The York Research Database

Direct mercuration and subsequent transformation of organomercurial intermediates into the corresponding nitroso derivatives enabled the construction of calix[4]arenes bearing azo moieties at the meta position (to the alkoxy groups). These compounds, representing a unique substitution pattern in calixarene chemistry, showed very unusual dynamic behaviour in solution. Temperature dependent¹H NMR spectra confirmed that the introduction of two bulky moieties (or even just one) into the meta position of calix[4]arene led to the rigidification of the molecule as demonstrated by complete arrest of the typical pinched cone – pinched cone interconversion in solution. The rigidified molecules can be used as ligands capable of cation−π interactions with N-methylpyridinium salts.