Correlation between Chromatograph Capacity Factors and Structural Parameters of Indole Derivatives

1 INTRODUCTION thods with which the retention factor of a series of compounds could be predicted accurately[1, . In 2] The capacity factor of reversed phased high per- addition, indole and its derivatives have been widely formance liquid chromatograph (RP-HPLC) is a used in the synthesis of medical intermediate, co- basis for quantifying chromatograph peaks and se- loring agent and pesticide etc. Dai et al. have repor- parating compounds. And it has been universally ac- ted the relation…     

气液色谱法研究Ni[(C8H17)O)2PS2]2与脂肪胺加合反应的热力学性质

The equilibium constants of acid-base interaction between Mi(Octyl_dtp)_2 and alkylamine were determined by GLC method at several temperatures. Thermodynamic parameters △H and △S were evaluted as follows:ethylamine: △H=-11.5kJ mol~(-1) △S=-22.7J K~(-1) mol~(-1)diethylamine: △H=-18.1kJ mol~(-1) △S=-42.1J K~(-1) mol~(-1)The variations of logK versus temperature fit following equations:ethylamine: lgK=-1.19+598.9/Tdiethylamine: lgK=-2.20+945.6/T     

Prediction of the lipophilicity of nine new synthesized selenazoly and three aroyl-hydrazinoselenazoles derivatives by reversed-phase high performance thin-layer chromatography

Using reversed-phase high-performance thin-layer chromatography and a methanol-water mixture as the mobile phase, the lipophilicity of 12 new synthesized derivatives is studied. The first eight compounds have as a basic chemical structure aryliden-hydrazino-selenazoles, and the second group of the three compounds belongs to aroyl-hydrazinoselenazoles. The linear correlation between R(Mw) and the methanol-water ratios showed high values for the correlation coefficient. The chromatographic hydrophobic index is determined by using the ratio -R(Mw)/S, and the obtained values ranged between 99 and 73. A good linear correlation is obtained between R(Mw) and the slope. The log P values are calculated using ACD/Labs Software. The matrices are formed with R(Mw) and log P and are subjected to a principal component analysis (PCA). The best way to extract information from PCA is graphically, by plotting the obtained matrices. By analyzing the scores, the compounds can be grouped as follows: a group containing nine compounds, and a second one containing three compounds. Each group of compounds has the same basic chemical structure.     

A QSRR Study on the Relative Retention Time of Halogenated Methyl-phenyl Ethers

1 INTRODUCTION Halogenated methyl-phenyl ethers (anisoles) are ubiquitous organic compounds in the environment. There are 134 possible congeners consisting of 19 chloroanisoles, 19 bromoanisoles and 96 bromo- chloroanisoles. Although they are not produced…     

高氯酸铊-18冠6-水体系的核磁共振研究

本文用核磁共振法测定了高氯酸铊-18冠6-水体系的各个热力学参数.该体系的络合稳定常数、热焓、熵和吉氏函数在25.1℃时的数值分别为:lgK=2.11±0.02、△H=-4.49±0.17kcal/mol、△S=-5.35±0.54cal/mol和△G⁰=-2.88kcal/mol。所得结果与用量热法测得的数值一致。     

Marine natural products: Deodactol,antineoplastic sesquiterpenoid from the sea hare aplysia dactylomela

Deodactol, a halogenated bisabolene-type sesquiterpene alcohol, has been isolated from the sea hare Aplysia dactylomela, and its structure and absolute configuration have been determined by X-ray diffraction. The compound crystallizes in the monoclinic system with the following crystal data: a=6.723(2), b = 11.838(1), c= 10.962(2) Å, β=99.41(2)°, V= 860.7; ?x= 1.669 g cm^?3 at ?135±2°C; space group P2₁. The structure was solved by the heavy-atom method from 3-dimensional diffractometer data collected at ?135±2°C using CuK_α radiation. The final R factor for 1854 reflections is 0.029. The absolute configuration of the molecule was determined by the “R Method” of Hamilton. Deodactol has a strong intramolecular OHO hydrogen bond bridging its tetrahydropyranyl and cyclohexanol rings. The alcohol shows moderate cytotoxic activity. The absolute configuration of deodactol corresponds to that of several halogenated chamigrenes and supports the proposed biogenetic hypothesis linking halogenated bisabolenes and chamigrenes.     

Correlation of Quantitative Structure and Inhibition Phytotoxicity for Aromatic Compounds Using Ab Initio Method

1 INTRODUCTION Quantitative structure-activity relationship (QSAR) is one of the necessary methods to evaluate the ha- zards of organic chemicals. QSAR equation could be employed to forecast the biological activity of un- known compounds, which is significant for initial screening and evaluation of toxic compounds[1]. Aro- matic compounds are toxic organic compounds with relatively low water solubility, and their structure- activity relationship has been investigated with AM1 method[2]…     

DFT calculations of the electric field gradient at the tin nucleus as a support of structural interpretation by 119Sn Mössbauer spectroscopy

DFT calculations, using an all-electron basis set and with full geometry optimization, were performed on 34 Sn(II) and Sn(IV) compounds of known structure and (119)Sn M?ssbauer parameters, to obtain the theoretical values of the electric field gradient components, V(xx), V(yy), and V(zz), at the tin nucleus. These were used to determine the quantity V = V(zz)[1+ 1/3((V(xx) - V(yy))/((V(zz))(2)](1/2), for each investigated compound, which is related to the quadrupole splitting (DeltaE) parameter according to DeltaE = 1/2eQV, where e is the electronic charge and Q is the quadrupole moment of the tin nucleus. The linear fitting of the correlation plot of the experimental DeltaE, versus the corresponding calculated V values, produced a slope that is equal to 0.93 +/- 0.03 and a correlation coefficient R = 0.982. The value of Q obtained, 15.2 +/- 4.4 fm(2), is in agreement with that previously experimentally determined or calculated by analogous procedures. The calculation method is able to establish the sign of the electric field gradient component V(zz), in agreement with the sign of DeltaE determined experimentally by M?ssbauer-Zeeman spectroscopy. The calculated structural parameters are in good agreement with the corresponding experimental data, determined by X-ray crystallography in the solid state, with average structural deviations of about 3 % for bond lengths and angles in the tin environment. Calculated values of DeltaE were obtained from the calibration fitting constant and from the values of V. By comparing experimental and calculated DeltaE parameters, the structure assignment of configurational isomers was successful in two test cases, in agreement with the experimental X-ray crystallographic structures. These results indicate that the method can be used as a tool to support the routine structure interpretation of tin compounds by (119)Sn M?ssbauer spectroscopy.     

稀土离子与乳铁蛋白结合的光谱研究

用紫外示差光谱、荧光光谱及圆二色谱等方法研究了Tb³⁺和Eu³⁺在pH7.4的条件下与乳铁蛋白及脱铁乳铁蛋白的结合作用.结果表明,Tb³⁺及Eu³⁺可特异性地结合在脱铁乳铁蛋白的两个Fe³⁺结合部位,但不能从已经结合铁的乳铁蛋白中把铁置换出来.测得Tb³⁺ 与这两个部位结合的条件平衡常数为lgK₁=8.48±0.24和lgK₂=6.72±0.18(25℃,0.10mol/L NaCl, 0.10mol/LHepes,pH=7.4). Tb³⁺在这两个位点结合时,蛋白质的构象发生变化.在 Tb³⁺ 与蛋白质的浓度比低时,构象趋于紧缩,色氨酸残基进入疏水的环境;当Tb³⁺结合得较多时,构象转而开放,色氨酸残基转向亲水性环境.但无论哪种情况,Tb³⁺与脱铁乳铁蛋白的结合都不影响蛋白的二级结构.     

Molecular Distance‐Edge Vector (μ) and Chromatographic Retention Index of Alkanes

A new method of quantitative structure‐retention relationship (QSRR) is proposed for estimating and predicting gas chromatographic retention indices of alkanes by using a novel molecular distance‐edge vector, called μ vector, containing 10 elements. The QSRR model (Ml), between the μ vector and chromatographic retention indices of 64 alkanes, was developed by using multiple linear regression (MLR) with the correlation coefficient being R = 0.9992 and the root mean square (RMS) error between the estimated and measured retention indices being RMS = 5.938. In order to explain the equation stability and prediction abilities of the M1 model, it is essential to perform a cross‐validation (CV) procedure. Satisfactory CV results have been obtained by using one external predicted sample every time with the average correlation coefficient being R = 0.9988 and average RMS = 7.128. If 21 compounds, about one third drawn from all 64 alkanes, construct an external prediction set and the 43 remaining construct an internal calibration set, the second QSRR model (M2) can be created by using calibration set data with statistics being R = 0.9993 and RMS = 5.796. The chromatographic retention indices of 21 compounds in the external testing set can be predicted by the M2 model and good prediction results are obtained with R = 0.9988 and RMS = 6.508.     

单取代烷烃定量结构-保留相关研究中的分子结构分区处理方法

将单取代烷烃RX(X=卤素,OH,SH,NH2等)分子结构分为两个区域(R和X)来提取分子结构参数,从三方面影响因素(烷基R、取代基X、R与X的相互作用)来定量关联RX的气相色谱保留时间。实验测定了37种单取代烷烃RX的气相色谱保留时间,并以键连接矩阵特征根之和EVM、烷基极化效应指数PEI、取代基质量分数w和取代基上氢原子所带部分正电荷ΔNH 4个参数为变量,建立了定量结构-保留相关模型。该模型具有良好的预测能力和外推能力,对醇在不同色谱柱上的保留指数进行了预测,结果与测定值符合得较好。     

3‐(2‐Bromoacetamido)‐N‐(9‐ethyl‐9H)‐carbazol fluorescent probe and its application for the determination of thiophenols in rubber products by HPLC with fluorescence detection and atmospheric chemical ionization mass spectrometry identification

A rapid, sensitive, and selective precolumn derivatization method for the simultaneous determination of eight thiophenols using 3‐(2‐bromoacetamido)‐N‐(9‐ethyl‐9H )‐carbazol as a labeling reagent by high‐performance liquid chromatography with fluorescence detection has been developed. The labeling reagent reacted with thiophenols at 50°C for 50 min in aqueous acetonitrile in the presence of borate buffer (0.10 mol/L, pH 11.2) to give high yields of thiophenol derivatives. The derivatives were identified by online postcolumn mass spectrometry. The collision‐induced dissociation spectra for thiophenol derivatives gave the corresponding specific fragment ions at m/z 251.3, 223.3, 210.9, 195.8, and 181.9. At the same time, derivatives exhibited intense fluorescence with an excitation maximum at λ_ex = 276 nm and an emission maximum at λ_em = 385 nm. Excellent linear responses were observed for all analytes over the range of 0.033–6.66 μmol/L with correlation coefficients of more than 0.9997. Detection limits were in the range of 0.94–5.77 μg/L with relative standard deviations of less than 4.54%. The feasibility of derivatization allowed the development of a rapid and highly sensitive method for the quantitative analysis of trace levels of thiophenols from some rubber products. The average recoveries (n = 3) were in the range of 87.21–101.12%.     

中空纤维膜液相微萃取-高效液相色谱测定有机化合物正辛醇/水分配系数

提出了一种中空纤维膜液相微萃取-高效液相色谱直接测定有机化合物正辛醇/水分配系数的新方法,并用该方法测定了不同脂溶性有机化合物的正辛醇/水分配系数。由于中空纤维膜液相微萃取有机萃取剂用量很少,故能显著提高萃取时的传质速度,缩短萃取时间。正辛醇装入中空纤维膜内,在萃取过程中,正辛醇相和水相不会形成乳化层。萃取完成后,可直接取出正辛醇相的样品进行分析,lgK测定能在30 m in内完成。本研究对6种化合物进行了测定,测定结果用文献报道值和经典摇瓶法进行了验证。表明方法快速、准确、样品消耗量少。     

双氰基二苯代乙烯型双光子荧光汞离子探针

分别以双氰基二苯代乙烯(DCS)和双[2-(2-羟乙基硫基)乙基]氨(HSA)为双光子荧光团和汞离子受体,合成了双光子荧光汞离子探针(DHg),并对其结构进行了分析.实验结果表明,DHg在甲苯、乙腈和水中的荧光量子产率(Φ)分别为0.78,0.42和0.20,对汞离子的络合常数通过单、双光子荧光滴定分别拟合为lg K=5.47±0.02和lg K=5.34±0.02.DHg在水溶液中对汞离子具有优良的选择性和高的灵敏性,可用于中性环境中汞离子的检测.DHg的双光子吸收截面(δTPA)在水溶液中高达840 GM,可用于细胞中汞离子的检测与成像.