title: Red-Emitting Ruthenium(II) and Iridium(III) Complexes as Phosphorescent Probes for Methylglyoxal in Vitro and in Vivo.
abstract: Transition-metal complexes, ruthenium(II) and iridium(III) complexes in particular, with fascinating triplet emissions are rapidly emerging as important phosphorescent dyes for application in the sensing and imaging of biological makers in live cells and organisms. In this contribution, two red-emitting transition-metal complexes, [Ru(bpy)2(DA-phen)](PF6)2and [Ir(ppy)2(DA-phen)](PF6) (bpy = 2,2'-bipyridine, DA-phen = 4,5-diamino-1,10-phenanthroline, and ppy = 2-phenylpyridine), were designed and synthesized as phosphorescent probes for the highly sensitive and selective detection of methylglyoxal (MGO), an essential biomarker in the etiopathogenesis of several diseases. Both probes showed weak emissions in aqueous media because of the existence of an effective photoinduced-electron-transfer process, while their emissions could be remarkably enhanced upon the addition of MGO. The photophysical and electrochemical properties, as well as phosphorescent responses of the probes toward MGO, were examined. The ground- and excited-state properties of the probes and their reaction products with MGO, [Ru(bpy)2(MP-phen)](PF6)2and [Ir(ppy)2(MP-phen)](PF6) (MP-phen = 2-methylpyrazino-1,10-phenanthroline), the sensing mechanism, and several important experimental facts were investigated and validated using density functional theory (DFT)/time-dependent DFT computations. The results indicated that the phosphorescence switch-ON is due to the elimination of electron transfer and followed the reestablishment of emissive triplet excited states. To evaluate the feasibility of [Ru(bpy)2(DA-phen)](PF6)2and [Ir(ppy)2(DA-phen)](PF6) as bioprobes, their cytotoxicity was examined, and their applicability for visualizing intracellular and in vivo MGO was demonstrated.
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology , Dalian 116024, P. R. China.
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology , Dalian 116024, P. R. China.
authors.forename: Feiyue
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology , SE-100 44 Stockholm, Sweden.
authors.forename: Yong-Lei
authors.identifier: http://orcid.org/0000-0003-3393-7257
authors.initials: YL
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology , Dalian 116024, P. R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Song
authors.affiliation: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland , St. Lucia, Queensland 4072, Australia.
authors.forename: Run
authors.identifier: http://orcid.org/0000-0002-0943-824X
authors.initials: R
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology , Dalian 116024, P. R. China.
authors.forename: Jingli
authors.initials: J
authors.lastname: Yuan
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D003621:Daphnia; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D051379:Mice; D015394:Molecular Structure; D011765:Pyruvaldehyde / Q000032:analysis*; D011789:Quantum Theory; D000067996:RAW 264.7 Cells; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D056831:Coordination Complexes; D005456:Fluorescent Dyes; D007495:Iridium; D011765:Pyruvaldehyde; D012428:Ruthenium