共查询到17条相似文献,搜索用时 171 毫秒
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芳酰胺-吖啶分子钳对中性分子的识别性能. II. 新型吖啶类分子钳的研究 总被引:1,自引:0,他引:1
采用差紫外谱法研究了新型芳酰胺-吖啶分子钳(1~7)对苯胺、苯二胺(邻, 间, 对)等中性分子的识别性能. 测定了结合常数(Ka)和自由能变化(ΔG°), 结果表明, 所有的分子钳受体与所考察的客体分子均形成1∶1型超分子配合物. 识别作用的主要推动力为多重氢键、van der Waals等的协同作用. 主客体间尺寸/形状匹配、几何互补等因素对识别性能均有重要的影响. 利用核磁氢谱与计算机模拟作为辅助手段对主要的实验结果与现象进行了解释. 相似文献
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用差紫外光谱滴定法考察了新型猪去氧胆酸分子钳1~6对苯胺、对甲氧基苯胺、对硝基苯胺等中性分子的识别性能,测定了主客体间的结合常数(Ka)和自由能变化(△G°)。结果表明,分子钳主体对所考察的客体分子显示良好的识别作用,主客体间形成1∶1型超分子配合物,最大结合常数可达3123.46L.mol-1,识别作用的主要推动力为氢键,范德华力等的协同作用。讨论了主体与客体的识别模式以及客体间形状、大小匹配和几何互补等因素对形成超分子配合物的影响,并利用核磁共振氢谱与计算分子模拟作为辅助手段对实验结果与现象进行了解释。 相似文献
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设计、合成了一种新的主体分子2,6-二(α-苯基苄基)-1,5-萘二酚 (1). 它可与许多有机小分子形成配位包合物. 用IR和1H NMR表征了配位包结物, 并测定了主客体分子的摩尔比: 1•DMF (1∶1), 1•DMSO (1∶2), 1•吡啶 (1∶1), 1•喹啉(1∶2), 1•N-甲基吡咯烷酮(1∶1). 用单晶X衍射分析了包结物 (1)•DMF的晶体结构, 属三斜晶系, 晶胞参数为P-1, a=0.9085(9) nm, b=0.9501(6) nm, c=2.0995(6) nm, α=99.59(3)°, β=90.13(4)°, γ=96.20(7)°, V=1.776(2) nm3, Dc=1.898 g•cm-3. 结果表明, 主体分子间的CH/π弱氢键在决定主体分子的层状框架结构和客体分子在层间的填充方式中发挥了重要作用; 两种不等效的客体分子与主体分子的作用方式是不同的, 一种客体分子是通过CH/π, CH/O弱氢键与同层的不同主体分子相互作用, 另一种是通过CH/π, CH/O弱氢键与相邻层的不同主体分子相互作用. 相似文献
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Da Ma Raymond Glassenberg Soumyadip Ghosh Peter Y. Zavalij 《Supramolecular chemistry》2013,25(5):325-332
The recognition properties of acyclic cucurbit[n]uril (CB[n]) congener 1 towards seven local anaesthetic drugs (2–8) are reported. Job plots constructed from 1H NMR experiments confirm the 1:1 host:guest nature of these complexes, whereas the changes in chemical shift observed upon complex formation (Δδ values) provide information about the geometry of the host–guest complexes. For complexes between host 1 and guests 2–5 and 8, a single geometry was preferred, whereas for guests 6 and 7 a mixture of two diastereomeric complexes was indicated. The K a values for complexes between 1 and 2–8 fall in the range of 103–108 M? 1 as determined by UV–vis and 1H NMR competition experiments. The results further establish that acyclic CB[n]-type receptor 1 is preorganised into the C-shape required for binding and that its aromatic o-xylylene walls endow it with a potency towards aromatic ammonium ions. The K a values reported in this paper constitute a blind data-set used in the SAMPL3 challenge aimed at testing computational methods relevant to protein√ligand systems. The work thus highlights the great potential of CB[n] receptors as model systems to promote synergy between the supramolecular and computational chemistry communities. 相似文献
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《中国化学快报》2022,33(11):4900-4903
A novel type of host–guest recognition systems have been developed on the basis of a Au(III) molecular tweezer receptor and chiral Pt(II) guests. The complementary host–guest motifs display high non-covalent binding affinity (Ka: ~104 L/mol) due to the participation of two-fold intermolecular π–π stacking interactions. Both phosphorescence and chirality signals of the Pt(II) guests strengthen in the resulting host–guest complexes, because of the cooperative rigidifying and shielding effects rendered by the tweezer receptor. Their intensities can be reversibly switched toward pH changes, by taking advantage of the electronic repulsion effect between the protonated form of tweezer receptor and the positive-charged guests in acidic environments. Overall, the current study demonstrates the feasibility to enhance and modulate phosphorescence and chirality signals simultaneously via molecular tweezer-based host–guest recognition. 相似文献
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Glycoluril‐Derived Molecular Clips are Potent and Selective Receptors for Cationic Dyes in Water 下载免费PDF全文
Prof. Dr. Nengfang She Dr. Damien Moncelet Dr. Laura Gilberg Dr. Xiaoyong Lu Prof. Dr. Vladimir Sindelar Prof. Dr. Volker Briken Prof. Dr. Lyle Isaacs 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15270-15279
Molecular clip 1 remains monomeric in water and engages in host–guest recognition processes with suitable guests. We report the Ka values for 32 1? guest complexes measured by 1H NMR, UV/Vis, and fluorescence titrations. The cavity of 1 is shaped by aromatic surfaces of negative electrostatic potential and therefore displays high affinity and selectivity for planar and cationic aromatic guests that distinguishes it from CB[n] receptors that prefer aliphatic over aromatic guests. Electrostatic effects play a dominant role in the recognition process whereby ion–dipole interactions may occur between ammonium ions and the C=O groups of 1 , between the SO3? groups of 1 and pendant cationic groups on the guest, and within the cavity of 1 by cation–π interactions. Host 1 displays a high affinity toward dicationic guests with large planar aromatic surfaces (e.g. naphthalene diimide NDI+ and perylene diimide PDI+) and cationic dyes derived from acridine (e.g. methylene blue and azure A). The critical importance of cation–π interactions was ascertained by a comparison of analogous neutral and cationic guests (e.g. methylene violet vs. methylene blue; quinoline vs. N‐methylquinolinium; acridine vs. N‐methylacridinium; neutral red vs. neutral red H+) the affinities of which differ by up to 380‐fold. We demonstrate that the high affinity of 1 toward methylene blue (Ka=3.92×107 m ?1; Kd=25 nm ) allows for the selective sequestration and destaining of U87 cells stained with methylene blue. 相似文献
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N. Kodiah Beyeh Altti Ala‐Korpi Mario Cetina Arto Valkonen Kari Rissanen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15144-15150
N‐Alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra‐ and intermolecular hydrogen bonds that leads to cavitand‐like structures. Depending on the upper‐rim substituents, self‐inclusion was observed in solution and in the solid state. The self‐inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self‐included dimers spontaneously reorganize to 1:1 host–guest complexes. These host compounds show an interesting ability to bind a series of N‐alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C?O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl?) and ammonium (NH2+) cations of the hosts, and also through CH ??? π interactions between the hosts and guests. The self‐included and host–guest complexes were studied by single‐crystal X‐ray diffraction, NMR titration, and mass spectrometry. 相似文献
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Grazia Cafeo Dr. Franz H. Kohnke Prof. Luca Valenti Andrew J. P. White Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(36):11593-11600
10α,20α‐Bis(4‐nitrophenyl)calix[4]pyrrole ( 1 ) forms 1:1 complexes with anions of selected aromatic hydroxy acids in which the host orientation within the guest is controlled by a change in the pH value. Some bis‐anionic guests, including those obtained from 4‐hydroxybenzoic acid, 1,4‐ and 1,3‐benzenedicarboxylic acids, induce the self‐assembly of molecular capsules involving two molecules of the receptor. 1H NMR data and solid‐state structures of the 1:1 complex of 1 with p‐C6H4(COOH)(COO?)+NMe4 and the 2:1 capsule [( 1 )2m‐C6H4(COO?)2(+NMe4)2] provide structural details in solution and in the solid state. 相似文献
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Harvey L. Wiener Lee Ilardi Patricia Liberati Lisa Dengler Sheryl A. Jeffas Shahrokh Saba Norman O. Smith 《Journal of inclusion phenomena and macrocyclic chemistry》1986,4(4):415-427
In continuing attempts to determine the basis for the selectivity shown by the host Ni(4-mepy)4(NCS)2 (1) toward aromatic guests, distribution data between solid and liquid phases are reported for seven ternary systems at room temperature. These consist of1,p-xylene, and each of the following:p-bromotoluene,p-chlorotoluene,p-fluorotoluene,p-dichlorobenzene, benzene, and 4-methylpyridine, as well as the system1-p-chlorotoluene-p-dichlorobenzene. The results, as well as those for five systems already published, have been reviewed and a hierarchy of selectivity developed. After correcting the observed selectivity for inequality of guest vapour pressures the order of decreasing preference is found to bep-bromotoluene >p-dichlorobenzene >p-chlorotoluene > deuterated and protiatedp-xylenes > ethylbenzene > 4-methylpyridine >p-fluorotoluene > toluene > benzene. With the exception of 4-methylpyridine, this is the same as the order of decreasing van der Waals length of the guest molecule and, where known, the order of enthalpy of inclusion. Although longer guest molecules and those with higher vapour pressures are favoured in selectivity, guests with longer molecules are likely to have lower vapour pressures. The activity coefficients of the included guests are calculated assuming that the liquid phases follow Raoult's law.Portions of this paper were presented at the Second and Fourth International Symposia on Clathrate Compounds and Molecular Inclusion Phenomena held in Parma, Italy, 1982 and Lancaster, England, 1986. 相似文献
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Michael Heilmann Prof. Dr. Konrad Tiefenbacher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(56):12900-12904
A molecular tweezer based on a glycoluril-derived framework bearing four phosphate groups was synthesized and shown to be capable of binding organic amines in aqueous solution. This work reports the Ka values for 30 complexes of this molecular tweezer and amine guests, determined by means of 1H NMR titrations. Both the hydrophobic cavity and the phosphate groups contribute to the binding. Bulkier molecules and molecules bearing negatively charged groups like carboxylates in amino acids bind less tightly due to a steric clash and coulombic repulsion. The narrow cavity and the strong ionic interactions of the phosphate groups with ammonium guests favor binding of aliphatic diamines. These binding properties clearly distinguish this system from structurally related molecular clips and tweezers. 相似文献