Synthesis of a water-soluble macrocyclic anthracenophane and its size-selective molecular recognition

A tetraazacyclophane having two anthracene moieties (3) was synthesized by a reaction of nosyl-protected diaminodiphenylmethane with 9,10-bis(bromomethyl)anthracene, followed by removal of the protecting groups. Water-soluble anthraceophane (1) was prepared by condensation of 3 with Fmoc-β-alanine, followed by removal of the Fmoc groups. Host 1 showed size-selective guest discrimination in aqueous media. Bis-ANS (4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonate) having a suitable molecular size was incorporated in the internal cavity of 1 with binding constant (K) of 2.6 × 105 M−1, although slightly smaller guests such as 1,8-ANS (8-anilinonaphthalene-1-sulfonate) were not, as confirmed by fluorescence titration experiments.