Highly Efficient Blue Photoexcitation of Europium in a Bimetallic Pt–Eu Complex |
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Authors: | Raymond Ziessel Dr Stéphane Diring Pascal Kadjane Loïc Charbonnière Dr Pascal Retailleau Dr Christian Philouze Dr |
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Institution: | 1. Laboratoire de Chimie Moléculaire, ECPM, UMR 7509, CNRS‐Université Louis Pasteur, 25 rue Becquerel, 67087 Strasbourg Cedex 02, France, Fax: (+33)?390‐24‐27‐42;2. Laboratoire de Cristallochimie, ICSN ‐ CNRS, Bat 27‐1 avenue de la Terrasse, 91198 Gif‐sur‐Yvette, Cedex, France;3. Laboratoire d'Etudes Dynamiques et Structurales de la Sélectivité (CNRS/UJF), Batiment Chimie Recherche, 301 rue de la Chimie, Domaine Universitaire, Saint‐Martin‐d'Hères, Gières, B.P. 53, 38041 Grenoble Cedex 9, France |
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Abstract: | We report the preparation and characterization of dinuclear Pt–Ln complexes constructed from a square‐planar PtII core bearing an ethynyl–terpyridine residue connected to platinum by the ethynyl bond. Complexation of the neutral Eu(hfac)3 (hfac=hexafluoroacetylacetonate) fragment to free terpyridine (terpy) gives a stable bimetallic complex (log β=6.7). In the crystal structure, the flat Pt?terpy core coordinates to EuIII, which is nonacoordinated with the three nitrogen atoms of the terpy subunit and six oxygen atoms of the three hfac ligands. These atoms form a distorted monocapped square antiprism with a pseudo‐C2 symmetry axis passing through the nitrogen atom of the central pyridine ring and the Eu atom. Spectroscopic measurements showed that irradiation with visible light of wavelength up to 460 nm in the 1MLCT state of the Pt subunit resulted in a quantitative energy transfer to the Eu center, which strongly luminesces in the red with an overall luminescence quantum yield of 38 %. The energy‐transfer process is quantitative and not sensitive to oxygen, and the complexation of Eu to the Pt metallosynthon allows the recovery of the energy lost due to triplet‐oxygen quenching of the 3MLCT state observed in the uncomplexed Pt precursor. |
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Keywords: | electrochemistry energy transfer europium luminescence platinum |
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