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Highly Efficient Blue Photoexcitation of Europium in a Bimetallic Pt–Eu Complex
Author(s) -
Ziessel Raymond,
Diring Stéphane,
Kadjane Pascal,
Charbonnière Loïc,
Retailleau Pascal,
Philouze Christian
Publication year - 2007
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700143
Subject(s) - terpyridine , chemistry , quantum yield , europium , bimetallic strip , crystallography , photochemistry , square antiprism , photoexcitation , platinum , pyridine , fluorescence , ion , lanthanide , excited state , catalysis , atomic physics , medicinal chemistry , biochemistry , physics , organic chemistry , quantum mechanics , metal
We report the preparation and characterization of dinuclear Pt–Ln complexes constructed from a square‐planar Pt II 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 Ptterpy core coordinates to Eu III , 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‐ C 2 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 1 MLCT 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 3 MLCT state observed in the uncomplexed Pt precursor.