Synthesis Of Helical Polymer And The Application In Chiral Recognition And RDC Value Extracted

The helical polymers possess unique properties due to the existenceof chiral helix conformation, and have versatility applications, such aschiral separation, chiral catalysis, for the formation liquid crystalline.This paper focuses on the synthesis of helical polymer and theirapplication in chiral recognition and the measurement of RDC. The thesisdivided into the following two parts:1. The L-valine-derived polyacetylene was achieved bypolymerization of the monomer. The synthesis of monomer was startingfrom L-valine.1H NMR experiment shows that the helical polyacetylenecan be used as a chiral reagent to carboxylic acid. Compared to themonomer prior to polymerization, it demonstrated that the formation ofhelical structure was critical to chiral recognition. To our delight, thehelical polyacetylene can realize chiral recognition by NMR withoutforming liquid crystal phase. To our knowledge, this is the first exampleof a helical polymer used as a chiral solvation reagent.2. The synthesis of L-leucine-derived polyacetylene was accordingto the above protocol. The helical polymer shows good solubility inchloroform. When its concentration reaches20%w/w in chloroform, theliquid crystal phase can be formed. It can be used as alignment media toobtain RDC of the molecule. The residual dipolar coupling was obtainedvia CLIP-HSQC NMR experiment. The analysis of model moleculestrychnine showed the synthetic polymer can be used as a good alignmentmedium for extracting residual dipolar coupling of the apolar molecules.The chiral helical polyisocyanides was prepared starting from D-valine.2H NMR experiment result showed that the polyisocyanides canform liquid crystal phase in chloroform when its concentration reached18%. The RDCs of strychnine extracted from this liquid crystal phaseshow good agreement with calculated one. The analysis of strychninedemonstrated that the polyisocyanides can be used as a new alignmentmedium to obtain residual dipolar coupling of the measured molecule.