Selective Enclathration of Methyl- and Dimethylpiperidines by Fluorenol Hosts

Abstract

Two similar fluorenyl diol hosts H1 and H2 have been employed to study their selectivity toward methylated piperidines. Crystal structures show strong similarities in the packing of these inclusion compounds, but the interesting result arises from the competition of these hosts for equimolar dimethylpiperidines (2,6DMP and 3,5DMP). H1 selects 3,5DMP, while H2 selects 2,6DMP. Packing analysis and lattice energy calculations failed to explain this result, but the differential scanning calorimetry profiles of the four host–guest compounds are in agreement with the selectivity experiments.