The 1D-ROESY NMR spectrum of macrocycle 2 showed strong NOEs of the NH protons (Hc) with both the azomethine protons Hd and the aromatic protons Hb. A weaker NOE can also be observed with the Ha protons, indicating that the NH can point out of the cavity. The modelling studies showed that macrocycle 2 can adopt conformations with 4, 3, or 2 NH groups pointing into the cavity, conformers which are in fast exchange on the chemical shift time scale, as only a single NH signal is observed in the NMR spectra. Considering that the shortest distances of NHc to Ha and to Hb are similar in the conformation of lowest energy derived from the modelling studies (Figure ), the larger NOE to Hb implies that in solution on average more NH groups point into the cavity than out of it. We noted that upon addition of an excess of TBAH2PO4 as guest to a solution of macrocycle 2, the NOE between protons Hc and Ha was no longer observed, while NOEs between Hc and protons Hd and Hb remained visible (Figure ), suggesting that in the presence of the guest the macrocycle adopts a conformation where all the NH protons are oriented into the binding cavity.