Fine pore mouth structure of molecular sieve carbon with GCMC-assisted supercritical gas adsorption analysis

N₂ adsorption isotherms of molecular sieve carbon were measured at 77 K and 303 K. The Ar adsorption isotherms of molecular sieve carbon samples were also measured at 303 K. The grand canonical Monte Carlo (GCMC) simulation technique was applied to calculate the N₂ and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H₂O adsorption. The comparative method of experimental and simulated isotherms of supercritical N₂ and Ar at 303 K gave the width of the micropore mouth of the molecular sieve carbon, which can be applied to the ultramicropore width determination for other noncrystalline porous solids.     

Novel configurational structures of sodium tetrakis(3-heptafluorobutylryl-(+)-camphorato) Ln(III) complexes with a trapped Na+ by Na+...FC interactions in the solid state and in solution

For newly prepared sodium tetrakis(3-heptafluorobutylryl-(+)-camphorato) Ln(III) complexes, the X-ray crystal analysis revealed an unprecedented pseudo-achiral dodecahedron (DD-8 (D(2d))), whereas in CHCl3 solution, the exciton CD and 19F NMR spectra showed a novel chiral Delta-SAPR-8 (C4) configuration which is stereospecifically formed by a trapped Na+ ion with Na+...FC (fluorocarbon) interactions.     

Production and Accumulation of 4-<Emphasis Type="Italic">O</Emphasis>-Methyl-α-<Emphasis Type="SmallCaps">d</Emphasis>-Glucuronosyl-Xylotriose by Growing Culture of Thermophilic <Emphasis Type="Italic">Anoxybacillus</Emphasis> sp. Strain JT-12

A thermophilic Anoxybacillus sp. strain JT-12, isolated from soil, produced acidic xylotriose, 4-O-methyl-α-d-glucuronosyl-xylotriose (MeGlcAX₃), as a main product from birchwood xylan and accumulated them in the culture under optimum conditions at pH 7.0 and 55 °C using 0.75% (w/v) birchwood xylan as a carbon source for 42–72 h. The acidic xylotriose was purified by ethanol precipitation and high-performance liquid chromatography using NH₂ Lichosher® 100 column. The results of electrospray ionization mass spectrometry, mass to charge ratio (m/z) 603.23, confirmed that the purified sample was acidic xylotriose that had benefits and applications in many fields.     

Photomagnetism of a sym‐cis‐Dithiocyanato Iron(II) Complex with a Tetradentate N,N′‐Bis(2‐pyridylmethyl)1,2‐ethanediamine Ligand

A comprehensive study of the magnetic and photomagnetic behaviors of cis‐[Fe(picen)(NCS)₂] (picen=N,N′‐bis(2‐pyridylmethyl)1,2‐ethanediamine) was carried out. The spin‐equilibration was extremely slow in the vicinity of the thermal spin‐transition. When the cooling speed was slower than 0.1 K min^?1, this complex was characterized by an abrupt thermal spin‐transition at about 70 K. Measurement of the kinetics in the range 60–70 K was performed to approach the quasi‐static hysteresis loop. At low temperatures, the metastable HS state was quenched by a rapid freezing process and the critical T(TIESST) temperature, which was associated with the thermally induced excited spin‐state‐trapping (TIESST) effect, was measured. At 10 K, this complex also exhibited the well‐known light‐induced excited spin‐state‐trapping (LIESST) effect and the T(LIESST) temperature was determined. The kinetics of the metastable HS states, which were generated from the freezing effect and from the light‐induced excitation, was studied. Single‐crystal X‐ray diffraction as a function of speed‐cooling and light conditions at 30 K revealed the mechanism of the spin‐crossover in this complex as well as some direct relationships between its structural properties and its spin state. This spin‐crossover (SCO) material represents a fascinating example in which the metastability of the HS state is in close vicinity to the thermal spin‐transition region. Moreover, it is a beautiful example of a complex in which the metastable HS states can be generated, and then compared, either by the freezing effect or by the LIESST effect.     

Photoluminescence and population analysis of single-walled carbon nanotubes produced by CVD and pulsed-laser vaporization methods

Band gap photoluminescence (PL) behaviors of single-walled carbon nanotubes (SWNTs) grown by the methods of chemical vapor deposition and pulsed-laser vaporization are investigated over the wide diameter range (≈0.8–1.4 nm). The peak intensity of the PL signals strongly depends on chirality and the ‘(2n + m) family type’ of SWNTs. Based on the PL results, a population analysis of these SWNTs is conducted by combining the calculated PL yields for each (n, m) tube. The results are directly compared with the histograms of diameter distributions estimated by the transmission electron microscope (TEM) observations to check the validity of the analysis.     

Flow characteristics and spinnability of sols prepared from silicon alkoxide solution

Structural evolution of the solution of tetraethoxysilane hydrolyzed with [H₂O]/[Si(OC₂H₅)₄] = 2 under acidic condition has been investigated by rheological measurements. It was found that the solution behaves as a Newtonian liquid up to a highly viscous state and shows spinnability before gelation when the evaporation of the solvent is allowed during gelation reaction. On the other hand, the solution behaved as a non-Newtonian liquid in the viscous state, showing no spinnability when the evaporation of the solvent was not allowed during the reaction. It was indicated from the Casson plots that the spinnable solution prepared in the open system has no yield stress up to highly viscous states, whereas the non-spinnable solution prepared in the closed system has a yield stress at viscous states. It was proposed that the increase in viscosity of the open system solution is attributable to the concentration of the sol particles whereas that of the closed system solution is attributable to the formation of the three dimensional network in the solution.     

Surface modification of a TiO2 film electrode prepared by the sol-gel method and its effect on photoelectrochemical behavior

The surface of a TiO₂ film electrode, about 1 μm thick, prepared by the sol-gel method, was modified by being additionally coated with about 0.1 μm thick TiO₂---SiO₂, TiO₂---ZrO₂ or TiO₂---Al₂O₃ films. The effect of the additional coating on the photoelectrochemical properties of a TiO₂ film electrode was investigated in detail. On addition of the second additive to TiO₂, the flat band potential was shifted toward negative potential for SiO₂ and positive potential for ZrO₂ and Al₂O₃, which is attributed to the change in the point of zero zeta potential (pzzp), not in the electron affinity (EA). However, enhancement in photocurrent was not observed for all the cases.     

Kinetics and mechanism of H+(aq)-assisted aquation of [Cr(N3)(S-pdtra)]− and [Cr(N3(edtrp)]−ions

Two new complex anions, [Cr(N3)(S-pdtra)]– and [Cr(N3)(edtrp)]–, were obtained in solution by N3–/HN3 anation of the aqua analogues (S-pdtra = S-propane-1,2-diamine-N,N,N-triacetate, edtrp = ethylenediamine-N,N,N-tripropionate). Aquation of these species in acidic media leads to the same geometrical isomers as those used for the synthesis. The aquation rate is strongly dependent upon [H] and is substantially higher in D2O than in H2O. Protonation of the coordinated azide was not observed spectrophotometrically. The rate law and activation parameters have been determined and discussed.     

Ethylenediammonium bis{bis[N‐(2‐aminoethyl)glycinato‐κ3N,N′,O]chromium(III)} tetrachloride dihydrate at 293 and 100 K

The crystal structure of the title compound, (C₂H₁₀N₂)[Cr(C₄H₉N₂O₂)₂]₂Cl₄·2H₂O, has been determined by single‐crystal X‐ray diffraction studies at 293 and 100 K. The analyses demonstrated that the crystal consists of ethyl­enedi­ammonium dications (which lie about inversion centres), bis­[N‐(2‐amino­ethyl)­glycin­ato]­chromium(III) monocations, Cl^? anions and hydrate water mol­ecules, in a molecular ratio of 1:2:4:2. The complex cation unit has a slightly distorted octahedrally coordinated Cr atom, with two Cr—O and four Cr—N bonds in the ranges 1.951 (1)–1.953 (1) and 2.054 (1)–2.089 (2) Å, respectively, at 293 K. The geometry of the bis­[N‐(2‐amino­ethyl)­glycinato]­chromium(III) moiety was found to be trans,cis,cis with respect to the carboxyl­ate O atom and the primary and secondary amine N atoms. The two analyses, at 293 and 100 K, exhibited no remarkable structural differences, although the colour of the crystals did differ, being red at 293 K and orange at 100 K.