title: Complex formation of p-nitrocalix[6]arene with rare earth metal ions.
abstract: p-Nitrocalix[6]arene (CALX-N6, L) formed a 1:1 metal complex, ML, with light rare earth metal ions (M3+), such as La3+, Pr3+ and Nd3+ except Ce3+, but formed a 1:2 (M(3+):L) complex, ML2 (the charge of the complex is omitted) with heavy rare earth metal ions, such as Sm(3+)-Lu3+ including Y3+. The conditional stability constants of these 1:1 and 1:2 complexes, KML and KML2, were measured by a ligand displacement method using absorption spectrophotometry in 4% (v/v) acetone aqueous solution at pH 9.65 +/- 0.15 and 25 degrees C.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Sojo University, Kumamoto, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Kajiwara
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Koga
authors.forename: Masashi
authors.initials: M
authors.lastname: Nishida
authors.forename: Isao
authors.initials: I
authors.lastname: Yoshida