A self-folding metallocavitand

The synthesis and characterization of novel metallocavitand 6 are described . This is a covalent hybrid of a deepened, self-folding cavity and a Zn-phe nanthroline fragment. Host 6 features a large molecular cavity of (similar to)8 x 10 Angstrom dimensions, and the metal binding site is directed in to ward the cavity. Binding abilities of the metallocavitand in solution was d emonstrated for quinuclidine 11 and Dabco 12 using UV-vis and H-1 NMR spect roscopy. Intramolecular hydrogen bonds at the upper rims of cavitand 6 resi st the unfolding of the inner cavities and thereby increase the energetic b arrier to guest exchange. The exchange is slow on the NMR time scale (at am bient temperatures, CD2Cl2), and kinetically stable complexes result. Both the polyaromatic cavity and metallosite participate simultaneously in the b inding event. Zinc-containing deep cavities may be attractive as catalytic chambers for hydrolysis and esterification.