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11.
研究了两亲性无规共聚物聚(苯乙烯-co-甲基丙烯酸)(P(St-co-MAA))(单体摩尔比分别为6:4和7:3)自组装胶束的物理化学性质,及其作为假固定相(PSP)的胶束电动色谱性能。测定了聚合物胶束的临界胶束浓度(CMC),对胶束内核微环境的极性、表面电荷密度和流体力学直径等微结构参数进行了表征,对时间窗口、亚甲基选择性等电动色谱参数进行了测定,并与聚(甲基丙烯酸甲酯-co-甲基丙烯酸)(P(MMA-co-MAA))胶束、十二烷基硫酸钠(SDS)胶束体系进行了比较;利用线性溶剂化能关系(LSER)研究了聚合物PSP的选择性差异。结果表明:P(St-co-MAA)体系具有最小的CMC、最宽的时间窗口和最好的亚甲基选择性;LSER表明,疏水作用是决定聚合物PSP选择性的最主要因素,氢键酸度其次,特别是P(St-co-MAA)(单体摩尔比7:3)体系具有最高的作用参数,显示了该PSP具有较高的分离选择性。 相似文献
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卤代芳烃的脂水分配系数与分子结构的定量关系 总被引：1，自引：0，他引：1
本文通过HMO法计算得到了46个卤代芳烃的部分量子化学参数,同时计算了它们的分子总表面积(TSA),以线性溶解能关系(LSER)理论为基础探讨了化合物的正辛醇/水分配系数与其分子结构间的定量关系,建立了一种良好的分配模型,该模型可准确计算出两种溶剂的表面张力之差。 相似文献
13.
A surface-confined ionic liquid (SCIL) and a commercial quaternary amine silica-based stationary phase were characterized
employing the linear solvation energy relationship (LSER) method in binary methanol/water mobile phases. The retention properties
of the stationary phases were evaluated in terms of intermolecular interactions between 28 test solutes and the stationary
phases. The comparison reveals a difference in the hydrophobic and hydrogen bond acceptance interaction properties between
the two phases. The anion exchange retention mechanism of the SCIL phase was demonstrated using nucleotides. The utility of
the SCIL phase in predicting logk
IL/water values by chromatographic methods is also discussed. 相似文献
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《液相色谱法及相关技术杂志》2012,35(15):2198-2218
Abstract We describe here the use of Gemini C18™ column, a new generation hybrid silica based column, for reversed-phase liquid chromatographic determination of lipophilicity parameters of several structurally different xenobiotics (neutral solutes and ionized drugs). Among the parameters discussed, we show that extrapolated retention factor values log k′ w , as well as retention factor values at 40% methanol (log k′40), obtained on the above column, were well correlated with literature values of log P (logarithm of the partition coefficient in n-octanol/water) of neutral compounds. Also found were linear relationships between measured log k′ w values and calculated values of the logarithm of the distribution coefficient at pH 7.0 (log D 7.0) for ionized acidic and basic drugs. In addition, the Gemini C18™ column was characterized using the linear solvation energy relationship (LSER) model of Abraham. The LSER system constants for the column were compared to the LSER constants of n-octanol/water extraction system. For the comparison, the Tanaka radar plots were used. In addition, the LSER system constants of the Gemini C18™ column allow estimating the log P values of steroid hormones based on calculated log k′ w values. 相似文献
16.
Liudmil Antonov Walter M. F. Fabian Peter J. Taylor 《Journal of Physical Organic Chemistry》2005,18(12):1169-1175
An LSER study on the tautomerism of some aromatic Schiff bases and related azo compounds has vindicated the picture presented by previous ab initio studies and added further detail of its own. As predicted, the aminoenone tautomer is always the more polar (positive π* term) and, in addition, is specifically favoured by proton donor solvents (α term positive) through binding to the second lone pair on carbonyl. As expected for chelates, the Schiff bases are unaffected by proton acceptors (β term zero) but owing to the poor proton acceptor properties of the azo linkage, those of the azo compounds are partially broken. Tautomer preference as earlier calculated by ab initio methods is linearly related to log KT in the gas phase as estimated by LSER. Comparison with other compounds clearly shows the effect of aromatization in reducing KT; for 1‐[(E)‐ methyliminomethyl]naphthalen‐2‐ol this is quantitatively similar to that for 2‐pyridone, of which it is a kind of vinylogue. However, the effect of benzo fusion is similar only in part, and a further apparent anomaly lies in the near‐identical KT values, for water, of Schiff bases and azo compounds. This is discussed in terms of their differing ‘intrinsic’ tautomeric bias, leading to a fortuitous cancellation of effects. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
17.
The linear solvation energy relationship (LSER) model is employed to correlate the tracer diffusion coefficients of 550 binary systems at 298.15 K. Among the selected solutes and solvents there exist apolar, polar and hydrogen-bonding substances that can interact with themselves (solvent polymerization) or with the other compound (solute–solvent complexes formation). The results of the proposed formulas are compared with those of other predictive equations. 相似文献
18.
Theoretical and experimental quantitative structure–retention relationships (QSRR) models are useful for characterizing solvent properties and column selectivity in reversed phase liquid chromatography (RPLC). The chromatographic behavior of a model analyte, the herbicide atrazine, in a system derived from nine organic solvents and three chromatographic columns was used for developing QSRR models. Multiple linear regression (MLR) and partial least squares regression (PLSR) were used as statistical approaches. The similarities and differences between linear solvation energy relationships (LSER), and semi-empirical and theoretical molecular models were demonstrated. QSRR models show high predictive power, and can successfully predict retention factor (log k) for new solvents. The models are useful for solvent optimization and reducing time for method development in RPLC. The herbicide atrazine can be readily analyzed at a low level, and all three columns provided good resolution, high-performance and symmetrical peaks. The method is suitable for analysis of atrazine in water samples. 相似文献
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《Arabian Journal of Chemistry》2020,13(1):932-953
The substituent and solvent effect on intramolecular charge transfer (ICT) of twelve monocarbohydrazones (mCHs) were studied using experimental and theoretical methodology. The effects of specific and non-specific solvent–solute interactions on the UV–Vis absorption maxima shifts were evaluated using linear free energy relationships (LFERs) principles, i.e. using the Kamlet-Taft and Catalán models. Linear free energy relationships in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on UV–Vis, NMR and pKa change. According to crystallographic data and quantum chemical calculations, the trans (E) form was found to be more stable. A photochromism of compounds with 2-hydroxyphenyl and 2-pyridylimino groups substituted at imine carbon atom results in E/Z isomerization due to creation of intermolecular hydrogen bond in E and Z form, respectively. Multiple stage mass spectrometry (MS-MSn) analysis was applied to define main fragmentation pathways. Furthermore, the experimental findings were interpreted with the aid of ab initio MP2/6–311 G(d,p) and time-dependent density functional (TD-DFT) methods. TD-DFT calculations were performed to quantify the efficiency of intramolecular charge transfer (ICT) with the aid of the charge-transfer distance (DCT) and the amount of transferred charge (QCT) calculation. It was found that both substituents and solvents influence electron density shift i.e. extent of conjugation, and affect ICT character in the course of excitation. 相似文献