共查询到20条相似文献,搜索用时 62 毫秒
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介绍一个面向高年级本科生的计算化学实验。通过利用量子化学计算,确定嘧啶碱基的酸碱性质以及它们与水分子之间的相互作用能,构建氢键复合物分子间相互作用与分子酸碱性之间的定量关系,使学生对分子的酸碱性、分子间相互作用、分子识别之间的关系有一定的直观认识。该实验有助于学生梳理课堂学到的碎片化知识,提升学生逻辑分析及创新能力。 相似文献
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描述了HEK-DDQ,(Co(C5H5)2(Ni(dmit)2)BBBT-DTT三个晶体结构中的π...π,S...S;Br...Br分子间相互作用,讨论了分子晶体中的分子间相线作用的材料化学意义。 相似文献
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原油是最复杂的化学体系之一,人们对原油这种复杂的胶态分散体及其稳定性的研究兴趣与日俱增,尤其是与石油稳定性密切相关的沥青质超分子聚集体。但人们对形成沥青质超分子聚集体的主要作用力长期以来颇有争议。本文重点介绍了石油组分及其模型化合物在溶液中形成超分子聚集体的超分子化学作用研究进展。通过实验方法和理论计算证明沥青质聚集体是沥青质分子间通过氢键、π-π堆积、偶极-偶极相互作用等多种分子间弱相互作用力协同作用形成的热力学稳定结构;合成具有沥青质结构特点的纯化合物,研究它们在溶液中的行为,是提高对沥青质在液态相中自缔合行为认识的有效方法;结合现阶段的研究状况,对石油组分模型化合物的超分子化学作用研究的发展前景进行了展望。 相似文献
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描述了HEK-DDQ,[Co(C_5H_5)_2][Ni(dmit)_2],BBBT-DTT三个晶体结构中的π…π;S…S;Br…Br分子间相互作用,讨论了分子晶体中的分子间相互作用的材料化学意义。 相似文献
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超分子体系弱相互作用的量子化学计算 总被引:6,自引:0,他引:6
介绍了近年来超分子体系弱相互作用的最子化学计算方法,重点讨论了严格的从头计算方法及其各种校正技术,介绍了当前进展及其所取得的成果。 相似文献
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HEPT类化合物的QSAR研究 总被引:3,自引:0,他引:3
为定量结构/活性相关性研究提取了量子化学参数,拓扑指数Am,分子连接性指数^mxt及疏水性常数,同时应用正交变换和最佳变量子集算法(Leaps-and-Bonds)进行了变量压缩和选择,进而实施了多元回归分析,并由此结果进行了HEPT类化合物(1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine derivatives)的结构/活性关系的理论解释,进行了人工神经网络法对于该类化合物的活性预测,其结构明显好于多元回归法。 相似文献
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V. P. Lezina N. A. Andronova L. D. Smirnov K. M. Dyumaev 《Chemistry of Heterocyclic Compounds》1971,7(11):1438-1440
The dependence of the chemical shifts of the ring protons on the pH of the medium for a number of 4-hydroxyquinoline derivatives was studied by means of PMR spectroscopy. The dipolar and uncharged hydroxy forms exist in equilibrium in aqueous solutions. The effect of intramolecular hydrogen bonding on the character of the dependence of the chemical shift on the pH of the medium in the case of 3-piperidinomethyl-4-hydroxyisoquinoline was investigated. The possibility of the separate protonation of the ring nitrogen and the side-chain nitrogen in 3-piperidinomethyl-4-hydroxyisoquinoline was established. The distribution of the -electron density in 4-hydroxyisoquinoline is in good agreement with its chemical behavior.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1549, November, 1971 相似文献
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V. P. Lezina N. A. Andronova L. D. Smirnov K. M. Dyumaev 《Chemistry of Heterocyclic Compounds》1971,7(11):1433-1437
The dependence of the chemical shift of the ring protons on the pH of the medium for a number of 3-hydroxyquinoline derivatives was studied by PMR spectroscopy. The regions of ionization of the molecules, which correspond to the ranges of acidic, neutral, and alkaline media, were found. In D2O, 3-hydroxyquinoline is present only in the uncharged hydroxy form. The presence of intramolecular hydrogen bonding in 4-dimethylaminomethyl-3-hydroxyquinoline has a substantial effect on the character of the dependence of the chemical shift on the pH of the medium; the existence of separate protonation of the nitrogen atoms of the ring and the side chain of 4-dimethylaminomethyl-3-hydroxyquinoline was established. The distribution of the -electron density in the 3-hydroxyquinoline molecule is in good agreement with its chemical behavior during electrophilic substitution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1540–1545, November, 1971. 相似文献
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通过在LS55型荧光-磷光-发光分光光度计上加装液滴产生及调节附件,采用计算机采集与分析处理数据,成功地研制了双通道液滴光化学传感装置.利用葡聚糖凝胶对复合维生素B中不同组分的选择性吸附来达到分离与同时检测的目的,并将其用于复合维生素B药片的分析,取得了满意的结果. 相似文献
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Tangney P 《The Journal of chemical physics》2006,124(4):044111
The theory underlying the Car-Parrinello extended-Lagrangian approach to ab initio molecular dynamics (CPMD) is reviewed and reexamined using "heavy" ice as a test system. It is emphasized that the adiabatic decoupling in CPMD is not a decoupling of electronic orbitals from the ions but only a decoupling of a subset of the orbital vibrational modes from the rest of the necessarily coupled system of orbitals and ions. Recent work [J. Chem. Phys. 116, 14 (2002)] has pointed out that, due to the orbital-ion coupling that remains once adiabatic decoupling has been achieved, a large value of the fictitious mass mu can lead to systematic errors in the computed forces in CPMD. These errors are further investigated in the present work with a focus on those parts of these errors that are not corrected simply by rescaling the masses of the ions. It is suggested that any comparison of the efficiencies of Born-Oppenheimer molecular dynamics (BOMD) and CPMD should be performed at a similar level of accuracy. If accuracy is judged according to the average magnitude of the systematic errors in the computed forces, the efficiency of BOMD compares more favorably to that of CPMD than previous comparisons have suggested. 相似文献
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