Study On Applications Of Cucurbituril And Its Derivatives In Chromatography

Macrocycle supramolecular chromatography stationary phases have been gaining great interest for the chromatography due to special molecular recognition based on supramolecular interaction retention mechanism. A great deal of studies have shown that cucurbit[n]urils (CB[n], n=5-10), the macrocyclic host molecules of the fourth generation supramolecular, possess special capacity of the molecular recognition for a wide variety of guest molecules based on supramolecular interactions. Although cucurbit[n]s are potentially as useful as well-known host molecules such as crown ethers, cyclodextrins, and calixarenes, their practical applications are still limited especially in separation science. How to promote separation selectivity via the molecular recognition of CB[n] ligands is an attracting subject in the overlapping area of modern chromatography with supramolecular chemistry, showing great promising prospect for the researches of separation theory and application. In this thesis, CB[n]s was used as stationary phase for gas chromatography for the first time. The preliminary evaluation of the new stationary phases for GC was carried out. Related separation mechanism was systematically studied. Meanwhile, the preparation, characterization, evaluation and retention mechanism of cucurbit[6]uril mono-rotaxane-bonded silica stationary phases for HPLC were studied systematically. The main contents studied are as follows:1. The progress of the study of crown ethers, cyclodextrins, and calixarenes in HPLC and GC were reviewed in detail. The main subject focused on the preparation, chromatographic property, retention mechanism and application of cucurbituril-bonded stationary phases for HPLC and molecular assembly of cucurbituril. The application prospect of cucurbituril for separation science and related techniques in the future is discussed. Above all provide the basis and start point for further research of the subject.2. Glycoluril, cucurbit[6]uril and perhydroxycucurbit[6]uril were synthesized. Their structures were characterized by infared fourier transform spectroscopy, elemental analysis, thermal analysis and mass spectrometry. This provided material for the preparation of GC stationary phases and bonded silica stationary for HPLC.3. A novel method of well-proportionally coating perhydroxycucurbit[6]uril stationary phase (PSP) on a packed column under acidic condition was developed, perhydroxycucurbit[6]uril has been used successfully as stationary phase for packed column gas chromatography for the first time. Perhydroxycucurbit[6]uril stationary phase exhibited wide operational temperature, outstanding thermostability and good selectivities for various organic compounds, such as alkanes, aromatic hydrocarbons, alcohols, esters, ketones and amines, etc. It was also found that some positional isomers, such as disubstituted benzenes could be well separated on this column. PSP has excellent separation abilities to some complicate samples, for example commercial toilet waters. PSP exhibits the promising application in the separation of complicate samples. Separation mechanism of the new packing for GC-separation was preliminary discussed.4. Cucurbit[6]uril and glycoluril packed column was prepared and glycoluril was used as stationary phase in packed column gas chromatography for the first time. Their chromatographic properties were studied by using different probes. The results showed that the glycoluril stationary phase (GSP) was a good GC stationary phase with wide operational temperature, outstanding thermostability and good separation ability for alkanes, halohydrocarbons, aromatic hydrocarbons, alcohols, esters, ketones, carboxylic acids and amines, etc. It was also found that some positional isomers such as disubstituted benzene can be well separated on GSP. The GC-separation mechanism of GSP was preliminary discussed. The results also showed that cucurbit[6]uril can absorbed and capture gas molecules. Cucurbituril will be well application prospect in environmental protection.5. The interactions between cucurbit[6]uril and organic volatile molecules were studied by using gas chromatography method. The results show that cucurbit[6]uril can absorb and capture gas molecules especially for small molecules, cucurbit[6]uril can be used in control indoor air pollution such as the treatment of indoor formaldehyde pollution. 6. A novel cucurbit[6]uril monorotaxane bonded silica stationary phase (CB6MRBS) for high performance liquid chromatography has been prepared successfully by combining supramolecular self-assembly technology with the immobilization technique of chromatographic stationary phase. A cucurbit[6]uril monorotaxane (CB6MR) was, for the first time, grafted to silica gel by usingγ-glycidoxypropyl-trimethoxysilane (KH-560) as a coupling reagent. CB6MRBS was characterized by FTIR, elemental analysis and thermal analysis.7. The chromatographic performance and retention mechanism of CB6MRBS were evaluated by using organic components including acidic, basic, neutral analytes and positional isomers of disubstituted benzene as probe molecules under both reversed-phase and normal-phase modes. The results show that CB6MRBS is a kind of multimode bonded stationary phase with excellent reversed-phase and normal-phase chromatographic properties. CB6MRBS shows obvious priority for separation of positional isomers, especially for the better separation of basic compounds. The new packing material can provide various action sites for different analytes, such as those of hydrogen-bonding,π-π, electrostatic and hydrophobic interactions. It may have good prospect for complexation chromatography, which is required to further stduy.8. The new cucurbit[6]uril monorotaxane-bonded stationary phases were used for the separation of solute series. The chromatographic behavior of purine derivatives on CB6MRBS were studied by high performance liquid chromatography under normal and reversed phase modes. A comparative study with ODS was carried out as well. The various influence factors on the chromatographic behavior of the solutes on CB6MRBS were investigated. The chromatographic conditions were optimized partially, which paid the way for further applications. Coffeine has been determined by using CB6MRBS under both reversed-phase and normal-phase modes. The results show that various interactions occurred between the analytes and CB6MRBS besides hydrophobic interaction under reversed-phase mode, which was different from that on ODS. CB6MRBS were superior to ODS in the above separations. According to the chromatographic analysis, the separation mechanism of multiple interactions also existed under normal-phase chromatography. CB6MRBS can provide various sites for analytes, such as the hydrophobic, hydrogen-bonding,π-πand dipole-dipole interactions. Separations of purine derivatives on CB6MRBS were achieved with satisfaction due to the various retention mechanisms both under reversed and normal phase modes. CB6MRBS exhibits the promising application in the rapid separation and determination of purine derivatives.9. Applying of cucurbituril in capillary column gas chromatography and the chromatographic application of CB6MRBS such as for biochemical samples will still be requiring to be developed in the next step.