title: Thermodynamic study of the complexation of p-isopropylcalix[6]arene with Cs+ cation in dimethylsulfoxide-acetonitrile binary media.
abstract: The complexation reactions between the macrocyclic ionophore, p-isopropylcalix[6]arene and Cs+ cation were studied in dimethylsulfoxide-acetonitrile (DMSO-AN) binary non-aqueous solvents at different temperatures using a conductometry method. The conductance data show that the stoichiometry of the (p-isopropylcalix[6]-arene·Cs)+ complex in all binary mixed solvents is 1:1. The stability of the complexes is affected by the composition of the binary solvent media and a non-linear behavior was observed for changes of log K(f) of the complex versus the composition of the binary mixed solvents. The thermodynamic parameters (DH°(c) and DS°(c)) for formation of (p-isopropyl-calix[6]arene·Cs)+ complex were obtained from temperature dependence of the stability constant and the obtained results show that the (p-isopropylcalix[6]arene·Cs)+ complex is enthalpy destabilized, but entropy stabilized, and the values of the mentioned parameters are affected strongly by the nature and composition of the binary mixed solvents.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. chem_ahmadzadeh@yahoo.com
authors.forename: Saeid
authors.initials: S
authors.lastname: Ahmadzadeh
authors.forename: Anuar
authors.initials: A
authors.lastname: Kassim
authors.forename: Majid
authors.initials: M
authors.lastname: Rezayi
authors.forename: Gholam Hossein
authors.initials: GH
authors.lastname: Rounaghi
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D047250:Calixarenes / Q000737:chemistry*; D002412:Cations; D002586:Cesium / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003217:Conductometry; D056831:Coordination Complexes / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D012997:Solvents; D013816:Thermodynamics
chemical_list: D000097:Acetonitriles; D002412:Cations; D002614:Chelating Agents; D002712:Chlorides; D056831:Coordination Complexes; D012997:Solvents; D047250:Calixarenes; D002586:Cesium; C028019:cesium chloride; D004121:Dimethyl Sulfoxide; C032159:acetonitrile