Dialkyl- and diarylammonium ions are able to form complexes with alpha-cyclodextrin and cucurbit[6]uril. These amines are able to complex two guest molecules simultaneously resulting in the formation of homogeneous or heterogeneous 1:2 (ratio of dialkylammonium to ligand) complexes. The stability constants and reaction enthalpies for the formation of 1:1 complexes have been measured using potentiometric and calorimetric titrations. Differences between the values obtained by these methods can be attributed to solvent composition. Only for the 1:2 complex formation with cucurbit[6]uril, the ligands influenced each other. The polar carbonyl groups at each portal of the cucurbit[6]urils interacted simultaneously with the protonated amino group resulting in an electrostatic repulsion between both molecules. No further interactions between two complexed molecules of alpha-cyclodextrin or cucurbit[6]uril and alpha-cyclodextrin were observed. The absence of polar groups in the case of alpha-cyclodextrin led to unaffected formation of homogeneous and even heterogeneous 1:2 complexes. (C) 2009 Elsevier B.V. All rights reserved.