Chiral Ruthenium Porphyrin:a Convenient Chiral Shift Reagent For Determining The Ee Of Primary And Secondary Amines By~1H NMR

In the whole world, many scientists are conducting the study of molecular recognition, which is a thriving field of organic analytical chemistry. Chiral primary and secondary amines have many important chemical and pharmaceutical applications, and as a consequence, a wide range of methodologies have been developed for the determination of the enantiomeric excess (ee) of chiral amino compounds. Study of the spatial structure based on chiral ruthenium porphyrin, we found that it can bind with amines via ruthenium-amine coordination and form a stable complex, so this thesis presents chiral ruthenium porphyrin as a chiral shift reagent to determine the ee of guest molecule by’H NMR. Specific research content as follows:1. The design and optimization of chiral host molecules (chiral porphyrin) are carried out. The setting of chiral environment is key in chiral recognition. In order to adjust the chiral environment of chiral porphyrin, we can not only change the chiral groups, but also change the steric groups. The change of steric groups are easier and more efficient.2. As part of our continuing efforts in this area, we found that ruthenium porphyrin is a strong Lewis acid that can form a stable complex with amines via ruthenium-amine coordination. Due to the special of chemical shift effect of chiral ruthenium porphyrin that it can be used as a chiral shift reagent for the determination of the ee of primary and secondary amines by1H NMR.3. We first studied the binding constants (Ka) of Ru porphyrin and amino compound by using an UV-vis titration method, which is stonger than that of the leucine derivative and Zn porphyrin or Mg porphyrin. Moreover, combined with a carbonyl, the ruthenium porphyrin molecule coordinates with only one amine substrate at the axial position. The porphyrin plane and bulky rigid meso-groups furnish a semienclosed cavity which hides nucleophilic groups and active hydrogens of the amine substrates and keeps them from not interfering with each other. Interestingly, the peaks of the complexes disperse in two regions in the1H NMR. The proton resonances of the alkyl part appear in the high-field region (-7-1ppm), whereas the aryl hydrogens resonate in the low-field region (4-7ppm). Combined with a good chiral environment is provided by chiral ruthenium porphyrin, so that△δ values of all the tested amines were tabulated.4. Further systematic study of the ee of chiral amines with different functional groups (alkyl, aryl, alcohol, ester, etc.). With chiral ruthenium porphyrin in hand,△δ values of the diastereomeric complexes were tabulated. Analysis of the△δ values, we found that the reaction is readily carried out without byproducts and the signals were clearly detected by1H NMR.5. As a supplement to the subject of absolute configurations of multiple amino acid resides systems in peptides,1H NMR method was used to determine their absolute configurations. Chiral ruthenium porphyrin is a potential receptor with strong binding affability for all common amino acids, so it could be used to investigate the chirality of a multianalyte system of amino acid resides from a peptide and these results are high in reliability.