A Calix[5]arene-Based Heterotetratopic Host for Molecular Recognition of Long-Chain, Ion-Paired a,w-Alkanediyldiammonium Salts

A calix[5]arene-based heterotetratopic host for molecular recognition of long-chain, ion-paired a,?-alkanediyldiammonium salts Angewandte Chemie-International Edition 44(31), 4892 2005 The anions went in two by two: Sep. ion-pair binding of nano-sized a,?-alkanediyldiammonium dichloride salts is achieved in org. media with high efficiency and selectivity by a heterotetratopic receptor that comprises two converging calix[5]arene units to tightly encapsulate the linear dication, as well as two ureido side functions to simultaneously bind the chloride counteranions through hydrogen bonding.