Polarizabilities inside molecular containers

A polarizability close to the gas phase is measured inside the cavity of the molecular container cucurbit[7]uril (CB7) by employing 2,3 diazabicyclo[2.2.2]oct-2-ene (DBO) as a solvatochromic guest (CB7 · DBO). Conversely, the previously studied photophysical properties of biacetyl as a guest in a hemicarcerand (HC · biacetyl) indicate an exceptionally high polarizability inside this host cavity. These conclusions can be drawn from the solvatochromism of DBO and biacetyl in different solvents and the gas phase, which reveals correlations with the bulk polarizability. The oscillator strength, that is, the integrated absorption intensity, of the novel probes is not sensitive to the solvent polarity, but responds strongly to the solvent polarizability.