Coordination of a carboxylic acid diaryl crown ether to a Sn(IV) porphyrin promotes its ability to act as a template for the formation of a[2]catenane: in the absence of the porphyrin the acid-crown yields only a tiny amount of the interlocked derivative. Once isolated the freeacid-[2]catenane presents extremely broad resonances in its 500 MHz
1H NMR spectrum, but complexation to a Sn(IV) porphyrin results indramatic resolution via a combination of dynamic and dispersive effects.