Encapsulated Guest Molecules in the Dimer of Octahydroxypyridine[4]arene

Recently a new type of calix[4]arenes has been synthesized via condensation of 2,6-dihydroxypyridine and a number of aldehydes. This type of pyridine[4]arenes forms capsules consisting of
two single pyridine[4]arenes. These capsules can incorporate different guest molecules, like carboxylic
acids and amides in this case. We proved that the guest acids really are incorporated inside the cavity of
the capsules by electrospray mass spectrometry, NMR spectroscopy, and theoretical calculations.