螯合萃取和协同萃取的溶剂效应

本文测定了1-苯基-3-甲基-4-苯甲酰基吡唑啉酮-5(HPZL)-Zn²⁺萃取体系在不同溶剂中的萃取平衡常数以及其他几个协萃体系的协萃平衡常数,结果列于表4～8.证实惰性溶剂对萃取平衡常数的影响可以近似地用正规溶液理论解释,非惰性溶剂的影响则和它们的配位作用有关.对于协萃体系,协萃平衡常数β_n0k⁰随溶剂不同有很大变化,其中中性协萃剂活度系数的变化起重要作用.     

葫芦[7]脲与紫精和香豆素修饰树枝形分子的分步结合及对体系发光性质的调控

合成了外围修饰香豆素PAMAM树枝形分子Gm-2(m+1)C, 外围和核心分别共价连接香豆素和紫精的树枝形分子EV-Gm-2(m+1)C (m=0, 1), 以及香豆素和紫精的模型化合物C-Model和EV, 化合物均通过了¹H NMR, IR和MALDI-TOF MS的鉴定. ¹H NMR和光物理研究结果表明, 在pH=4.5的醋酸-醋酸钠缓冲溶液中, CB[7]与紫精和树枝形分子外围的香豆素基团均可形成1:1的包结复合物, 结合常数分别为3.3×10⁶ mol^-1·L和1.4～1.6×10⁵ mol^-1·L. 香豆素基团中7位二乙氨基及取代侧部分香豆素环包裹在CB[7]刚性的疏水空腔内, 包结复合物的形成限制了香豆素7位N,N'-二乙氨基的扭转, 抑制了香豆素基团从发光的分子内电荷转移(ICT)态向不发光的扭曲的分子内电荷转移(TICT)态的转变, 而且CB[7]内腔的疏水环境有利于香豆素ICT态辐射跃迁, 使体系发光大大增强. EV-Gm-2(m+1)C与CB[7]的主客体作用为分步结合机制, 加入的CB[7]先与紫精基团作用形成包结复合物, 待体系中紫精基团与CB[7]结合后, 体系中香豆素基团再与CB[7]作用形成包结复合物. 无论是Gm-2(m+1)C还是EV-Gm-2(m+1)C体系, 均可以通过加入CB[7]的量调节体系中香豆素基团与CB[7]形成包结复合物的多少, 从而实现对Gm-2(m+1)C和EV-Gm-2(m+1)C体系发光的调控. 本工作为可调控发光树枝形聚合物的发展提供了一种新的策略.     

反相胶束中能量由C-藻蓝蛋白向金属酞菁的传递

利用藻类天线的C 藻蓝蛋白和锌酞菁络合物建立一种新的光合器模拟体系 .C 藻蓝蛋白通过总浓度 2 0 % (质量体积比 )的非离子型表面活性剂Tween 80和助表面活性剂正戊醇 (Tween 80∶正戊醇 =4∶1 ,质量比 )与环己烷形成反相胶束增溶 .当 [H2 O]/[Tween 80 ](Rw)≥ 9.0时 ,C 藻蓝蛋白的活性得到保持 .当激发C 藻蓝蛋白时 ,能量由C 藻蓝蛋白传递给酞菁 .能量传递效率与C 藻蓝蛋白的浓度无关 ,而仅与酞菁浓度有关 ,并且近似遵循Perrin公式 .证明能量传递属于刚性体系中的偶极 偶极作用机制 .通过计算得出不同酞菁浓度下的猝灭范界半径 .例如 ,当酞菁浓度为 2 .1 0× 1 0 -4 mol/L时 ,体系的猝灭范界半径为 1 0 .9nm .     

平衡态近似及其与稳定态近似的关系

对平衡态近似作了简述,表明它与稳定态近似是两种不同的处理方法。当平衡常数K 1时,平衡态近似是稳定态近似的一个特例。两种近似可以归纳成一个统一的反应速率方程,它具有更广的适用范围。     

无溶剂酶促合成癸酸偏甘油酯的热力学和动力学

以Candida antarctic脂肪酶（CAL）为催化剂,对无溶剂微水体系中癸酸与甘油酯化反应的热力学平衡和动力学行为进行研究。用平板冷却猝灭法观察反应体系的初始相态。反应物猝灭态照片表明,相间传质与反应物分散状态有关;酶粒表面局部癸酸浓度相对过剩于界面相浓度。在无溶剂体系中癸酸和甘油的酶促反应不符合Ping-Pong Bi-Bi机制。敞开物体系中单、二、三酯形成的表观热力学平衡方程为：[C]0N[C]/[M]=1/K1 [C] K2[C]^2 K2K3[C]^3,其中[C]0为癸酸的初始摩尔数,[C]为反应物中癸酸的摩尔数,N为甘油与癸酸的初始摩尔比,[M]为反应物中癸酸单甘酯的摩尔数;K1、K2、K3分别为单、二、三酯形成的表观热力学平衡常数：K1＝0.103mmol^-1,K2=0.055mmol/^-1,K3=0.004mmol^-1。     

高效液相钴离子催化化学发光抑制法测定茶叶中的茶氨酸

 研究了用高效液相分离、抑制化学发光测定茶叶中茶氨酸的分析方法。该法采用YWG C18(10μm,250mm×5 0mmi d )柱,以0 01mol·L-1醋酸钠 醋酸缓冲液(pH5 5)为流动相,流速为0 8mL·min-1。对茶氨酸抑制Co2+催化鲁米诺(luminol)与过氧化氢(H2O2)化学发光反应的条件进行了优化:Co2+的质量浓度为2μg·L-1,鲁米诺浓度为0 25mmol·L-1,H2O2浓度为0 5mmol·L-1。在茶氨酸的质量浓度为0 2g·L-1～5 0g·L-1时,茶氨酸抑制化学发光产生负峰的相对峰面积Y(将实际峰面积缩小至万分之一)与其质量浓度X(kg·L-1)的线性回归方程为Y=33862X+1 0605(r=0 9983)。     

咪唑键合细胞色素C的核磁共振共振研究

我们用^1HNMR双共振技术测定了在pH=7.04,温度303-319K范围内咪唑键合氧化型细胞色素C的平衡常数,从Van'tHoff和Arrhenius方程得到键合的热力学常数△H=48.5kj·mol^-1,△S°=184J·mol^-1·K^-1和活化能E~a=159kj·mol^-1,并与其它血红素蛋白和模型化合物的热力学常数作了比较和讨论.用饱和转移法归属了cytc·Im的血红素环上甲基峰,首次用NMR方法确证咪唑在与氧化型cytc反应中取代了轴向Met80,形成新的Fe-N键.     

咪唑键合细胞色素C的核磁共振共振研究

我们用^1HNMR双共振技术测定了在pH=7.04,温度303-319K范围内咪唑键合氧化型细胞色素C的平衡常数,从Van'tHoff和Arrhenius方程得到键合的热力学常数△H=48.5kj·mol^-1,△S°=184J·mol^-1·K^-1和活化能E~a=159kj·mol^-1,并与其它血红素蛋白和模型化合物的热力学常数作了比较和讨论.用饱和转移法归属了cytc·Im的血红素环上甲基峰,首次用NMR方法确证咪唑在与氧化型cytc反应中取代了轴向Met80,形成新的Fe-N键.     

在非平衡态热力学的基础上探索建立催化理论的新途径

平衡态热力学一直被认作多相催化理论的基石之一.但是,它并不能概括工作中的催化剂的状态和行为,这主要是这里还发生一些非平衡过程.催化体系常常处于非平衡状态之下,而非平衡态条件下体系的状态和行为,同时取决于体系的动力学和热力学.联系动力学和热力学最一般的关系式并非原来的DeDonder不等式:Ar≥0,而是新的De Donder方程ln r/ r=A/RT.同时发生的总反应之间的热力学耦合对总反应的作用只是形式上的,远不及催化反应链中各基元步骤之间在动力学上的耦合那么重要.通过在动力学方程中引入反应亲和力(热力学位)得到的动力学-热力学结合近似分析,可以用来分析非平衡态的催化反应和催化剂状态.非平衡态热力学在建立多相催化理论中,较之原来的平衡态热力学将能提供更能采纳的和更有意义的物理化学背景.     

四元交互体系Li~ ,Na~ //CO_3~(2-),B_4O_7~(2-)-H_2O 298K相关系的理论预测及实验研究

采用三元体系的溶解度数据 ,运用多元线性回归法拟合了 Li2 CO3(a) ,Na2 CO3(b) ,Li2 B4O7(c)的单盐参数、溶解平衡常数及有关的混合离子作用参数 .它们的值分别为 :β(0 )a =-1 .2 3 5 5 ,β(1)a =-2 .65 46,Ca=-0 .0 0 4660 7,β(0 )b =-3 .0 3 0 6,β(1)b =-3 .0 2 3 8,Cb=-0 .2 90 89,β(0 )c =-0 .2 93 0 4,β(1)c =2 .1 5 5 6,Cc=-0 .0 0 42 5 60 ,θL i,Na=1 .0 41 8,θB,C=-2 .63 0 5 ,ΨL i,Na,C=-0 .0 63 91 ,ΨL i,Na,B=0 .493 5 6,ΨL i,B,C=-0 .47842 ,ΨNa,B,C=0 .3 0 61 6,ln K(Li2 CO3) =-8.962 9,ln K(Na2 CO3· 1 0 H2 O) =3 .0 64 6,ln K(Li2 B4O7·3 H2 O) =-7.3 5 66,ln K(Na2 B4O7· 1 0 H2 O) =-7.4778.以盐的溶解平衡常数为判据 ,运用 Pitzer方程计算了四元体系 Li ,Na //CO2 -3,B4O2 -7-H2 O 2 98K时的溶解度 ,并采用等温溶解平衡法 ,对该体系 2 98K时溶解度进行了实验测定 ,同计算值相比 ,二者基本吻合     

Rotational spectra and properties of complexes B···ICF3 (B = Kr or CO) and a comparison of the efficacy of ICl and ICF3 as iodine donors in halogen bond formation

The ground-state rotational spectra of two weakly bound complexes B···ICF(3) (B = Kr or CO) formed by trifluoroiodomethane have been observed in pulsed jets by using two types of Fourier-transform microwave spectroscopy (chirped-pulse and Fabry-Perot cavity). Both complexes exhibit symmetric-top type spectra, thus indicating that the Kr atom in Kr···ICF(3) and both the C and O atoms in OC···ICF(3) lie along the C(3) axis of ICF(3). The rotational constant B(0), the centrifugal distortion constants D(J) and D(JK), and the iodine nuclear quadrupole coupling constant χ(aa)(I) were determined for each of the isotopologues (84)Kr···ICF(3), (86)Kr···ICF(3), (16)O(12)C···ICF(3), (16)O(13)C···ICF(3), and (18)O(12)C···ICF(3). Interpretation of the spectroscopic constants reveals that the carbon atom of CO is adjacent to I and participates in the weak bond in OC···ICF(3). Simple models based on unperturbed component geometries lead to the distances r(Kr···I) = 3.830(1) ? and r(C···I) = 3.428(1) ? in Kr···ICF(3) and OC···ICF(3), respectively, and to the quadratic force constants for stretching of the weak bond k(σ) = 2.80 N m(-1) and 3.96 N m(-1), respectively. The distances r(Z···I) (Z is the acceptor atom in B), the k(σ) values, and the angular geometries of the pair of complexes B···ICF(3) and B···ICl for a given B are compared when B = Kr, CO, H(2)O, H(2)S, or NH(3). The comparison reveals that the iodine bond in B···ICF(3) is systematically longer and weaker than that of B···ICl, while the angular geometry of the B···I moiety is isomorphic in B···ICF(3) and B···ICl for a given B. It is concluded that -CF(3) is less effective than -Cl as an electron-withdrawing group when attached to an I atom and that the angular geometries of the B···ICF(3) can be predicted by means of a simple rule that holds for many hydrogen- and halogen-bonded complexes.     

Homopolar dihydrogen bonding in alkali-metal amidoboranes and its implications for hydrogen storage

The solid-state structures of LiNH(2)BH(3) and NaNH(2)BH(3) have been shown recently to exhibit intricate M(δ+)···(δ-)H-B and N-H(δ+)···(δ-)H-B interactions. However, closer inspection of these structures reveals additional homopolar H···H interactions, viz., B-H(δ-)···(δ-)H-B and N-H(δ+)···(δ+)H-N, which contribute to the relative stability of the extended structures of these crystalline materials. In addition, an NMR study of the isotopomer LiND(2)BH(3) shows that a significant quantity of H(2) is desorbed thermally along with HD, which can only arise from hydride-hydride interactions, either directly from B-H(δ-)···(δ-)H-B moieties or indirectly through the participation of Li-H intermediates.     

硼钼杂多酸-罗丹明B缔合显色反应的研究与应用

研究了在聚乙烯醇存在下 ,罗丹明 B( RDB)与硼钼杂多酸的离子缔合显色反应。在合适的硫酸介质环境下 ,形成硼钼杂多酸 ,再与 RDB形成离子缔合物 ,其 λmax=570 nm,ε570 =1 .0× 1 0 5L· mol-1· cm-1,硼浓度范围在 0～1 .2μg/2 5m L符合比尔定律。用等摩尔连续变化法 ,平衡移动法确定 B∶ Mo∶RDB=1∶ 7∶ 4。方法已用于添加硼烧结矿中微量全硼的测定     

阳离子表面活性单体DMOHAC的合成及其胶束化行为

以环氧氯丙烷、丙烯酰胺及N,N-二甲基十八烷基叔胺为原料,经开环和季铵化两步反应合成了新型阳离子表面活性单体,N,N-二甲基十八烷基(2-羟基-3-丙烯酰胺丙基)氯化铵（DMOHAC, 1）,其结构经FT-IR表征。用TG和摩尔电导率法研究了1的热稳定性和1、十八烷基三甲基氯化铵(OTAC)、1/OTAC混合胶束的CMC值。结果表明：1的热稳定性能良好,1和OTAC的CMC值分别为0.10 mmol·L^-1和0.33 mmol·L^-1。当n（1）: n（OTAC）=2 : 1时,1/OTAC混合胶束的CMC值为0.12 mmol·L^-1;当n（1）: n（OTAC）=1 : 2时,1/OTAC混合胶束的CMC值为0.21 mmol·L^-1。1/OTAC混合胶束的CMC值介于1和OTAC之间。     

Molecular interactions between pyrazine and n-propanol, chloroform, or tetrahydrofuran

The molecular interactions of pyrazine (PZ) with n-propanol, chloroform, and tetrahydrofuran (THF) have been investigated by employing ultraviolet spectroscopy and quantum chemical calculation methods. A new quantity, excess absorption coefficient, was introduced to represent the strength of the interaction. It was found that the interaction decreased in the order: PZ-propanol>PZ-chloroform>PZ-THF. The Benesi-Hildebrand method indicated that the interaction stoichiometries of the PZ-chloroform and PZ-THF systems were both 1:1 and the equilibrium constants were determined to be 2.07 and 0.64M(-1), respectively. Using a nonlinear fitting method, we demonstrated that the PZ-propanol was a two-step 1:2 interaction pair and the equilibrium constants were determined to be 8.8 and 0.19M(-1). Quantum chemical calculations showed the existence of hydrogen-bonding interactions in all the three system: normal Ncdots, three dots, centeredH-O hydrogen bond in the PZ-propanol system, unconventional Ncdots, three dots, centeredH-C hydrogen bond in the PZ-chloroform, and weak N-C-Hcdots, three dots, centeredO hydrogen bond in the PZ-THF system. Methodologically, we pointed out that special care must be taken when the Benesi-Hildebrand method is used to evaluate 1:2 interactions.     

四元交互体系Li+，K+/CL-，CO2-3-H2O在298 K时相平衡及物理化学性质研究

Zabuye Saline Lake, Tibet, China, is unrivalled in the world for its very high salinity, in particular, for the very high concentration of ions of lithium, potassium, and boron in the brine. It belongs to alkaline and carbonate-borate-type salt lake. As a part of the study on phase equilibrium of the 6component subsystem Li+, Na+, K+/C1-, CO2-3, B4O2-7-H2O of the brine system, a study on the reciprocal quaternary system Li+, K+/C1-, CO32-H2O at 298 K was done with isothermal dissolution equilibrium method in the present work. The phase equilibrium of the reciprocal quaternary system Li+,K+/C1, CO2-3-H2O at 298 K was studied with isothermal dissolution method in this work. The physicochemistry properties of the corresponding equilibrium solutions such as densities, viscosities, refractive index, conductivities and pH value were determined. The dried salt diagram of the system consists of four crystallization fields (KC1, Li2CO3, LiCI·H2O, K2CO3·3/2H2O) and five isothermal solubility curves.There are no double slat or solid solution found. Pitzer′s model of the electrolyte solution theory was used for parameterization from the results of solubility determination for subsystems and the prediction of solubilities for the reciprocal quaternary system was made. The solubility data of the experiment are in agreement with those calculated.     

大环三胺1,4,7-三氮杂环癸烷锌(Ⅱ)配合物催化水解作用研究

在25℃、离子强度I=0.10(KNO3)条件下,采用pH电位滴定法测定了大环三胺配体1,4,7-三氮杂环癸烷(TACD)与Zn(Ⅱ)离子的配位平衡常数,讨论了配体与金属离子的配位情况.利用分光光度法,在pH=7～9范围内[2×10-4mol.L-1三羟甲基氨基甲烷(tris)为缓冲溶液]研究了配合物在对硝基苯酚乙酸酯(NA)水解中的催化动力学行为,得到了NA酯的水解速率常数kcat.结果表明,催化水解速率对底物(NA)及配合物浓度均呈一级反应,水解反应遵循速率方程v=(kcat.cZn2++kOH-.cOH-+…).在中性和弱碱性条件下,配合物对NA酯的水解具有很好的催化作用,当pH=9.19时,催化速率常数达3.420×10-2mol-1.L.s-1;催化反应受酸碱平衡控制.     

Microwave measurements of proton tunneling and structural parameters for the propiolic acid-formic acid dimer

Microwave spectra of the propiolic acid-formic acid doubly hydrogen bonded complex were measured in the 1 GHz to 21 GHz range using four different Fourier transform spectrometers. Rotational spectra for seven isotopologues were obtained. For the parent isotopologue, a total of 138 a-dipole transitions and 28 b-dipole transitions were measured for which the a-dipole transitions exhibited splittings of a few MHz into pairs of lines and the b-type dipole transitions were split by ~580 MHz. The transitions assigned to this complex were fit to obtain rotational and distortion constants for both tunneling levels: A(0+) = 6005.289(8), B(0+) = 930.553(8), C(0+) = 803.9948(6) MHz, Δ(0+)(J) = 0.075(1), Δ(0+)(JK) = 0.71(1), and δ(0+)(j) = -0.010(1) kHz and A(0-) = 6005.275(8), B(0-) = 930.546(8), C(0-) = 803.9907(5) MHz, Δ(0-)(J) = 0.076(1), Δ(0-)(JK) = 0.70(2), and δ(0-)(j) = -0.008(1) kHz. Double resonance experiments were used on some transitions to verify assignments and to obtain splittings for cases when the b-dipole transitions were difficult to measure. The experimental difference in energy between the two tunneling states is 291.428(5) MHz for proton-proton exchange and 3.35(2) MHz for the deuterium-deuterium exchange. The vibration-rotation coupling constant between the two levels, F(ab), is 120.7(2) MHz for the proton-proton exchange. With one deuterium atom substituted in either of the hydrogen-bonding protons, the tunneling splittings were not observed for a-dipole transitions, supporting the assignment of the splitting to the concerted proton tunneling motion. The spectra were obtained using three Flygare-Balle type spectrometers and one chirped-pulse machine at the University of Virginia. Rotational constants and centrifugal distortion constants were obtained for HCOOH···HOOCCCH, H(13)COOH···HOOCCCH, HCOOD···HOOCCCH, HCOOH···DOOCCCH, HCOOD···DOOCCCH, DCOOH···HOOCCCH, and DCOOD···HOOCCCH. High-level ab initio calculations provided initial rotational constants for the complex, structural parameters, and some details of the proton tunneling potential energy surface. A least squares fit to the isotopic data reveals a planar structure that is slightly asymmetric in the OH distances. The formic OH···O propiolic hydrogen bond length is 1.8 ? and the propiolic OH···O formic hydrogen bond length is 1.6 ?, for the equilibrium configuration. The magnitude of the dipole moment was experimentally determined to be 1.95(3) × 10(-30) C m (0.584(8) D) for the 0(+) states and 1.92(5) × 10(-30) C m (0.576(14) D) for the 0(-) states.     

β-环糊精对氯诺昔康的包合作用

采用荧光光谱、差热扫描和核磁共振法研究了不同酸度和温度下β-环糊精（β-CD）、羟丙基β-环糊精（HP-β-CD）和磺丁醚β-环糊精（SBE-β-CD）对氯诺昔康（LX）的包合特性。 结果表明,3种环糊精与氯诺昔康均形成1∶1的包合物。 以包合常数作为包合稳定性的量度,包合稳定性为SBE-β-CD＞HP-β-CD＞β-CD。     

透析-高效液相色谱-氢化物发生-原子荧光光谱联用系统研究无机砷与牛血清白蛋白的结合平衡

采用透析-高效液相色谱-氢化物发生-原子荧光光谱联用法研究了生理pH(7.4)条件下As(Ⅲ)或/和As(Ⅴ)与牛血清白蛋白的结合平衡模型. 当As(Ⅲ)浓度[cAs(Ⅲ)∶cBSA≤1∶1]较低时, As(Ⅲ)与BSA的结合符合Scatchard模型, 在BSA中有1.4个强结合部位, 结合常数为1.7×106; 当As(Ⅲ)的浓度[cAs(Ⅲ)∶cBSA≥2∶1]较高时, 符合Plasvento的相分配模型, 没有明显的特征结合点, 而As(Ⅴ)与BSA无任何结合作用. 研究了HCl和KBH4的浓度和流速等对色谱分离的影响, 并对检测器参数等实验条件进行了优化, 使不同价态无机砷在10 min内达到良好的基线分离, As(Ⅲ) 和As(Ⅴ)的检测限分别为2.89和6.38 ng/L.