杂环芳胺的结构与致突性之间的定量关系研究

基于杂环芳胺在生物体内的代谢特征 ,对 19种杂环芳胺类致突变化合物进行了半经验分子轨道法理论计算 ,求得了该类化合物的结构与致突变活性相关关系 .结果表明 ,杂环上氨基经羟基化后形成亲电活性中心的难易程度以及活性中心的稳定性等因素决定其致突性 ,计算预测值与实验结果相吻合 ,19种杂环芳胺的致突性实验值与PM 3计算结果之间存在非常显著的相关性 ,其相关系数r =0 .919,F =19.0 >F 0 .0 1 .     

The relationship between the physical structure and the mechanical properties of polycarbonate

The room-temperature tensile mechanical properties and fracture topographies of polycarbonate are reported as a function of strain rate, sample preparation, and thermal history above and below T_g. The bulk physical structural changes produced by various thermal treatments were monitored by density, yield stress, and differential scanning calorimetry observations. Ordered regions do not form in bulk polycarbonate at or below 145°C. The changes produced in the mechanical properties of polycarbonate on annealing below T_g, relative to a quenched or 145°C equilibrium-state glass, are caused by liquidlike packing changes in free volume. In room-temperature tensile a 125°C–6 day annealed glass exhibits transitional behavior from shear free volume, such as quenched and 145°C equilibrium-state glasses, this transition occurs at higher strain rates. Polycarbonate embrittles as a result of the cessation of shear yielding and reversion to a crazing failure mode with a corresponding decrease in molecular flow and energy to failure. Density measurements indicate that ordered regions do start to grow immediately above 145°C in bulk polycarbonate. This phenomenon allows precrystalline and/or crystalline entities to grow below the bulk T_g in thin films and on the free surfaces of thick films where mobility restrictions are less severe than in the bulk. From bright-field transmission electron micrographs of thin films and carbon–platinum surface replicas of etched thick films it is suggested that the observed spherical precrystalline structures are aggregates of 50–60 Å ordered molecular do mains.     

Analysis of the relationship between the structure and aromatic properties of chemical compounds

This paper presents the results of research on the relationship between the structure and odour properties of a selection of chemical compounds. The research concerns five groups of esters, each with a different smell: almond, apricot, apple, pineapple and rose. The supposed relationship between the smell and certain selected attributes of each molecule was examined by various pattern recognition techniques using programs developed in the Department of Computer Chemistry at Rzeszów University of Technology.     

On the relationship between the luminescence of heterometallic terbium-copper-podand complexes and the ligand structure

The formation conditions and luminescence of heterometallic Tb-Cu complexes with structurally similar podands containing different numbers of oxymethylene fragments were studied (n = 2?7). The component ratio in mono- and different-metal complexes were 1: 1 and 1: 1: 1, respectively. The possibility of complex formation for the carbonyl and enol forms was estimated by molecular mechanics. The results were in good agreement with experimental data. The most pronounced enhancement of luminescence intensity of Tb(III) ions in heterometallic Tb-Cu complexes was observed for podands containing two and three oxymethylene fragments (L1 and L2, respectively) and the probability of complex formation with these podands is higher than with the podands containing four to seven oxymethylene fragments (L3–L5).     

Unraveling the relationship between structure and stabilization of triarylpyridines as G-quadruplex binding ligands

A series of novel 2,4,6-triarylpyridines have been synthesized and their interactions with intramolecular G-quadruplexes have been measured by F?rster Resonance Energy Transfer (FRET) melting and Fluorescent Intercalator Displacement (FID) assays. A few of these compounds exhibit stabilization of G4-DNA that is comparable to other benchmark G4-DNA ligands with fair to excellent G4-DNA vs. duplex selectivity and significant cytotoxicity towards HeLa cells. The nature of the 4-aryl substituents along with side chain length governs the G4-DNA stabilization ability of the compounds. In addition, we demonstrate that there is a strong correlation between the ability of the compounds to stabilize the same G4-DNA sequence in K(+) and Na(+) conditions and a strong correlation between the ability of the compounds to stabilize different G4-DNA sequences in K(+) or Na(+) buffer.     

硅烷摩尔折射度与其分子结构之间关系的探讨

本文首次用图论方法探讨了硅烷的摩尔折射度与其分子结构之间的关系, 提出了一个结构基础明确的定量关系。应用本文定量关系，不仅能够预测硅烷的摩尔折射度, 而且可以合理表征物质结构与性能之间的关系。     

The relationship between the structure of Cu(II) complexes and their chemical transformations: VI

Data on the activation energies of dehydration of the complexes [Cu(en)₂(H₂O)]X₂, [Cu(, -bipy)₂(H₂O)]S₂O₆ and [Cu(o-phen)₂(H₂O)]X₂ were gained by means of dynamic TG, and theH values of the same reactions by DSC. The results were correlated with known data on the crystal structures of the studied complexes. No significant differences betweenE and/orH values were found for tetragonal pyramidal and trigonal bipyramidal complexes. For complexes with sufficiently exactly solved crystal structures, the activation energies increase with decreasing values of the anisotropic temperature factors (in the Cu-OH₂ bond directions). Activation energy values are also influenced by the type of structural changes accompanying the formation of the intermediate of thermal decomposition.

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Zusammenfassung Werte für die Aktivierungsenergien bzw.H-Werte der Dehydratisierung der Komplexe [Cu(en)₂(H₂O)]X₂, [Cu(,-bipy)₂(H₂O)]S₂O₆ und [Cu(o-phen)₂(H₂O)] wurden durch dynamische TG bzw. DSC erhalten. Die Ergebnisse wurden mit bekannten Daten über die Kristallstruktur der untersuchten Komplexe verglichen. Keine signifikanten Unterschiede zwischenE ^*- und/oderH-Werten wurden für tetragonal-pyramidale und trigonal-bipyramidale Komplexe gefunden. Die Untersuchung von Komplexen mit genügend genau bekannter Kristallstruktur hat ergeben, daß die Aktivierungsenergie mit abnehmenden Werten des anisotropen Temperaturfaktors (in der Cu-OH₂-Bindungsrichtung) abnimmt. Die Aktivierungsenergie wird auch durch den Typ der die Bildung von intermediären thermischen Zersetzungsprodukten begleitenden strukturellen Veränderungen beeinflußt.

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H [u()₂(H₂O)]X₂, [Cu(, -)₂(H₂O)]S₂O₆ [Cu(o-)₂(₂)]₂. - . - - - E H. - - Cu-OH₂. - , - .

     

On the relationship between the electron-pair distribution function and the correlation energy of an atom

The pair distribution function h(r₁₂;r₁, γ) and the virial theorem are used to derive a general expression for the local contributions to the total correlation energy of an atom. A direct link between correlation effects and the correlation energy is obtained by use of G(r₁, γ) and Γ(r₁, y). The former is the probability associated with a given choice of r₁ and γ, while the latter describes the local contribution to the correlation energy. Explicit calculations for the ground state of helium indicate that the angular dependence of the local contribution to the correlation energy is essentially independent of r₁, whereas the local correlation energy shows a strong r₁ dependence. The maximum contribution to the correlation energy occurs at intermediate values of γ where there is close agreement between the Hartree–Fock and exact densities.     

Nanostructured polyelectrolyte-surfactant complex pervaporation membranes for ethanol recovery: the relationship between the membrane structure and separation performance

Polyelectrolyte-surfactant complexes (PESCs) were fabricated through the interaction of poly(acrylic acid) and four different cationic surfactants or their mixtures.PESC membranes were prepared by solution casting method and were applied in ethanol recovery from aqueous solution via pervaporation.Elemental analysis (EA),Fourier transform infrared spectroscopy (FTIR),water contact angle (CA) measurement,differential scanning calorimetry (DSC) and X-ray scattering were employed to characterize the composition,structure and properties of PESCs.The results reveal that the investigated PESCs are similar in hydrophobicity but different in hierarchical nanostructures.In separating 5 wt％ ethanol/water mixture,PESC membranes with high crystallinity will have both low flux and ethanol selectivity because of the high packing density and low permeability of crystalline regions.Meanwhile,the hierarchical nanostructures of PESC membranes change under pervaporation environment as was revealed by in situ synchrotron radiation X-ray scattering measurement.That is,the crystalline region could melt at high temperature in swelling state,thus consequently enhancing the ethanol selectivity.     

The relationship between the chemical structure of nematic liquid crystals and their pretilt angles

About 50 different additives in one or more of three different nematic mixtures have been investigated to clarify the relationship between the chemical structure of the liquid crystal and the pretilt angle on a polyimide surface. The pretilts found for cells have been explained within our recently proposed population distribution model. For compounds with cyano-groups at one end, we find that the in-plane order is governed both by the surface-mesogen interaction and by the relative strength of the intermolecular interactions in the nematic phase. This strength is nearly linear in alkyl chain length for the compounds investigated. Changes in the strength due to variations in the core of the molecules can be calculated easily by using group contributions from the known Parachors. The in-plane order can be treated as a simple product of the contributions from the liquid crystal and from the polyimide. Different polar end groups will give different angles between the surface and the optical axis of the individual mesogens in the first monolayer. The cyano-group gives the highest angle and alkyl groups the lowest. For nitro-compounds the dimers formed are so strongly bound that they do not break up at the surface. Nitro-compounds will thus act as dialkyl compounds. For dialkyl compounds the pretilt angles are dominated by the difference between the chain lengths at the two ends of the molecule.     

The relationship between gas-phase processes and the structure of polyaniline obtained by plasma polymerization

The composition of the gas phase during plasma polymerization of aniline was studied with the use of mass spectrometry; it was shown that at least 20% of aniline is consumed for the formation of secondary products (C₂H₂ and HCN). According to solid-state NMR data, the macromolecular chain of polyaniline obtained by plasma polymerization includes both aniline and aliphatic units. The latter units appear as a result of polymerization of the secondary product acetylene.     

Synthetic study on the relationship between structure and sweet taste properties of steviol glycosides

The structure activity relationship between the C??-C?? methylene double bond on the aglycone of steviol glycosides and the corresponding impact on their sweet taste has been reported here for the first time. It has been observed that converting stevioside and rebaudioside A to their corresponding ketones by switching the doubly bonded methylene on C-17 for a ketone group actually removes the sweet taste properties of these molecules completely. Regenerating the original molecules tends to restore the sweet taste of both the steviol glycosides. Thus this C??-C?? methylene double bond in rebaudioside A and stevioside can be regarded as a pharmacophore essential for the sweetness property of these molecules.     

烷基苯凝聚型性能与分子结构之间关系的探讨

本文根据分子结构的特点，用图论方法探讨了烷基苯的凝聚型性能与其分子结构之间的关系，用四个结构信息指数描述了分子的大小和形状、烷基的大小和数目及烷基在苯环上的位置对凝聚型性能的影响，据此提出一个具有一定结构基础的定量关系式。应用这一定量关系，不仅能够预测烷基苯的沸点、密度和折光指数，而且有助于揭示物质结构与性能之间的奥秘。计算结果表明计算值与实验值的一致性令人满意。