Preparation And Analytical Application Of Calixtriazine Chromatographic Separation Medium

Along with the advances in the field of supramolecular chemistry, more and moer macrocyclic host molecules have emerged with excellent molecular recognition performance. How to promote separation selectivity via the molecular recognition of macrocylic host molecule ligands is an attracting subject in the overlapping area of modern chromatography with supramolecular chemistry. Modern separation and analysis requires muti-mode separation media with multiple interactions to deal with more and more complex sample matrix, so as to improve the efficiency, selectivity and sensitivity. In this dissertation, a new type of macrocyclic host molecule, namely calix[2]arene[2]triazine, was selected as chromatographic ligand, several bonded silica gel HPLC stationary phases and solid phase extraction sorbents were successfully prepared. Based on molecular recognition of macrocyclic host molecules, with the assistance of quantum chemistry, thermodynamics and linear salvation energy equation, chromatographic performance and retention mechanisms were discussed in detail. The main contents are as follows: 1. The basic knowledge and research progress involved in dissertation was reviewed including multi mode liquid chromatography stationary phase and solid phase extractionsorbent, calixarene liquid chromatography stationary phase and heterocalixaromaitcs, providing the foundation for the new idea,object and design of technical scheme of the dissertation. 2. Using 3-aminopropyltriethoxysilane as coupling reagent, under proper reaction conditions, tetraoxocalix[2]arene[2]triazine, tetraazacalix[2]arene[2]triazine, tetra(benzylaza) calix[2]arene[2]triazine and bis(tetraoxacalix[2]arene[2]triazine) as ligands, four bonded stationary phase(OCS,NCS,Bz NCS and BTOSP) for high performance liquid chromatography(HPLC) were prepared. Their structures were characterized by infared spectroscopy,elemental analysis,thermal analysis and specific surface analysis.3. The HPLC properties of the new stationary phases were evaluated by using aromatics and organic anions as probes based on molecular recognition. Mechanism involved in the chromatographic separation is the multi-interaction including hydrophobic, π-π, hydrogen-bonding, inclusion and anion-exchange interactions. Based on these interactions, successful separation could be achieved among polycyclic aromatic hydrocarbons, aromatic position isomers, organic bases and phenols in reversed-phase chromatography. Inorganic anions were also shown to be individually separated in anion-exchange chromatography by using the same column. 4. The retention mechanism of the stationary phases were explained with the assistance of quantum chemistry calculation results using DFT-B3LYP/STO-3G* base group. Based on the thermodynamics, the entropy change(ΔH) and enthalpy change(ΔS) of solute molecules transfer from the mobile phase to the stationary phase was calculated. Based on capacity factor, solutes properties and mobile phase composition, linear solvation energy relationship was also applied to evaluate the hydrophobic, π-π, hydrogen-bonding and dipole interactions between stationary phase, mobile phase and solutes. The supramolecular recognition model of calixtriazine host molecules based on the chromatographic theory was contructed. 5. Changes of bridging atoms, introduction of substituents and cavity numbers of the macrocyclic compounds affected the macrocyclic host molecule electron cloud distribution, cavity size and the molecular recognition properties, and then the chromatographic performance of stationary phase. Some conclusions can be made as follows : the more larger conjugated system and stronger protonation ability on tetraazacalix[2]arene[2]triazine than tetraoxocalix[2]arene[2]triazine caused larger retention of polycyclic aromatic hydrocarbons and different selectivility of hydroquinone isomers between OCS and NCS; The introduction of benzyl changed hydrophobic abilicty, cavity size and r protonation ability of bridging-nitrogen atoms, also improved the separation selectivity of mono-substituted benzenes and inorganic anions; Due to the different cavity numbers between bis(tetraoxacalix[2]arene[2]triazine) and tetraoxocalix[2]arene[2]triazine, the separation of inorganic anions on BTOSP and OCS showed different selectivity. 6. Tetraazacalix[2]arene[2]triazine was bonded to the silica to get a functionalized sorbent for SPE with multipoint recognition sites and mixed-mode character. Based on the π-π interaction with polycyclic aromatic hydrocarbons(PAHs), chelating interaction with Cu2+ respectively, the simultaneous extraction of different types of trace analytes and stepwise elution through tuning the eluent or p H of the sample matrix were successfully achieved. The SPE conditions affecting the extraction efficiency were optimized, including type and concentration of organic modifier, sample solution p H, flow rate and volume. A new method was developed for simultaneous determination of polycyclic aromatic hydrocarbons and Cu2+ in water samples.