二硝酸根二4′，5′-二氮-9′-(4，5-二(硫乙基)-1，3-二硫杂环戊烯-2-叶立德)-芴合镉的合成、结构及光谱性质

Cd(NO₃)₂·4H₂O与配体4′,5′-二氮-9′-(4，5-二(硫乙基)-1，3-二硫杂环戊烯-2-叶立德)-芴(L)在甲醇和二氯甲烷的混合溶剂中生成配合物Cd(NO₃)₂(L)₂。晶体的空间群是Pbcn(#60)，晶体学参数分别是a=1.578 7(2) nm，b=0.987 96(11) nm，c=2.719 5(3) nm。V=4.241 6(8) nm³，Z=4。2个硝酸根离子各提供1个氧原子，2个配体L各提供2个氮原子，形成了镉的6配位结构。晶体结构显示分子通过平面之间的π-π相互作用沿b轴形成柱状结构，这些柱通过中心原子镉(Ⅱ)的配位连接形成二维层状结构，再通过2个硫乙基上的短距离S…S接触进一步形成了三维结构。对其 ¹H NMR、UV-Vis和荧光光谱进行了研究。     

(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二硫基)-金的三阶非线性光学性质

合成了一种新的配位化合物(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二硫基)-金(BTEAADT). 利用旋涂技术制备了该材料与聚甲基丙烯酸甲酯(PMMA)掺杂的复合薄膜, 该材料在复合薄膜中的质量分数为1%. 采用Z扫描方法, 分别测试了该材料的乙腈溶液和该材料与PMMA复合薄膜在波长为1064 nm, 脉宽为20 ps条件下的三阶非线性光学特性. 同时还研究了复合薄膜的线性光学性质. Z扫描的结果表明, 复合薄膜和该材料的乙腈溶液都具有自散焦效应, 非线性折射率都是负值. 在实验条件下, 两者的非线性吸收效应都是可以忽略的. 经过计算得出溶液样品的非线性折射率为-1.459×10^-18 m²·W^-1, 复合薄膜样品的非线性折射率为-3.978×10^-15 m²·W^-1. 该材料在1064 nm处的非线性光学器件方面有潜在应用价值.     

4,5-二[2-(邻甲酰苯氧基)乙硫基]-1,3-二硫环戊烯-2-酮的合成及晶体结构

以水杨醛与1,2-二溴乙烷为反应物, 乙腈为溶剂, 在无水K₂CO₃存在下合成了2-溴乙氧基水杨醛(1), 1和二-(1,3-二硫杂环戊烯-2-硫酮-4,5-二硫)合锌酸四乙基铵盐在乙腈中回流, 得到新型的四硫富瓦烯(TTF)前体(2). 在Hg(OAc)₂存在下, 2可转化为4,5-二[2-(邻甲酰苯氧基)乙硫基]-1,3-二硫环戊烯-2-酮(3), 其结构经¹H NMR, FT-IR, 元素分析和单晶X射线衍射分析得到确证.     

N,N'-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺的热分解动力学研究

以TG-DTG为手段, 研究了N,N'-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺(DPTDEDA)在氮气气氛中的热分解动力学, 利用 Kissinger法、Flynn-Wall-Ozawa(FWO)法对DPTDEDA进行了动力学分析, 求出了该物质的热分解动力学参数, 同时利用Satava-Sestak法研究了该物质的热分解机理. 结果表明, Kissinger法所求得的表观活化能为137.37 kJ•mol^－1, 指前因子ln A＝28.00; Flynn-Wall-Ozawa法所求得的活化能为139.83 kJ•mol^－1. DPTDEDA的热分解机理为相边界反应, 其动力学方程为G(α)＝1－(1－α)⁴, 反应级数n＝4.     

N-2-多氟烷基乙基取代1,3,4-噁二唑-2-硫酮及1,2,4-三唑-5-硫酮类化合物的合成和密度泛函理论研究

为改善二唑及三唑类化合物的生物活性, 设计合成了一系列多氟烷基乙基取代的1,3,4-噁二唑-2-硫酮6a～6l及1,2,4-三唑-5-硫酮类化合物9a～9l. ¹H NMR, ¹⁹F NMR, IR和MS谱以及元素分析表征了它们的结构; 实验结果与Materials Studio 3.0中的Dmol3计算模块理论计算表明了唑环上的NH较之CONH中的NH更易进行烷基化反应.     

2-氰基-2,3,3-三甲基-5-硫代-吡咯烷的合成新法

以3,3-二甲基-4-戊烯酸甲酯为原料, 经过6步反应合成了目标产物2-氰基-2,3,3-三甲基-5-硫酮-吡咯烷, 反应的总收率约为37%, 其中关键步骤为分子内环化和碘化氢消除反应. 通过元素分析, ¹H NMR, IR和MS对所合成化合物的结构进行了表征.     

N,N′-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺在空气中的热分解动力学研究

以TG-DTG为手段, 研究了N,N′-二(5,5-二甲基-2-磷杂-2-硫代-1,3-二噁烷-2-基)乙二胺(DPTDEDA)在空气中的热分解动力学,利用Friedman法、Flynn-Wall-Ozawa(FWO)法对DPTDEDA进行了动力学分析, 求出了该物质两个主要的热分解阶段的热分解动力学参数, 同时利用Coats-Redfern法、Achar法研究了该物质的热分解机理. 结果表明, 用Friedman法所求得的两个热分解阶段的表观活化能的平均值分别为128.03和92.59 kJ•mol^－1; 而Flynn-Wall-Ozawa法所求得的两个热分解阶段的表观活化能的平均值分别为138.75和106.78 kJ•mol^－1. 由Coats-Redfern法、Achar法得出DPTDEDA在空气中的热分解过程虽主要分为两段反应, 但经过推理其反应机理函数却是相同的, 为f(α)＝3/2(1－α)^4/3[(1－α)^－1/3－1]^－1.     

二硫纶修饰的β-环糊精的自包合以及对金属离子的响应

利用圆二色光谱, 核磁, 等温滴定量热法和化学滴定方法研究单-6-马来二氰二硫代酸钠-β-环糊精在水溶液中的自包合性质。化学滴定实验结果表明十二烷基硫酸钠(SDS), Cu²⁺和Co²⁺可以改变单-6-马来二氰二硫代酸钠-β-环糊精的构象, 并且得出单-6-马来二氰二硫代酸钠-β-环糊精在水溶液中的存在形式是自包合的结论;Cu²⁺可以作为打开单-6-马来二氰二硫代酸钠-β-环糊精自包合结构的"钥匙", 使其构象改变后可以与中性红(NR)发生包合作用;加入EDTA与Cu²⁺配位后, 单-6-马来二氰二硫代酸钠-β-环糊精恢复自包合结构, 同时释放中性红客体分子。     

二硫纶修饰的β-环糊精的自包合以及金属调控

利用圆二色光谱, 核磁, 等温滴定量热法和化学滴定方法研究单-6-马来二氰二硫代酸钠-β-环糊精在水溶液中的自包合性质。化学滴定实验结果表明十二烷基硫酸钠(SDS), Cu²⁺和Co²⁺可以破坏单-6-马来二氰二硫代酸钠-β-环糊精的构象, 并且得出单-6-马来二氰二硫代酸钠-β-环糊精在水溶液中的存在形式是自包合的结论; Cu²⁺可以作为打开单-6-马来二氰二硫代酸钠-β-环糊精的自包合结构的"钥匙", 使其构象改变后可以与中性红发生包合作用; 加入EDTA与Cu²⁺配位后, 单-6-马来二氰二硫代酸钠-β-环糊精恢复自包合结构, 同时释放中性红客体分子。     

[1-芳基甲羰基-2-(1,2,4-三唑-1-基)]乙基-N,N-二烷基二硫代氨基甲酸酯衍生物的合成、结构表征及生物活性研究

以芳香基三唑类杀菌剂三唑酮为先导物设计并合成了5个含N,N-二烷基二硫代氨基甲酸酯的芳香三唑类化合物, 通过元素分析、红外光谱、核磁共振氢谱和质谱对其结构进行了表征. 用X射线单晶衍射测定了[α-(4-甲氧基苯甲酰基)-2-(1,2,4-三唑-1-基)]乙基-N,N-二甲基二硫代氨基甲酸酯的晶体结构, 晶体属于三斜晶系, 空间群, 晶胞参数为: a＝0.73482(15) nm, b＝1.1051(2) nm, c＝1.1209(2) nm, α＝90.32(3)°, β＝101.97(3)°, γ＝105.13(3)°, V＝0.8578(3) nm³, Z＝2, D_c＝1.357 g/cm³, F(000)＝368, µ＝0.324 mm^－1. 生物测试结果显示这5种有机化合物都具有杀菌性和植物生长调节活性     

Polarographic determination of osmium with the osmium(VIII)-cerium(IV)-arsenic(III) system

A highly sensitive and novel polarographic method has been developed for determination of ultratrace amounts of osmium, based on the catalysis of the cerium(IV)-arsenic(III) reaction by osmium(VIII). The reaction rate is monitored by measuring the arsenic(III) with a single-sweep oscillopolarograph. Osmium concentrations from 7.0 x 10(-11) to 5.0 x 10(-9)M can be determined by the initial rate method. The method has been applied to determination of osmium in refined ore and chlorination residues with satisfactory results.     

Simultaneous Determination of Nickel(II) and Cobalt(II) by Second-Derivative Spectrophotometry

4-(2-Pyridylazo) resorcinol, PAR, is shown to be useful for simultaneous determination of cobalt(II) and nickel(II) using second-derivative spectrophotometric method with controlled experimental parameters. This method allows the determination of 0.20-1.25 ppm of nickel(II) and 0.25-1.50 ppm of cobalt(II) in mixtures with good precision and accuracy. This method has advantages of simplicity, speed and requires no prior separations.     

Colour reaction of platinum(II) with 5-(4-nitrophenylazo)-8-(p-toluenesulphonamido)-quinoline and its analytical applications

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of platinum. 5-(4-Nitrophenylazo)-8-(p-toluenesulphonamido)quinoline (NPTSQ) reacts with platinum(II) almost instantaneously in alkaline solution to form a violet-red 1:2 complex with an absorption maximum at 640 nm. Beer's law is obeyed over the concentration range 0-1 mug/ml platinum. The molar absorptivity is 1.37 x 10(5) 1.mole(-1).cm(-1). The method has been used for the determination of microamounts of platinum in catalysts and anode slime.     

Liquid chromatography/tandem mass spectrometry for analysis of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) and 1,2,5,6-tetrabromocyclooctane (TBCO)

Although the two flame retardants 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) and 1,2,5,6-tetrabromocyclooctane (TBCO) have been widely used, a selective instrumental method of analysis for these compounds has not been developed to date. In this study, we demonstrate the feasibility to utilize liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the separation and analysis of α- and β-TBCO and α-, β-, γ-, and δ-TBECH. Acetone was initially used in a tetrahedron solvent system for LC optimization. A simple isocratic elution allowed near-baseline separation of these compounds. Different ionization approaches and mechanisms were investigated. The mass spectrometric transition of [M + O(2)](-) => Br(-) (459.8 => 78.9) was a selective detection method for the target analytes. Good instrument detection limits (5 pg for γ-/δ-TBECH, 125 pg for α-/β-TBECH, and 30 pg for α-/β-TBCO with 2.0 μL injection) were obtained. Excellent linearity up to 50 ng/μL (R(2) >0.999) was also achieved. This method has been applied to environmental samples (surface water) for screening purposes with recoveries ranging from 76-92% (CV%: 5-8%). This method shows significant improvement over previous methods.     

Determination of trace aluminum (III) using a novel cerium (IV)-calcein chemiluminescence detection

A simple, sensitive and selective chemiluminescence (CL) method was developed for the direct determination of aluminum (Al). This method is based on that the weak CL of cerium (IV)-calcein can be greatly enhanced by Al(III). The calibration curve was linear over the range 2.0 x 10(-10) to 4.0 x 10(-8)g mL(-1) with a detection limit of 8 x 10(-11)g mL(-1) (3sigma). The R.S.D. was 2.5% by 11 replicated determinations of 1.0 x 10(-9)g mL(-1) Al(III). The proposed method has been used to determine the concentration of Al(III) in real water samples with satisfactory results. The mechanism of the CL reaction was also discussed.     

Spectrophotometric determination of H(2)-receptor antagonists via their oxidation with cerium(IV)

A simple, accurate and sensitive spectrophotometric method has been developed and validated for determination of H(2)-receptor antagonists: cimetidine, famotidine, nizatidine and ranitidine hydrochloride. The method was based on the oxidation of these drugs with cerium(IV) in presence of perchloric acid and subsequent measurement of the excess Ce(IV) by its reaction with p-dimethylaminobenzaldehyde to give a red colored product (lambda(max) at 464nm). The decrease in the absorption intensity of the colored product (DeltaA), due to the presence of the drug was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9990-0.9994) were found between DeltaA values and the concentrations of the drugs in a concentration range of 1-20microgml(-1). The assay limits of detection and quantitation were 0.18-0.60 and 0.54-1.53microgml(-1), respectively. The method was validated, in terms of accuracy, precision, ruggedness and robustness; the results were satisfactory. The proposed method was successfully applied to the determination of the investigated drugs in pure and pharmaceutical dosage forms (recovery was 98.3-102.6+/-0.57-1.90%) without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods.     

New renin inhibitors with pseudodipeptidic units in P(1)-P(1') and P(2')-P(3') positions

A series of four new potential renin inhibitors has been synthesized. The structure of the compounds was designed in such a way as to produce agents resistant to enzymatic degradation, metabolically stable, possibly potent and with improved oral absorption. All positions of the 8-13 fragment of the human angiotensinogen were occupied by unnatural units (two unnatural amino acids in positions P(3) and P(2) and two pseudodipeptides in positions P(1)-P(1') and P(2')-P(3')). Both N- and C-terminal functions of the inhibitors were blocked with tert-Boc and ethyl ester groups. Their hydrophobicity evaluated as a log P value, calculated by a computer method, was 6.57 and 6.08 respectively. All peptides were obtained by the carbodiimide method in solution and purified by chromatography on the SiO(2) column. Their resistance to enzymatic degradation was assayed by determination of stability against chymotrypsin activity. The potency was measured in vitro by a spectrofluorimetric method (assay of Leu-Val-Tyr-Ser released from the N-acetyltetradecapeptide substrate by renin in the presence of the inhibitor). All inhibitors were stable to chymotrypsin. Their IC(50) (M/l) values were: 9.6 x 10(-4) (12), 1.6 x 10(-5) (17), 1.0 x 10(-5) (22) and 1.0 x 10(-5) (23) respectively.     

Low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W)

Multiple low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W) arise from the occupation of the near-degenerate low-lying virtual orbitals in the neutral clusters. We used density functional theory (DFT) and coupled cluster theory (CCSD(T)) with correlation consistent basis sets to study the structures and energetics of the electronic states of these anions. The adiabatic and vertical electron detachment energies (ADEs and VDEs) of the anionic clusters were calculated with 27 exchange-correlation functionals including one local spin density approximation functional, 13 generalized gradient approximation (GGA) functionals, and 13 hybrid GGA functionals, as well as the CCSD(T) method. For M(3)O(9)(-), CCSD(T) and nearly all of the DFT exchange-correlation functionals studied predict the (2)A(1) state arising from the Jahn-Teller distortion due to singly occupying the degenerate e' orbital to be lower in energy than the (2)A(1)' state arising from singly occupying the nondegenerate a(1)' orbital. For W(3)O(9)(-), the (2)A(1) state was predicted to have essentially the same energy as the (2)A(1)' state at the CCSD(T) level with core-valence correlation corrections included and to be higher in energy or essentially isoenergetic with most DFT methods. The calculated VDEs from the CCSD(T) method are in reasonable agreement with the experimental values for both electronic states if estimates for the corrections due to basis set incompleteness are included. For M(3)O(9)(2-), the singlet state arising from doubly occupying the nondegenerate a(1)' orbital was predicted to be the most stable state for both M = Mo and W. However, whereas M(3)O(9)(2-) was predicted to be less stable than M(3)O(9)(-), W(3)O(9)(2-) was predicted to be more stable than W(3)O(9)(-).     

Potentiometric flow injection determination of amylase activity by using hexacyanoferrate(III)-hexacyanoferrate(II) potential buffer

A highly sensitive potentiometric flow injection determination of amylase activity was carried out, utilizing a redox reaction of hexacyanoferrate(III) in alkaline media with reducing sugar as product of the enzymatic hydrolysis reaction of starch with amylase. The analytical method is based on the potential change detection of a flow-through type redox electrode detector due to the composition change of a [Fe(CN)(6)](3-)-[Fe(CN)(6)](4-) potential buffer solution, which is caused by the redox reaction with the product of the enzymatic reaction. A linear relationship exists between the potential change (peak height) and the activity of amylase. Amylase of a wide activity range from 2.5x10(-2) to 1.2x10(-4) U ml(-1) can be determined by the changing the concentrations of the [Fe(CN)(6)](3-)-[Fe(CN)(6)](4-) potential buffer from 10(-3) to 10(-5) M. The lower detection limit of amylase activity is 6.0x10(-5) U ml(-1). The sampling rate and relative standard deviation are 15 h(-1) and 0.9% (n=5) for 3.8x10(-3) U ml(-1) of amylase. The present method was successfully applied to determine amylase activity in real samples (commercial digestive medicines) with an accuracy of 4% compared with analytical results obtained using the present method with those achieved using the conventional titration method.     

Interaction of nickel with 4-(2'-benzothiazolylazo) salicylic acid (BTAS) and simultaneous first-derivative spectrophotometric determination of nickel(II) and iron(III)

The solution properties of nickel complex with 4-(2'-benzo-thiazolylazo) salicylic acid (BTAS) have been studied by zero-order absorption spectrophotometry in 40% (v/v) ethanol at 20 degrees C and an ionic strength of 0.1 mol dm(-3) (KNO(3)). The equilibria that exist in solution were established and the basic characteristics of complexes formed were determined. A new direct spectrophotometric method for the determination of trace amounts of the nickel is proposed based on the formation of the Ni (BTAS) complex at pH 7.0. The absorption maximum, molar absorbtivity, and Sandell's sensitivity of 1:1 (M:L) complex are 525 nm, 0.6 x 10(4) l mol(-1) cm(-1) and 2.824 x 10(-9) microg cm(-2), respectively. The use of first-derivative spectrophotometry eliminates the interference of iron and enables the simultaneous determination of nickel and iron using BTAS. Quantitative determination of Ni(II) and Fe(III) is possible in the range (0.59-7.08) and (2.1-8.4) microg ml(-1), respectively with a relative standard deviation of 0.5%. The proposed method has been successfully applied to the simultaneous spectrophotometric determination of nickel and iron in steel alloys and aluminum alloys.