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采用荧光光谱法研究了羟基葫芦[6]脲(HOCB[6])对孟加拉红(TSS)的包结作用,考察了HOCB[6]浓度、缓冲液pH、温度、包结时间、有机溶剂等因素对包结作用的影响,结果表明,体系的荧光强度随着HOCB[6]浓度的升高而增强,呈现显著荧光增敏现象,同时荧光峰位有一定蓝移,Hildebrand-Benesi法计算结果显示HOCB[6]与TSS形成了1∶1的包结配合物,包结反应的热力学参数表明该包结过程为自发放热过程,这可能是主客体分子之间的疏水作用与离子偶极作用所引起的。 相似文献
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葫芦脲[7]与核黄素包结物的可能结构和光谱性质 总被引:1,自引:0,他引:1
利用密度泛函理论对葫芦脲[7]和核黄素包结物的可能结构进行了理论计算.从5种可能结构分析主客体在包结物中的作用得出:核黄素作为客体分子与主体葫芦脲[7]分子通过不同官能团作用可形成稳定性不同的包结物,其中以核糖醇的羟基插入到葫芦脲[7]分子的腔体与其端羰基氧原子形成较多的氢键最稳定.在理论上证明了此包结反应为一放热反应的实验事实,并进一步说明了包结物分子的相对稳定性受主客体分子的几何畸变能和主客体之间作用能的影响,说明了成键能和稳定性之间的区别.在此基础上利用时间相关的密度泛函理论进行了不同构型包结物的激发态计算并对光谱性质进行了理论预测.比较了包结物中核黄素分子的跃迁轨道的组成变化,分析得出:葫芦脲[7]的包结作用改变了核黄素分子的电子跃迁性质,使其吸收光谱发生红移.并预测出其荧光猝灭的微观机理,此理论计算结果很好地解释了相应的实验现象. 相似文献
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甘脲是羟基葫芦[6]脲(HOCB6)的前体, 本文设计了一种在酸性条件下均匀涂渍固定液的新方法, 首次将甘脲和羟基葫芦[6]脲用作气相色谱固定相. 将甘脲和HOCB6填装成气相色谱填充柱后, 以烷烃、卤代烃、芳香烃、醇、酮、酯、酸、胺等物质为探针, 用复杂样品花露水对它们的色谱分离性能进行了比较研究. 结果表明, 甘脲和HOCB6 都是良好的气相色谱固定相, 热稳定性高, 柱性能稳定. 两种固定相对以上溶质探针都有较好的分离能力, HOCB6固定相(PSP)与甘脲固定相(GSP)相比较, 总体上具有更好的分离选择性, 对难分离的芳香族位置异构体(如二甲苯、甲基苯胺)具有良好的分离能力, 显示出较高的立体选择性, 对花露水中的高沸点组分有较好的分离效果. 上述研究也表明, 由于溶质在载气中传质比葫芦脲内腔快得多, 全包结尽管有利于提高分离选择性, 但展宽后的柱效不理想; 适当的高柱温既保留了部分包结作用, 同时存在端口协同作用, 能兼顾高选择性和高柱效. 相似文献
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合成了外围修饰香豆素PAMAM树枝形分子Gm-2(m+1)C, 外围和核心分别共价连接香豆素和紫精的树枝形分子EV-Gm-2(m+1)C (m=0, 1), 以及香豆素和紫精的模型化合物C-Model和EV, 化合物均通过了1H NMR, IR和MALDI-TOF MS的鉴定. 1H NMR和光物理研究结果表明, 在pH=4.5的醋酸-醋酸钠缓冲溶液中, CB[7]与紫精和树枝形分子外围的香豆素基团均可形成1:1的包结复合物, 结合常数分别为3.3×106 mol-1·L和1.4~1.6×105 mol-1·L. 香豆素基团中7位二乙氨基及取代侧部分香豆素环包裹在CB[7]刚性的疏水空腔内, 包结复合物的形成限制了香豆素7位N,N'-二乙氨基的扭转, 抑制了香豆素基团从发光的分子内电荷转移(ICT)态向不发光的扭曲的分子内电荷转移(TICT)态的转变, 而且CB[7]内腔的疏水环境有利于香豆素ICT态辐射跃迁, 使体系发光大大增强. EV-Gm-2(m+1)C与CB[7]的主客体作用为分步结合机制, 加入的CB[7]先与紫精基团作用形成包结复合物, 待体系中紫精基团与CB[7]结合后, 体系中香豆素基团再与CB[7]作用形成包结复合物. 无论是Gm-2(m+1)C还是EV-Gm-2(m+1)C体系, 均可以通过加入CB[7]的量调节体系中香豆素基团与CB[7]形成包结复合物的多少, 从而实现对Gm-2(m+1)C和EV-Gm-2(m+1)C体系发光的调控. 本工作为可调控发光树枝形聚合物的发展提供了一种新的策略. 相似文献
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基于已报道的以葫芦脲-过硫酸钾体系的羟基葫芦脲合成反应,本文研究了加入KOH对原体系的影响,在优化的反应条件下,可以较理想的产率(27%)得到目标产物。产物的结构经~1H NMR、~(13)C NMR和HR-ESI-MS进行确证。 相似文献
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Host-guest complexation between the dicationic viologen 1-tri(ethylene glycol)-1'-methyl-m-xylyl-4,4'-bipyridinium and cucurbit[7]uril (CB7) was studied at pH = 4.5 in water. The stability constants of the mono- and bis-CB7 adducts were determined at 25 °C by UV-vis spectroscopy. Stopped-flow kinetic experiments were performed to measure the formation and dissociation rate constants of the monoadduct: k(1) = (6.01 ± 0.03) × 10(6) M(-1)s(-1) and k(-1) = 52.7 ± 0.4 s(-1), respectively. Possible mechanisms of complexation are discussed in view of the kinetic results. 相似文献
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MA Peihua DONG Jun XIANG Shuangchun XUE Saifeng ZHU Qianjiang TAO Zhu ZHANG Jianxin & ZHOU Xin . Institute of Applied Chemistry Guizhou University Guiyang China . The Key Laboratory of Chemistry for Natural Products of Guizhou Province Guiyang China 《中国科学B辑(英文版)》2004,47(4)
Since the structure of cucurbituril(Q[6]) has been determined in 1981[1] and its homologues cucurbit [n = 5,7,8 and 10]uril(Q[5], Q[7], Q[8] and Q[10]) have been reported in 2000[2,3], 2002[4], a series of host-guest complexes[5—7], novel supramolecular as-semblies[8—10], molecular encapsulates[11,12] and mo-lecular containers[13,14] based on Q[n] have been stud-ied extensively. All cucurbituril homologues have common char-acteristic features, i.e. hydrophobic cavity, and polar carbonyl gr… 相似文献
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MEIER Herbert 《中国科学:化学(英文版)》2012,55(2):223-228
A facile method for the synthesis of pillar[6]arenes was developed.A series of pillar[6]arenes were prepared with FeCl 3 as catalyst and chloroform as solvent at room temperature in moderate yields(30%-40%).Their host-guest properties with n-cetyltrimethyl ammonium bromide were investigated by 1 HNMR.The results showed that high selectivity in the host-guest relationship became apparent between pillar[6]arenes and pillar[5]arenes based on the different size of the inner cavity. 相似文献
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Botta B D'Acquarica I Monache GD Subissati D Uccello-Barretta G Mastrini M Nazzi S Speranza M 《The Journal of organic chemistry》2007,72(24):9283-9290
Four cone resorc[4]arene octamethyl ethers (10, 11, ent-10, and ent-11) tetrafunctionalized at the feet with valyl-leucine [LL- (6); DD- (ent-6)] and leucyl-valine [LL- (9); DD- (ent-9)] methyl esters have been synthesized. These compounds, obtained by conjugation of macrocycle tetracarboxylic acid chlorides with the appropriate terminal amino groups of the above dipeptides, are N-linked peptidoresorc[4]arenes. We found that these macrocycles (M) are capable of recognizing the homologue dipeptides as guests (G), both in solution and in the gas phase, by forming relatively stable host-guest complexes ([M.G]), resistant to chromatographic purification but not to heating. Complexation phenomena between M and G in solution were investigated by NMR methods, including NMR DOSY experiments, for the detection of translational diffusion. Heteroassociation constants of 2030 and 186 M(-1) were obtained by the Foster-Fyfe method for the complexes [10.6] and [10.ent-6], respectively, the latter being comparable to the self-association constant of dipeptide itself. Conversely, the structural features of the proton-bound complexes [M.H.Gn]+ (n = 1, 2), generated in the gas phase by electrospray ionization mass spectrometry (ESI-MS), were investigated by collision-induced dissociation (CID) experiments. In both cases, the four N-linked peptidoresorc[4]arenes were shown to act as synthetic receptors and to recognize the homologue dipeptide by means of hydrogen bonds. 相似文献
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In this paper, the synthetic route of a potential antitumor reagent, benzo[b][1,10] phenanthrolin-7(12H)-one (BPO), was improved. A sulfonic group was introduced to BPO to form a new compound, 7-oxobenzo[b][1,10]phenan-throline-12(7H)-sulfonic acid (OPSA), in order to enhance its water-solubility. The molecular structure of OPSA has been confirmed by IR, UV, MS, 1H NMR and elements analysis. It was proved in our experiments that DNA could quench the fluorescence of OPSA and the maximum quenched intensity appeared at 408 nm (λex = 284 nm). The quenched fluorescence intensity was proportional to the concentration of DNA. Based on this phenomenon, OPSA had been used as the fluorescent probe for detection of calf thymus DNA (ct-DNA) and the corresponding linear response range was from 1.0 to 150.0 μg mL−1 and the limit of detection (LOD) was 3.8 ng mL−1. Its interaction with ct-DNA was investigated by fluorescence, absorption and viscosity measurements. When binding to ct-DNA, OPSA showed obvious fluorescence quenching and the quenched intensity was stable with the presence and absence of NaCl. The absorption spectra of OPSA had no evidence of increasing or decreasing when ct-DNA was added. The viscosity of OPSA and ct-DNA mixture showed no obvious change comparing with the viscosity of ct-DNA along. The results suggested that the interaction between OPSA and ct-DNA was groove binding in nature. Scatchard plots constructed from fluorescence titration data gave a binding constant of 8.9 × 105 L mol−1 and a binding site size of 0.35 base pairs per bound drug molecule. 相似文献
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《Electrochemistry communications》2001,3(2):91-96
A novel fluorenylidene containing a ferrocene unit has been electropolymerized. In this polymer, the ferrocene unit is grafted to the main polyfluorenylidene chain as a pendant group. The polymer is electroactive in non-aqueous and aqueous media. 相似文献
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Two novel calix[4]arene receptors containing ferrocene units in cone (L1) and 1,3-alternate (L2) conformations have been synthesized from 25,27-dihydroxy-26,28-bis[(3-aminopropyl)oxy]calix[4]arene 4 or 25,26,27,28-tetra[(3-aminopropyl)oxy]calix[4]arene 6 and ferrocenecarboxaldehyde via condensation, respectively. Their structures have been characterized by 1H, 13C, APT, COSY NMR, FTIR, HSMR, and UV–vis spectral data. The electrochemical behavior of L1 and L2 has been investigated in the presence of F?, Cl?, Br?, H2PO4?, CH3COO? anions. Electrochemical studies show that these receptors electrochemically recognize CH3COO?, H2PO4?, and Cl?, anions. Using an UV–vis study, the selectivity to these anions in DMSO solution was confirmed. 相似文献
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V. V. Bakovets E. A. Kovalenko T. P. Chusova L. N. Zelenina P. E. Plyusnin 《Russian Chemical Bulletin》2013,62(10):2109-2115
The state of water in cucurbiturils CB[6] and CB[8], which were synthesized in hydrochloric acid solutions of glycoluril and formaldehyde, was studied. The amount of water coordinated in the macrocycle cavity and on its portals was shown to depend on the moisture content of the medium, being 2.4 molecules per 1 molecule of CB[6] and 3.2 per 1 molecule of CB[8], and in CB[8] coordinated water exists in two energy states. The state with the vaporization parameters Δvap H ○ 381.5 = 29.2±0.4 kJ mol?1 and Δvap S ○ 381.5 = 50.7±1.0 J mol?1 K?1 coincides with the state of water in CB[6]. For another state, the vaporization parameters are Δvap H ○ 373 = 31.7±0.5 kJ mol?1 and Δvap S ○ 373 = 63.2±1.2 J mol?1 K?1. The number of molecules bound to the oxygen atoms of the macrocycle portals is 1.7 and 2.6 for CB[6] and CB[8], respectively. 相似文献
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The host-guest stability constants for the inclusion of a series of small neutral polar organic guests in cucurbit[7]uril (CB[7]) have been determined in aqueous solution by (1)H NMR titrations. The dependence of the stability constant on the nature of the guests indicates that hydrophobic and dipole-quadrupole interactions are responsible for the binding. The complexation-induced chemical shift changes in the guest proton resonances, coupled with energy-minimization calculations, suggest that the guests are located such that their dipole moment is aligned perpendicular with the quadrupole moment of the CB[7] host. The stability constants for acetone and acetophenone decrease in the presence of Na(+) or K(+) cations as a result of cation capping of the CB[7] portals. 相似文献