Pentamacrocyclic tris-crown hosts: selective binding of cationic, anionic, and neutral guests

The tris-crown host compounds (1)–(4) were synthesized and the structures of (2) and of the 3:1 potassium complex of (1)(with the SCN- anion projecting inside the cavity) were studied by X-ray analyses; specific organic guest molecules like β-naphthol and naphthalene diols are selectively bound inside the fitting cavities of the hosts (2) and (3)[but not (1) and (4)] in acidic water solution.