Comparison of Reliability of log P Values Calculated from a Group Contribution Approach and from the Autocorrelation Method

Abstract

The values of log P (n-octanol/water partition coefficient) for 1449 chemicals were calculated from the fragmental/regression model of Klopman and co-workers (J. Chem. Inf. Comput. Sci. 1994, 34, 752-781) and from the autocorrelation/backpropagation neural network model implemented in AUTOLOGP_TM (Version 4.0). Both models provided good simulation results but the superiority of the latter was demonstrated.     

油溶性CuInS2/ZnS量子点的制备及其温敏性聚丙烯酰胺胶束介导的水相转移

采用非热注法成功制备了高质量的油溶性CuInS2/ZnS核壳量子点,量子点的荧光发射峰在可见光到近红外范围内可调(550～800 nm),且荧光量子产率最高达80%。本文进一步利用具有温敏特性的聚丙烯酰胺胶束作相转移剂,成功地将油溶性的CuInS2/ZnS核壳量子点转移入水相。水相中自组装形成的CuInS2/ZnS量子点-胶束复合物不仅具有良好的荧光性质,而且胶束原有的灵敏的热响应性被保留。这些研究初步表明,无镉的低毒的CuInS2/ZnS量子点可作为纳米胶束的荧光示踪探针。     

油溶性CuInS2/ZnS量子点的制备及其温敏性聚丙烯酰胺胶束介导的水相转移

采用非热注法成功制备了高质量的油溶性CuInS₂/ZnS核壳量子点, 量子点的荧光发射峰在可见光到近红外范围内可调(550~800 nm), 且荧光量子产率最高达80%。本文进一步利用具有温敏特性的聚丙烯酰胺胶束作相转移剂, 成功地将油溶性的CuInS₂/ZnS核壳量子点转移入水相。水相中自组装形成的CuInS₂/ZnS量子点-胶束复合物不仅具有良好的荧光性质, 而且胶束原有的灵敏的热响应性被保留。这些研究初步表明, 无镉的低毒的CuInS₂/ZnS量子点可作为纳米胶束的荧光示踪探针。     

保留时间两点校正反相高效液相色谱法测定持久性有机污染物的正辛醇-水分配系数

采用改进的反相高效液相色谱法(RP-HPLC)测定了持久性有机污染物(POPs)包括多环芳烃(PAHs)、多氯二苯并二恶英(PCDDs)、多氯二苯并呋喃(PCDFs)和十溴二苯乙烷(DBDPE)等的正辛醇-水分配系数(logKow)。采用保留时间双点校正法(DP-RTC)校正因色谱柱老化等引起的保留时间漂移。以37种有可靠logKow实验值的苯系物、PAHs、PCDD/Fs类似物为模型化合物,建立了logKow和外推至纯水相的保留因子logkw的定量结构-色谱保留关系(QSRR)模型,回归方程为logKow=(1.18±0.02)logkw+(0.36±0.11),其相关系数(R2)为0.985,交叉验证相关系数(R2cv)为0.983,标准偏差(SD)为0.16。进而,用4个已有可靠logKow实验值的验证化合物(联苯、芴、PCDD 1和PCDF 114)对模型进行了外部验证,表明RP-HPLC测得的logKow值与摇瓶法/慢搅法结果有很好的一致性,尤其是对疏水性强的化合物。采用该模型测定了29种特别受关注的POPs的logKow值,这些化合物的logKow实验值均未见报道。所建立的DP-RTC-HPLC是测定强疏水性POPs的logKow值的一种值得推荐的方法。     

CO和NO在CuO及Cu2O(110)表面吸附选择规律研究

采用离散变分Xα方法分别计算了CO和NO以C（或N）端顶位吸附在CuO（110）及Cu2O（110）表面上的基态势能曲线,结果表明：CO在Cu2O表面上的吸附强,而在CuO表面上的吸附弱;NO则在CuO表面上吸附强,在Cu2O表面上吸附弱．它们的吸附能的大小顺序为：CuO－NO＞Cu2O－CO＞Cu2O－NO＞CuO－CO．对于CuO－NO（或CO）吸附体系,主要是Cu的3d轨道与吸附分子的2π轨道间的相互作用;对于Cu2O－CO（或NO）吸附体系,则主要是吸附质分子的5σ及2π分子轨道与其顶位Cu1的4s及4p轨道和侧位Cu2的3d轨道相互作用．本文通过吸附势能曲线、态密度分析、成键分析及电荷转移量和方向等方面对实验现象做了合理的解释．     

QSAR Study on Binding Affinity of PATs (Rodenticides) to the [3H]-Mepyramine-Labelled H1 Receptor In Rat and Guinea Pig Brain

Abstract

The binding of a series of PAT analogues (rodenticides) to the [³H]-mepyramine-labelled H₁ receptor in rat and guinea pig brain was investigated topologically using negentropy (N), molecular redundancy (MRI), first-order molecular connectivity (¹X _v ), Wiener (W), and Szeged (Sz) indices. Multiple regression analyses showed that MRI provided excellent results upon introduction of indicator parameters. Predictive ability of the proposed models was discussed using cross-validation parameters.     

Determination of Free L-T4 and Free L-T3 from Blood Using the Immunosensors/Sequential Injection Analysis System

An immunosensors/sequential injection analysis system is proposed for the assay of thyroid hormones free L-T₄ and free L-T₃ in blood samples. The working concentration ranges for free L-T₄ and free L-T₃, are between 2.0 and 720.0 pmol/L and between 2.0 and 340.0 pmol/L, respectively, with detection limits of 1.0 and 1.7 pmol/L, respectively. The selectivity of the immunosensors, as well as the recovery tests done for free L-T₄ and free L-T₃ (99.90 ± 0.01% (n = 10) and 99.94 ± 0.02% (n = 10)), made the immunosensors/sequential injection analysis system suitable for the direct assay of thyroid hormones in blood samples.     

Molecular Lipophilicity Potential,a tool in 3D QSAR: Method and applications

Summary A new method is presented to calculate the Molecular Lipophilicity Potential (MLP). The method is validated by showing that the MLP thus generated on the solvent-accessible surface can be used to back-calculate log P. Because the MLP is shown to be sensitive to conformational effects, the MLP/log P relation is best sought by taking all conformers into account. The MLP method presented here can be used as a third field in CoMFA studies, as illustrated with two series of ₁ ligands. In the first series, the steric, electrostatic and lipophilic fields are highly intercorrelated, and taken separately yield comparable models. In the second series of ligands, the best model is obtained with the lipophilic field alone, allowing insights into ligand-receptor interactions.     

Simple and highly predictive QSAR method: application to a series of (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-6-methoxybenzamides

A simple quantitative structure-activity relationship (QSAR) method of analysis used to predict biological activity for congeneric series of compounds is reported. This method is based on the application of bilinear or multilinear partial least squares regression to a data set, which is a binary matrix representing the substituents of a framework. It is appraised here to a series of (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-6-methoxybenzamides, compounds with affinity towards the dopamine D₂ receptor subtype and showed high predictive ability, even when compared to a refined three-dimensional (3D) approach.     

Chemical and ecotoxicological assessment of poly(amidoamine) dendrimers in the aquatic environment

Poly(amidoamine) (PAMAM) dendrimers are attracting great interest as a consequence of their unique properties as carriers of active molecules in aqueous media, as we expect their presence in the environment to be widespread in the future.In this article, we focus on the analytical methods to characterize and to determine these polymeric materials in waters and on their ecotoxicity for aquatic organisms. We review physical characterization techniques (e.g., light scattering, electron microscopy, atomic force microscopy) and analytical techniques, mainly based on liquid chromatography, so as to consider their main capabilities, advantages and drawbacks. We assessed the toxicity of certain PAMAM dendrimers for the green alga Pseudokirchneriella subcapitata by determining the EC₅₀ and correlating it with the ζ-potential.     

An enzymatic method for the rapid measurement of the hemoglobin A1c by a flow-injection system comprised of an electrochemical detector with a specific enzyme-reactor and a spectrophotometer

A flow-injection analytical (FIA) system, comprised of an electrochemical detector with a fructosyl-peptide oxidase (FPOX-CET) reactor and a flow-type spectrophotometer, was proposed for the simultaneous measurement of glycohemoglobin and total hemoglobin in blood cell. The blood cell samples were hemolyzed with a surfactant and then treated with protease. In the first stage of operation, total hemoglobin in digested sample was determined spectrophotometrically. In the second stage, fructosyl valyl histidine (FVH) released from glycohemoglobin by the selective proteolysis was determined specifically using the electrochemical detector with the FPOX-CET reactor. The FIA system could be automatically processed at an analytical speed of 40 samples per hour. The proposed assay method could determine selectively only the glycated N-terminal residue of β-chain in glycohemoglobin and total hemoglobin in blood cell. The enzymatic hemoglobin A_1c (HbA_1c) value calculated by the concentration ratio of the FVH to total hemoglobin, was closely correlated with the HbA_1c values certified by the Japan Diabetic Society (JDS) and the International Federation of Clinical Chemistry (IFCC).     

Advances in the preparation of organofluorine compounds involving iodine and/or iodo-compounds

The intriguing properties of iodine have drawn the attention of organic chemists. In this paper, we will describe the recent development of stereo- and/or regioselective synthesis of fluorine-containing organic compounds employing hypervalent iodine fluorides such as ArIF₂ (1), IF₅ (22), and (E)-2-fluoro-alk-1-enyl-4-aryl iodonium salts R(F)C=C(H)IF-Ar (12). The electrochemical fluorination procedures involving iodo-compounds will also be presented to prepare fluoro-organic compounds.     

Synthesis, structural characterization and antimicrobial activity evaluation of metal complexes of sparfloxacin

The synthesis and characterization of binary Cu(II)- (1), Co(II)- (2), Ni(II)- (3), Mn(II)- (4), Cr(III)- (5), Fe(III)- (6), La(III)- (7), UO₂(VI)- (8) complexes with sparfloxacin (HL₁) and ternary Cu(II)- (9), Co(II)- (10), Ni(II)- (11), Mn(II)- (12), Cr(III)- (13), Fe(III)- (14), La(III)- (15), UO₂(VI)- (16) complexes with sparfloxacin (HL₁) and dl-alanine (H₂L₂) complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV–Vis, thermal analysis and ¹H-NMR spectral studies.The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature.All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complexes which were four coordinate, square planar and U- and La-atoms in the uranyl and lanthanide have a pentagonal bipyramidal coordination sphere. The antimicrobial activity of these complexes has been screened against two Gram-positive and two Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with reference drug sparfloxacin. All the binary and ternary complexes showed remarkable potential antimicrobial activity higher than the recommended standard agents. Ni(II)- and Mn(II) complexes exhibited higher potency as compared to the parent drug against Gram-negative bacteria.