一种新型羟基葫芦[6]脲气相色谱固定相性能的研究

本文首次成功地制备和利用羟基葫芦[6]脲((HO)12CB[6])作填充柱气相色谱固定相。研究表明,羟基葫芦[6]脲固定相(PSP)具有较宽的操作柱温、高度的化学和热稳定性,对多种类型的化合物展示较高的色谱分离选择性,这包括烷烃、芳烃、醇类、酯类、酮类和胺类等多种化合物。新柱对一些二取代苯环芳族位置异构体有较强的分离能力。实验发现,羟基葫芦[6]脲固定相对日用花露水中复杂的挥发性成分有高效快速分离能力。同时,初步探讨了新固定相的色谱分离机理,发现羟基葫芦[6]脲对溶质的部分包结作用,而不是完全包结作用,有利于提高其色谱分离选择性和柱效。此外,在极速程序升温色谱中,该固定相低流失基线漂移小,有利于实现宽沸点范围复杂样品的快速气相色谱分离分析。     

葫芦[6]脲单轮烷键合固定相的制备、表征及色谱性能

将超分子自组装技术与色谱键合硅胶固定相制备技术相结合,采用γ-[(2,3)-环氧丙氧]丙基三甲氧基硅烷(KH-560)为偶联剂,首次将一种葫芦[6]脲单轮烷(CB6MR)键合到硅胶上,制备了一种新型的葫芦[6]脲单轮烷键合固定相(CB6MRBS)。通过元素分析、红外光谱和热分析对该固定相进行了结构表征。以中性、酸性、碱性化合物和二取代苯位置异构体等溶质为探测因子,分别在反相和正相色谱模式下对固定相的色谱性能和保留机理进行了研究。结果表明：CB6MRBS是一种多模式键合固定相,具有良好的正相和反相色谱性能,对位置异构体具有较高的识别能力,尤其是可有效地用于碱性化合物的分离分析。其保留机理存在氢键、静电、π-π和疏水作用等多种作用力机制,协同作用提高了CB6MRBS对溶质的分离选择性。由于CB6MR配体中含有酰胺基和众多极性羰基,CB6MRBS可能在络合色谱面有应用前景。     

硅藻土载负葫芦[7]脲气相色谱固定相的制备及其性能评价

在酸性条件下,将自制的葫芦[7]脲均匀地涂覆到102白色硅藻土担体上,制得葫芦[7]脲气相色谱固定相。 采用红外光谱、质谱、元素分析和热重分析表征了葫芦[7]脲在载体表面的结构。 利用相关探针测定了新固定相的麦氏常数,表征了其基本色谱性能。 考察了葫芦[7]脲气相色谱固定相填充柱对芳香烃、卤代烃、醇、酮、酯及硅氧烷的分离能力。 结果表明,葫芦[7]脲固定相热稳定性高,柱色谱性能稳定,对较广泛的化合物尤其对高沸点的酯类及硅氧烷类化合物显示出良好的色谱分离能力(7 min内分离),作为气相色谱固定相有较好的应用前景。 初步讨论了葫芦[7]脲固定相对上述化合物的分离机理。     

Preparation and characterization of perhydroxyl-cucurbit[6]uril bonded silica stationary phase for hydrophilic-interaction chromatography

In this paper, perhydroxyl-cucurbit[6]uril ((HO)₁₂CB[6]) was, for the first time, grafted to silica gel as a hydrophilic-interaction chromatographic stationary phase. Several alkaloids were used as probes to investigate the retention mechanism on the new stationary phase. The effect of mobile phase variables such as acetonitrile content, ionic strength and pH on their chromatographic behavior was investigated. The results indicate that the stationary phase behaves as a hydrophilic-interaction chromatographic packing. Finally, several alkaloids were separated on the stationary phase.     

Improvement of Dispersion and Release Properties of Nifedipine in Suppositories by Complexation with 2-Hydroxypropyl-β-cyclodextrin

Geometries, electronic properties and NMR-shielding of cucurbit[5]uril, decamethylcucurbit[5]uril, cucurbit[6]uril, cucurbit[7]uril, and cucurbit[8]uril are investigated with DFT calculations. All molecules are highly symmetrical with a distinct geometric flexibility. In addition with a characteristic partial charge distribution these findings account for their chemical complex building ability.     

Cucurbit[5]uril, Decamethylcucurbit[5]uril and Cucurbit[6]uril. Synthesis, Solubility and Amine Complex Formation

A simple way to prepare cucurbit[5]uril is described. The macrocycles of the cucurbituril type are nearly insoluble in water. The solubilities of cucurbit[5]uril, decamethylcucurbit[5]uril and cucurbit[6]uril in hydrochloric acid, formic acid and acetic acid of different concentrations have been investigated. Due to the formation of complexes between cucurbit[n]urils and protons the solubility increases in aqueous acids. The macrocyclic ligands are able to form complexes with several organic compounds. Thus, the complex formation of the cucurbituril macrocycles with different amines has beenstudied by means of calorimetric titrations. The reaction enthalpy gives noevidence of the formation of inclusion or exclusion complexes. ¹H-NMR measurements show that in the case of cucurbit[5]uril and cucurbit[6]uril the organic guest compound is included within the hydrophobic cavity. Decamethylcucurbit[5]uril forms only exclusion complexes with organicamines. This was confirmed by the crystal structure of the decamethylcucurbit[5]uril-1,6-diaminohexane complex.     

Separation performance of polydopamine-based cucurbit[7]uril stationary phase for capillary gas chromatography

Polydopamine(PDA) coating, a nature-inspired polymer, has attracted great attention in many areas due to its high adhesion strength and stability on almost all types of substrate surfaces. This work presents the first example of using PDA coating as a column pretreatment method in capillary gas chromatography(GC) and its employment in the column fabrication of cucurbit[7]uril(CB7) stationary phase. The fabricated PDA-CB7 column exhibited weakly polar nature and had advantages over CB7 column without PDA for the separations of some critical analytes in GC. This work demonstrates the advantage and potential of using PDA as a facile column pretreatment method in capillary GC column fabrication.     

Efficient Room‐Temperature Phosphorescence of a Solid‐State Supramolecule Enhanced by Cucurbit[6]uril

Efficient emission of purely organic room‐temperature phosphorescence (RTP) is of great significant for potential application in optoelectronics and photobiology. Herein, we report an uncommon phosphorescent effect of organic single molecule enhanced by resulting supramolecular assembly of host–guest complexation. The chromophore bromophenyl‐methyl‐pyridinium (PY) with different counterions as guests display various phosphorescence quantum yields from 0.4 % to 24.1 %. Single crystal X‐ray diffraction results indicate that the chromophore with iodide counterion (PYI) exhibits the highest efficiency maybe due to the halogen‐bond interactions. Significantly, the nanosupramolecular assembly of PY chloride complexation with the cucurbit[6]uril gives a greatly enhanced phosphorescent quantum yield up to 81.2 % in ambient. Such great enhancement is because of the strict encapsulation of cucurbit[6]uril, which prevents the nonradiative relaxation and promotes intersystem crossing (ISC). This supramolecular assembly concept with counterions effect provides a novel approach for the improvement of RTP.     

Opposing substitution in cucurbit[6]urils forms ellipsoid cavities: the symmetrical dicyclohexanocucurbit[6]uril is no exception highlighted by inclusion and exclusion complexes

The symmetrical dicyclohexanocucurbit[6]uril has been synthesised by the controlled condensation of the diether of cyclohexanoglycoluril (1) and the dimer of glycoluril (2). The symmetrical dicyclohexanocucurbit[6]uril, (CyH)₂Q[6], characterised by the ¹H NMR spectroscopy, ESMS and further confirmed by single crystal X-ray diffraction of a cobalt aqua exclusion complex, which demonstrates an ellipsoid cavity. Within a cucurbit[6]uril ellipsoid cavity, an inclusion complex of 5,5′-dimethyl-2,2′-bipyridine adopts a preferred orientation, aligning with the longest axis. The ellipsoid cavity is further supported by semiempirical AM1 gas phase calculations.

Preferential orientation of a guest within the ellipsoid cavity of the symmetrical dicyclohexanocucurbit[6]uril     

甘脲和羟基葫芦[6]脲气相色谱固定相的制备及其色谱分离性能比较研究

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.     

Chromatographic behavior of a new hybrid type RP material containing silica bonded 1,3‐alternate 25,27‐bis‐[cyanopropyloxy]‐26,28‐bis‐[3‐propyloxy]‐calix[4]arene

A novel 1,3‐alternate 25,27‐bis‐[cyanopropyloxy]‐26,28‐bis‐[3‐propyloxy]‐calix[4]arene‐bonded silica gel stationary phase (CalixPrCN) was prepared and its structure was confirmed by ATR‐FTIR spectroscopy and elemental analysis. The CalixPrCN phase was characterized in terms of its surface coverage, hydrophobic selectivity, aromatic selectivity, shape selectivity, hydrogen bonding capacity, residue metal content, and silanol activity based on Tanaka, Lindner, and SMR 870 test protocols. The effect of the acetonitrile content on the retention and selectivity of the selected neutral, basic, and acidic solutes was studied. The neutral and acidic analytes exhibited classical RP behavior, in which retention time decreases with increasing acetonitrile content. In contrast, basic analytes showed an increase in retention at low and high percentages of acetonitrile, forming “U‐shaped” retention profiles. The new calixarene phase was compared with previously reported 1,3‐alternate 25,27‐bis‐[propyloxy]‐26,28‐bis‐[3‐propyloxy]‐calix[4]arene stationary phase and commercial cyanopropyl column. The results indicate that the CalixPrCN stationary phase behaves like RP packing; however, inclusion complex formation, dipole–dipole, and π–π interactions seem to be involved in the separation process. The selectivity of this phase was demonstrated in separation of polynuclear aromatic hydrocarbons, non‐steroidal anti‐inflammatory drugs, and sulfonamides as analytes.     

Complexation behavior of cucurbit[6]uril with short polypeptides

The binding properties of cucurbit[6]uril towards various peptides have been investigated in acidic aqueous solution. Stability constants and thermodynamic values of the complex formation between following peptides: glycyl-l-alanine, l-leucyl-l-valine, glycyl-l-asparagine, l-leucyl-l-phenylalanine, l-leucyl-l-tryptophan, glycyl-l-histidine, l-glutathione reduced (γ-l-glutamyl-l-cysteinyl-glycine, GSH), and dl-leucyl-glycyl-dl-phenylalanine) with cucurbit[6]uril in aqueous formic acid (50%, v/v) have been calculated from calorimetric titrations. From these results it can be seen that the peptides form exclusion complexes with cucurbit[6]uril. Due to the polar peptide bond they are not included within the hydrophobic cavity of cucurbit[6]uril. The complex formation is favoured by entropic contributions. The release of water molecules from the polar amino groups of the peptides and the carbonyl groups of cucurbituril are responsible.     

Open‐tubular capillary electrochromatography using carboxylatopillar[5]arene as stationary phase

Pillar[n]arenes have achieved much interest in material chemistry and supramolecular chemistry due to unusual pillar shape structure and high selectivity toward guest. However, pillar[n]arenes have not yet been applied in capillary electrochromatography. This work at first time reports that carboxylatopillar[5]arene is used as a stationary phase in open‐tubular capillary electrochromatography. Carboxylatopillar[5]arene not only possess the advantages of pillar[n]arenes but also provide free carboxy groups for immobilizing on the inner wall of capillary column via covalent bonding. The characterization of SEM and FT‐IR indicated that carboxylatopillar[5]arene was successfully grafted on the inner wall of capillary. The baseline separation of model analytes including neutral, basic, and acidic compounds, nonsteroidal anti‐inflammatory drugs and dansyl‐amino acids have been achieved thanks to the electron‐rich cavity of carboxylatopillar[5]arene and hydrophobic interactions between the analytes and stationary phase. The intraday, interday, and column‐to‐column precisions (RSDs) of retention time and peak area for the neutral analytes were all less than 3.34 and 9.65%, respectively. This work indicates that pillar[n]arenes have great potential in capillary electrochromatography as novel stationary phase.     

六元瓜环与磺基水杨酸主客体配合物的晶体结构

合成了六元瓜环与磺基水杨酸主客体配合物,并测定了其单晶结构.晶体结构表明六元瓜环包结了3个水分子,磺基水杨酸位于六元瓜环的外侧,且与水分子通过氢键与六元瓜环相连,瓜环之间通过端口的羰基O原子、磺基水杨酸以及水分子间的氢键作用形成一维超分子.     

Synthesis of Cucurbit[5]uril-Spermine-[2]Rotaxanes

Cucurbit[5]uril and decamethylcucurbit[5]uril are cyclic pentamers built from glycoluril or dimethylglycoluril respectively. Two different experimental methods have been used for the synthesis of the different [2]rotaxanes. The formed rotaxanes are characterized using ¹H-NMR spectroscopy, mass spectrometry and elemental analysis. In contrast to cucurbit[5]uril no [2]rotaxane could be obtained with decamethylcucurbit[5]uril.     

两种部分甲基取代瓜环配合物的晶体结构(英文)

本文报道了2种新的部分甲基取代瓜环配合物的晶体结构,利用X-射线单晶衍射技术表征了2种配合物的结构,在CdCl2溶液中,1,2,4,5-八甲基六元瓜环选择性的包结客体分子1,2-(2,2′-bisbenzimidazolyl)ethanedichloride,形成2∶1的哑铃型主客体包结配合物;而1,2,4-六甲基五元瓜环(HMeQ[5])与钠离子配位形成包结一个水分子的"分子胶囊","分子胶囊"之间通过氢键自组装形成一维的超分子长链。     

Investigation of Host–Guest Compounds of Cucurbit[n=5–8]uril with Some Ortho Aminopyridines and Bispyridine

Host–guest complexes of cucurbit[n=5–8]uril and some examples of ortho substituted pyridines or aminopyridines were examined by ¹H NMR spectroscopy. Portal binding of two ortho aminopyridine free bases, by cucurbit[5]uril, was observed in ¹H NMR spectra. Combined cavity and portal binding in cucurbit[6]uril were observed for both the free base 2-aminomethylpyridine, ampy, the HCl salt, ampy·1HCl, and the salt of 2,2′-bispyridine, bpy·1HCl. Two novel complexes were formed with cucurbit[6]uril. The free base ampyas a dual occupant, formed a 2:1 complex, and bpy·1HCl formed a stable asymmetric 1:1 complex. Only portal binding of 2,6-bisaminomethylpyridine and its salts was observed for cucurbit[6]uril. Fast exchange of the free base and pyridineammonium salts was observed for cucurbit[7-8]uril.This revised version was published online in July 2005 with a corrected issue number.     

Features of adsorption phenomena in strontium salt solutions in the presence of some cavitands of cucurbituril family

The influence of the electrolyte nature and cation charge on the adsorption properties of cucurbit[6]uril supramolecular complexes are established and discussed. The results show the narrowing of the adsorption potential region of these complexes with increasing cation charge, and the possibility to form an adsorbate layer of supramolecular cations associated with surface-active electrolyte anions at the positive boundary of the adsorption potential region.     

Understanding behaviour of vitamin-C guest binding with the cucurbit[6]uril host

The present study describes non-covalent interaction and complexation behaviour of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na₂SO₄ solution. The interaction behaviour is investigated using various analytical techniques like NMR, UV–Vis, fluorescence, TGA and DRS. The substantial increase in the intensity of emission and absorption spectra of sodium ascorbate is observed. The Benesi–Hildebrand evaluation method is used to determine the stoichiometry and equilibrium constant of the cucurbit[6]uril–sodium ascorbate complex, which suggested the 1:1 complex. Time-dependent ¹H NMR, ¹³C CP MAS and CD studies also echoed non-covalent interaction between SA with CB[6].     

羟基葫芦[6]脲与孟加拉红包结作用的荧光光谱研究

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。