Dinuclear Complexes of the N2O2 Oxime Chelate Ligand with Zinc(II)-Lanthanide(III) as a Selective Sensitization System for Sm3+

A series of zinc(II)-lanthanide(III) dimetallic complexes have been synthesized by the one-pot reaction of the oxime-based N2O2 chelate ligand H2L with zinc(II) acetate and lanthanide(III) salts. The heavier lanthanides (Sm-Lu) produced heterodinuclear complexes [LZnLn](3+) (Ln = Sm-Lu) in which the zinc(II) ion occupies the N2O2 chelate site of H2L and the lanthanide(III) ion is located in the semicircular O-4 site. In contrast, the trinuclear complex [(LZn)(2)La](3+) was obtained by the reaction of H2L with zinc(II) and lanthanum(III) salts. The heterometallic complexes [LZnLn](3+) and [(LZn)(2)La](3+) were also formed by the reaction of [L2Zn3](2+) with the heavier lanthanides (Sm3+-Lu3+) and La3+, respectively. The dinuclear complex [LZnSm(OAc)(3)] exhibited a relatively intense red emission due to Sm3+, whereas [LZnEu(OAc)(3)] gave no detectable emission. The corresponding complexes containing other lanthanides showed only a weak blue emission due to the ligand moiety. Therefore the ligand L2- can selectively sensitize Sm3+ from among Sm3+, Eu3+, Tb3+, and Dy3+, although these complexes would often exhibit f-f luminescence. The deep-red luminescence from samarium(III) at around 650 nm is potentially useful for a full-color display. In addition, [LZnYb(OAc)(3)] exhibited near-infrared luminescence.