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Synfacts 2006(12): 1225-1225  
DOI: 10.1055/s-2006-955583
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart · New York

A Squaramide-Based Citrate Receptor

Contributor(s): Timothy M. Swager, Mark S. Taylor
A. Frontera*, J. Morey*, A. Oliver, M. N. Piña, D. Quiñonero, A. Costa, P. Ballester, P. M. Deyà, E. V. Anslyn*
Universitat de le Illes Balears, Palma de Mallorca and Institute of Chemical Research of Catalonia, Tarragona, Spain; University of Texas at Austin, USA
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Publication History

Publication Date:
22 November 2006 (online)

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Significance

The authors have developed a tridentate receptor that binds citrate and other tricarboxylates in aqueous ethanol, using ammonium-substituted squaramide groups as recognition elements. Calculations suggested that such substituted squaramides would be tight binders for carboxylates through a combination of hydrogen bonding and electrostatic interactions (see scheme above). Indeed, these predictions were borne out through calorimetric measurements of the binding affinity of 1 for various carboxylates. Displacement of fluorescein by citrate from receptor 1 was employed as the basis for a fluorescence-based assay that was used to determine the citrate content of commercial toothpaste.