Multicavitands III: Synthesis and NMR studies of a tri-directional koiland composed of three p-tert-butylcalix[4]arene units fused by two silicon atoms

Abstract 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°C and −90°C revealed that all 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 Δ G ‡ of ca. 46 kJ mol −1 .