Synthesis of Upper and Lower Rim Binaphthyl Bridged Calix[4]arenes: New Potential Chiral Hosts for Molecular Recognition and Catalysis

New chiral upper and lower rim (R)-binaphthyl-bridged calix[4]arenes in the cone conformation (5, 10, 11, 15, 17, 18) have been synthesized by exploiting the selective functionalization of the calix[4]arene skeleton, The conformational properties of the new hosts in CDCl3 and DMSO-d(6) have been clarified by dynamic NMR measurements, and their complexation properties toward neutral molecules, alkali metal, and silver(I) cations have been explored. The upper rim binaphthyl-bridged calix[4]arene 5 is able to form a 1:1 complex with Ag+ in CDCl3:CD3OD 1:1 v/v solution, where the silver cation is encapsulated into the apolar cavity. The determined association constant (log K = 3.51) is substantially higher than for unbridged calix[4]arenes in the cone conformation. These new macrobicyclic compounds are potential hosts for chiral recognition and catalysis.