Luminescent Electropolymerizable Ruthenium Complexes and Corresponding Conducting Metallopolymers

Tris(2,2′-bipyridyl)ruthenium(II) dichloride [Ru(bpy)3Cl2] and analogous complexes have been studied extensively in the literature due to their luminescent and photochemical properties as well as their excited-state lifetimes. Conducting polymers with similar ruthenium groups have also been investigated for various applications. In this study, syntheses of four ruthenium complexes with a polymerizable tridentate ligand, bis[4-[2-(3,4-diethylenedioxy)thiophene]pyrazol-1-yl]pyridine (EDOT2NNN), and with bidentate ligands, two of which were anionic (hfac: 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; dbm: dibenzoylmethane) and two of which were neutral (bpy: 2,2′-bipyridyl; phen: 1,10-phenanthroline), were achieved for potential OLED/PLED applications. Saturated CH2Cl2 solutions of monomers were oxidatively and electrochemically polymerized, and the scan rate dependences of the polymers were measured. UV–vis spectroscopic characterizations of the complexes and the EDOT-functionalized ligand were obtained. [Ru(EDOT2NNN)(phen)(Cl)](PF6) was electropolymerized on an ITO (indium tin oxide)-coated glass surface to obtain the solid-state absorption spectrum of the corresponding polymer. Photophysical data for each complex, i.e., excitation and emission spectra at 77 K and RT, in EtOH/MeOH (4:1) and in 2-MeTHF (dry, air-free, and aerated), quantum yield, and luminescence lifetime have been measured. The radiative and nonradiative decay constants as well as the oxygen quenching rate coefficient for each complex were calculated. [Ru(EDOT2NNN)(phen)(Cl)](PF6), having the highest quantum yield of phosphorescence and the longest lifetime, was electropolymerized on an ITO-coated glass surface to obtain the solid-state excitation and emission spectra of the corresponding polymer. Luminescence studies of the polymer had promising results for photoluminescence.