Reduced Arene Complexes of Scandium

Alkali metal naphthalenide or anthracenide reacted with scandium(III) anilides [Sc(X){N(tBu)Xy}₂(thf)] (X=N(tBu)Xy ( 1 ); X=Cl ( 2 ); Xy=C₆H₃-3,5-Me₂) to give scandium complexes [M(thf)_n][Sc{N(tBu)Xy}₂(RA)] (M=Li–K; n=1–6; RA=C₁₀H₈²⁻ ( 3-Naph-K ) and C₁₄H₁₀²⁻ ( 3-Anth-M )) containing a reduced arene ligand. Single-crystal X-ray diffraction revealed the scandium(III) center bonded to the naphthalene dianion in a σ²:π-coordination mode, whereas the anthracene dianion is symmetrically attached to the scandium(III) center in a σ²-fashion. All compounds have been characterized by multinuclear, including ⁴⁵Sc NMR spectroscopy. Quantum chemical calculations of these intensely colored arene complexes confirm scandium to be in the oxidation state +3. The intense absorptions observed in the UV/Vis spectra are due to ligand-to-metal charge transfers. Whereas nitriles underwent C−C coupling reaction with the reduced arene ligand, the reaction with one equivalent of [NEt₃H][BPh₄] led to the mono-protonation of the reduced arene ligand.     

Alkali Metal Triphenyl- and Trihydridosilanides Stabilized by a Macrocyclic Polyamine Ligand

Potassium silanide [KSiH₃]_∞ contains 4.2 wt % of hydrogen and has been intensely studied as hydrogen storage material. The macrocyclic ligand Me₄TACD (1,4,7,10-tetramethyl-1,4,7,10-tetraaminocyclododecane, L ) stabilizes the full range of triphenylsilyl complexes [( L )MSiPh₃]_n (M=Li–Cs), which react with H₂ or PhSiH₃ to form molecular [( L )MSiH₃]_n that can be isolated in soluble form and fully characterized.     

Non-separating even cycles in highly connected graphs

We prove that every k-connected graph (k ≥ 5) has an even cycle C such that G-V (C) is still (k-4)-connected. The connectivity bound is best possible.     

Onsager coefficients of a Brownian Carnot cycle

We study a Brownian Carnot cycle introduced by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] from a viewpoint of the linear irreversible thermodynamics. By considering the entropy production rate of this cycle, we can determine thermodynamic forces and fluxes of the cycle and calculate the Onsager coefficients for general protocols, that is, arbitrary schedules to change the potential confining the Brownian particle. We show that these Onsager coefficients contain the information of the protocol shape and they satisfy the tight-coupling condition irrespective of whatever protocol shape we choose. These properties may give an explanation why the Curzon-Ahlborn efficiency often appears in the finite-time heat engines.     

The effect of various calcination treatments on the photocatalytic activity of a rod-type TiO<Subscript>2</Subscript> electrode for oxidation of ethanethiol

It was found that the photoelectrochemical performance and photocatalytic activity of rod-type TiO₂ electrodes were affected by various post-calcination treatments, for example, calcination in NH₃ or under vacuum. Post-calcination treatment in NH₃ at 773 K was particularly effective in increasing the photoelectrochemical performance and photocatalytic activity of rod-type TiO₂ electrodes. A unique photoelectrochemical circuit was constructed by connecting a rod-type TiO₂ electrode to a Pt electrode through a silicon solar cell in which the negative bias was applied on the rod-type TiO₂ electrode. It was found that the photoelectrochemical circuit can effectively oxidize ethanethiol in water into CO₂.     

Synthesis of water-soluble C60-porphyrin hybrid compounds

Water-soluble C60-porphyrin hybrid molecules were first synthesized toward their pharmaceutical applications.     

Matrix effect and correction by standard addition in quantitative liquid chromatographic-mass spectrometric analysis of diarrhetic shellfish poisoning toxins

An evaluation of the feasibility of liquid chromatography-mass spectrometry (LC-MS) with atmospheric pressure ionization was made for quantitation of four diarrhetic shellfish poisoning toxins, okadaic acid, dinophysistoxin-1, pectenotoxin-6 and yessotoxin in scallops. When LC-MS was applied to the analysis of scallop extracts, large signal suppressions were observed due to coeluting substances from the column. To compensate for these matrix signal suppressions, the standard addition method was applied. First, the sample was analyzed and then the sample involving the addition of calibration standards is analyzed. Although this method requires two LC-MS runs per analysis, effective correction of quantitative errors was found.