DFT-calculated structure of protonated tetraphenyl <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylcalix[4]arene tetraketone

Using DFT calculations, two of the most probable structures (A, B) of the tetraphenyl p-tert-butylcalix4]arene tetraketone·H₃O⁺ cationic complex species were derived. The hydroxonium ion H₃O⁺, placed in the coordination cavity formed by the calix4]arene lower-rim groups, is bound by strong hydrogen bonds to the phenoxy oxygen atoms of the calix4]arene ligand (structures A, B) and also to one carbonyl oxygen (structure B). Correspondence: Emanuel Makrlík, Faculty of Applied Sciences, University of West Bohemia, Pilsen, Czech Republic.