title: Cooperative assembly of discrete stacked aggregates driven by supramolecular host-guest complexation.
abstract: p-Sulfonatocalix[4]arene (SC4) interacts with the aromatic dye crystal violet (CV) to form complexes with stoichiometries ranging from SC4:CV = 1:1 up to 1:5 both in solution and in the gas phase. While the 1:1 complex is of the inclusion type, as frequently observed for other guests, in the higher-order complexes the CV molecules interact with SC4 in a peripheral manner. The formation of such complexes is driven by ionic interactions established between the dye and the calixarene and by CV-CV stacking interactions. The application of an advanced fitting procedure made possible a quantitative analysis of the UV-vis data and allowed the determination of the stepwise binding constants. This unprecedented approach provides evidence that the formation of the highest-order complexes occurs through a cooperative mechanism. Moreover, the development of a quantitative analytical model enables the possibility of using this type of system for water-soluble sensing assays, as is also exemplified in the present work.
authors: Departamento de Química Física, Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors: Nuno
authors: N
authors: Basílio
authors: Ángel
authors: Á
authors: Piñeiro
authors: José P
authors: JP
authors: Da Silva
authors: Luis
authors: L
authors: García-Río
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D005840:Gentian Violet / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D004396:Coloring Agents; D046911:Macromolecular Substances; D010636:Phenols; C511968:p-sulfonatocalix(4)arene; D047250:Calixarenes; D005840:Gentian Violet