Preparation of C2-symmetric chiral crown eters derivatives and investigation of their enantiomeric recognition properties

Synthesis of first synthetic chiral macrocyclic compound by Wudl and Geata n 1972 and behaving of these synthetic chiral macrocycles similar to enzyme-substrate make enantiomeric recognition in supramolecular chemistry an interesting area.Homotopic chiral crown ethers have an important advantage especially in chiral recognition processes due to their C2- symmetry giving two same faces similar to host-guest interaction. Since guest molecules having homotopic surface and high symmetry facilitate NMR spectra of complexes, conformational changes and interactions formed in the complexation can be studied and understood beter by using these receptors.When compared to other crown ethers, existence of one more nitrogen atom in the macrocycle enhances cation binding. Especially 18-Crown-6 ether derivative ligands including pyridine substituent exhibit better ?-? interaction with tripodal hydrogen bond and the aromatic structure in the ammonium cations.In the present study, C2- symmetric 18-Crown-6 ether derivatives including dipyridine substituent and having ethyl-(4), isopropyl-(5), phenyl-(6) and benzyl-(7) substituents in the stereogenic center respectively, have been synthesized. Because influence of substituent in stereo centers is an important factor in enantiomeric recognition, effect of ethyl-, isopropyl-, phenyl- and benzyl- substituents on enantiomeric recognition was investigated as well.