Ionic liquid adsorbate enhanced electrogenerated chemiluminescence of ruthenium, osmium, and iridium complexes in water
The electrochemistry, UV–vis absorption, photoluminescence (PL) and coreactant electrogenerated chemiluminescence (ECL) of (where bpy = 2,2′-bipyridine), (bpy)2Ru(DM-bpy)2+ (DM-bpy = 4,4′-dimethyl-2,2′-bipyridine), (bpy)2Ru(DC-bpy)2+ (DC = 4,4′-dicarboxy-2,2′-bipyridine), Os(phen)2(dppene)2+ (phen = 1,10-phenanthroline; dppene = 1,2-cis-bis-2-diphenylphosphinoethylene), and Ir(ppy)3 (ppy = 2-phenylpyridine) have been obtained in aqueous solution containing the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]). Tri-n-propylamine (TPrA) was used as the oxidative–reductive ECL coreactant. Minor shifts in the RuII/RuIII oxidation potential and no shifts in UV–vis absorbance and photoluminescence emission maxima are observed in the presence of 0.3% (v/v) [emim][EtSO4]. However, dramatic increases in ECL intensities between 2.4 and 3.5-fold are observed when [emim][EtSO4] is present for the ruthenium systems. Experiments indicate that adsorption of the IL occurs at the electrode surface, favoring the co-localization of luminophore and coreactant within the adsorbate layer (solid-phase co-extraction), leading to higher ECL intensities. Ir(ppy)3 and Os(phen)2(dppene)2+ are poorly soluble in aqueous solution. However, when these compounds are placed in aqueous solution containing trace amounts of [emim][EtSO4], adsorption onto the electrode takes place, yielding ECL intensity increases of ∼27- and 5-fold, respectively.
Ionic liquids, electrogenerated chemiluminescence, electrochemluminescence, ECL
Roop, Jared, Michael Nothnagel, Megan Schnuriger, Mark M. Richter, and Gary A. Baker. "Ionic liquid adsorbate enhanced electrogenerated chemiluminescence of ruthenium, osmium, and iridium complexes in water." Journal of electroanalytical chemistry 656, no. 1-2 (2011): 34-40.