A study of the inclusion complex formed between cucurbit[8]uril and isonicotinic acid

The complexation between cucurbit[8]uril, Q[8], and isonicotinic acid has been studied using 1 H NMR spectroscopy, UV–Vis absorption spectroscopy, Raman spectroscopy and single crystal X-ray diffraction. The results revealed that the 2:1 inclusion complex (4-PA) 2 @Q[8]·25H 2 O is formed, with two guests simultaneously encapsulated in the hydrophobic cavity; the mean planes of the guests are 3.535 Å apart. Graphical abstract