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Mixed-anion compounds, in which multiple anions such as O2−, N3−, and H− are contained in the same compound, have recently attracted attention. Because mixed-anion compounds have a unique crystal s...

For mass spectroscopy (MS)-based protein structural analyses, effective digestion by proteases is one of the key steps. In this study, we developed a protein digestion method using immobilized enzy...

A novel organic semiconductor, 2,9-bis(perfluorobutyl)pentacene, was synthesized in seven steps, and was characterized by NMR, IR, and UV spectroscopy. From differential scanning calorimetry analyses, no liquid crystalline phase was observed, unlike 2,9-dibutylpentacene. The morphology of thin films formed at different substrate temperatures was investigated by atomic force microscopy (AFM) and X-ray diffraction analysis. Organic field-effect transistors (OFETs) fabricated with this compound showed electron mobility of 1.7 x 10- 3 cm 2 V- 1 s -1 using Ag source-drain electrodes.

The reaction of the mixed-ligand iron–sulfur cluster [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2)] ([3]) (Cp* = C5Me5) with iodomethane gave a methylated cluster, [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2Me)]I ([4]I),...

Photolysis of a 2 : 1 mixture of [Cp*Fe(CO)2Me] and Ph2CHSiH3 produces mainly the mononuclear silyl complex [Cp*Fe(CO)2{Si(H)2CHPh2}] (1) together with two silanediyl-bridged diiron complexes: cis- and trans-[Cp*2(CO)2Fe2(μ-CO){μ-Si(H)CHPh2}] (2), and [{Cp*Fe(CO)2}2]. The trans-2 complex isomerizes to cis-2 photochemically, but no cis–trans isomerization occurs thermally below 100 °C. Photolysis of [CpFe(CO)2SiMe3] or [CpW(CO)3Me] in the presence of 1 produces novel silanediyl-bridged complexes [Cp*Fe(CO)(μ-CO){μ-Si(H)CHPh2}(CO)nMCp] (3: M = Fe, n = 1; 4: M = W, n = 2) in moderate yields. Complexes 3 and 4 have been characterized by X-ray diffraction analysis. To the best of our knowledge, complex 4 is the first example of a silanediyl-bridged Fe–W complex. The Cp and Cp* rings are mutually cis with the dihedral angle of 78.7(2)° in complex 3, but they are trans with the dihedral angle of 13.1(6)° in complex 4.

Photolysis of 2 molar amounts of CpFe(CO)2SiMe3 (= FpSiMe3, 1) with s-alkylsilanes R2CHSiH3 (2a: R = Et; 2b: R = Ph) produces the silylene (or silanediyl)-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(H)CHR2] (3a: R = Et; 3b: R = Ph) which exist mainly in cis-form. The treatment of cis-3 with an excess amount of CH2I2 stereoselectively affords the iodosilylene-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(I)CHR2] (4a: R = Et; 4b: R = Ph) in cis-form. The reaction of complexes 4 with 4-(dimethylamino)pyridine (= DMAP) gives the base-stabilized silylyne (or silanetriyl)-bridged diiron complexes Cp2(CO)2Fe2(μ-CO)[μ-Si(DMAP)CHR2]+I− (5a: R = Et; 5b: R = Ph) in 35 and 43% yields, respectively. The cis–trans isomerization of complexes 3 was studied under thermal and photochemical reaction conditions. The molar ratios of the cis and trans isomers of complexes 3 in the thermal equilibrium at 50 °C were 95 : 5 (3a) and 78 : 22 (3b), respectively, and in the photostationary state at 10 °C were 80 : 20 and 30 : ...

The reactions of [CpS12Fe2(CO)4] and [CpS22Fe2(CO)4] with elemental sulfur afforded a tetrairon cluster containing two end-on type S2 ligands [CpS14Fe4S6] (1) and a diiron complex containing an end-on type S2 and a side-on type S2 ligands [CpS22Fe2S4] (2), respectively, where CpS1 and CpS2 stand for mono- and bis(trimethylsilyl)cyclopentadienyl ligands, respectively. From these results and the previously reported results which were obtained for the reactions of [Cp2Fe2(CO)4] and [Cp*2Fe2(CO)4] with elemental sulfur, it is suggested that [Cp′2Fe2S4] is an intermediate to give tetrairon sulfur clusters, where Cp* and Cp′ denote pentamethylcyclopentadienyl and substituted cyclopentadienyl ligands, respectively. X-Ray crystal structure analysis was carried out for the compounds 1 and 2. Crystallographic data are as follows: 1: Monoclinic, P21/c, a = 17.302(6), b = 18.646(3), c = 15.310(4) A, β = 120.71(2)°, V = 4246(2) A3, Z = 4, and R = 0.061 for 5850 reflections with |Fo| > 3σ(Fo); 2: Triclinic, space group...

The reactivities and the site-selectivities of the hydrolyses of ATP and UTP by the catalysts of the metal complexes of adenine-linked di-2-pyridylamine ligands, (Py)2N–(CH2)n–Ade (L: n = 3, 4, 5, and 6), were examined. It was found that these adenine–dipyridylamine coordinated Cu2+ complexes (with 2 : 1 ratios of [CuII(L)]2+ : ATP or [CuII(L)]2+ : UTP) were more reactive for the hydrolyses of ATP and UTP than the complexes of ligands containing other metal ions (Mg2+, Ni2+, and Zn2+) at 40 °C and pH 7.3 (HEPES buffer), as reflected in much higher product ratios of ADP/AMP and UDP/UMP than those of Cu2+ alone. The observed high reactivity and selectivity are interpreted in terms of the base-base stackings between an adenine moiety of ATP or an uracil moiety of UTP and an adenine of the ligands, and of the selective coordination of Cu2+ to oxide ions in phosphate residues in the ternary complexes of ligand–Cu2+–ATP. The Cu2+-complex of di-2-pyridylamine having no adenine moiety, which is the active center ...

A synthetic peptide, H–Ser–Phe–Leu–Leu–Arg–Asn–Pro–NH2, which corresponds to a ligand peptide tethered to a human thrombin receptor, was able to activate the thrombin receptor with no thrombin. In order to inspect the structural requisites of two consecutive leucines (Leu-3 and Leu-4) in receptor activation, two sets of analogs with substitutions at either position 3 or 4 were synthesized and evaluated for their ability to hydrolyze phosphoinositide in human neuroblastoma SH-EP cells. The replacement of Leu-4 by Ala drastically decreased the activity of the parent peptide (only about 4% activity), while that of Leu-3 retained about 50% activity. A similar result was obtained when replaced by Gly. Substitution by Phe for Leu-3 sustained full activity. Although the Leu-4/Phe substitution exhibited a slight reduction in activity, Leu-4/Ile substitution unexpectedly diminished the activity (20%). These results suggested that two consecutive leucines have different roles in receptor activation; i.e., Leu-3 beh...

Isomerization between two geometrical isomers of the methoxy-bridged bis(silylene)iron complex, anti-and syn-Cp*(OC)Fe{(SiMe2)···OMe···(SiMeOMe)} (Cp* = η5-C5Me5), was investigated by means of a variable-temperature 1H NMR experiment. The equilibrium constant (K) for the isomerization and its thermodynamic parameters were determined to be K = [syn-isomer]/[anti-isomer] = 0.53 at 293 K in toluene-d8, ΔG°298 = 1.5 ± 0.5 kJ mol−1, ΔH° = 3.8 ± 0.2 kJ mol−1, and ΔS° = 7.7 ± 1.0 J mol−1 K−1. Computer simulation of the VT spectra and calculation using Eyring equation yielded activation parameters, ΔH‡ = 83.8 ± 3.2 kJ mol−1, ΔS‡ = 42.3 ± 9.6 J mol−1 K−1, and ΔG‡298 = 71.2 ± 6.0 kJ mol−1, for the isomerization from the anti-isomer, in which the terminal OMe group is located on the opposite side of the Cp* group with respect to the Fe–Si–O(bridged)–Si ring, to the syn-isomer. A mechanism in which the bridging OMe group is replaced by the terminal OMe group is proposed for the isomerization.

In order to inspect the structural elements of Ser-1 in receptor activation by SFLLRNP (one-letter amino acid code), a ligand peptide tethered to the thrombin receptor, a series of analogs with such replacements as D-Ser, Ala, Thr, and Ac-Ser have been synthesized. These analogs were evaluated for their ability to hydrolyze the phosphoinositide in human neuroblastoma SH-EP cells. It was found that the α-amino group and L-configuration of Ser-1 are very important in the activation of receptors. N-Acetylation or deletion of Ser-1 completely eliminated the activity of SFLLRNP (a half-maximal effective concentration, EC50 = 0.89 μM (1 M = 1 mol dm−3)), and these modifications induced no antagonist activity. Incorporation of D-Ser also drastically diminished the activity, but retained about 50% activity of the maximal response by 100 μM SFLLRNP. The Ser/Ala substitution sustained 30% of the activity of SFLLRNP to elicit a full stimulation. The Ser/Thr substitution, however, enhanced the activity (20%) in spite...

Acetaldehyde reacted over various ion-exchanged ZSM-5 zeolites at 15 ± 0.5 °C under a nitrogen pressure of 1 × 105 Pa. The main products of the reaction were 2α,4α,6α-trimethyl-1,3,5-trioxane (cis-paraldehyde) and its isomer, 2α,4α,6β-trimethyl-1,3,5-trioxane (trans-paraldehyde). Several rare earth ZSM-5 (REZSM-5) and M/HZSM-5 (partially proton exchanged ZSM-5) catalysts exhibited high activities for trans-paraldehyde formation. The reaction appeared to proceed by the following scheme: cis-paraldehyde ← acetaldehyde → trans-paraldehyde. A comparison of the catalytic activity with the IR intensity of acidic OH groups over the catalyst suggested that the active site for cis-paraldehyde formation was the Bronsted acidic site, while the active site for trans-paraldehyde formation was a Bronsted acid site in the neighborhood of an Mn+ site in the ZSM-5 zeolite pore.

Chemical state analysis of Sn–Sb–O solid surfaces was performed by means of Auger electron spectroscopy (AES). Differential and numerically integrated AE spectra were curve-fitted using standard spectra obtained from pure substances. The fitting revealed, for the first time, the possibility of differentiating two antimony oxide components, Sb(III) and Sb(V), by AES. Using the AE spectral parameters obtained for these two chemical states, a correlation between the Sb AE peak positions and the average Sb oxidation number was constructed and it was applied for the determination of the average Sb oxidation state in Sn–Sb mixed oxide systems.

The compounds, 4-(nonafluorobutyl)aniline, 4-(tridecafluorohexyl)aniline, and 4-(heptadecafluorooctyl)aniline were prepared by the reaction of corresponding perfluoroalkyl iodide with 4-iodoaniline in the presence of copper bronze. Six azobenzene derivatives (4-(4-fluorophenylazo)phenol, F(C6H4)N=N(C6H4)OH (1) (C6H4 = p-phenylene), 4-(4-trifluoromethylphenylazo)phenol, CF3(C6H4)N=N(C6H4)OH (2), 4-(4-heptafluoropropylphenylazo)phenol, C3F7(C6H4)N=N(C6H4)OH (3), 4-(4-nonafluorobutylphenylazo)phenol, C4F9(C6H4)N=N-(C6H4)OH (4), 4-(4-tridecafluorohexylphenylazo)phenol, C6F13(C6H4)N=N(C6H4)OH (5), and 4-(4-heptadecafluorooctylphenylazo)phenol, C8F17(C6H4)N=N(C6H4)OH (6)) were prepared by the usual diazo coupling reactions using 4-(perfluoroalkyl)aniline and phenol. The monomolecular film formations of the azobenzene derivatives at the air/water interface were investigated by surface pressure measurements to be dependent on the fluoroalkyl chain length (n). The compounds 5 (n = 6) and 6 (n = 8) formed stable mo...

Co-micelles of hexadecyltrimethylammonium bromide and a lipophilic bis-imidazole ligand, 1-dodecyl-4-hydroxymethyl-α-(1-dodecyl-2-imidazolyl)-2-imidazolemethanol (4) having two primary and secondary hydroxyl groups, together with the co-micelles of the related lipophilic ligands, were investigated for their catalytic activities in the hydrolysis of p-nitrophenyl 2-pyridinecarboxylate (PNPP) in the presence of Zn2+ or Cu2+. The kinetic and product analyses indicated that the reaction proceeds through the transacylation from PNPP to the hydroxyl group of ligand : metal ion complexes and that the active complexes undergoing transacylation are a 2 : 1 and a 1 : 1 complex for Zn2+ and a 1 : 1 complex for Cu2+, respectively. As for the ligand 4, the transacylation was found to be highly site-selective, i.e. it occurred predominantly on the secondary hydroxyl group with Zn2+, while on the primary hydroxyl group with Cu2+, respectively. Such selectivity was discussed in terms of the coordination structures of the...

The kinetics of the oxygen atom transfer reactions between cis-[MoO2(R2dtc)2] [R=CH3, C2H5, i-C3H7, i-C4H9, C6H5CH2 (Bz), C6H5 (Ph)] and PPh3 (coupled reactions 1 and 2) have been investigated.[MoO2(R2dtc)2]+PPh3\xrightarrowk1[MoO(R2dtc)2]+OPPh3 (1)[MoO2(R2dtc)2]+MoO(R2dtc)2]\oversetKd\ightleftharpoons[Mo2O3(R2dtc)4] (2)The rate constants (k1) of oxygen atom transfer reaction 1 correlate with the formal potentials of [MoO2(R2dtc)2]0⁄−1 except for R=Bz and Ph. The equilibrium constant values (Kd) of dimerization reaction 2 decrease with increase of the electron-donating ability of the substituents on the dithiocarbamate ligands.

K[V(edta)(H2O)]·2H2O (1a) was prepared by the reaction of VCl3 with K4 edta. The compound was converted to its sodium and ammonium salts by use of a cation exchange resin. Crystal structure analyses of Na[V(edta)(H2O)]·3H2O (1b) and NH4[V(edta)(H2O)]·2.5H2O (1c) revealed that in both compounds the vanadium atom adopts a capped trigonal-prismatic structures with a hexadentate ethylenediammetetraacetato ligand and an aqua ligand. Crystal data are as follows: 1b: Monoclinic, P21⁄a, a=17.831 (3), b=8.408 (1), c=11.595 (2) A, β=109.39 (1)°, Z=4, R=0.045 for 6321 reflections; 1c: Monoclinic, Aa, a=8.552 (1), b=59.948 (6), c=7.226 (A), β=114.95 (1)°, Z=8, R=0.050 for 6087 reflections.

[Fe4(η5-C5H5)4S4](PF6) crystals showed polymorphism depending on the recrystallization conditions. Recrystallization from acetonitrile–H2O solution gave monoclinic crystals: C2/c with lattice constants a=18.555(2), b=7.650(1), c=17.850(3) A, β=96.81(2)°, and Z=4. Recrystallization from N,N dimethylacetamide–ether solution gave tetragonal crystals: I\bar4 with lattice constants a=12.917(2), c=7.637(1) A, and Z=2. Molecular structures of both crystal systems are almost the same as each other, if the structure for the latter was analyzed assuming that enantiomeric cations are disordered.

The activation of the hydroxyl groups of two N-methyl/dodecyl-2-(hydroxymethyl)imidazole ligands by complexation with Cu2+ was investigated kinetically by observing the rates of the release of p-nitrophenol in the transacylation of p-nitrophenyl picolinate (PNPP). The kinetics were carried out in aqueous buffers of pH ranging from 4.5 to 8.0 at 25 °C in the absence of surfactant micelles for a hydrophilic N-methyl ligand, and in the presence of micelles for a lipophilic N-dodecyl ligand. The kinetic analyses indicated that the 1:1 and 2:1 complexes of the ligand and Cu2+ are active nucleophiles with the N-methyl and N-dodecyl ligand, respectively. The pKa’s of the hydroxyl groups of these complexes were determined to be 7.00 in water and 6.41 in aqueous CTABr micelles, respectively, by analyses of the pH-rate profiles. The rate constants, which show the nucleophilic reactivities of ionized hydroxyl anions of complexes toward PNPP, were determined to be kN=1.11×104 and 1.25×106 mol−1 dm3 s−1 with N-methyl ...

A study was made concerning the removal of leachables released from mixed-bed ion exchange resins. The key concerns were to determine the optimum mixed ratio of strong acid cation exchange resins (SACERs) and strong base anion exchange resins (SBAERs), which give the minimum value of total organic carbon (TOC) released from the resin mixtures and to investigate the effect of synthetic carbonaceous adsorbents on the adsorption of the leachables. The leaching rates of the leachables from the resin mixtures were dependent on the mixed ratios of SACERs and SBAERs. The TOC value for the leachables showed a minimum for a SACER-to-SBAER volume ratio of 9:1, far different from the mixed ratio in ordinary water treatment. The release of leachables from resin mixtures was mainly due to SBAER. The carbonaceous adsorbent having a higher hydrophobic surface adsorbed the leachables well from the resin mixtures.

[Fe4(η5)-C5H5)4S4](PF6) and [Fe4(η5-C5H5)4S4](PF6)2 were prepared in 81 and 82% yields, respectively, by bulk electrolysis of [Fe4(η5-C5H5)4S4] at the requisite potentials according to the results of voltammetric studies. [Fe4(η5-C5H5)4S4](PF6)3 was prepared and isolated first by electrolysis of [Fe4(η5-C5H5)4S4](PF6)2 in acetonitrile at +0.95 V vs. SCE in 83% yield. The electronic spectral data for [Fe4(η5-C5H5)4S4]n (n=0, 1+, 2+, 3+) were collected.

The kinetics of the substitution reactions of [N′-(2-hydroxyethyl)ethylenediamine-N,N,N′-triacetato]-aquaruthenium(III), [Ru(hedtra)(H2O)], with X (Br−, CH3CN, SCN−, and pyridine) to give [RuX(hedtra)] were carried out at 25 °C and I=0.5 mol dm−3. The substitution reactions were found to be unusually rapid. The rate constants of the forward reaction (kf) and of the backward reaction (kb) were kf=0.13±0.01 mol−1 dm3 s−1 and kb=(1.9±0.2)×10−2 s−1 for the reaction with Br−, kf=0.48±0.02 mol−1 dm3 s−1 and kb=(3.0±0.2)×10−2 s−1 for the reaction with CH3CN, and kf=7.5±0.2 mol−1 dm3 s−1 and kb=(1.3±0.8)×10−2 s−1 for the reaction with SCN−, respectively. The kinetics of the reaction of [Ru(hedtra)(H2O)] with py was studied as a function of pH. The observed rate constants of the reaction were separated into two rate constants; the rate constant of the forward reaction of [Ru(hedtra)(H2O)] with py (18±2 mol−1 dm3 s−1) and that of [Ru(OH)(hedtra)]− with py (3.0±1.0 mol−1 dm3 s−1). The mechanisms of the reactions are...

Potassium, sodium, and ammonium salts of [V(cydta)(H2O)]− complexes were prepared, where cydta denotes trans-1,2-cyclohexanediamine-N,N,N′,N′,-tetraacetate. Crystal structure analysis of Na[V(cydta)(H2O)]·5H2O revealed that the vanadium(III) atom adopts a capped trigonal-prism structure, a cydta acting as a sexidentate ligand and an aqua ligand occupying the capping position.

The mutarotation of α-D-glucose to β-D-glucose has been studied at 25±0.1 °C using five kinds of alumina as catalysts. Two kinds of alumina with measurable surface basicities have exhibited high catalytic activities while the others with little surface basicities have exhibited low activities. Thus, the surface basic sites have been considered to be responsible for the catalytic activity observed. Any of crystal structures, surface areas, pore structures, and surface elemental compositions have no relation to the catalytic activity. It has also been revealed that the kinetics of the reaction is explained by a surface reaction mechanismα+1 \undersetKα\ightleftharpoons αad \oversetk1\undersetk2\ightleftharpoons βad \undersetKβ\ightleftharpoons β+1,where 1, Kα, Kβ, k1 and k2 denote the active site, the adsorption equilibrium constant for α, the adsorption equilibrium constant for β, the rate constant for the surface forward reaction, and the rate constant for the surface backward reaction, respectively, and ...