A pH switch in supramolecular polymeric capsules.

[structure: see text] A switchable, supramolecular polymer is introduced which is held together through hydrogen bonding and reversibly precipitates-redissolves upon subtle pH control. Precipitating, it entraps and stores guest molecules within the self-assembling capsules incorporated within the polymeric chain.

Supramolecular fixation of NO2 with calix[4]arenes.

Reaction of NO2 with simple calix[4]arenes in chloroform in the presence of a Lewis acid rapidly results in intense coloration caused by the encapsulation of nitrosonium cation.