title: A calix(4)arene pyridine derivative and its monomeric component: structural and thermodynamic aspects of their complexation with metal cations.
abstract: The interaction of a calix(4)arene derivative, namely 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra[2-(4-pyridyl)methoxy]calix(4)arene, 1a, and its monomeric component, p-tert-butylphenoxy-4-pyridine, 1b, with metal cations has been investigated in acetonitrile and methanol. (1)H NMR measurements carried out in CD(3)CN show the primary role played by the pyridyl nitrogens in their complexation with metal cations. Conductance measurements demonstrated that for all cations (except mercury) the composition of the metal ion complexes of 1a is 1:1 (ligand:metal cation). However, 1a hosts two mercury cations per unit of ligand. For the monomer 1b, complexes of 2:1 (ligand:metal cation) stoichiometries are formed with the exception of Pb(2+) (1:1 composition). The thermodynamics of complexation of these systems are reported in acetonitrile. Data in methanol are limited to stability constant values for mercury(II) and these ligands. This paper demonstrates for the first time that thermodynamic data for the complexation of the monomeric component of the ligand and metal cations contribute significantly to the interpretation of systems involving cation-calixarene interactions in solution.
authors.affiliation: Laboratory of Thermochemistry, Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom. A.Danil-De-Namor@surrey.ac.uk
authors.forename: Angela F
authors.initials: AF
authors.lastname: Danil de Namor
authors.forename: Adolfo
authors.initials: A
authors.lastname: Aguilar-Cornejo
authors.forename: Rachida
authors.initials: R
authors.lastname: Soualhi
authors.forename: Mohammed
authors.initials: M
authors.lastname: Shehab
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Nolan
authors.forename: Naaila
authors.initials: N
authors.lastname: Ouazzani
authors.forename: Laila
authors.initials: L
authors.lastname: Mandi
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010636:Phenols / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D002412:Cations; D019216:Metals, Heavy; D010636:Phenols; D011725:Pyridines; C121325:calix(4)arene; D047250:Calixarenes; C023666:pyridine