Anthracene-Based Amido-Amine Cage Receptor for Anion Recognition under Neutral Aqueous Conditions.

A new amido-amine cage receptor, which combines 1,8-anthracene diacarboxamide subunit and a polyammonium azamacrocycle, is reported. Bearing both the hydrogen bond donor and the acceptor binding sites, the receptor is able to bind phosphate selectively under neutral (pH 7.2) aqueous conditions. The recognition events for phosphate and dicarboxylates are accomplished by a fluorescence enhancement in the anthracene emission. As revealed by experimental and theoretical studies, phosphate and oxalate show different recognition modes. Phosphate demonstrates hydrogen bond acceptor properties, while the coordination of oxalate favours the protonation of the receptor.