MULTICAVITANDS-III - SYNTHESIS AND NMR-STUDIES OF A TRI-DIRECTIONAL KOILAND COMPOSED OF 3 P-TERT-BUTYLCALIX[4]ARENE UNITS FUSED BY 2 SILICON ATOMS

The synthesis of a divergent trireceptor composed of three hydrophobic cavities was achieved by fusing three p-tert-butylcalix[4]arene units in their cone conformation with two silicon atoms. Complete structural analysis was possible using multidimensional NMR techniques. Variable temperature NMR studies between 40 degrees C and -90 degrees C revealed that ail three calix units were in their cone conformation and that the only conformational change observed was a rotation around the silicon-oxygen bonds with a Delta G(double dagger) of ca. 46 kJ mol(-1).