It might be expected that the orientation of rimantidine would be influenced by electrostatic interactions between its cationic ammonium group and the charges of the various cyclodextrin substituents. Thus, a substituent at the secondary face with a negative or positive charge might lead to secondary or primary orientation binding, respectively, with analogous logic holding for charges at the primary face. Although MGLab8 fits this pattern, any attractive electrostatic interactions that may have led rimantindine to adopt the secondary orientation in this host are not obviously manifest in the binding affinity (Table ), which is not especially strong. Unfortunately, the other negatively charged hosts, MGLab9 and 35, gave inconclusive NOESY results. MGLab19, with a positive charge at the secondary face and primary binding orientation, also seems to fit the expected pattern, but MGLab34, does not, as it has a positive charge at the primary face, but shows a primary binding orientation. For the host molecules that have succinic acid linkers, MGLab8, MGLab 23 and MGLab 24, NOEs are observed between the CH3 (H2) on the guest and the succinic acid side chain CH2 groups for those complexes which show secondary face binding. This means that the rimantidine's amino group is directed away from the amide linker and thus that no hydrogen bond is formed between this amino group and the carbonyl group of the amine linker (Figure ).