title: A highly selective and sensitive ratiometric chemodosimeter for Hg2+ ions based on an iridium(III) complex via thioacetal deprotection reaction.
abstract: A novel luminescent biscyclometalated iridium(III) complex [Ir(C^N)2bpy]PF6 (Ir-S, bpy = 2,2'-bipyridine) containing two 2-phenylpyridine (ppy) cyclometalating ligands (C^N) functionalized with 1,3-dithiane for the detection of Hg(2+) ions has been synthesized and characterized by spectroscopic and photophysical measurements. The luminescence of Ir-S exhibits a ratiometric response upon the addition of Hg(2+) ions. The absorption, emission, (1)H NMR and ESI mass spectral changes of Ir-S in the absence and presence of Hg(2+) ions have all demonstrated the Hg(2+)-promoted thioacetal deprotection reaction of Ir-S and the generation of a complex [Ir(pba)2bpy]PF6 (Ir-CHO, Hpba = 4-(pyridin-2-yl)benzaldehyde). DFT calculation studies suggest that the dominant participation of the 1,3-dithiane group in the HOMO of Ir-S leads to different excited states and distinct excited energies of Ir-S and Ir-CHO and consequently results in their different emission properties. The titration and competition experiments significantly reveal the highly sensitive and selective properties of Ir-S as a promising indicator for Hg(2+) ions over other metal cations.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
authors.forename: Fengniu
authors.initials: F
authors.lastname: Lu
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nabeshima
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001547:Benzaldehydes; D056831:Coordination Complexes; D007477:Ions; D007495:Iridium; D015082:2,2'-Dipyridyl; D008628:Mercury; C032175:benzaldehyde