A new versatile receptor platform

We prepared a molecular receptor based on the molecular tweezer concept. Ou r system offers versatility, an extremely short synthetic route, good yield , large quantities, and finally having binding constants that equal the bes t known tweezer molecules when it comes to binding various nitroaromatics s uch as 1,3,5-trinitrotoluene (24 M-1), 1,3,5-trinitrobenzene (182 M-1), and 2,4,7-trinitrofluorenone (490 M-1) as determined using H-1 NMR in CDCl3. I t is notable that these binding constants are achieved although the molecul ar framework is not locked in a fixed and rigid conformation. The rigidity has been claimed to be the governing factor when it comes to achieving a la rge binding constant. We propose that our molecular tweezer system may be p reorganized and that this explains the high binding constants observed. Fur ther, we investigated the crystal structures of both the neutral receptor m olecule and a complex with 1,3,5-trinitrobenzene and found that the molecul e forms a pocket suited to accommodate flat aromatic analytes.