Competitive counterion complexation allows the true host : guest binding constants from a single titration by ionic receptors.
Counterion competitive complexation is a background process currently ignored by using ionic hosts. Consequently, guest binding constants are strongly affected by the design of the titration experiments in such a way that the results are dependent on the guest concentration and on the presence of added salts, usually buffers. In the present manuscript we show that these experimental difficulties can be overcome by just considering the counterion competitive complexation. Moreover a single titration allows us to obtain not only the true binding constants but also the stoichiometry of the complex showing the formation of 1 : 1 : 1 (host : guest : counterion) complexes. The detection of high stoichiometry complexes is not restricted to a single titration experiment but also to a displacement assay where both competitive and competitive-cooperative complexation models are taken into consideration.
Laboratório Associado para a Química Verde (LAQV), REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Monte de Caparica, Portugal. m.pessego@fct.unl.pt.
Márcia
M
Pessêgo
Laboratório Associado para a Química Verde (LAQV), REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Monte de Caparica, Portugal. m.pessego@fct.unl.pt.
Nuno
N
Basílio
Departamento de Matemática Aplicada, Facultad de Matemáticas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
M Carmen
MC
Muñiz
Departamento de Química Física, Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Facultade de Química, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain. luis.garcia@usc.es.
Luis
L
García-Río