Structural characterization of inclusion complexes of para-sulphonato-calix[8]arene with 1,2-bis(4-pyridyl)-ethane and 1,3-bis(4-pyridyl)-propane. New 'double cone' and 'up-flat-down' conformations of para-sulphonato-calix[8]arene

The solid-state structures of two complexes (organic salts) between para-sulphonato-calix[8] arene (C8S) and bipyridinium derivatives 1,2-bis(4-pyridyl)-ethane (BPE) and 1,3-bis(4-pyridyl)-propane (BPP), have been determined. In the para-sulphonato-calix[8] arene-BPE complex structure a total of six different channels are observed, four wide, along [100], [010], [110] and [101] and two narrow but real, along [001] and [011]. One of the wide channels is partially occupied by a BPE cations while the others contain water and co-solvents (methanol and ethanol) molecules. Reversible gas adsorption of propane has been observed at pressures below 1 bar.