Host-guest chemistry of aromatic-amide-linked bis- and tris-calix[4]pyrroles with bis-carboxylates and citrate anion.

ABSTRACT

A small library of polytopic receptors has been synthesized from meso-p- and meso-m-aminophenylcalix[4]pyrroles and p- or m-phthaloyl or trimesic chloride. Selected bis-carboxylates and the citrate anion, which either exhibit altered distribution profiles in cancerous tissues in comparison with healthy tissues or are metabolites of carcinogenic substances (for example, trans,trans-muconic acid from benzene exposure in humans) were tested as ligands. Varied affinities and binding modes were observed as a function of the number of calix[4]pyrroles and the topology of amide units present in each of the polytopic receptors. The structures of the 11 complexes derived by molecular modeling are in excellent agreement with the results of (1)H NMR complexation studies.