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The microscopic structure and photosensitive function of encapsulated dye in the single-wall carbon nanotubes (SWCNTs) are studied. The findings suggest that the photoexcitation of such dyes leads to the enhancement of transient absorption saturation in the nanotubes, which also proves the transfer of ultrafast energy from the dye to SWCNTs.

A mathematical model that simulates potential oscillations in formic acid oxidation was proposed on the basis of surface-enhanced infrared absorption spectroscopy SEIRAS. The model was constructed within the framework of the dual-path mechanism and a direct path via a reactive intermediate and an indirect path via strongly bonded CO formed by dehydration of formic acid.

A novel iodo-bridged linear chain platinum compound is synthesized having the quasi-two-dimensional charge-density-wave (CDW) ground state and the smallest band gap. In this compound, an anomalous valence state is discovered in the boundary region at which the CDW phase alternates in the crystal by means of electron spin resonance (ESR), X-ray diffuse scattering, scanning tunneling microscopy (STM), and electrical resistivity.

Potential oscillations that occur during galvanostatic formic acid oxidation on a Pt electrode are investigated by time-resolved surface-enhanced infrared absorption spectroscopy (SEIRAS). Temporal potential oscillations allowed carbon monoxide (CO) and formate to adsorb on the surface and change their coverages synchronously.

Research has been conducted on the quasi-one-dimensional halogen-bridged Cu (super)II- Pt (super)IV mixed-metal complexes of the form [Cu(chxn) (sub)2][PtX (sub)2 (chxn) (sub)2]X (sub)4, where chxn= 1R,2R-diminocyclohexane and X is Cl or Br. The synthesis of these complexes has been carried out and the crystal structures of the compounds determined by the single-crystal X-ray diffraction have been investigated.

Research has been conducted on the quasi-one-dimensional bromo-bridged Ni-Pd compound single crystals. These mixed-metal MX chain compounds obtained by the electrical oxidation methods have been examined.

A series of quasi-one-dimensional halogen-bridged Ni(super III) complexes were synthesized to determine the effect of the bridging halogens and counteranions on their crystal, electronic structures and spin density wave strengths. Judging by x-ray photoelectron, Auger and reflectance spectra studies, these compounds were not Mott insulators but charge-transfer insulators. The spin density wave strengths were found to be tuned by substituting the bridging halogens and the counteranions.

The role of intermittencies and related phenomena in the oxidation of formaldehyde at a constant current was investigated. Results showed that type I and III intermittencies exist in the galvanostatic oxidation of formaldehyde on platinum at 43 degrees Celsius. Type I intermittency is usually observed after a periodic oscillation in a sequence of periodic oscillations as potential oscillation patterns change with time. Periodic oscillations were also found to appear in decreasing order and are interposed between chaotic states.

A study was conducted on the binding mode of the succinyl-Gln-val-val-ala-ala-p-nitroanilide papain inhibitor using the hanging drop method and crystal structure analysis at 1.7 Angstrom resolution. X-ray analysis located the inhibitor at the R-domain side. This binding mode clarifies the biological behavior of the noncompetitive reversible inhibitor of papain. The inhibitor's structure also shows that it is not an essential component of inhibitoy activity.

Research has been conducted on the quasi-one-dimensional mixed-halogen-bridged nickel(III) complexes with strong electron correlation. The syntheses of these complexes have been carried out and the study of the spin density wave strengths of the compounds is presented.

The structure, magnetic and optical properties of a ferromagnetic chain system catena-(mu-CrO4-O,O'){Ni(super II)(cyclam)}*2H2O were studied under x-ray crystallographic studies. It was shown that the coordination geometry about each Ni(super II) ion was octahedral with four nitrogen atoms from cyclam occupying the equatorial coordination sites of the Ni(II) ions. Magnetic susceptibility data indicated a ferromagnetic interaction secondary to the intrachain interaction.

A new charge-ordering (CO) state in quasi-one-dimensional (Q1D) halogen-bridged dinuclear metal complexes (MMX-chains) with binary countercations, [K.sub.2]([H.sub.3]NC[H.sub.2]CHMeC[H.sub.2]N[H.sub.3])[[Pt.sub.2][(pop).sub.4]I].4[H.sub.2]O (pop = [P.sub.2][H.sub.2][O.sub.5.sup.2-]) is described. The [super 31]P MAS NMR spectrum has supported the presence of a new ACP+CDW CO state.

The electronic structure of the [Co.sup.III] coped Br bridged [Ni.sup.III] complexes, [[Ni.sub.1-x][Co.sub.x][(chxn).sub.2]Br][Br.sub.2], is examined by using a optical spectroscopy, scanning tunneling microscopy and electron spin resonance spectroscopy. The Curie spin concentration is increased with increasing [Co.sup.III] ions, which is described by the scissons of the S = 1

The disordered patterns of R- and rac-1,2-diaminopropane (pn) in quasi-one-dimensional bromo-bridged Ni(III) complexes, [[Ni.sup.III][(pn).sub.2]Br][Br.sub.2] is investigated. Results reveal that the tunnel current from the scanning tunneling microscopy tip to metal ions are detected via methyl groups of pn ligands.

A study is conducted to relate the peaks present in the voltammograms among the three substances, namely formic acid, formaldehyde and methanol and to examine the conditions to obtain distinct peaks in the voltammogram. Results strongly support the idea that the electrochemical oxidation mechanisms for the three substances have the same dominating elementary reaction steps, which induce oscillation phenomena, although different reaction and adsorption rate constants.

Research has been conducted on Ni(III) complexes. The authors report that the electron doping effect into these complexes caused by Cu(II) ions has been investigated via the use of electrochemical oxidation method.

New molecular charge-transfer complexes of several (ethylenedithio)tetrathiafulvalene (ET) compounds were obtained by slowly diffusing Cu(super II)Br2 and ET. X-ray analyses revealed that ET molecules coordinated to the copper ions with the sulfur atoms of the ethylenedithio groups in all compounds.

The appearance of chaos and windows of periodic oscillations in the galvanostatic oxidation of formaldehyde on platinum was investigated using different applied currents and formaldehyde concentrations. The oscillation mechanism was also examined by focusing on a negative resistance during the evaluation of cyclic voltammograms. Experimental results showed that potential oscillation patterns change with time, resulting in the appearance of a sequence of periodic oscillations interposed between chaotic states.

A series of hydration experiments of the Ruddlesden--Popper phase PrSr3Co1.5Fe1.5OI0_8 with varying levels of oxygen nonstoichiometry were performed with the goal to clarify phase formation and underlying mechanisms and driving forces. The hydration reaction is most intense for partly reduced samples with a vacancy concentration corresponding to δ ∼ 1 Fully oxidized samples show little or no tendency toward hydration. Presence of oxygen vacancies acts as a prerequisite for hydration. Probably, the basicity of the materials owing to A-site cations is another contributing factor to the hydration ability. Under CO2 free conditions pure hydrates and oxide hydroxides are formed. In CO2- containing atmosphere, additional carbonate anions are easily incorporated into thehydrate, probably at the expense of hydroxyl groups. The I-centered PrSr3CO1.5Fe1.5 O8(OH) • 1H2O achieves a highly expanded c-axis upon the topochemical insertion reactions. In situ powder synchrotron X-ray diffraction (SXRD) shows that the hydrate converts to an oxide hydroxide, PrSr3CO1.5Fe1.5O8(OH)2, at 70 °C with a primitive orthorhombic unit cell. Upon heating above 170 °C, an I-centered product is formed for which further dehydroxylation occurs at around 400--500 °C. Rietveld refinement of SXRD data shows that the absorbed water molecules fill the tetrahedral voids of the [AO]RS rock salt layer of the monoclinic hydrate. [ABSTRACT FROM AUTHOR]

Examines the structure and magnetic and optical properties of a ferromagnetic chain system of nickel complexes. Increased interest in low-dimensional magnetic systems; Details on the study.

A -PdIII-Br-PdIII- Mott-Hubbard state was observed in a quasi-one-dimensional bromo-bridged Pd compound [Pd(en)2Br](C5-Y)2·H2O (en = ethylenediamine, C5-Y = dipentylsulfosuccinate) for the first time. The phase transition between Mott-Hubbard and charge-density-wave states occurred at 206 ± 2 K and was confirmed by using X-ray, ESR, Raman and electronic spectroscopies, electrical resistivity, and heat capacity. From X-ray powder diffraction patterns and Raman spectra of a series of Pd-Br compounds, [Pd(en)2Br](Cn-Y)2·H2O (n = 4,5,6,7,8,9, and 12), chemical pressure from the alkyl chains of the counterions caused the phase transition. [ABSTRACT FROM AUTHOR]

We synthesized a novel iodo-bridged linear chain platinum compound, having the quasi-two-dimensional charge-density-wave (CDW) ground state and the smallest band gap. In this compound, we discovered an anomalous valence state in the boundary region at which the CDW phase alternates in the crystal by means of ESR, X-ray diffuse scattering, STM, and electrical resistivity. This anomalous state can be explained by the fast fluctuation between ptIV-I⋯PtII and PtII⋯I-PtIV in the double well potential. This is the first observation of the dynamical fluctuation of the CDW phase among the quasi one-dimensional halogen-bridged complexes. [ABSTRACT FROM AUTHOR]

Examines the synthesis of quasi-one-dimensional mixed-halogen-bridged nickel complex. Assessment on the tuning of spin density wave strengths of compounds; Observation on single peak in the electronic spectra; Use of interchain hydrogen-bond networks to control dimensionalities of density wave states.

We report on our investigation of C-C bonding longer than 2.0 Å, which can be realized by perpendicularly facing two fluorenyl rings in the title compound. A small orbital overlap between the distantly positioned carbon atoms is observed as a small concentration of electrons on the X-ray electron density map. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the compound originate from the in-phase and out-of-phase interactions of the overlapping orbitals, respectively, with a gap of 2.39 eV. Solid-state 13 C NMR spectroscopy shows a sharp peak at 82.9 ppm for the long-bonded carbons, and a CASSCF(6,6) calculation indicates small diradical character. The experimental and theoretical analyses reveal sufficient covalent-bonding interaction in the long-bonded carbon pair.

The development of NO x -trapping catalysts for automobiles is highly desired to meet the current strict exhaust emission regulations. This study demonstrates that NO x oxidation and storage reactions proceed over Pt-free Sr 3 Fe 2 O 7-δ with a Ruddlesden-Popper-type layered perovskite structure. Two types of Sr-Fe perovskite with oxygen storage capacity, namely, SrFeO 3-δ and Sr 3 Fe 2 O 7-δ , are studied as NO x -trapping catalysts. Sr 3 Fe 2 O 7-δ shows higher NO x storage capacity than SrFeO 3-δ ; its activity is comparable to that of Pt/Ba/Al 2 O 3 calcined at 1273 K. NO x temperature-programmed desorption and diffuse reflectance infrared Fourier transform experiments confirm the superior NO x -trapping ability of Sr 3 Fe 2 O 7-δ over SrFeO 3-δ . In addition, NO temperature-programmed reactions and O 2 temperature-programmed desorption experiments reveal that these catalysts operate through a novel NO oxidation mechanism involving the consumption of their lattice oxygens and topotactic structural changes at a temperature of around 350-400 K. The reduction performance of trapped NO x on Pd-modified Sr-Fe perovskites is investigated by lean-rich cycle experiments using H 2 as the reductant. Pd/Sr 3 Fe 2 O 7-δ shows significantly high NO x removal efficiency over the entirety of each lean-rich period. Modifying Sr 3 Fe 2 O 7-δ with Pd is also effective for NO x storage in the presence of H 2 O and CO 2 and the regeneration of the catalyst following SO x sorption. Sr 3 Fe 2 O 7-δ , with both NO x adsorption and NO oxidation capabilities, acts as a Pt-free NO x -trapping catalyst, exhibiting both high NO x storage capacity and high thermal tolerance.

A Br-bridged Pd chain complex with the Pd ion in an uncommon +3 oxidation state, [Pd(dabdOH) 2 Br]Br 2 (3), was prepared using a new method involving multiple hydrogen bonds. The PdBr chain complex exhibited superior electrical conductivity and thermal stability. An in-plane ligand with an additional hydrogen donor group (hydroxy group), (2S,3S)-2,3-diaminobutane-1,4-diol (dabdOH), was used to create a multiple-hydrogen-bond network, which effectively shrinks the Pd-Br-Pd distance, stabilizing the Pd(III) state up to its decomposition temperature (443 K). 3 shows semiconducting behavior with quite high electrical conductivity (3-38 S cm -1 at room temperature), which is 10 6 times larger than the previous record for analogous PdBr chains. Indeed, 3 is the most conductive MX-type chain complex reported so far. The precise positional control of ions via a multiple-hydrogen-bond network is a useful method for controlling the electronic states, thermal stability and conductivity of linear coordination polymers.

The optical gap in a series of bromo-bridged platinum chain complexes, [Pt(en)2Br](C(n)-Y)2·H2O (en = ethylenediamine; C(n)-Y = dialkyl sulfosuccinate; n = the number of carbon atoms), was controlled by using chemical pressure. From the single-crystal structure, [Pt(en)2Br](C6-Y)2·H2O is in a mixed-valence state at 200 K. In addition, Pt-Pt distances decreased with an increase in n or with a decrease in the temperature. Continuous decreases in the optical gaps upon cooling were observed for n = 5, 7. The smallest gap of 1.20 eV was observed for n = 7 at 50 K. For n = 12, the complex was still in a mixed-valence state at 5 K, although the Pt-Pt distance was quite short. This is probably because of the energetic mismatch between 5dz(2) orbitals of the Pt ions and 4pz orbitals of the Br ions.

MMX-type quasi-one-dimensional iodide-bridged dinuclear Pt complexes (MMX chains) with binary countercations show a new alternating charge-polarization + charge-density-wave (ACP+CDW) electronic state and reversible switching of the electronic states and physical properties upon dehydration and rehydration process. By comparing several MMX chains with various binary countercations with previous chains, we found that the short backbone of the aliphatic diammonium ion was indispensable for realizing the ACP+CDW state because it induces a 2-fold periodicity along the chain axis via twisting of the ligands. Moreover, the reversibility of the changes in the structure and electrical conductivity upon dehydration and rehydration depend on the length of aliphatic diammonium ion. Short diammonium ions support a robust framework, which undergoes reversible structural changes. On the other hand, long and bent aliphatic diammonium ions weaken the framework, which causes partial degradation of the crystal and a decrease in the electrical conductivity when the structure changes. However, the decrease in the activation energy of the electrical conductivity after the dehydration process is independent of the robustness of the complex, indicating that the orbital overlap in MMX chains with binary countercations increases upon dehydration. Controllable electronic states and physical properties provide a platform for designing the multifunctional materials based on MMX chains.

A series of hydration experiments of the Ruddlesden-Popper phase PrSr(3)Co(1.5)Fe(1.5)O(10-δ) with varying levels of oxygen nonstoichiometry were performed with the goal to clarify phase formation and underlying mechanisms and driving forces. The hydration reaction is most intense for partly reduced samples with a vacancy concentration corresponding to δ ≈ 1. Fully oxidized samples show little or no tendency toward hydration. Presence of oxygen vacancies acts as a prerequisite for hydration. Probably, the basicity of the materials owing to A-site cations is another contributing factor to the hydration ability. Under CO(2) free conditions pure hydrates and oxide hydroxides are formed. In CO(2)-containing atmosphere, additional carbonate anions are easily incorporated into the hydrate, probably at the expense of hydroxyl groups. The I-centered PrSr(3)Co(1.5)Fe(1.5)O(8)(OH)(2)·1H(2)O achieves a highly expanded c-axis upon the topochemical insertion reactions. In situ powder synchrotron X-ray diffraction (SXRD) shows that the hydrate converts to an oxide hydroxide, PrSr(3)Co(1.5)Fe(1.5)O(8)(OH)(2), at 70 °C with a primitive orthorhombic unit cell. Upon heating above 170 °C, an I-centered product is formed for which further dehydroxylation occurs at around 400-500 °C. Rietveld refinement of SXRD data shows that the absorbed water molecules fill the tetrahedral voids of the [AO](RS) rock salt layer of the monoclinic hydrate.

This article describes the electronic structure of the Co(III) doped Br bridged Ni(III) complexes, [Ni(1-x)Cox(chxn)2Br]Br2 (x = 0.01, 0.02, 0.05, and 0.11) by using a optical spectroscopy, scanning tunneling microscopy (STM), and electron spin resonance spectroscopy. In the optical reflectivity spectrum, the new band was formed at about 0.5 eV, which is reasonably recognized as the d(z2) band of doped Co(III) ions. In the STM images of [Ni(1-x)Cox(chxn)2Br]Br2, the bright spots attributable to the tunnel current from the Fermi level of the STM tip to the conduction band of the sample were observed. In addition, some brighter spots were also observed. Because the number of the brighter spots is in good agreement with that of doped Co species, the brighter spots can be assigned to doped Co(III) sites. These are reasonably explained by the tunnel current from the Fermi level of the tip to the d(z2) band of Co(III). The Curie spin concentration was gradually increased with increasing Co(III) ions, which is explained by the scissions of the S = 1/2 1D antiferromagnetic chains.