Efficient synthetic route to anhydrous mononuclear tris(8-quinolinolato)lanthanoid complexes for organic light-emitting devices

A new lanthanoid 8-quinilinolates type structure was found for lanthartum complex La-3(q(Me))(9)(H)(NO3) (1) formed in the reaction of La(NO3)(3) (.) 6H(2)O with 2-methyl-8-hydroxyquinoline (Hq(Me)) and aqueous ammonia in methanol. The molecule of I contains three La atoms connected by six bridging quinolinolate ligands, two terminated eta(2)-coordinated q(Me) ligands, one terminated eta(1)-coordinated q(Me) ligand and one terminated NO3 group. The geometry and H-1 NMR spectrum of the complex suggest that it is bearing -1 charge balanced by proton, which was localized objectively. The arrangement of the compound in crystalline state and in pyridine solution is discussed. Syntheses of water- and acid residual-free mononuclear lanthanoid quinolinolates La(q(Me))(3)(py)(2) (2) and Lnq(3)(py)(2) (Ln = Y (3), La (4), Sm (5), Eu (6), Tb (7), Er (8), Tm (9); q = 8-quinolinolate, py = pyridine) by the reaction of appropriate amido complexes Ln[N(SMe3)(2)](3) with 3 equiv. of 2-methyl-8-hydroxyquinoline or 8-hydroxyquinoline in pyridine solution is also described. The complex Laq(3)(Ph3PO)(2) (10) was prepared by treatment of 4 with triphenylphosphine oxide in pyridine solution. Lanthanum 2 complex revealed photoluminescence intensity ca. 3 x 10(3) times higher than that of the compound 1 prepared by the traditional way in water-alcohol medium. These data give a ground to consider the Lnq(3)(py)(2) complexes as promising material for design of light-emitting devices. (c) 2005 Elsevier B.V. All rights reserved.