UCL Discovery

Abstract

The 1,4,5,8-tetracations 5 and 11 have been prepared from 1,4,5,8-tetrakis(bromomethyl)naphthalene and 1,4,5,8-tetrakis(bromomethyl)-2,3,6,7-tetramethylnaphthalene, respectively by treatment with DABCO in acetonitrile. Their interactions with the benzene-1,2,4,5-tetracarboxyl ate and naphthalene-1,4,5,8-tetracarboxylate tetraanions in water were investigated by H-1 NMR titration and both tetracations were found to have greater binding affinity to the benzene tetracarboxylate. Both also gave precipitates with ferricyanide but only the naphthalene tetracation 5 gave a precipitate with ferrocyanide. The X-ray structure of the crystalline ferricyanide tetracation 14 from tetra-methylnaphthalene showed the methylDABCO cationic anus to be alternately above and below the naphthalene ring, which was itself distorted from the plane. The bound water in the non-charge-matched complex 14 appears to have a more intimate role in the crystal structure than does the bound water in the charge-matched ferricyanide 15 derived from 2,4,6-tris(DABCO-N-methyl)mesitylene tribromide which we reported previously. An analogy with interactions in biological receptors is made. (C) 2002 Elsevier Science Ltd. All rights reserved.