Abstract
Summary In the development of synthesizing new Schiff base complexes, derivatives of (2,3-diphenylquinoxaline-2X) where (X=H, CH3, OCH3, Br, OH) have been synthesized and some of them have been successfully used as ligands with the transition metal "Iridium" to design new complexes that can be applied as red emission materials suitable for organic light emitting diodes (OLEDs). The Schiff base ligand derivatives where synthesized through two main steps, first the preparation of p-diketones by the catalyzed condensation of the corresponding aromatic aldehydes in the presence of potassium cyanide and copper acetate, the resulted diketones were analyzed by GC-MS and 1H NMR spectroscopy. Second, the reaction of the 1:1 equivalent amounts of the diketones with ophenylenediamine and the obtained Schiff base ligands were analyzed by Elemental Analysis, GC-MS, 1H and 13C NMR. The iridium complexes Ir(2,3-diphenylquinoxaline)2(2-phenylpyridine), Ir[2,3(4`,4``-dimethyl)dpqx]2(2-phenylpyridine) and Ir[2,3(4`,4``- dimethoxy)dpqx]2(2-phenylpyridine) were synthesized from the two-step reaction of IrCl3.H2O with the corresponding ligand and characterized by UV and fluorescence spectroscopy. The UV-spectra of the Iridium complexes showed the strong 3MLCT transition; also, the three complexes exhibited the maximum luminescence pure red peaks at 617 nm with 8.5% quantum yield. The photochemical properties of the Iridium complexes showed the minor effect of the substitution of methyl and methoxy groups on the diphenylquinoxaline (dpqx) ring.
