Second Derivative Spectrophotometric Determination Of The Dissociation Constant Of Covalently-Bound Phenol Red-Polyacrylamide

Abstract

Knowledge of possible variability in the dissociation constant (pKa) among preparations of phenol red-polyacrylamide was needed during development of a fiber optic probe to monitor fetal blood pH. Determination of the pKa through absorbance-wavelength spectra on opaque 50% glycerol suspensions of phenol red-resin required second derivative spectrophotometry. The apparent pKa was 8.0 for both the dye and several batches of its resin derivative. Spectrophotometry of comparable aqueous solutions of phenol red yielded a pKa of 7.78 ± 0.02, at μ=0.25M.     

环糊精衍生物在荧光分析中的应用进展（下）

本文介绍了环糊精衍生物开发概况及目前已或将商品化的环糊精衍生物的合成思路与方法．重点阐述环糊精在荧光分析中的增效作用机理和应用，及环糊精母体和衍生物分析特性的不同．较详细地详述了光活性基团修饰的衍生物的开发和发展远景     

环糊精衍生物在荧光分析中的应用进展（上）

本文介绍环糊精衍生物开发概况及目前已或将商品化的环糊精衍生物的合成思路与方法，重点阐述环糊业在荧光分析中增效作用机理和应用，及环糊精母体和衍生物分析特性的不同，较详细地详述了光活性基团修饰性生物对开发和发展远景。     

Inclusion of Bisphenols by Cyclodextrin Derivatives

Complexation of various kinds of bisphenols (BPs) with cycloheptaamylose(β-cyclodextrin, β-CD) derivatives (β-CD, hydroxyethyl-β-CD (HE-β-CD), 2,6-di-O-methyl-β-CD (DM-β-CD) and polymerised β-CD (L-Poly-β-CD)) was examined fluorimetrically using2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) as a probe. From the inhibitory effectof BPs on the inclusion of 2,6-ANS by the β-CD derivatives, the associationconstants (K_ass) of BPs with the β-CD derivatives were determined.The K_ass values for bisphenol B (BPB) with β-cyclodextrin derivatives except for L-Poly-β-CD were always larger than those for other BPs including bisphenol A (BPA), due to the interaction between the non-polar cavity and hydrophobic BPB. Thermodynamic parameters indicated that the entropy change was always largely negative (-90～ -120 J/mol...K in the β-CD system, for example), and the inclusion of bisphenols into the CD cavity was completely enthalpy-driven. The very largely negative entropy change might be mainly due to the tight fixation of guest molecules in the CD cavity, resulting in the loss of freedom of both CD and guest molecules. The effect of the structure of guest and host molecules on the association was also examined.     

泛昔洛韦解离常数和结合常数的测定

采用紫外分光光度法,在225 nm与305 nm波长处测得泛昔洛韦的解离常数pKa均为3.8.在含有泛昔洛韦的pH值为7.0的Na2HPO4-KH2PO4缓冲溶液中加入牛血清白蛋白,以双倒数公式法测定二者的结合常数.结果表明,牛血清白蛋白与泛昔洛韦形成了1∶4的配合物,其结合常数是4.51×106 L/mol.方法简便,结果可靠。     

酚类衍生物解簇集行为的研究

Aggregation and deaggregation behaviors of the phenol derivatives with a branched hydrocarbon chain have been studied in the CH3OH and buffer solution. Combination with the aggregation number measurement and the cell adhesion experiment, the structure effect on the deaggregating abilities of the target molecules are discussed. The results indicate that 2-phytyl-4-methoxylphenol （11） is the most effective deaggregator in the system studied.     

环糊精诱导胶束形成的TICT荧光探针法研究

环糊精与表面活性剂的相互作用研究已有诸多报导，但主要涉及环糊精与表面活性剂的包络物的稳定常数和其中主客体的化学剂量比［１，２］，至于环糊精对表面活性剂胶束化性质的影响则少见涉猎，这或许与研究方法有关，分子内扭转电荷转移激发态涉及到一个完整的电荷转移，具有很高的极性，其荧光特性显示出显著的介质性质敏感性［３］，因此将ＴＩＣＴ荧光探针法用于环糊精－表面活性剂相互作用研究可能会提供一些新的信息，本文的结     

环糊精衍生物在液相有机合成中的应用

综述了环糊精(包括α-环糊精、β-环糊精和y-环糊精)衍生物在液相有机合成中的应用,主要包括其作为人工合成酶、超分子光学手性源、亲偶极体和微通道反应器在氧化、水解、还原、光催化异构化、1,3-偶极环加成等反应中的应用.其中环糊精衍生物作为人工合成酶应用最广,该催化剂中起催化作用的为环糊精衍生物的修饰基团.与环糊精母体相比,修饰基团的引入增加了环糊精分子中官能团的种类和数量,拓展了环糊精在液相有机合成中的应用,并提高了催化反应的催化活性和选择性.     

环糊精衍生物在金属催化有机合成中的应用

综述了环糊精(包括α-环糊精,β-环糊精和γ-环糊精)衍生物在金属催化有机合成中的应用,主要包括其作为金属离子配体、金属纳米粒子稳定剂和反相相转移催化剂在氧化、水解、还原、偶联等金属催化反应中的应用.其中环糊精衍生物作为金属离子配体应用最广,由于环糊精部分与底物形成包结络合物,拉近了底物和具有催化活性的金属离子的距离,并固定了底物的反应部位,往往可以显著提高催化反应的反应速率,增强反应的区域选择性和对映选择性.     

Gas Chromatographic Separation of Enantiomers on Cyclodextrin Derivatives

In investigations concerned with the phenomenon of molecular chirality, the use of gas chromatography for the enantiomeric analysis of stable, volatile compounds is a technique of steadily growing importance. ^[1] In the last three years an important breakthrough in gas-chro-matographic separation of enantiomers has been achieved by using alkylated cyclodextrins (α, β, and γ) as chiral stationary phases in high-resolution capillary columns. In academic and commercial practice two different and complementary strategies have been adopted up to now. In the first, alkylated cyclodextrins are diluted with polysiloxanes and coated on glass or fused silica capillary columns. In the second, lipophilic per-n-pentylcyclodextrins and hydrophilic di-n-pentyl- and hydroxyalkylpermethylcyclodextrins are coated directly in the form of liquid phases onto suitably pretreated glass or fused silica surfaces. These techniques permit enantiomer separations not only for polar diols and alcohols, derivatized hydroxycarboxylic acids, amino acids, sugars, and alkyl halides, but also for nonpolar alkenes, cyclic saturated hydrocarbons, and metal π complexes. An important aspect for practical applications is that in many cases the enantiomers can be separated without previous derivatization. Whereas the resolution of racemates of unfunctionalized hydrocarbons is attributed to an enantioselective host–guest inclusion complex, some observations indicate that for polar guest molecules additional enantioselective interactions are also involved. The new chiral stationary phases can be used over a wide range of temperatures (25 to 250°C). The technique described is likely to become widely adopted as a simple, accurate and highly sensitive method for the enantiomeric analysis of chiral compounds that can be vaporized without decomposition. It will also stimulate future research aimed at finding universal cyclodextrin phases and elucidating the mechanisms of enantioselectivity.     

Inclusion Behavior of 4-Nonylphenol into Cyclodextrin Derivatives

The solubilities of 4-nonylphenol in five kinds of hydroxypropyl-cyclodextrin (HP-CDs) solutions were investigated in order to evaluate them for soil remediation. The relative aqueous-phase concentration of 4-nonylphenol linearly increased with the increasing HP-CD concentration. The addition of HP-beta-CD (degree of substitution, D.S.=0.6) produced the largest change because the inner core of HP-beta-CD is the most hydrophobic. The solubility of 4-nonylphenol in the HP-CD solutions depended upon the cavity diameter and the degree of HP-CD substitution. Both ozone and activated carbon treatments have been using for removing organic compounds and foul odor compounds from tap water. As the inclusion complexes moved into the groundwater, the ozone degradation of the inclusion complexes was estimated. The 4-nonylphenol-HP-CD inclusion complexes were easily degraded by ozone. The degree of degradation increased with the increasing ozonization time. Weakly acidic compounds were produced from the 4-nonylphenol-HP-CD inclusion complexes by ozonization. HP-CDs could be used for the removal of 4-nonylphenol from soil. Copyright 2001 Academic Press.     

Characterization of Some Cyclodextrin Derivatives by Thermal Analysis

Acetyl-cyclodextrins, maltosyl-β-cyclodextrin, methyl-β-cyclodextrin and hydroxypropyl-cyclodextrins were characterized from data obtained with hot stage microscopy, differential scanning calorimetry and thermogravimetry. Phase transformation processes were studied by thermomicroscopy. Enthalpy values of dehydration processes have been explained with the different chemical composition of the substituent groups of cyclodextrins. This revised version was published online in August 2006 with corrections to the Cover Date.     

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.     

荧光各向异性法研究环糊精包络物

推导了用荧光各向异性法测定环糊精包络物平衡结合常数的方程式,并用于测定芘-β-环糊精包络物的结合常数,获得了满意的结果,依据推得的方程式并结合各向异性～环糊精浓度曲线讨论了环糊精包络物存在形式及主-客体作用方式,预计了以蔡衍生物为配体的金属离子分析方法应用β-环糊精的可能性。     

Cocrystal Phenomena of DABCO with Phenol Derivatives

It has been reported that 1,4-diazabicyclo[2,2,2] octane(DABCO) can form complexed crystals with lithium alkals. Our experimental results show that DABCO can also form cocrystals with phenol derivatives such as phenol(2), o-cresol(3), m-cresol(4), p-cresol(5), p-chlorophenol(6), and p-nitrophenol(7). The separa-     

吖啶类衍生物的荧光性质

用比较法测得23种啶类衍生物的荧光量子效率（Φf)，以评估这些化合物的荧光性质，结果表明，N－烃基吖啶酮类化合物的荧光量子效率要比9－取代苯基吖啶类和9－取代苯亚甲基－10－甲基－9，10－二氢吖啶类化合物的荧光量子效率大，在非极性溶剂中，9－聚代苯亚甲基－9，10二氢吖啶分子内的强吸电子基NO2增强荧光量子效率，强推电子基OCH3降低荧光量子效率，这些测量结果与取代基的电子作用经验规律不相符，这种现象可以用分子内电荷转移理论进行解释。     

间氯偶氮安替比林的纯化鉴定及其离解常数和质子化常数的测定

本文研究提出了适合于新显色剂间氯偶氮安替比林的纯化新方法,经该方法纯化后的试剂在纸色谱图上仅有一个斑点,元素分析结果也令人满意。经过元素分析、热重分析和红外吸收光谱的测定,进一步确定了试剂的组成和结构。首次用光度法测定了试剂的离解常数(pKa=7.35±0.03)和质子化常数(1ogKp=-3.50±0.17)。     

Solvent Extraction of Alkali Metal Picrates by Lipophilic Cyclodextrin Derivatives

Lipophilic cyclodextrin (CD) derivatives were prepared to extract alkali metal cations from a water phase into an organic phase. The extraction equilibrium constant, K ex, was determined by the solvent extraction method using UV absorption spectroscopy. Hydroxyl groups at the carbons in the 2,6-positions of CD molecules were dipropylated to add the hydrophobicity for dissolving into organic solvents, and furthermore hydroxyl groups at the carbons in the 3-position of these derivatives were acylated as complexing sites with the alkali metal cations. These CD derivatives formed a 1 : 1 complex with alkali metal cations, except for the case of Li+, and transported the alkali metal cations from a water phase into a benzene phase. The initial concentrations of alkali metal cation and picrate anion in the water phase and that of the CD derivatives in the organic phase strongly influenced the extraction equilibrium. Extraction of the alkali metal cation by the derivative without acyl groups was not detected. K ex values of these CD derivatives are of the same order of magnitude as or larger than those of crown ethers. The order of the K ex values in all cases is Li+ < Na+ < K+ Rb+ Cs+, although these CD derivatives have no special selectivity for the alkali metal cations. The cation extraction mechanism was interpreted by an induced-fit mechanism.     

弱碱性阴离子交换树脂的本征解离常数

根据Donnan膜平衡模型及外推法提出弱碱性阴离子交换树脂本征解离常数的测定方法。并测得大孔丙烯酸系弱碱性阴离子树脂D705的本征解离常数的负对数pK_b~(int)为3.72士0.04,结果表明,Marinsky在测弱酸性阳离子树脂的pK_a~(int)时,引入交换剂相中H~+及Na~+的活度系数相等的假定并非必要。     

离子色谱法测定一元弱酸的离解常数

本文探索了抑制电导离子色谱法测定pK_a<7的一元弱酸的离解常数,对以HCl为标准测定HF、HNO_2的离解常数和以HF为标准测定乳酸、乙酸和甲酸的离解常数及测定方法的主要误差来源进行了讨论。