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杯芳烃是继冠醚、环糊精之后的第三代主体分子 ,在主客体化学、超分子化学中占有重要地位 [1~ 3] .据文献报道 ,在杯 [4]芳烃衍生物中存在各种各样的作用力 [4 ] ,如分子内氢键 [3,4 ]、分子间氢键 [5]、阳离子 -π作用 [6 ]、CH3-π作用 [7]和 π-π相互作用 [8,9]等 .本文报道了杯 [4]芳烃衍生物 5 ,1 1 ,1 7,2 3 -四叔丁基 -2 6,2 8-二 [2 -(甲氧基羰基 )苄氧基 ]-2 5 ,2 7-二羟基杯 [4]芳烃 (简称 L,结构式见 Scheme1 )的晶体结构 .研究中发现 ,分子中存在分子内氢键和分子间π-π相互作用 ,后者使化合物 L形成了一维锯齿形的超分子… 相似文献
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杯芳烃吡啶衍生物作为液膜载体对金属离子的选择传质 总被引:3,自引:0,他引:3
超分子化学主要研究以非共价键弱相互作用力结合的分子聚集体体系,分别识别作为超分子化学的基础,是目前研究的热点.冠状化合物、天然和修饰环糊精以及环番等主体的分子识别已被广泛研究,而杯芳烃等人工合成受体体系的分子识别研究还相对有限.杯芳烃,正如环糊精一样,起源于19世纪,但直到70年代末,Gutsche对其大小可调的空腔产生兴趣,设想可以用来作为广泛的人工酶模型,对其合成方法进行了深入研究,优化出合成路线,可以方便地制备较大量的价廉样品,从而启动了杯芳烃化学的发展[1]....... 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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Emma Hocker 《Macromolecular Symposia》2006,238(1):16-21
Sweden's famous warship, Vasa, sank on her maiden voyage in August 1628, and remained on the bottom of Stockholm harbour for 333 years. Raised in 1961, she became the first large-scale wooden object to be treated with polyethylene glycol (PEG). In the summer of 2000 a number of acidic salt precipitations were noticed on the surface of the ship and on wooden artefacts in the storerooms. An international research project has been established to look into the causes of this problem and suggest possible re-treatments. Meanwhile projects are underway to monitor movements in the ship, to build a better support system, and to replace the thousands of iron bolts holding the structure together, while a sophisticated new climate system has recently been installed in the museum. 相似文献