(b) Spectroscopic characterization. 2D NMR spectroscopy, especially TOCSY and NOESY, established the constitution (regiochemistry) of the calixcorrole skeleton. However, the diastereomeric relationship of F1 and F2, i.e., their cisoid or transoid character, still remains unresolved. A cluster of broad singlets at ~8.0-8.4 ppm were assigned to the NH protons of the two appended pyrroles and the "isolated pyrrole" between the two saturated meso-carbons. TOCSY cross-peaks identified the remaining protons of the appended pyrroles and the b-protons 12 and 13. Next, the 10-and 15-aryl protons were identified via their NOESY cross-peaks with the appended pyrrolyl protons. Additional NOESY crosspeaks of 10/15-aryl allowed the assignment of the adjacent b-protons 17 and 8. The remaining peaks were assigned by "tracing around the macrocycle" with NOESY and TOCSY.