The Molecular Recognition of Amines with Calix[6]arene: Conclusive X-ray and NMR Evidence for Endo and Exo Complex Formation between Calix[6]arene and Amines

Calix[6]arene formed an endo-complex with piperidine and its inclusion properties were investigated by NMR spectroscopy and X-ray crystallography. Especially, the DOSY spectrum showed that piperidine formed a unique complex with calix[6]arene.