Hydrogen bonding effects in anion binding calixarenes

A series of disubstituted urea, thiourea and dansyl amide calix[4]arene based anion receptors have been prepared and characterised by X-ray crystallography. The structures show a fine balance of intramolecular urea α-tape, and urea⋯calixarene phenolic oxygen atom hydrogen bonding patterns. Both motifs are in competition with the anion binding behaviour of the compounds in solution.