are highly branched organic macromolecules with successive layers or "generations" of branch units surrounding a central core. Metal-organic hybrid versions have also been produced by trapping metal ions or metal clusters within the voids of dendrimers. Here, we report a technique to form a dendritic organic structure, which includes various metals, with fine control over the number and location of the metal salts through a radial stepwise complexation. FeCl₃, GaCl₃,VCl ₃, and SnCl₂ were decorated on a phenylazomethine dendrimer with 4th generations at the first, second, third, and forth layers, respectively. These stepwise complexation and heterometal assembling were also supported by TEM observation, ⁵⁷Fe Mössbauer spectroscopy, XPS measurement, and NMR spectroscopy. © 2007 The Chemical Society of Japan.</p>

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Pulsed amperometry for anti-fouling of boron-doped diamond in electroanalysis of β-agonists

Karuwan Chanpen, Mantim Thitirat, Chaisuwan Patcharin, Wilairat Prapin, Grudpan Kate, Jittangprasert Piyada, Einaga Yasuaki, Chailapakul Orawon, Suntornsuk Leena, Anurukvorakun Oraphan, Nacapricha Duangjai

Sensors 6 ( 12 ) 1837 - 1850 2006.12

ISSN  1424-3210

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<p>This work presents the construction and application of boron-doped diamond (BDD) thin film electrode as sensor for the determination of three β-agonists, viz. salbutamol, terbutaline and clenbuterol. Although well-known as a chemically inert material, BDD film however shows fouling in detection of these compounds using fixed-potential mode amperometry. A suitable waveform for pulsed amperometric detection (PAD) was developed and used to determine the agonist compounds. It was seen that the developed PAD significantly refreshed the BDD surface for long-term detection in flow injection analysis. Linear working ranges were 0.5-100 μM, 1.0-100 μM and 0.5-50 μM for salbutamol, terbutaline and clenbuterol, respectively. The developed PAD-BDD system was applied to successfully determine salbutamol and terbutaline in commercial pharmaceutical products. The methods were validated with a capillary electrophoresis method. © 2006 by MDPI.</p>

Extremely long axial Cu-N bonds in chiral one-dimensional zigzag cyanide-bridged Cu^II-Ni^II and Cu^II-Pt ^II bimetallic assemblies

Akitsu Takashiro, Einaga Yasuaki

Inorganic Chemistry 45 ( 24 ) 9826 - 9833 2006.11

ISSN  0020-1669

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<p>Preparations, crystal structures, and spectral and magnetic properties of two new chiral one-dimensional cyano-bridged coordination polymers, [Cu ^IIL₂][M^II(CN)₄]·2H ₂O (M^II = Ni^II (1) and Pt^II (2), L = trans-cyclohexane-(1 R,2R)-diamine) have been presented. Complex 1 crystallizes in the monoclinic P2₁ space group with a = 9.864(4) Å, b = 15.393(8) Å, c = 7.995(4) Å, β = 110.32(3)°, V = 1138.4(10) ų, and Z = 2, while 2 crystallizes in the monoclinic P2 ₁ space group with a = 9.899(3) Å, b = 15.541(4) Å, c = 8.102(2) Å, β = 111.02(2)°, V = 1163.6(5) ų, and Z = 2. The unique zigzag cyano-bridged chains along the crystallographic b axis consist of alternate chiral [CuL₂]²⁺ cations and square-planar [M(CN)₄]^2- anions. One side of the axial Cu-N(≡C) bond distances are 2.324(6) and 2.34(1) Å with Cu-N≡C angles of 137.8(6)° and 138.2(9)° for 1 and 2, respectively. On the other hand, the opposite side of the axial Cu-N(≡C) bond distances are 3.120(8) and 3.09(1) Å with significantly large bent Cu-N≡C angles of 97.9(5)° and 96.8(7)° for 1 and 2, respectively. The novel axial bonding features of extremely long semi-coordination Cu-N bonds are attributed to coexistence of pseudo-Jahn-Teller elongation and electrostatic interaction in the unique zigzag cyano-bridged chains. The characteristic bonding features with overlap between small 3d (Ni^II) or large 5d (Pt^II) and 3d (Cu^II) orbitals results in larger shifts in XPS peaks of not only Cu2p_1/2 and Cu2p_3/2 but also Ni2p_1/2 and Ni2p_3/2 for 1 than those of 2, which is also consistent with weak antiferromagnetic interactions with Weiss constants of -5.31 and -5.94 K for 1 and 2, respectively. The d-d, π-π*, and CT bands in the electronic, CD, and MCD spectra for 1 and 2 in the solid state at room temperature are discussed from the viewpoint of magneto-optical properties. © 2006 American Chemical Society.</p>

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Selective detection method derived from a controlled diffusion process at metal-modified diamond electrodes

Watanabe Takeshi, Ivandini Tribidasari A., Makide Yoshihiro, Fujishima Akira, Einaga Yasuaki

Analytical Chemistry 78 ( 22 ) 7857 - 7860 2006.11

ISSN  0003-2700

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<p>A novel, selective methodology is derived based on the difference between the diffusion processes at microelectrodes (i.e., hemispherical diffusion) and the macroelectrode (i.e., linear diffusion) in a metal-implanted boron-doped diamond electrode (metal-BDDs). As an example, the selective detection of glucose in a solution containing interference species such as ascorbic acid and uric acid is demonstrated. The electrochemical properties of BDD, which are low background current, extremely high stability, and (especially) inactivity toward glucose, play an important role in realizing these differences in the diffusion characteristics. The present methodology can be applied not only to selective glucose detection by the metal-BDD system but also to other selective detection systems. © 2006 American Chemical Society.</p>

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Novel photo-induced aggregation behavior of a supramolecular system containing iron(III) magnetic ionic liquid and azobenzene

Akitsu Takashiro, Einaga Yasuaki

Inorganic Chemistry Communications 9 ( 11 ) 1108 - 1110 2006.11

ISSN  1387-7003

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<p>New photo-controllable supramolecular system containing magnetic ionic liquid (iron(III) chloride with 1-butyl-3-methylimidazolium chloride) and azobenzene has been prepared. Reversible structural changes due to cis-trans photoisomerization of azobenzene could be observed by means of resonance Raman and electronic spectroscopy. Field dependence of magnetic moment at 298 K exhibited paramagnetic behavior similar to pure iron(III) magnetic ionic liquid. Alternate irradiation of UV and visible light at 298 K resulted in a monotonous increase of magnetic moment. In analogy with previous study, the novel behavior can be explained as irreversible aggregation of paramagnetic iron(III) complexes forming a short-range order in the supramolecular system. © 2006 Elsevier B.V. All rights reserved.</p>

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Photo-switching magnetic materials

Einaga Yasuaki

Journal of Photochemistry and Photobiology C: Photochemistry Reviews 7 ( 2-3 ) 69 - 88 2006.10

ISSN  1389-5567

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<p>The development of new magnetic materials in which magnetic properties can be controlled by optical stimuli has been extensively studied. So far, several photo-responsive molecular solids have been reported. First, in this review, several photo-magnetic molecular solids are introduced briefly. Then, a new strategy for realizing photo-functional magnetic systems such as photo-chromic magnets is also introduced in detail. © 2006 Elsevier B.V. All rights reserved.</p>

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A chiral photochromic Schiff base

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 62 ( 10 )  2006.10

ISSN  1600-5368

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<p>The title chiral photochromic Schiff base compound, C₁₅H ₁₄BrNO, was synthesized from (R)-1-phenylethylamine and 5-bromosalicylaldehyde. The molecule is the phenolimine tautomer, the C=N and N-C bond distances being 1.261(7) and 1.482 (7) Å, respectively. There is an intramolecular O-H⋯N hydrogen bond with an O⋯N distance of 2.593 (7) Å. © 2006 International Union of Crystallography. All rights reserved.</p>

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Electrochemical detection of arsenic(III) using indium-implanted boron-doped diamond electrodes

Ivandini Tribidasari A., Sato Rika, Makide Yoshihiro, Fujishima Akira, Einaga Yasuaki

Analytical Chemistry 78 ( 18 ) 6291 - 6298 2006.09

ISSN  0003-2700

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<p>Indium-modified, boron-doped diamond electrodes fabricated by an ion implantation method have been developed for electrochemical detection of arsenite (As(III)). Ir⁺ ions were implanted with an energy of 800 keV and a dose of 10¹⁵ ion cm^-2. An annealing treatment at 850 °C for 45 min in H₂ plasma (80 Torr) was required to rearrange metastable diamond produced by an implantation process. Characterization was investigated by SEM, AFM, Raman, and X-ray photoelectron spectroscopy. Cyclic voltammetry and flow injection analysis with amperometric detection were used to study the electrochemical reaction. The electrodes exhibited high catalytic activity toward As(III) oxidation with the detection limit (S/N = 3), sensitivity, and linearity of 20 nM (1.5 ppb), 93 nA μM ^-1 cm^-2, and 0.999, respectively. The precision for 10 replicate determinations of 50 μM As(III) was 4.56% relative standard deviation. The advantageous properties of the electrodes were its inherent stability with a very low background current. The electrode was applicable for analysis of spiked arsenic in tap water containing a significant amount of various ion elements. The results indicate that the metal-implanted method could be promising for controlling the electrochemical properties of diamond electrodes. © 2006 American Chemical Society.</p>

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Structures and XPS studies of several 3d-4f cyano-bridged Ln^III-Fe^III/Co^III heterometallic complexes

Akitsu Takashiro, Einaga Yasuaki

Polyhedron 25 ( 13 ) 2655 - 2662 2006.09

ISSN  0277-5387

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<p>Characterization and crystal structure determination of 3d-4f cyano-bridged bimetallic assemblies, Ln(DMF)₄(H₂O)₃Co(CN)₆ · H₂O (DMF = N,N′-dimethylformamide, Ln = Tb, Dy, Ho and Er) have been newly carried out. We have observed their isostructural features and gradual decreasing cell constants and corresponding changes of local bond distances and angles around the cyano-bridges in accord with the ionic radii changes due to lanthanoid contraction. In order to elucidate the reasons that only Nd-Fe and Nd-Co complexes can exhibit photo-induced magnetic functions, we have also investigated the electronic properties for several analogous 3d-4f complexes, Ln(DMF)₄(H₂O)₃M(CN)₆ · H₂O (Ln = Ce, Nd, Sm, Gd, Tb, Dy, Ho and Er; M = Co and Fe), by means of X-ray photoelectron spectroscopy (XPS). We found that the characteristic bent features of Nd-N-C bond angles and the slight shift of binding energies of Ln 4d_3/2 peaks in the 3d-4f systems being closed to mixed-valence states might be the reasons for the novel functions. © 2006 Elsevier Ltd. All rights reserved.</p>

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Photocontrolled magnetization of CdS-modified prussian blue nanoparticles

Taguchi Minori, Yagi Ichizo, Nakagawa Masaru, Iyoda Tomokazu, Einaga Yasuaki

Journal of the American Chemical Society 128 ( 33 ) 10978 - 10982 2006.08

ISSN  0002-7863

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<p>The first photocontrollable magnetic nanoparticles containing CdS and Prussian blue (PB) have been created using reverse micelles as nanoreactors. Photoinduced electron transfer from CdS to PB in the reverse micelle changed the magnetic properties of the composite nanoparticles from ferromagnetic to paramagnetic. The magnetization in the ferromagnetic region below 4 K was substantially decreased after UV light illumination and could be restored almost to its original level by thermal treatment at room temperature. This novel strategy of designing composite nanoparticles containing photoconductive semiconductors and magnetic materials to create photoswitchable magnetic materials may open many possibilities in the development of magneto-optical devices. © 2006 American Chemical Society.</p>

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Photomodulation of a chiral nematic liquid crystal by the use of a photoresponsive ruthenium(III) complex

Mitsuoka Tadashi, Sato Hisako, Yoshida Jun, Yamasishi Akihiko, Einaga Yasuaki

Chemistry of Materials 18 ( 15 ) 3442 - 3447 2006.07

ISSN  0897-4756

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<p>We have attempted to control the helical pitch of a chiral nematic liquid crystal by the use of a photoresponsive chiral metal complex. For this purpose, a novel Ru(III) complex [Ru(acac)₂(L)] was synthesized, where acac and L denote acetylacetonato and 1,3-bis-{4-[6-(4-phenylazo-phenoxy)-hexyloxy]- phenyl}-propane-1,3 -dionato, respectively. The complex underwent cis-trans photoisomerization in methanol when under UV (λ_max = 360 nm) or visible (λ_max = 450 nm) light illumination, respectively. When the complex was doped into a room-temperature nematic liquid crystal (ZLI-1132), it induced a chiral nematic phase. Under illumination with UV or visible light, the helical pitch of the chiral nematic phase could be changed reversibly by up to 50%. Corresponding to this change, the helical twisting power (HTP) of the complex varied between 34.0 and 22.0 μm^-1, or between -43.9 and -26.6 μm^-1 at 35.0 °C, where the positive and negative signs corresponded to the A- and Δ-enantiomers, respectively. This has been the first attempt at combining the ΔΛ chirality of an octahedral metal complex with the cis-trans isomerization of an azobenzene group in the development of a photoresponsive dopant. © 2006 American Chemical Society.</p>

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Electrical conductivity modulation coupled to a high-spin-low-spin conversion in the molecular system [Fe^III(qsal)₂][Ni(dmit) ₂]₃·CH₃CN·H₂O

Takahashi Kazuyuki, Cui Heng Bo, Okano Yoshinori, Kobayashi Hayao, Einaga Yasuaki, Sato Osamu

Inorganic Chemistry 45 ( 15 ) 5739 - 5741 2006.07

ISSN  0020-1669

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<p>The synergy between the electrical conductivity within the stacks of Ni(dmit)₂ in the newly electrocrystallized [Fe(qsal) ₂][Ni(dmit)₂]₃· CH₃CN· H₂O and the spin conversion of Fe(qsal)₂ is evidenced. In addition, the presence of a light-induced excited spin state trapping effect suggests that this complex is a prototypal photoswitchable spin-crossover molecular conductor. © 2006 American Chemical Society.</p>

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Electrochemical oxidation of oxalic acid at highly boron-doped diamond electrodes

Ivandini Tribidasari A., Rao Tata N., Fujishima Akira, Einaga Yasuaki

Analytical Chemistry 78 ( 10 ) 3467 - 3471 2006.05

ISSN  0003-2700

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<p>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 μM, with an estimated detection limit of ∼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. © 2006 American Chemical Society.</p>

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Bis(N-ethylethylenediamine-κ²N,N′)copper(II) -hexacyanocobaltate(III)-water (3/2/4)

Akitsu Takashiro, Einaga Yasuaki

Acta Crystallographica Section E: Structure Reports Online 62 ( 4 )  2006.04

ISSN  1600-5368

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<p>The title compound, poly[[tetracyano-octa-μ-cyano-hexakis-(N- ethylethylenediamine)tricopper(II)dicobaltate(III)] tetrahydrate], [Cu(C ₄H₁₂N₂)₂]₃[Co(CN) ₆]₂·4H₂O or {[Cu₃Co ₂-(CN)₁₂(C₄H₁₂N₂) ₆]·4H₂O}_n, was crystallized from an aqueous reaction mixture containing Cu(ClO₄)₂, N-ethylethylenediamine and K₃[Co(CN)₆] in a self-assembling process. The polymeric chains are extended through -Co ^III-CN-Cu^II-linkages involving four or two cyanide ligands of the centrosymmetric [Co(CN)₆]^3- complex ions, forming a two-dimensional ladder structure. The Cu^II atoms, one of which also lies on an inversion centre, have a distorted octahedral coordination geometry, the degree of tetragonal Jahn-Teller distortion being T = 0.785 and 0.810 (T is the ratio of mean inplane Cu - N bond lengths to axial Cu - N bond lengths). This local Jahn-Teller distortion results from the anisotropic features of this two-dimensional cyano-bridged structure. © 2006 International Union of Crystallography All rights reserved.</p>

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