Br. Cameron et Sj. Loeb, BIS(AMIDO)CALIX[4]ARENES IN THE PINCHED CONE CONFORMATION AS TUNABLE HYDROGEN-BONDING ANION RECEPTORS, Chemical communications, (6), 1997, pp. 573-574
Calix[4]arene units functionalized at the 1,3-positions of the upper r
im with amido groups, -NHC(O)X, act as neutral, hydrogen-bonding recep
tors for hydrogen sulfate, dihydrogen phosphate, acetate, benzoate, ni
cotinate, oxalate, terephthalate, isophthalate and fumarate with bindi
ng strength and selectivity tunable by varying the electron-withdrawin
g ability of the terminal substituent X (X = CH2Cl, CHCl2, CCl3).