title: Ca2+- and Ba2+-selective receptors based on site-selective transmetalation of multinuclear polyoxime-zinc(II) complexes.
abstract: Ca2+-selective recognition was achieved by using the site-selective transmetalation of homotrinuclear metallohost [L1Zn3]2+ containing a linear tetraoxime ligand. The selectivity (log(KCa/KMg) > 5.1) is comparable to those of the excellent Ca2+ receptors or sensors such as BAPTA, Quin2, and K23E1. X-ray crystallography revealed that the Ca2+ complex [L1Zn2Ca]2+ has a helical structure. On the other hand, the larger analogue H6L2 gave a mixture of [L2Zn4]2+ isomers, which selectively recognizes Ba2+ to give a single tetranuclear complex, [L2Zn3Ba]2+.
authors.affiliation: Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Shigehisa
authors.initials: S
authors.lastname: Akine
authors.forename: Takanori
authors.initials: T
authors.lastname: Taniguchi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Saiki
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nabeshima