title: A Tris(diisocyanide)chromium(0) Complex Is a Luminescent Analog of Fe(2,2'-Bipyridine)32.
abstract: A meta-terphenyl unit was substituted with an isocyanide group on each of its two terminal aryls to afford a bidentate chelating ligand (CNtBuAr3NC) that is able to stabilize chromium in its zerovalent oxidation state. The homoleptic Cr(CNtBuAr3NC)3complex luminesces in solution at room temperature, and its excited-state lifetime (2.2 ns in deaerated THF at 20 °C) is nearly 2 orders of magnitude longer than the current record lifetime for isoelectronic Fe(II) complexes, which are of significant interest as earth-abundant sensitizers in dye-sensitized solar cells. Due to its chelating ligands, Cr(CNtBuAr3NC)3is more robust than Cr(0) complexes with carbonyl or monodentate isocyanides, manifesting in comparatively slow photodegradation. In the presence of excess anthracene in solution, efficient energy transfer and subsequent triplet-triplet annihilation upconversion is observed. With an excited-state oxidation potential of -2.43 V vs Fc+/Fc, the Cr(0) complex is a very strong photoreductant. The findings presented herein are relevant for replacement of precious metals in dye-sensitized solar cells and in luminescent devices by earth-abundant elements.
authors.affiliation: Department of Chemistry, University of Basel , St. Johanns-Ring 19 and Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Büldt
authors.affiliation: Department of Chemistry, University of Basel , St. Johanns-Ring 19 and Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Xingwei
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Chemistry, University of Basel , St. Johanns-Ring 19 and Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Vogel
authors.affiliation: Department of Chemistry, University of Basel , St. Johanns-Ring 19 and Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Prescimone
authors.affiliation: Department of Chemistry, University of Basel , St. Johanns-Ring 19 and Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Oliver S
authors.identifier: 0000-0002-0739-0553
authors.initials: OS
authors.lastname: Wenger