Synthesis and Structure of Molecular Tweezers Containing Active Site Functionality

A series of molecules has been synthesized in which a functional group is buried inside an aromatic binding cleft. These novel compounds, called “molecular tweezers”, have a methyl ester (6a, 7–9a, 10a), a carboxylic acid (6b, 9b, 10b, 45), or a nitrile (50) in their clefts. Molecular tweezer 21 has a metal ligand, an annelated terpyridine, oriented toward the binding cleft. The structures of 7–10 have been determined either by X-ray analysis or by molecular modeling techniques and were found to contain different inter-anthracene (acridine) distances and varying degrees of twist in their spacers. As precursors to nucleotide base receptors, these molecules represent four discrete steps toward the development of an optimized receptor for adenine.