Solvatochromism and piezochromism of pentacyanoferrates(II) and of mixed valence iron(II)—iron(III) and ruthenium(II)—ruthenium(III) species

Pressure effects on the MLCT bands of the pyrazine- and 4-cyanopyridine-pentacyanoferrate(II) anions have been established. The relation of these piezochromic effects to the solvatochromism of each complex is put into the correlation between these parameters developed for other d⁶ ternary complexes. The conformance of piezochromic and solvatochromic efrects on MMCT bands for diiron and diruthenium mixed valence complexes to this correlation is examined.     

Thermal Analysis of Poly(AN—co—St) and Poly(AN—St—MMA)

Poly(AN—co—St) (PAS) and poly(AN—St—MMA)(PASM) were synthetized by emulsion polymerisation. The glass transition temperatures (T_g) of the copolymers and the relationship between T_g and the components of the copolymers were investigated by differential scanning calorimetry. The results show that T_g for the AN—St bipolymers has apeak value in the range 115–118°C at a content of 50 mass% St. When methyl methacrylate was added, the T_g of the terpolymer was decreased by about 2–6°C.The thermostability and the activation energy E of degradation were determined by thermogravimetric analysis.This revised version was published online in November 2005 with corrections to the Cover Date.     

Chemistry of imidobis(sulphuryl chloride)—IV measurements of physical properties of imidobis(sulphuryl chloride)

Density, viscosity and specific conductance have been measured at 5° interval between 25 to 50° for imidobis(sulphuryl chloride). The surface tension, freezing point and cryoscopic constant have also been determined. Its IR and proton NMR spectra have been recorded. Relative acidity strength measurements in acetic acid suggest that imidobis(sulphuryl chloride) is a stronger protonic acid than HBr, HSO₃Cl and (CF₃)₂POOH.     

Synthesis of a C(9)—C(13) fragment of acutiphycin from levoglucosan

Alkylation of (1R,2R,5R)-2-benzenesulfonyl-6,8-dioxa-bicyclo[3.2.1]octan-3-one, which is accessible from levoglucosan, afforded (1R,2R,5R)-2-benzenesylfonyl-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-one. This was further converted into (1S,2R,3S,5R)-2,4,4-trimethyl-6,8-dioxabicyclo[3.2.1]octan-3-ol representing the C9—C13 fragment of acutiphycin molecule.     

Molecular Dynamics Studies of Solid-Liquid Phase Transitions Ⅱ——Homogeneous Nucleation of (KI)_(108) Clusters

在一系列分子动力学计算中，（ＫＩ）１０８离子簇冷却时自发地由液相变为立方面心相．在３５０Ｋ和４００Ｋ的成核速率大于１０３６核／ｍ３·ｓ．由成核速率得到的固－液界面自由能约为５０ｍＪ／ｍ２．     

Monomeric and dimeric products of protonation of dioxotetracyanometalates(IV)—I: Complexes of tungsten(IV)

A series of tungsten(IV) complexes of formula Me₃[WO(OH)(CN)₄]xH₂O and Me₆[W₂O₃(CN)₈]xH₂O (where Me = Na, K) have been synthesized. The solids obtained were characterized by chemical analysis, thermogravimetric and differential thermal analysis, IR, Raman and visible spectrophotometry and magnetic susceptibility measurements. The analysis of the IR and Raman spectra has led to an assignment of the fundamental vibrations which was supported by studies of IR spectra of the deuterated and anhydrous salts.     

Vibrational spectroscope of complexes of platinum(0)—I. Tetrakis(triphenylphosphine)platinum(0) and Dioxygenbis(triphenylphosphine)platinum(0)

Assignment of i.r. and Raman spectra for Pt(PPh₃)₄ and Pt(O₂)(PPh₃)₂ yielded values for νPtP of 137 and 157 cm⁻¹ (Pt(PPh₃)₄); 132 (antisymmetric) and 145 cm⁻¹ (symmetric) (Pt(O₂)(PPh₃)₂). For the dioxygen complex, solution phase Raman spectra gave values for both ν PtO₂ modes for the first time. Data from the ¹⁶O₂, ¹⁶O¹⁸O and ¹⁸O₂ isotopomers were used in a normal coordinate analysis of the PtO₂ fragment. The OO stretching force constant (3.0 mdyn Å⁻¹) is consistent with extensive net π-back-donation into the π* m.o.s of the O₂ ligand.     

An Efficient Synthesis of Dicarbonyl (η5—Cyclopentadien—YL)Iron(II) Complexes of Two Cyclic Enol Ethers

An efficient synthesis of dicarbonyl(η⁵—cyclopentadienyl)iron—(II)—complexes of 2,3—dihydrofuran and 3,4—dihydro—2H—pyran from 3—bromo—2—methoxytetrahydrofuran and—pyran, respectively, is described.     

Comparison of Differential Pulse Voltammetry (DPV)—a new method of carbamazepine analysis—with Fluorescence Polarization Immunoassay (FPIA)

Carbamazepine is a widely used anti-epileptic drug with narrow therapeutic range. Many methods have been developed for monitoring the serum drug level. Differential pulse voltammetry (DPV), an electrochemical method advantaged by simple, inexpensive, and relatively short analysis time, has recently been developed for carbamazepine detection. We used a newly developed DPV method with glassy carbon as a working electrode to determine the carbamazepine level. The performance of DPV is compared with the widely used fluorescence polarization immunoassay (FPIA) technique in precision, accuracy, linearity and detection limit. The precision, linearity and accuracy of the DPV and FPIA techniques were comparable at most clinical used levels. The detection limit was 1 μg/mL for the DPV technique and 0.5 μg/mL for the FPIA technique. The performance of the DPV technique was within the FDA guidelines for bioanalytical methods, which ensures the clinical applicability of the DPV technique. The DPV technique may have the potential to be a good alternative for carbamazepine analysis.     

Free-radical copolymerization of L-(—)-menthyl methacrylate with acetylphenyl (meth)acrylates

The free-radical copolymerization of L-(—)-menthyl methacrylate with o- and p-acetylphenyl (meth)acrylates is performed to obtain new carbonyl-containing optically active copolymers. It is shown that the reactivity ratios and the yield of copolymers are lower for o-acetylphenyl methacrylate than those for the corresponding para isomer because of the steric hindrance from acetyl substituents in phenyl rings. The optical activity of the synthesized copolymers is estimated.     

Photophysical studies of uranyl complexes—VI. Luminescence spectra of bis(imidazolium) tetrachlorodioxouranate(VI) and bis(2-methylimidazolium) tetrachlorodioxouranate(VI)

The photoluminescence spectra of the title compounds have been studied under conditions of high resolution at cryogenic temperatures. The luminescence obtained from the 2-methyl imidazolium salt was found to be well behaved, in that all emission originated from intrinsic uranyl centers and all luminescence decay curves consisted of single exponentials. In contrast, the emission associated with the imidazolium salt was found to originate both from intrinsic uranyl groups and from luminescence traps. The analysis of the luminescence decay curves obtained at cryogenic temperatures revealed that the lifetimes characteristic of the trap emission were significantly shorter than those associated with the intrinsic luminescence. The magnetic dipole allowed origins were found to be split by the rhombic crystal field in each system, but this splitting was observed to be 11 cm⁻¹ or less. All other features present in either spectrum were assigned as vibronic in nature and they represent coupling of the various O-U-O or U-Cl vibrational modes with the pure electronic origins.     

Catalytic oxidation of aliphatic alcohols in the tetraaquapalladium(ii) complex—iron(iii)—dioxygen system

The selective low-temperature (40—70 °C) catalytic oxidation of methanol, propan-1-ol, and propan-2-ol in the presence of the tetraaquapalladium(ii) complex and iron(iii) ions and/or molecular oxygen as cooxidants was studied. The corresponding carbonyl compound is the product of alcohol oxidation. The kinetic regularities of the reaction were established. In the reaction mechanism proposed, the key step is palladium(i) formation.     

X-ray photoelectron spectral study of dinitrosylbis (1,10-phenanthroline)vanadium(— I) perchlorate

XPS study of dinitrosylbis(1,10-phenanthroline)vanadium(— I) perchlorate is reported.     

Reactions of uranium pentafluoride — The preparation of the first chloridefluorides of uranium (V)

The reactions between UF5 and either Me₃SiCl or UCl₅ in anhydrous acetonitrile yield soluble uranium (V) chloridefluorides. The crystalline complexes UF₅·2tppo and UCl₂F₃·2tppo are obtained in the presence of an excess of triphenylphosphine oxide (tppo).     

Anticancer Drugs (V)─—Synthesis of Etoposide Derivatives

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Dielectric polarization of cross-linked poly(ethylene oxide)—phenomenology

Results of dielectric relaxation studies will be discussed. It turns out that competition of electric and structural relaxation coins permittivity and as a result conductivity mechanism at low temperature. It dominates long-ranging relaxation in the molten state. In the opposite limit of temperature, cross-linked poly(ethylene oxide) (PEO) with low mesh size can be transferred into super-cooled liquid state. Then, PEO behaves like a hydrogen-bonded liquid since crystallization is strongly suppressed. As a result, one observes slow Debye-like relaxation at low temperature. Beyond the low-frequency region, there appears an extended region between crossings of impedance components, where Z′ ≈ Z″ at acceptable approximation. It is coined by damped oscillation under action of the electric field. These effects lessen with increasing mesh size of the sample as clearly shown by M″(ω) spectra. The dipole moment of the PEO samples in molten state decreases only slightly with increasing mesh size.     

Synthesis and characterization of silver—poly(methylmethacrylate) nanocomposites

The optical properties of silver nanoparticles embedded in poly(methylmethacrylate) (PMMA) was investigated as well as the influence of silver nanoparticles on the thermal properties of polymer matrix. The average size and particle size distribution of silver nanoparticles was determined using transmission electron microscopy. The obtained transparent nanocomposite films were optically characterized using UV-Vis and FTIR spectroscopy. Thermal stability of polymer matrix was improved upon incorporation of small amount of silver nanoparticles. Also, silver nanoparticles have pronounced effect on thermo-oxidative stability of PMMA matrix. The glass transition temperatures of nanocomposites are lower compared to the pure polymer.     

The Chlorination of O-Alkyl S-Alkyl(aryl) Thiophosphoric(-nic) Acid Derivatives with Phosphorus Oxychloride——A New Convenient Method for Synthesis of Chiral S-Alkyl(aryl) Thiophosphoro(-no) Chloridates

In our laboratory, the isomerization/chlorination of a variety of O,O-dialkyl phosphoro(-no)thionates 1 with phosphorus oxychloride have been systematically studied. It was found that when R' equals aryloxy^[1], alkylthio^[2], arylthio^[2], dialkylamino^[3], phenyl^[4], methyl^[5],and nitrogen heterocyclic group^[6] in 1,respectively, this reaction can proceed smoothly and gives the desired products ² and ³. Hence, it provides a general synthitic method for S-alkyl thiophosphoro(-no)chloridates, especially for the asymmetric ones.     

Complexes of tetracyanobiimidazole—V. Self-association of Ir(I) complex anions

The self-association of the planar anion [Ir(CO)₂Tcbiim]⁻ where H₂Tcbiim is 4,4′,5,5′-tetracyano-2,2′-biimidazole has been studied in acetontrile solution by analysis of the charge-transfer spectra. At low concentrations (∼ 10⁻⁵ M) monomer units prevail. At intermediate concentrations (∼ 10⁻³ M) dimerization is evident and a very strong (ε = 18 500 M⁻¹ cm⁻¹) new absorption appears at 475 nm. A novel procedure was used to obtain this value and to estimate the equilibrium constant for dimerization, 13.2 M⁻¹ at 24.4°C. From the temperature dependence of the spectra, ΔH is calculated to be −28 to −30 kJ M⁻¹. At higher concentrations (∼ 10⁻² M) spectral changes consistent with further oligomerization are observed.     

Highly Sensitive Spectrophotometric Determination of Trace Amounts of Tin with the Tungstate——Basic Dyes——Poly (vinyl-alcohol)System

A few new spectrophotometric methods for the determination of trace amounts of tin(IV) have been developed based on the reaction of tin(Ⅳ) with tungstate and basic dyes(BD), which consists of rhodamine B(RB),butylrhodamine B(BRB) and nile blue(NB),to form ion-associations complexes of the kind in the presence of polyvinyl alcohol(PVA).