New enantiopure crown ethers containing either an ethyl diarylphosphinate moiety [(S,S)‐4 to (S,S)‐7] or a proton‐ionizable diarylphosphinic acid unit [(S,S)‐8 to (S,S)‐11] have been synthesized. Electronic circular dichroism (ECD) studies on the complexation of these new enantiopure crown ethers with the enantiomers of α‐(1‐naphthyl)ethylammonium perchlorate (1‐NEA) and with α‐(2‐naphthyl)ethylammonium perchlorate (2‐NEA) were also carried out. These studies showed appreciable enantiomeric recognition with heterochiral [(S,S)‐crown ether plus either (R)‐1‐ or (R)‐2‐NEA] preference. Theoretical calculations found three significant intermolecular hydrogen bonds in the complexes of (S,S)‐9. Furthermore, preference for heterochiral complexes was also observed, in good agreement with ECD results. Complex formation constants were determined by NMR titration for four selected crown ether/NEA pairs.
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