Binding of Ru(NH₃)₅pz²⁺ to 4-Sulfocalix[4]arene Sodium Salt. Effects of the Host−Guest Interaction on Electron Transfer Processes

Abstract

The reactions [Ru(NH3)5pz]2++S2O8(2-) and [Ru(NH3)5pz]2++[Co(C2O4)3]3- have been studied in solutions of 4-sulfocalix[4]arene sodium salt. Results show a binding of the ruthenium complex to the calixarene with a 2:1 stoichiometry; that is, a ruthenium molecule binds to two calixarene molecules. This stoichiometry changes when NaCl is added to the medium. Thus, a mixture of 1:1 and 2:1 adducts is found in the presence of 0.1 mol dm(-3) NaCl and only 1:1 adducts when the salt concentration is increased up to 0.3 mol dm(-3). Results show that the binding of the ruthenium complex to the calixarene is due to electrostatic and nonelectrostatic interactions. Kinetic data are interpreted by using the pseudophase model and taking into account the stoichiometry of the ruthenium binding to calixarene. The presence of a supporting electrolyte in the medium produces ion pair formation which exerts an influence on the kinetic rate constants.

Study of ionic surfactants interactions with carboxylated single-walled carbon nanotubes by using ion-selective electrodes

“…Supramolecular chemistry, defined as the chemistry of molecular assemblies, studies the structures and functions of entities consisting of two or more species linked by noncovalent bonds. Electrostatic interactions, hydrogen bonds, π-π stacking, metal-ligand, and hydrophobic interactions and stearic repulsions join in the formation of such assemblies [1][2][3][4][5]. Carbon nanotubes, CNT, are building blocks used in the construction of molecular assemblies.…”

Microheterogeneous Catalysis

“…Lopez-Cornejo et al . [ 115 ] have studied the effects of 4-sulfocalixarene on the kinetic of the oxidation of [Ru(NH 3 ) 5 Pz] 2+ by [Co(C 2 O 4 ) 3 ] 3- and . In this case the complex [Ru(NH 3 ) 5 Pz] 2+ /calixarene has a 1:2 stoichiometry.…”

Calix[4,6,8]arenesulfonates Functionalized Reduced Graphene Oxide with High Supramolecular Recognition Capability: Fabrication and Application for Enhanced Host–Guest Electrochemical Recognition

“…Calixarenes, cavity-shaped cyclic phenol molecules, considered the third best host molecules after cyclodextrins and crown ethers, have been of potential interest because they can form stable host–guest complexes with various organic, inorganic, and biological guest molecules, − which show high molecular selectivity and the engaging supramolecular recognition ability. Specifically, the selective association of target molecules to the hydrophobic cavities of Calixarenes has been used to develop different sensors and separation matrices based on the strong recognition and enrichment function of Calixarenes. − However, because most calixarenes have poor water-solubility, the application of calixarenes is often in organic solvents such as toluene, chloroform, dichloromethane, etc., − which bring environmental pollution.…”