Rational Design, Synthesis, and Application of a New Receptor for the Molecular Recognition of Tricarboxylate Salts in Aqueous Media

• Published in: Journal of organic chemistry 2006-09, Vol.71 (19), p.7185-7195
• Main Authors: Frontera, Antonio, Morey, Jeroni, Oliver, Antònia, Piña, M. Neus, Quiñonero, David, Costa, Antoni, Ballester, Pablo, Deyà, Pere M, Anslyn, Eric V
• Format: Article
• Language: English
• Subjects: Binding Sites; Chemistry; Cyclobutanes - chemical synthesis; Cyclobutanes - chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; Models, Molecular; Molecular Structure; Organic chemistry; Preparations and properties; Quaternary Ammonium Compounds - chemical synthesis; Quaternary Ammonium Compounds - chemistry; Solutions; Tricarboxylic Acids - isolation & purification
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo0609327

A rational design of a tripodal receptor for the molecular recognition of tricarboxylate salts in aqueous media, based on squaramide, has been performed using high-level DFT calculations (RI-BP86/SVP level of theory) in solution using the COSMO treatment, including some preliminary ab initio calculations at the higher RI-MP2/TZVP level of theory, comparing the ability of squaramide to bind carboxylate salts with two widely used guanidinium salts. The tripodal receptor has been synthesized using a new methodology that has been recently reported by some of us, and its capability of recognizing several mono-, di-, and tricarboxylate salts has been studied experimentally by means of microcalorimetry experiments in a very high competitive media, H2O:EtOH 1:3. These experiments give enthalpic and entropic data, which are unfortunately scarce in the literature of molecular recognition of anions. Finally, a fluorimetric ensemble of the receptor with fluorescein has been found to be useful for the fluorimetric determination of zinc citrate in a commercial toothpaste using competition assays.