(THIO)UREA RESORCINARENE CAVITANDS - COMPLEXATION AND MEMBRANE-TRANSPORT OF HALIDE ANIONS

Reaction of aminomethylcavitands with iso(thio)cyanates gives (thio)ur ea-functionalized resorcinarene cavitands, which represent a novel cla ss of neutral anion receptors. The complexation of halide anions has b een studied both with infrared and H-1 NMR spectroscopy. The receptors have a small preference for chloride over the other halides; p-fluoro phenylthiourea cavitand 8a gives the highest association constant (K-a ss = 4.7 x 10(5) M-1 with chloride in CDCl3). A cooperative effect of the ligating (thio)urea moieties is indicated by the lower affinity of the corresponding tris(thio)urea-functionalized cavitands. For the fi rst time facilitated membrane transport of halide anions through suppo rted liquid membranes is achieved.