钐离子在油／水界面迁移的电化学行为

钐离子在油／水界面迁移的电化学行为①狄俊伟＊徐肖邢＊＊吴莹范瑞溪（苏州大学化学化工学院苏州２１５００６）近年来，人们对中性载体推动金属离子在油／水界面转移的报道较多［１～４］．通常的实验研究大多采用水相中的金属离子ＭＺ＋大大过量，而于油相中溶解少量的...     

N_(235)二甲苯-醋酸铵-液膜体系萃取Cd(Ⅱ)的研究

本文研究了反萃剂、料液 HCl浓度、温度、 N_(235)浓度对 N_(235)二甲苯醋酸铵大块液膜体系迁移 Cd~(2＋)的影响。当膜相添加不同浓度的表面活性剂 Span 80时，测定了膜料液界面的萃取反应表观速率常数 k_1和膜反萃相界面的反萃取表观速率常数 k_2，并进行了相应的动力学分析。实验证明， Cd~(2＋)的迁移可用两个连续单向不可逆的一级反应来描述。在本文的液膜体系中， Cd2＋的跨膜迁移和 H＋的同向迁移耦合。     

AOT-正庚烷微乳状液的制备及迁移痕量金属离子的研究

研究了以二－(2－乙基已基)磺化琥珀酸钠为表面活性剂、以正庚烷为油性溶剂的W/O型微乳状液的形成及迁移痕量金属离子的行为,确定了制乳和迁移的适宜条件.在此条件下,一些金属离子可较完全地从水相或料相迁移到微乳相中,显示出较高的迁移率.     

AOT—正庚烷微乳状液的制备及迁移痕量金属离子的研究

研究了以二－（２－乙基己基）磺化琥珀酸黄为表面活性剂，以正庚烷为油性溶剂的Ｗ／Ｏ型微乳状液的形成及迁移痕量金属离子的行为，确定了制乳和迁移的适宜条件，在此条件下，一些金属离子可较完全地水相或料相迁移到微乳相中，显示出较高的迁移率。     

离子选择性PVC膜电极中溶剂化作用的研究 I: 碱金属离子由水相到TBP溶剂相的标准迁移自由能

电位法测量了碱金属离子由水相到TBP(磷酸三丁酯)-CH~3OH混合溶剂相的标准迁移自由能△G^0~t。研究了溶剂化作用同PVC膜对金属离子选择性的关系。碱金属离子的△G^0~t随着TBP在混合溶剂中含量的增加而增大。△G^0~t还随着离子半径的增大而增大, 这同TBP-PVC膜对碱金属离子的选择性次序相一致; 而与四苯硼酸盐-TBP-PVC膜对碱金属离子的选择性次序不完全相同。说明了TBP为溶剂的四苯硼酸盐膜对金属离子的选择性除了同溶剂化作用有关外, 还同膜相和水相中离子的交换反应常数等因素相关。     

基于相转化全过程的聚合物微孔膜功能化研究进展

传统的相转化过程主要通过相分离的热力学及动力学因素对聚合物膜的微孔结构进行调控,该过程是一个典型的物理过程,不涉及膜的表/界面功能调控。微孔膜的表/界面功能如抗污染性能、抗菌性能和抗凝血性能等对于分离性能具有重要影响。本文提出了基于相转化全过程赋予聚合物微孔膜表/界面特定化学功能的方法,即"化学相转化",其本质是围绕相转化全过程控制功能分子在膜及微孔表面的迁移路径及固定方式,实现了膜的表/界面功能化。总结了通过"化学相转化"进行聚合物微孔膜的表/界面功能化策略,根据功能分子迁移路径可分为:基于铸膜液的由内而外(Inside-out)迁移及原位交联功能化策略、基于凝固浴的由外而内(Outside-in)迁移及离域交联功能化策略、基于微孔膜的自上而下(Top-down)迁移及界面交联功能化策略,从而实现了聚合物微孔膜的表/界面功能化改性及其在水处理、油水分离和血液净化等方面的应用。"化学相转化"理论为高性能、多功能聚合物微孔膜的制备及其分离应用提供了新的研究思路。功能分子的引入也会对相转化过程产生影响,从而影响膜的微孔结构,本课题组将从微孔结构调控和表/界面功能化这两个方面完善"化学相转化"理论。     

离子选择性PVC膜电极中溶剂化作用的研究 Ⅰ.碱金属离子由水相到TBP溶剂相的标准迁移自由能

电位法测量了碱金属离子由水相到TBP(磷酸三丁酯)-CH_3OH混合溶剂相的标准迁移自由能⊿G_t~0研究了溶剂化作用同PVC膜对金属离子选择性的关系。碱金属离子的⊿G_t~0随着TBP在混合溶剂中含量的增加而增大。⊿G_t~0还随着离子半径的增大而增大,这同TBP-PVC膜对碱金属离子的选择性次序相一致;而与四苯硼酸盐-TBP-PVC膜对碱金属离子的选择性次序不完全相同。说明了TBP为溶剂的四苯硼酸盐膜对金属离子的选择性除了同溶剂化作用有关外,还同膜相和水相中离子的交换反应常数等因素相关。     

离子选择性PVC膜电极中溶剂化作用的研究 I: 碱金属离子由水相到TBP溶剂相的标准迁移自由能

电位法测量了碱金属离子由水相到TBP(磷酸三丁酯)-CH~3OH混合溶剂相的标准迁移自由能△G^0~t。研究了溶剂化作用同PVC膜对金属离子选择性的关系。碱金属离子的△G^0~t随着TBP在混合溶剂中含量的增加而增大。△G^0~t还随着离子半径的增大而增大, 这同TBP-PVC膜对碱金属离子的选择性次序相一致; 而与四苯硼酸盐-TBP-PVC膜对碱金属离子的选择性次序不完全相同。说明了TBP为溶剂的四苯硼酸盐膜对金属离子的选择性除了同溶剂化作用有关外, 还同膜相和水相中离子的交换反应常数等因素相关。     

N235二甲苯-醋酸铵-液膜体系萃取Cd(Ⅱ)的研究

本文研究了反萃剂,料液ＨＣｌ浓度、温度、Ｎ２３５浓度对Ｎ２３５－二甲苯－醋酸铵大块液膜体系迁移Ｃｄ＾２＋的影响,当膜相添加不同浓度的表面活性剂Ｓｐａｎ－８０时,测定了膜－料液界面的萃取反应表观速率常数ｋ１和膜－反萃相界面的反萃取表观速率常数ｋ２,并进行了相应的动力学分析。实验证明,Ｃｄ＾２＋的迁称可用两个连续单不可逆的一级反应来描述,在本文的液膜体系中,Ｃｄ＾２＋的跨膜迁移和Ｈ＾＋的同向迁移耦合。     

铜在乳状液膜体系中的迁移行为

近年来膜分离技术在环境治理方面得到广泛应用。本文研究了铜在span80-TBP（磷酸三丁酯）-煤油-NH3液膜分离体系中的迁移行为。用TBP作为载体,在溶液中迁移时,在外相与膜相界面上形成中性络合物后穿过膜相,在膜相与内相界面上络合物再与NH3反应,生成铜氨络离子,释放出来的TBP又返回膜相。     

A kinetic model of the formation of organic monolayers on hydrogen-terminated silicon by hydrosilation of alkenes

We have analyzed a kinetic model for the formation of organic monolayers based on a previously suggested free radical chain mechanism for the reaction of unsaturated molecules with hydrogen-terminated silicon surfaces (Linford, M. R.; Fenter, P. M.; Chidsey, C. E. D. J. Am. Chem. Soc 1995, 117, 3145). A direct consequence of this mechanism is the nonexponential growth of the monolayer, and this has been observed spectroscopically. In the model, the initiation of silyl radicals on the surface is pseudo first order with rate constant, ki, and the rate of propagation is determined by the concentration of radicals and unreacted Si-H nearest neighbor sites with a rate constant, kp. This propagation step determines the rate at which the monolayer forms by addition of alkene molecules to form a track of molecules that constitute a self-avoiding random walk on the surface. The initiation step describes how frequently new random walks commence. A termination step by which the radicals are destroyed is also included. The solution of the kinetic equations yields the fraction of alkylated surface sites and the mean length of the random walks as a function of time. In mean-field approximation we show that (1) the average length of the random walk is proportional to (kp/ki)1/2, (2) the monolayer surface coverage grows exponentially only after an induction period, (3) the effective first-order rate constant describing the growth of the monolayer and the induction period (kt) is k = (2ki kp)1/2, (4) at long times the effective first-order rate constant drops to ki, and (5) the overall activation energy for the growth kinetics is the mean of the activation energies for the initiation and propagation steps. Monte Carlo simulations of the mechanism produce qualitatively similar kinetic plots, but the mean random walk length (and effective rate constant) is overestimated by the mean field approximation and when kp > ki, we find k approximately ki0.7kp0.3 and Ea = (0.7Ei+ 0.3Ep). However the most striking prediction of the Monte Carlo simulations is that at long times, t > 1/k, the effective first-order rate constant decreases to ki even in the absence of a chemical termination step. Experimental kinetic data for the reaction of undec-1-ene with hydrogen-terminated porous silicon under thermal reflux in toluene and ethylbenzene gave a value of k = 0.06 min(-1) and an activation energy of 107 kJ mol(-1). The activation energy is in reasonable agreement with density functional calculations of the transition state energies for the initiation and propagation steps.     

烷基咪唑型卤盐类离子液体的合成机理研究

用密度泛函理论考察了甲基咪唑和一系列的卤代烷烃(氯乙烷,氯丁烷,溴乙烷,溴丁烷)反应合成咪唑类离子液体的反应机理. 在B3LYP/6-31++G**//B3LYP/6-31G*基组水平上找到了两条反应路径：路径A(反应物→TS1→P1)和路径B(反应物→TS2→P2). 在路径A中, 卤素离子和咪唑环C2上的氢质子形成氢键；在路径B中, 卤素离子和咪唑环C5上的氢质子形成氢键. 计算发现, 氢键的形成在反应中起到了非常重要的作用, 特别是咪唑环C2上的氢质子在和卤素离子成氢键后形成了一个五员环结构的过渡态, 该过渡态能量较低. 经过渡态TS1的反应途径其活化能要低于经过渡态TS2的反应途径, 反应路径A为主要的反应通道. 计算结果表明, 经过渡态TS1的反应途径是一放热过程, 这和实验观察现象一致.     

Manifestation of macroscopic correlations in elementary reaction kinetics. II. Irreversible reaction A+B→C

The applicability of the Encounter Theory (ET) (the prototype of the Collision Theory) concepts for widely occurring diffusion assisted irreversible bulk reaction A+B→C (for example, radical reaction) in dilute solutions with arbitrary ratio of initial concentrations of reactants has been treated theoretically with modern many-particle method for the derivation of non-Markovian binary kinetic equations. The method shows that, just as in the reaction A+A→C considered earlier, the agreement with the Encounter Theory is observed when the familiar Integral Encounter Theory is used which is just a step in the derivation of kinetic equations in the framework of the method employed. It allows for two-particle correlations only, and fails to consider the correlation of reactant simultaneously with a partner and with a reactant in the bulk. However, the next step leading to the Modified Encounter Theory under reduction of equations to a regular form both extends the time applicability interval of ET homogeneous rate equation (as for reactions proceeding in excess of one of the reactants), and yields the inhomogeneous equation of the Generalized Encounter Theory (GET) that reveals macroscopic correlations induced by the encounters in a reservoir of free walks in full agreement with physical considerations. This means that the encounters of reactants in solution are correlated at rather large time interval of the reaction course. However, unlike the reaction A+A→C of identical reactants, the reaction A+B→C accumulation of the above macroscopic correlations (even with the initial concentrations of reactants being equal) proceeds much slower. Another distinction is that for the reaction A+A→C the long-term behavior of ET and GET kinetics is the same, while in the reaction A+B→C these kinetics behave differently. It is of interest that just taking account of the above macroscopic correlations in the reaction A+B→C (in GET) results in the universal character of the long-term behavior of the kinetics for the case of equal initial concentrations of reactants and that where one of the reactants is in excess. This is more natural from the point of view of the reaction course on the encounters of reactants in solutions.     

Theoretical study on the structure and formation mechanism of [C6H5Mm]- (M=Ag, Au; m=1-3)

The structures and formation mechanisms of the important intermediate phenyl-coinage metal complexes [C(6)H(5)M(m)](-) (M==Ag, Au, m = 1-3) are investigated at B3LYP//6-311G(d, p)/Lanl2dz level using Gaussian 03 program. The adiabatic electron affinity and vertical dissociation energy of [M(m)](-) and [C(6)H(5)M(m)](-) are calculated, which are excellently coincident with the experimental determination. The C(6)H(5) group bonds on metal clusters through M--C sigma bond in the complex [C(6)H(5)M(m)](-). The complexes [C(6)H(5)M(m)](-) (M==Ag, Au; m = 2-3) are generated through a stepwise reaction. The first step is a direct insertion reaction between [M(m)](-) (M==Ag, Au, m = 1-3) and C(6)H(6,) which leads to the generation of intermediate [C(6)H(5)M(m)H](-) (m = 1-3) with the activation and cleavage of C--H bond. The second step is the neutral metal atom abstracting the H atom to yield the product [C(6)H(5)M(m)](-).     

一种新颖海洋微生物酯酶的功能鉴定及其在 D-乳酸甲酯制备中的应用

手性药物不同对映体往往表现出截然不同的生理活性和毒性,为了减少有毒副作用的对映体,并降低其生物活性,光学纯手性药物的合成一直是制药行业的研究热点.由于手性药物中间体是合成手性药物的重要构建模块,因此手性药物中间体的合成至关重要.手性乳酸及其酯是合成各类药物、农药和聚合物的重要中间体,在制药工业和材料工业中手性乳酸及其酯的制备非常重要.手性乳酸及其酯可以通过传统的有机化学合成和生物酶催化合成,通过有机化学合成法往往很难得到光学纯度较高的手性乳酸及其酯,而生物酶催化法可以得到光学纯的手性乳酸及其酯,同时避免了有机化学合成所导致的金属残留和环境污染等问题.生物酶法合成光学纯的乳酸及其酯可以通过脱氢酶不对称还原酮的前体得到,然而生物催化使用脱氢酶法需要价格昂贵的辅助因子,如 NADH和 NADPH.而另外一种生物催化方法是通过利用酯酶或者脂肪酶不对称水解外消旋的酯,从而得到光学纯度较高的手性中间体.目前市场上的 L-乳酸甲酯价格不太昂贵,因为 L-乳酸甲酯可以直接通过大发酵的方法取代有机化学法和酶法直接得到.然而 D-乳酸甲酯不能使用廉价的发酵法直接得到,因而其价格昂贵.生物酶催化法可能会成为制备 D-乳酸甲酯的主要方法,因为利用生物酶法可以得到光学纯度较高的 D-乳酸甲酯.本文从西太平洋深海来源的微生物Pseudomonas oryzihabitans HUP022中克隆并异源表达了一种新颖酯酶 PHE14.通过对酯酶 PHE14的酶学性质鉴定表明,酯酶 PHE14的最适反应底物为对硝基苯酚乙酸酯(C2),最适 pH为9.0,最适温度为60°C. PHE14催化最适反应底物 C2的活性达到293.07 U/mg,Vmax和Km分别为200μM/(mg·min)和0.24 mmol/L.酯酶 PHE14对多种有机溶剂、表面活性剂和金属离子都具有非常好的耐受性.深海微生物酯酶 PHE14对高浓度 NaCl具有很好的耐受性,在4 mol/L NaCl存在下,相对酶活力为71.4%.同时,酯酶 PHE14能够催化消旋乳酸甲酯的不对称水解反应制备重要的手性化工产品— D-乳酸甲酯.与先前的一些酯酶拆分的报道不同,有机溶剂和表面活性剂对酯酶 PHE14催化的动力学水解反应没有促进作用.而且,本研究是首次通过酶动力学水解拆分反应制备光学纯的 D-乳酸甲酯.经过实验优化,在 pH 9.0和30°C的条件下,反应产物 D-乳酸甲酯的对映体过量值和产率分别为99%和88.7%.深海微生物酯酶 PHE14作为一种绿色生物催化剂,在多种工业的不对称合成中都具有非常好的应用潜力.     

An Indium‐Seamed Hexameric Metal–Organic Cage as an Example of a Hexameric Pyrogallol[4]arene Capsule Conjoined Exclusively by Trivalent Metal Ions

A hexameric metal–organic nanocapsule is assembled from pyrogallol[4]arene units, which are stitched together with indium ions. This indium‐seamed capsule is the first instance of a M₂₄L₆ type hexameric coordination cage held together exclusively by trivalent metal ions. Explicitly, unlike previously reported pyrogallol[4]arene‐based metal‐seamed capsules, the current In³⁺ seamed capsule is entirely supported by O→In coordinate bonds. This work demonstrates the important proof of concept of the ability of pyrogallol[4]arene to react with metals in higher oxidation states to assemble into atomically‐precise hexameric coordination cages. As such, these results open up exciting avenues toward the assembly of previously unanticipated metal–organic capsules, for example offering inspiration for tackling metals exhibiting high valence states such as in the lanthanide and actinide series.     

An Indium-Seamed Hexameric Metal–Organic Cage as an Example of a Hexameric Pyrogallol[4]arene Capsule Conjoined Exclusively by Trivalent Metal Ions

A hexameric metal–organic nanocapsule is assembled from pyrogallol[4]arene units, which are stitched together with indium ions. This indium-seamed capsule is the first instance of a M₂₄L₆ type hexameric coordination cage held together exclusively by trivalent metal ions. Explicitly, unlike previously reported pyrogallol[4]arene-based metal-seamed capsules, the current In³⁺ seamed capsule is entirely supported by O→In coordinate bonds. This work demonstrates the important proof of concept of the ability of pyrogallol[4]arene to react with metals in higher oxidation states to assemble into atomically-precise hexameric coordination cages. As such, these results open up exciting avenues toward the assembly of previously unanticipated metal–organic capsules, for example offering inspiration for tackling metals exhibiting high valence states such as in the lanthanide and actinide series.     

Mass spectrometric characterization of beta-caryophyllene ozonolysis products in the aerosol studied using an electrospray triple quadrupole and time-of-flight analyzer hybrid system and density functional theory

The components of the organic aerosol formed due to gas-phase beta-caryophyllene ozonolysis were characterized by the use of a triple quadrupole and time-of-flight analyzer hybrid system coupled to an electrospray ionization source operated in the negative ion mode. A reversed-phase high-performance liquid chromatography (HPLC) column was used to achieve chromatographic separations at neutral pH which has been proved to induce ionization of organic compounds bearing aldehyde moieties. In addition to the detected oxo- and dicarboxylic acids, isomeric oxidation products, which bear multi-functional groups such as aldehyde, carbonyl and hydroxyl groups, could be differentiated by examining their corresponding collision-induced dissociation (CID) fragmentation pathways. Proposed fragmentation mechanisms were drawn for the experimentally observed fragmentation pathways in all the CID experiments. Cyclic oxidation products could also be discerned and their fragmentation behaviour under low energy collisional conditions was studied in detail. Gas-phase deprotonation potentials were calculated by the use of DFT B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d) + ZPVE to estimate the most thermodynamically favourable deprotonation site for efficient negative ion formation in the ion source. The optimized gas-phase geometries for the most prominent oxidation products reveal a strong intramolecular interaction between the upper and lower C4 carbon chains, which are formed after the decomposition of the primary ozonide generated by ozone attack of the reactive endocyclic C==C bond.     

Stabilities and Transfer Activity Coefficients from Water to Polar Nonaqueous Solvents of Benzo-15-Crown-5- and 15-Crown-5-Alkali Metal Ion Complexes

Stability constants (K_ML) of 1 : 1 benzo-15-crown-5 (B15C5) complexes with alkali metal ions were conductometrically measured in water at 25°C. Transfer activity coefficients of B15C5 and 15-crown-5 (15C5) from water to polar nonaqueous solvents were determined at 25°C. By using these data and the literature values, transfer activity coefficients of the B15C5 and 15C5 complexes with alkali metal ions from water to the polar nonaqueous solvents were calculated to study the solute-solvent interaction of the crown ether complexes. The stability of the B15C5 complex is lower in water than in any other nonaqueous solvent. The K_ML value for B15C5 is always smaller than the corresponding K ML value for 15C5. The interaction of the B15C5 or the 15C5 complex with the solvents depends on the alkali metal ion in the crown cavity. All the B15C5 and 15C5 complexes undergo hydrophobic hydration, which is particularly stronger for the B15C5 complexes with Na⁺ and K⁺. The unexpectedly lowest stability of the B15C5- or the 15C5-alkali metal ion complex in water among all the solvents is caused by the hydrogen bonding between ether oxygen atoms of uncomplexed B15C5 or 15C5 and water.     

Extraction of sodium and potassium perchlorates with benzo-18-crown-6 into various organic solvents. Quantitative elucidation of anion effects on the extraction-ability and -selectivity for Na(+) and K(+)

To investigate quantitatively the anion effect on the extraction-ability and -selectivity of benzo-18-crown-6 (B18C6) for alkali metal ions, the constants for overall extraction into various diluents having low dielectric constants (K(ex)) and aqueous ion-pair formation (K(MLA)) of B18C6-sodium and potassium perchlorate 1:1:1 complexes (MLA) were determined at 25 degrees C. The K(ex) value was analyzed by the four fundamental equilibrium constants. The K(MLA) values were determined by applying our established method to this perchlorate extraction system. The K(M(B18C6)A) value of the perchlorate is much larger for K(+) than for Na(+), and is much smaller than that of the picrate. The K(M(B18C6)A) value makes a minor contribution to the magnitude of K(ex) for the perchlorate system, but a major contribution to that for the picrate one. The distribution behavior of the B18C6 1:1:1 complexes with the alkali metal perchlorates follows the regular solution theory. For the diluent with a high dipole moment, however, the 1:1:1 complexes somewhat undergo the dipole-dipole interaction. B18C6 always shows very high extraction selectivity for KClO(4) over NaClO(4), which is determined mostly by the much greater log/(log K(MLA)) value for K(+) than for Na(+). The extraction-ability and -selectivity of B18C6 for Na(+) and K(+) ions with a perchlorate ion were compared with those with a picrate ion in terms of the fundamental equilibrium constants. The K(+) extraction-selectivity of B18C6 over Na(+) for the perchlorate system is superior to that for the picrate one, which is caused largely by the greater log/(log K(K(B18C6)A))-log/(log K(Na(B18C6)A)) value for the perchlorate than for the picrate. The perchlorate system is recommended for extraction separation of K(+) from Na(+).