| Molecular recognition is the basic aspect of the bio-system of nature. Chiral recognition, an important and special recognition, is the basic model of molecular recognition in the bio-system and one of the important fields of chemistry. A better understanding of the interactions operating in chiral recognition is helpful in developing new methods of asymmetric synthesis and chromatographic resolution of enantiomers.In this dissertation, the investigations were performed about amino acids primarily. Several systems on chiral discrimination were established and a series of the innovative results were obtained.In chapter one, the importance of chiral recognition and the type based on the research have been reviewed. Many chiral molecules exist in nature and organism. The researches on chiral discrimination have important effects in biology, pharmacology and materials science. The studies on chiral recognition had been carried out since its' importance was recognized by researchers. The contents reported in literatures as follows: (1) host-guest; This system is consist of the weak interactions between some cage molecules and small molecules, the specific recognition of antigen for antibody and the interactions between artificial receptors and substrates. In this part, the chiral discrimination of cyclodextrins, calixarenes, crown ethers and porphyrins for amino acids were detailedly reviewed. The details of molecule imprinted polymers (MIP) for chiral recognition were dissertated here. (2) supermolecules for chiral discrimination and amplification; There are two kinds of receptor for chiral discrimination and amplification. These receptors may be classified into two types with respect to the mechanism or origin of the chirality induced in the receptors from the chiral guests; one is induced-fit type receptor. These molecules are flexible and achiral, but upon the binding of specific chiral guests, the chirality transforms to the receptors the resulting complexes exhibited exciton-coupled ICDs whose signal can be used to detect the chirality of the guest molecules. The other isinherently chiral receptor. The receptors exist as an equal mixture of enantiomeric twisted or helical conformers, which are in rapid equilibrium. In the presence of chiral guests, however, the equilibrium shifts to one of the enantiomeric conformers (so-called asymmetric transformation or enantiomerization) as a result of the diastereoselective complexation with chiral guests, thus leading to ICDs in the receptors' chromophore regions. (3) chirality sensing by helical polymers; The development of helical polymers for chiral recognition and amplification was described in this part. (4) chiral recognition and separation using metal complexes; lanthanide complexes and transition metal complexes were summarized using for the recognition and separation of enantiomers. (5) surface chirality; Chiral surface can be obtained by the adsorption of chiral molecules and achiral molecules on metal surface or directly incising the metals carefully. These surfaces can be expressed by STM or related surface resonance techniques.In chapter two, a new approach was developed based on the self-assembled film of copper complexes on electrode via electrochemical detection. The chiral discrimination for histidine, tryptophan, phenylalanine, proline and penicillamine was carried out by ligand exchange with the complexes of copper and N-acetyl-L-cysteine assembled on the electrodes. Many techniques were used in the experiments such as square wave voltammetry, impedance, circular dichroism, NMR, X-ray photoelectron spectrum and quantum chemistry etc. The experimental results showed Cu-π weak interactions were important for chiral discrimination because the ternary complex of N-acetyl-L-cysteine and copper ions on electrodes had no discrimination for amino acid without phenyl. The difference of the potential shown on the square wave voltammetry was 32 mV for the disastereoisomers, which formed after ligand exchange. The results of computation displayed stereo effect of the disastereoisomers. The discrepancy of the energy calculated by quantum chemistry for the disastereoisomers with Phe was 3.5 KJ/mol, which was matched with the difference shown on the potential. This method provides theory evidence for the design of new electrochemical probe. The acetyl had some effects for the discrimination because the ternary complex of penicillamine and copper ions on electrodes did not discriminatethe amino acids with phenyl. Thus the weak interactions are necessary for chiral discrimination using metal complexes.In chapter three, the phenylalanine was detected via the sensors fabricated by optical active polyaniline film. Chiral polyaniline were synthesized by electrochemical and chemical methods and characterized by transmission electron microscopy (TEM) and circular dichroism (CD). The polyaniline prepared by chemical methods was modified on the glassy carbon electrode in experiments. The details of the sensors for phenylalanine were studied by open circuit potential measurements. The line scope of the sensor was 2.0 × 10-3 1.8 × 10-2 M, the detection limit was 5.0 × 10-6 M and the enantioselective coefficient was 0.23. The sensors exhibited an excellent Nernstian slope of 59 mV per decade for the matching configuration of phenylalanine and 35 mV per decade for the unmatched configuration. In addition, when the sensor was exposed to the mixture of enantiomers, the slope of the response changed along with their proportions, which would be employed as an index of the enantiomeric purity of the mixture. The effect of pH, medium, coverage, other amino acids and the stability of the sensor were also studied. At last the mechanism of chiral discrimination for Phe was discussed.In chapter four, BSA was used for receptor. BSA was modified on electrodes by self-assembly. The amino acids were detected with the changes of capacitance of the monolayer film by chronoamperammetry. However amino acids molecules are so small that the combination between BSA and amino acid has no effect on the thickness of the film. The capacitance has almost no changes. The results of the experiments showed this method was unfit for the detection of amino acids. According to the theory of capacitance, two strategies were made for the chiral discrimination of tryptophan. One is preparation of Au colloidal protected by tryptophan. Thus the tryptophan molecule becomes large. The method of capacitance may be used for the detection of tryptophan. Another is derivation of tryptophan by OPA, which is used for fluorescence label. Then the interactions between BSA and tryptophan are studied.
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