Calixarenes as hosts for ammonium cations: A quantum chemical study and mass-spectrometric investigations

Rozhenko AB, Schoeller W, Letzel M, Decker B, Agena C, Mattay J. Calixarenes as hosts for ammonium cations: A quantum chemical study and mass-spectrometric investigations. Chemistry. A European Journal. 2006;12(35):8995-9000.Host-guest complexes of tetramethylcavitand with different ammonium cations were investigated by using a quantum chemical method at the density func tional level (BP86, B3LYP). The NH4+ cation is strongly bound to the host. Increasing creasing methyl substitution at the cation decreases its inclination towards the complex formation. The calculated data are in line with results from electrospray ionization mass spectrometry (ESI-MS) experiments. They reveal stable aggregates only for the NH4+ cation and for the primary alkylammonium cations