Nanotek & Expo

Biography

Biography: Adewale O. Adeloye

Abstract

Four novel highly luminescent cationic homoleptic Ir(III) cyclometalated complexes of the type [Ir(NË„C)3]PF6 based on derivatives of 4-methoxyphenylvinylquinoline containing electron donating and withdrawing groups as aryl-substituent at 2-position of the quinoline scaffold were design, synthesized and characterized. While the ligands were initially prepared via palladium catalyzed Suzuki-Miyaura cross-coupling of the 2-aryl-4-chloroquinoline, cyclometalation of Ir (III) complex was accomplished in one-pot reaction method. The compounds were characterized by employing various techniques such as FT-IR, 1H and 13C-NMR, UV-Vis, PL and cyclic voltammogram. In methanol, all complexes display strong spin-allowed 1MLCT (singlet metal-to-ligand charge transfer) absorption bands between λabs 315 – 380 nm. The photoluminescence properties of the ligands measured in solvents of different polarity with excitation wavelength of λex 350 nm were colour-tuned by modification of wavelengths displaying a red-shift emission from λem 438 – 479 nm compared to λem 489 – 545 nm in the corresponding complexes. Enhanced fluorescence intensities and high quantum yield were observed in chloroform and methanol unlike in dimethylformamide (DMF). The cyclic voltammetry properties of the complexes relative to a ferrocenium/ferrocene redox couple showed a metal-centered to be redox-active in nature, which clearly support the introduction of electron-releasing groups raising the HOMO energy level in phosphorescence of iridium (III) complexes. It is suggested that the synthesized homoleptic iridium complexes may be efficiently used on the basis of enhanced PL intensities as emissive dopants in nano-sensing of biological molecules and/or suitable red-emitting materials for OLEDs applications.