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

Abstract A new lanthanoid 8-quinilinolates type structure was found for lanthanum complex La 3 (q Me ) 9 (H)(NO 3 ) ( 1 ) formed in the reaction of La(NO 3 ) 3  · 6H 2 O with 2-methyl-8-hydroxyquinoline (Hq Me ) and aqueous ammonia in methanol. The molecule of 1 contains three La atoms connected by six bridging quinolinolate ligands, two terminated η 2 -coordinated q Me ligands, one terminated η 1 -coordinated q Me ligand and one terminated NO 3 group. The geometry and 1 H 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(SMe 3 ) 2 ] 3 with 3 equiv. of 2-methyl-8-hydroxyquinoline or 8-hydroxyquinoline in pyridine solution is also described. The complex Laq 3 (Ph 3 PO) 2 ( 10 ) was prepared by treatment of 4 with triphenylphosphine oxide in pyridine solution. Lanthanum 2 complex revealed photoluminescence intensity ca. 3 × 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.