title: Metal complexes of a boron-dipyrromethene (BODIPY)-tagged N-heterocyclic carbene (NHC) as luminescent carbon monoxide chemodosimeters.
abstract: Several metal complexes with a boron dipyrromethene (BODIPY)-functionalized N-heterocyclic carbene (NHC) ligand 4 were synthesized. The fluorescence in [(4)(SIMes)RuCl2(ind)] complex is quenched (Φ = 0.003), it is weak in [(4)PdI2(Clpy)] (Φ = 0.033), and strong in [(4)AuI] (Φ = 0.70). The BODIPY-tagged complexes can experience pronounced changes in the brightness of the fluorophore upon ligand-exchange and ligand-dissociation reactions. Complexes [(4)MX(1,5-cyclooctadiene)] (M = Rh, Ir; X = Cl, I; Φ = 0.008-0.016) are converted into strongly fluorescent complexes [(4)MX(CO)2] (Φ = 0.53-0.70) upon reaction with carbon monoxide. The unquenching of the Rh and Ir complexes appears to be a consequence of the decreased electron density at Rh or Ir in the carbonyl complexes. In contrast, the substitution of an iodo ligand in [(4)AuI] by an electron-rich thiolate decreases the brightness of the BODIPY fluorophore, rendering the BODIPY as a highly sensitive probe for changes in the coordination sphere of the transition metal.
authors.affiliation: Organometallic Chemistry, Technische Universität Darmstadt, Alarich-Weiss-Strasse 12, 64287 Darmstadt (Germany).
authors.forename: Pavlo
authors.initials: P
authors.lastname: Kos
authors.forename: Herbert
authors.initials: H
authors.lastname: Plenio
keywords: BODIPY; carbon monoxide; fluorescence; ligand substitution; transition metals