离子液体中Pb^2+／Pb^4+溶质局域结构的EXAFS研究

在超稀浓度条件下ω[Pb(OAc)2]或ω[Pb(OAc)4]<0.2,我们使用EXAFS方法对 溶解在离子液体中的铅化合物的局域结构进行了研究。从结果中可以看出,Pb (OAc)4的铅中心在（0.200±0.003）nm处有8个氧近邻,而Pb(OAc）2的铅中心在（ 0.225±0.003)nm处有6个氧近邻。但是溶解在离子液体中的铅化合物均具有较低的 配位数（一般小于4）,这显示出离子液体具有较低的配位性能。另一方面,铅中 心与最近邻氧的原子间距有较大的变化。例如：溶解于[bmim]PF6的Pb^4+的Pb-O间 距为（0.186±0.005)nm,配位数仅为2.4,从Fourier变换谱上可清楚地看出有第 二配位壳层的贡献;溶解于[bmim]PF6的Pb^2+的Pb-O间距也明显地小于纯样品中 Pb-O的间距。相比之下,溶解于[ bmim]BF4的铅离子显示出的Pb-O间距与纯样品几 乎没有差别,对于Pb^2+为0.223nm,而对于Pb^4+为0.210nm。     

伴有盆腔黏连的妇科腹腔镜手术临床分析

目的 分析伴有盆腔黏连的妇科腹腔镜手术临床应用价值。方法 选择2015年3月至2016年3月珠海市妇幼保健院收治的伴有盆腔黏连妇科疾病患者96例,随机分为两组,各48例。对照组采用传统开腹手术,观察组应用腹腔镜手术。比较两组手术疗效及手术情况。结果观察组手术总有效率为95.8%,明显高于对照组的83.2%,差异有统计学意义(P0.05);观察组手术时间、出血量及住院时间分别为(76.7±9.4)min、(45.6±4.7)m L、(4.6±1.3)d,均明显少于对照组[(89.3±10.2)min、(98.4±11.6)m L、(10.3±2.4)d],差异有统计学意义(P0.05)。结论 伴有盆腔黏连的妇科腹腔镜手术应用价值显著,是一种安全可靠的盆腔黏连治疗手段,值得推广。     

[Ru(phen)2dppz]2+二聚及对DNA键合性质的影响

研究发现, [Ru(phen)2dppz]2+表现出非常强的自聚合倾向, 并显著影响DNA的键合性质, 有关方面的研究应引起科研工作者的足够重视.     

A one-step fully automated radio-synthesis of a dopamine transporter PET imaging agent 18F-FECNT and its in vivo evaluations

2β-Carbomethoxy-3β-(4-chlorophenyl)-8-(2-[¹⁸F]fluoroethyl)nortropane ([¹⁸F]-FECNT) is a potential dopamine transporter PET imaging agent. However, its current radio-synthesis is tedious and time consuming. In this article, we reported a fully automatic method for the synthesis of [¹⁸F] FECNT through only one step, using a TRACERlab FX_N module, with decay corrected radiochemical yield of 25 ± 5 % (n = 5). The total synthesis time was 50–55 min. The synthesized [¹⁸F]FECNT was evaluated in vivo in Parkinson’s disease model rats.     

Enantioselective Oxidation of Thioethers. An Improved Route to the Resolution of [1,1′-Binaphthalene]-2,2′-Dithiol

Abstract

(±)-[1,1′-Binaphthalene]-2,2′-bis-methylthioether (±)-1 was oxidized with high enantioselectivity by using our asymmetric reagent [Ti(IV) : (+)-DET : TBHP = 1 : 4 : 2]. An appropriate substrate/oxidant ratio afforded such a product distribution that allowed us to obtain, after chromatographic separation and chemical transformations, optically pure [1,1′-binaphthalene]-2,2′-dithiol in ca. 80% yield based on the racemic starting material.     

Full automatic synthesis of [<Superscript>18</Superscript>F]THK-5351 for tau protein PET imaging in Alzheimer’s disease patients: 1 year experience

[¹⁸F]THK-5351, a new candidate for tau protein imaging, is based on an aryl quinoline structure. We report the full automatic synthesis using disposable cassettes under pH controlled [¹⁸F]fluorination. After the trapping of 88.5 ± 21.9 GBq of [¹⁸F]fluoride, it was eluted with potassium methansulfonate (KOMs) (pH 7.8)/K₂₂₂. After drying, 3 mg of the precursor was added to 1 mL DMSO and subjected to [¹⁸F]fluorination at 110 °C for 10 min. After hydrolysis, the final product was purified by HPLC. The overall radiochemical yield was 31.9 ± 11.1% (n = 22), satisfying all quality control criteria. It was stable for up to 6 h with high radiochemical purity as 99.8 ± 0.5%.     

The Radical Anions of [2.2.2.2]Paracyclophane-1,9,17,25-tetraene and Some of its Heteroaromatic Analogues

The radical anions of [2.2.2.2]paracyclophane- 1,9,17,25-tetraene (I), [2] (2, 5)-furano [2]paracyclo [2] (2,5)furano [2]paracyclophane-1,8, 16,23-tetraene (II), [2]-(2,5)thiopheno [2]paracyclo [2] (2,5)thiopheno [2]paracyclophane-1,8,16,23-tetraene (III) and [2.2.2.2](2,5)thiophenophane-1,8,15,22-tetraene (IV) have been studied by ESR. and ENDOR. spectroscopy. The assignment of the proton coupling constants, a_Hμ is to a large extent based on investigations of deuteriated derivatives. These investigations impressively demonstrate the potential of ENDOR. spectroscopy as an analytical tool. The Arrhenius activation energies, E_a, for the rotation of phenylene fragments about the bonds linking them with the ethylenic parts in I ? and II ? are 36±6 and 28±4 kJ/mol, respectively. The value a_Hμ of the olefinic protons in I? appears substantially smaller than expected for the corresponding planar radical anion. The hyperfine data for II ?, III ? and IV ? are consistent with the conformations which should minimize the deviations of the macrocyclic π-systems from planarity. In the case of II ?, tight ion pairs are formed by the radical anion and its counter-ion, K ⊕, in DME , owing to the strong association of the alkali metal cation with one of the furan moieties. An analogous interaction of K ⊕ with a thiophene moiety in III ? must be weaker, since no effects of ion pairing on the ESR. and ENDOR. spectra have been observed for this radical anion.     

Homo- and heteroleptic mercury(II) complexes with monoamino complexones in aqueous solution

Reactions of mercury(II) with iminodiacetic (H₂Ida), 2-hydroxyethyliminodiacetic (H₂Heida), and nitrilotriacetic acids (H₃Nta) were studied by spectrophotometry and pH potentiometry. The resulting complexes included [HgIda], [Hg(OH)Ida]^?, [HgIda₂]^2?, [HgHeida], [Hg(OH)Heida]^?, [Hg(Heida)₂]^2?, [HgNta]^?, [HgNta₂]^4?, [Hg(Ida)Heida]^2?, [Hg(Ida)Nta]^3?, and [Hg(Heida)Nta]^3?. The logarithms of their stability constants calculated for I = 0.1 (NaClO₄) and T = 20 ± 2°C were 11.14 ± 0.07, 20.33 ± 0.08, 19.40 ± 0.10, 11.42 ± 0.04, 19.68 ± 0.11, 18.48 ± 0.09, 13.42 ± 0.05, 20.80 ± 0.08, 19.05 ± 0.06, 20.64 ± 0.11, and 20.53 ± 0.16, respectively. The experimental data were analyzed in terms of the mathematical models that predict the existence of a wide spectrum of complex species in solution and allow one to consider only those species that are sufficient for accurate reproduction of the observed pattern.     

Oxygen promoted radical polymerization of acrylonitrile in aqueous nitric acid. A kinetic study

The polymerization of acrylonitrile (AN) initiated by oxygen-ascorbic acid (AA)-ferric ion system was studied in dil. HNO₃ at 40°. The rate of polymerization, R_p, was found gravimetrically. In the [Fe³⁺] range, (2–5 × 10^?5 M, R_p was proportional to [AN]^{1.5 ± 0.05}, [O₂]^{0.5 ± 0.02} [AA]⁰ and [Fe³⁺]⁰; for [Fe³⁺] = (5–30) × 10^?5 M, it was proportional to [AN]^{1.8 ± 0.05}, [O₂]^{0.6 ± 0.02}, [AA]⁰ and [Fe³⁺]^{?0.9 ± 0.05}. A plausible reaction scheme is proposed and rate law presented to explain these results. R_p increased with ionic strength and [HNO₃] (up to ～0.25 M). An initial rate increase with temperature followed by a decrease was noticed. Chain lengths of the polymers were determined viscometrically.     

Metallderivate von Molekülverbindungen. IV. Synthese,Struktur und Reaktivität des Lithium-[tris-(trimethylsilyl)silyl]tellanids · DME

Metal Derivatives of Molecular Compounds. IV Synthesis, Structure, and Reactivity of Lithium [Tris(trimethylsilyl)silyl]tellanide · DME Lithium tris(trimethylsilyl)silanide · 1,5 DME [3] and tellurium react in 1,2-dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide · DME ( 1 ). An X-ray structure determination {-150 · 3·C; P2₁/c; a = 1346.6(4); b = 1497.0(4); c = 1274.5(3) pm; β = 99.22(2)·; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li? Te? Li? Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li? Te 278 and 284; Si? Te 250; Li? O 200 pm (2X); Te? Li? Te 105°; Li? Te? Li 75°; O? Li? O 84°}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 ± 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane ( 2 ), methyl-[tris(trimethylsilyl)silyl]tellane ( 4 ) and bis[tris(trimethylsilyl)silyl]ditellane ( 5 ) are formed.     

Heteroligand mercury(II) complexes with aspartic,tartaric, and citric acids

Mercury(II) complexes with aspartic (H₂Asp) and tartaric acids (H₂Tart) and heteroligand mercury(II) complexes with H₂Asp, H₂Tart, and citric acids (H₃Cit) were studied by spectrophotometry in aqueous solutions with I = 0.1(NaClO₄) at 20 ± 2°C. It was found that the complexation in both binary and ternary systems depends on the concentrations of the reagents and the pH of the medium. The resulting complexes included [HgAsp], [Hg(OH)Asp]^?, [HgAsp₂]^2?, [HgTart], [Hg(OH)Tart]^?, [Hg(OH)₂Tart]^2?, [HgAspCit]^3?, [HgAspTart]^2?, and [Hg(OH)AspTart]^3?. The logarithms of their stability constants were 11.74 ± 0.12, 20.18 ± 0.17, 20.11 ± 0.10, 5.40 ± 0.11, 15.52 ± 0.09, 24.70 ± 0.12, 19.19 ± 0.12, 14.55 ± 0.16 and 23.80 ± 0.14, respectively. The experimental data were analyzed in terms of the mathematical models that predict the existence of a wide spectrum of complex species in solution and allow one to consider only those species that are sufficient for accurate reproduction of the observed pH-dependence of the optical density.     

Rate constants for the gas-phase reactions of OH radicals with a series of bi- and tricycloalkanes at 299 ± 2 K: Effects of ring strain

Relative rate constants for the gas-phase reactions of OH radicals with a series of bi- and tricyclic alkanes have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10^?12 cm³/molec·s, the rate constants obtained are (× 10¹² cm³/molec·s): bicyclo[2.2.1]heptane, 5.53 ± 0.15; bicyclo[2.2.2]octane, 14.8 ± 1.0; bicyclo[3.3.0]octane, 11.1 ± 0.6; cis-bicyclo[4.3.0]nonane, 17.3 ± 1.3; trans-bicyclo[4.3.0]nonane, 17.8 ± 1.3; cis-bicyclo[4.4.0]decane, 20.1 ± 1.4; trans-bicyclo[4.4.0]decane, 20.6 ± 1.2; tricyclo[5.2.1.0^2,6]decane, 11.4 ± 0.4; and tricyclo[3.3.1.1^3,7]decane, 23.2 ± 2.1. These data show that overall ring strain energies of ?4–5 kcal mol^?1 have no significant effect on the rate constants, but that larger ring strain results in the rate constants being decreased, relative to those expected for the strain-free molecules, by ratios which increase approximately exponentially with the overall ring strain.     

The gas phase structures of the isomers of benzene: IV. Hexafluoro-dewar-benzene

Gas phase electron diffraction data for HFDB were analyzed, following conventional procedures, and a structure was deduced for the perfluoro-bicyclo-[2.2.0]hexa-2,5-diene consistent with its C_2v symmetry. A least squares analysis of the molecular scattering function gave the following r_g values: [-C-C-] = 1.597 ± 0.006 Å, [C-C-] = 1.503 ± 0.002 Å, [-C-C-] = 1.356 ± 0.007 Å, [-C-F](bridge) = 1.331 ± 0.008 Å, [-C-F] (terminal) = 1.323 ± 0.004 Å. The flap angle between the rings is 115.3( ± .7)°. The terminal fluorines are in the planes of the corresponding rings.The most notable feature of the structure is the long C-C bridge bond, which was also observed in hexamethyl-Dewar-benzene. The geometrical features of HFDB are compared with corresponding ones in HMDB, and with perfluoro- cyclobutene as well as with theoretical estimates.     

Benzoyl transfer reactivities of racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters in the solid state: molecular packing and intermolecular interactions correlate with the ease of the reaction

Racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters undergo transesterification catalyzed by sodium carbonate with varying ease of reaction in the solid state; reactions in solution and melt do not show such varied differences. An interesting crystal of a 1:1 molecular complex of highly reactive racemic 2,4-di-O-benzoyl-myo-inosityl 1,3,5-orthoformate and its orthoacetate analogue exhibited better reactivity than the latter component alone. Single-crystal X-ray structures of the reactants have been correlated with the observed differences in the acyl-transfer efficiencies in the solid state. Although each of the derivatives helically self-assembles around the crystallographic 2(1) axis linked through O-H...O hydrogen bonding, the pre-organization of the reactive groups (C=O [El] and OH [Nu]), C-H...O and the C-H...pi interactions are significantly more favourable for the reactive derivatives than the less reactive ones. Bond-length distributions also showed differences; the O-C bond of the axial benzoyl group, which gets cleaved during the reaction, is longer (1.345-1.361 A) relative to the chemically equivalent O-C bond of the equatorial benzoyl group (1.316-1.344 A) in the reactive derivatives. These bond-length differences are not significant in the less reactive derivatives. The overall molecular organization is different too; the strikingly discrete helices, which may be viewed as "reaction tunnels" and are held by interhelical interactions, are clearly evident in the reactive derivatives in comparison with the less reactive ones.     

Effects of ring strain on gas-phase rate constants. I. Ozone reactions with cycloalkenes

Rate constants for the gas-phase reactions of O₃ with a series of cycloalkenes and with cis-2-butene have been determined at 297 ± 1 K. The rate constants obtained were (in units of 10^?16 cm³/molecule·s): cis-2-butene, 1.38 ± 0.16; cyclopentene, 2.75 ± 0.33; cyclohexene, 1.04 ± 0.14; cycloheptene, 3.19 ± 0.36; 1,3-cyclohexadiene, 19.7 ± 2.8; 1,4-cyclohexadiene, 0.639 ± 0.074; bicyclo[2.2.1]-2-heptene, 21.4 ± 3.5; bicyclo[2.2.1]-2,5-heptadiene, 46.8 ± 12.9; and bicyclo[2.2.2]-2-octene, 0.728 ± 0.090. These data for cis-2-butene, cyclopentene, and cyclohexene are compared with previous literature data, and the effects of ring strain on the rate constants are discussed.     

Ambiguousness of GC-MS identification of spiro[2.4]hepta-4,6-diene in natural objects

The publications on the GC-MS identification of spiro[2.4]hepta-4,6-diene in various natural objects were critically considered. Significant similarity of the mass spectra and coincidence of the GC retention indices on standard nonpolar phases of spiro[2.4]hepta-4,6-diene (761±3) and its isomer (toluene, 760±8) do not allow one to assert that the spirocyclic hydrocarbon was found in all the cases. Additional analytical parameters should be applied to differentiate such isomers.     

Thermodynamics of vinyl ethers—XXI: Evaluation of some cis interaction energies

Thermodynamics of isomerization reactions on some substituted vinyl methyl ethers have been studied for evaluating the magnitudes of the interaction energies S[R¹... R²] between the substituents R¹ and R², juxtaposed in a cis position across the CC bond of vinyl ethers. The results obtained are (values given in kJ mol^-1): S[Me... t-Bu]=18.2±1.0, S[Ph...i-Pr]=11±2, S[i-Pr...Et] =6.1±0.6, S[i-Pr... i-Pr] = 6.0 ± 0.6, S[0...t-Bu]=2.9±0.5, S[O...i-Pr]= -0.7±0.5, S[O...Et] = ?1.5±0.5, S[O...Ph]= ?2.1+-0.6, and S[O... Me] =?2.9 ±0.2 (the symbol O stands for the ethereal oxygen atom of vinyl ethers). The negative interaction energy values reveal that the cis interaction between the ethereal oxygen and the alkyl (aryl) group concerned is stabilizing.     

Physicochemical Studies on Cu(II)-Ferron Complexes

Experiments were carried out at 25°C and μ of 0.1 M. Spectrophotometric and potentiometric methods gave the ionization constants of ferron, pK₁=2.50±0.02 and pK₂=7.12±0.02. Cu(II) and ferron form a sparingly soluble 1:1 complex, [Cu(H₂O)₂L]⁰ (L: ferronate ion) which in higher acidity media, protonates to give [Cu(H₂O)₂HL]⁺and in lower acidity media, ionizes to give [Cu(H₂O)(OH)L]^?. At pH 2.3, the 1:1 complex gives a minimum solubility and the intrinsic solubility was found to be 1.1×10^-4. The Job's continuous variation method and the molar ratio method gave a formation constant (–pK) for Cu²⁺+L^z??CuL, 10.8±0.1 in the pH range of 0.64 to 1.18 and in the pH range of 5.0 to 5.5 (optimum pH condition for formation of complex), the stoichiometry of the Cu(II)-ferron chelate is essentially 1:2 (Cu:L) but with slight tendency to form 1:1 chelate if [L]/[Cu] is less than 2. The overall formation constant (–pK) was determined to be 20.0±0.3.     

γ-Radiation-Initiated Polymerization of Acrylonitrile in Aqueous Solution and in Emulsion

The γ-radiation-initiated polymerization of acrylonitrile (AN) at 25[ddot] C has been studied, both in aqueous solution and in emulsion, at dose rates between 70 and 175 krad/hr. The effect of added emulsifier, sodium lauryl sulfate (SLS), on reaction rates, R_p, and on polymer molecular weight, M_n, has been investigated. G (monomer polymerized) values ranged from 7,500 in aqueous solution to 20,000 in bulk to 45,000 in emulsion, all based on the total energy absorbed. In the aqueous solution polymerization, where R_p is approximately first order in initial monomer concentration over the range 0.15 ± [AN]_o ± 1.06 moles/liter, addition of SLS increases R_p but does not influence the order of the reaction with respect to [AN]_o. In the emulsion system at 70 krad/hr and at a phase volume ratio AN/H₂O of 1/2, (PR = 1/2), R_p varies as [SLS]^0.1 over the concentration range 0.01 ± [SLS] ± 2.5± wt/vol of aqueous phase. At the same PR value, and at 80 krad/hr, M_n of the polymer (measured by viscometry in dimethylformamide solution) is effectively independent of [SLS] in the range of 0.01 ± [SLS] ± 10± wt/vol of aqueous phase. Initial R_p values are either independent of PR in the range 1/3 ± PR ± 1/1 or exhibit an insensitive and unsystematic dependence thereon. Based on measurements at 70 and at 175 krad/hr, the intensity exponent of R_p at PR = 1/2 is approximately 0.4.     

The Homoconjugated Electron-Releasing Carbonyl Group of 1-Methylbicyclo[2.2.1]hept-5-en-2-one. Regioselective syntheses of 5-chloro- and 6-chloro-1-methylbicyclo[2.2.1]hept-5-en-2-one

Syntheses of (±)-2-exo-cyano-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-endo-yl acetate ( 1 ) and of (±)-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-one ( 2 ) are reported. The additon of PhSeCl to 1 afforded (±)-5-endo-chloro-2-exo-cyano-1-methyl-6-exo-(phenylselenenyl)-7-oxabicyclo[2.2.1]hept-2-endo-yl acetate ( 6 ), whereas 2 added to PhSeCl with the opposite regioselectivity giving (±)-6-endo-chloro-1-methyl-5-exo-(phenylselenenyl)-7-oxabicyclo[2.2.1]heptan-2-one ( 7 ). These adducts were converted into 5-chloro-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-one ( 9 ) and 6-chloro-1-methyl-7-oxabicyclo[2.2.1]hept-5-en-2-one ( 10 ), respectively.