Determine The Absolute Configurations Of Chiral Compounds With Free Ruthenium Porphyrin By Circular Dichroism

As ruthenium porphyrins are strong Lewis acids, the thesis describes them as chromophoric groups which are able to bond to a diamine and to form the host-guest sandwich complex with a preferential chiral twist in the porphyrin-porphyrin arrangement. The free-two-porphyrin sandwich complex generates an exciton-coupled CD response, whose signals represent the absolute configuration of the chiral diamines. The absolute configurations of chiral amino acids determined by this method are completely concordant with the methodology proposed by Nakinishi. We have successly determined the absolute configurations of chiral amino acids by this method. Due to the strong Lewis acidity of ruthenium porphyrins, the two free Ru porphyrins need no "chain" to link to a diamine, and the ruthenium porphyrins are easy to be prepared. The bonding force between the same substrate and Zn or Mg porphyrin are weaker than Ru porphyrin. Moreover, these ruthenium porphyrins in our method are commercialization and easy to be obtained by purchase. The method for determining the absolute configurations applied for a series of amino acids has achieved good results.Our work in this thesis contains the following two parts.The first, we found that ruthenium porphyrins are strong Lewis acids and be able to bond amines via ruthenium-amine coordination. We have tested the association constant between ruthenium porphyrin and amine. The association constant between the same substrate and Zn or Mg porphyrin (103～106 mol-1) were weaker than Ru porphyrin (～108 mol-1). Moreover, we conjecture that ruthenium porphyrins need no "chain" to link the two free Ru porphyrins to bond to a diamine and to form a host-guest sandwich complex with a preferential chiral twist in the porphyrin-porphyrin arrangement. The free-two-porphyrin sandwich complex generates an exciton-coupled CD response, whose signals represent the absolute configuration of the chiral diamines. Then we will introduce the two free Ru porphyrins with no "chain" linked to bond to the amino acid derivative and form a host-guest sandwich complex through bidentate ruthenium coordination. The absolute configuration of a series of chiral amino acids was determined though exciton-coupled CD response generated by preferred interporphyrin helicity. We have successly determined the absolute configurations of chiral amino acids by this method.The second, in order to extend the application of our method, we choose another three ruthenium porphyrins [RuⅡ(TMP)CO], [RuⅡ(TPP)CO], and [RuⅡ(F20-TPP)CO] as hosts, and L-Isoleucine derivative are applied for guest to form the sandwiches complex with such three Ru porphyrins, and we can also determine the absolute configuration of the guest by the CD spectra. These ruthenium porphyrins are commercial and easy to be obtained by purchase. It is not only to extend the application of this CD method, but also to make such a method much easier.