title: Cation-pi interaction in complex formation between Tl+ ion and calix[4]crown-6 and some calix[4]biscrown-6 derivatives: thallium-203 NMR, proton NMR, and X-ray evidence.
abstract: Metallocapped complexation of the thallium(I) ion with calix[4]crown-6 (1) and three different calix[4]biscrown-6 derivatives (2-4) has been investigated by a combination of (203)Tl and (1)H NMR in a CD(3)CN/CDCl(3) (4:1 v/v) solution. The results clearly revealed the formation in solution of mono- and dithallium(I) complexes in which the metal cations are held in the ligands' cavities close to the calix[4]arene ring. In addition, a solid state mononuclear complex between 1,3-calix[4]bis-o-benzo-crown-6 (3) and TlClO(4) was prepared, and its X-ray crystal structure was determined. The results of the structural data in solution and the solid state suggested that the calix[4]crown-6 derivatives considered provide pi cavities as active sites for the complexation of thallium(I) ions.
authors.affiliation: Department of Chemistry, Faculty of Basic Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
authors.forename: Hedayat
authors.initials: H
authors.lastname: Haddadi
authors.forename: Naader
authors.initials: N
authors.lastname: Alizadeh
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Shamsipur
authors.forename: Zouhair
authors.initials: Z
authors.lastname: Asfari
authors.forename: Vito
authors.initials: V
authors.lastname: Lippolis
authors.forename: Carla
authors.initials: C
authors.lastname: Bazzicalupi
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature; D013793:Thallium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D047250:Calixarenes; D013793:Thallium