Insights into the Self‐Filling Effects of Branched Isopropyl Groups on the Conformational and Supramolecular Properties of Isopropoxyprism[6]arene
Rocco Del Regno, Paolo Della Sala, Neal Hickey, Silvano Geremia, Carmen Talotta, Placido Neri, Carmine Gaeta
Abstract
Abstract In this work, the direct macrocyclization of a prism[6]arene macrocycle bearing branched alkyl chains on the rims is reported. Isopropoxyprism[6]arene adopts in solution and in the solid state a cuboid D 2 ‐conformation in which four isopropyl groups are folded inside the cavity, to give C−H⋅⋅⋅π interactions and filling the internal void. The conformational features of isopropoxyprism[6]arene have been studied by dynamic 1 H NMR experiments. The presence of branched isopropyl chains on the prism[6]arene rims, stabilizes the cuboid D 2 ‐conformation to a greater extent than ethyl or propyl groups in PrS[6] Et and PrS[6] nPr . The higher resistance of PrS[6] iPr to open its cuboid D 2 conformation, with respect to PrS[6] Et and PrS[6] nPr , also affected its binding abilities. In fact, alkylammonium‐based endo ‐cavity complexes of PrS[6] iPr show lower binding constant values than the analogous propoxy/ethoxy‐prism[6]arene complexes.