Abstract
We designed and prepared trefoil-shaped host molecules 1 with dynamic helicity on the basis of structural features of terephthalamides. The hosts 1 consist of threefold syn-adopted terephthalamide molecules attached to a benzene core at the center through six triple bonds, and provide dynamic helicity by adopting conformations in which all the amide groups are tilted in a conrotatory manner to afford P- and M-helicities, which are interconvertible. Through transmission of point chirality to the dynamic helicity of 1, the host is induced to prefer a particular handedness being active in CD spectroscopy. The successful transmissions were both intra- and intermolecularly achieved when a chiral auxiliary was put on the amide nitrogen atoms ((RRR)-1C), and when a chiral guest was bound at the amide groups of 1A, which has no chirality other than dynamic helicity. Thus, the cooperative transmission of chiralities enabled us to observe stereospecific chiroptical modulation upon complexation of (RRR)-1C with a couple of enantiomeric guests (RR)/(SS)-5.
