title: Mononuclear and tetranuclear compounds of yttrium and dysprosium ligated by a salicylic schiff-base derivative: synthesis, photoluminescence, and magnetism.
abstract: The Schiff-base (2-aminoethyl)hydroxybenzoic acid (H(2)L) as a proligand was prepared in situ from 3-formylsalicylic acid and ethanolamine (ETA). The mononuclear {[Y(HL)(4)][ETAH]·H(2)O} (1) and {[Dy(HL)(4)] [ETAH]·3MeOH·H(2)O} (2) and tetranuclear {[Y(4)(HL)(2)(L)(4)(μ(3)-OH)(2)]·4MeOH·4H(2)O} (3), {[Dy4(HL)(2)(L)(4)(μ(3)-OH)(2)]·5(MeOH)(2)·7H(2)O (4), and {[Dy(4)(HL)(8)(L)(2)]·4MeOH·(2)H(2)O}(5) rare-earth metal complexes of this ligand could be obtained as single-crystalline materials by the treatment of H(2)L in the presence of the metal salts [Ln(NO(3))(3)·(H(2)O)m] (Ln = Y, Dy). In the solid state, the tetranuclear compounds 3 and 4 exhibit butterfly structures, whereas 5 adopts a rectangular arrangement. Electrospray ionization mass spectrometry data of the ionic compounds 1 and 2 support single-crystal X-ray analysis. The yttrium compounds 1 and 3 show fluorescence with 11.5% and 13% quantum yield, respectively, whereas the quantum yield of the dysprosium complex 4 is low. Magnetic studies on the dysprosium compounds 4 and 5 suggest the presence of weak antiferromagnetic interactions between neighboring metal centers. Compound 4 shows single-molecule-magnet behavior with two relaxation processes, one with the effective energy barrier U(eff) = 84 K and the preexponential factor τ(0) = 5.1 × 10(-9) s.
authors.affiliation: Institut für Anorganische Chemie, Karlsruher Institut für Technologie , Engesserstrasse 15, 76131 Karlsruhe, Germany.
authors.forename: Munendra
authors.initials: M
authors.lastname: Yadav
authors.forename: Valeriu
authors.initials: V
authors.lastname: Mereacre
authors.forename: Sergei
authors.initials: S
authors.lastname: Lebedkin
authors.forename: Manfred M
authors.initials: MM
authors.lastname: Kappes
authors.forename: Annie K
authors.initials: AK
authors.lastname: Powell
authors.forename: Peter W
authors.initials: PW
authors.lastname: Roesky