Abstract: In contrast to the multitude of different binding motifs for the molecular recognition of ammonium cations very few efficient guanidinium receptors have been reported and even less amidinium hosts [1]. The latter is surprising in view of important role of the amidinium functionality in drugs targeting binding pockets for the arginine sidechain etc. The challenge, however, is quite clear: One has to surround the amidinium group in a halfmoon-like array with at least four hydrogen bond acceptors, which are ideally preoriented for maximum electrostatic as well as hydrogen bond interactions.