Jean-Claude Bunzli - Surprisingly Bright Near-Infrared Luminescence and Short Radiative Lifetimes of Ytterbium in Hetero-Binuclear Yb-Na Chelates

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  Publication Details (including relevant citation   information):

  Shavaleev,N.M., Scopelliti,R., Gumy,F., Bunzli,J.C.G.   Inorganic Chemistry 2009 48  (16) 7937-7946

  Abstract: New heterobinuclear lanthanide   complexes with benzoxazole-substituted 8-hydroxyquinolines,   [Ln(ligand)(2)(mu-ligand)(2)Na] (Ln: Yb, Lu), have been prepared   and their structure established by X-ray crystallography, (1)H   NMR spectroscopy, and photophysical studies. The complexes   display efficient ligand-sensitized near-infrared luminescence of   ytterbium at 9251075 nm with lifetimes and quantum yields as high   as 22 mu s and 3.7%, in the solid state, and 20,us and 2.6% in   CH(2)Cl(2) solution, respectively. These quantum yields are the   highest reported to date for ytterbium complexes with organic   ligands containing C-H bonds. A long-wavelength and intense   intraligand charge-transfer transition (lambda(max)=446-456 nm;   epsilon approximate to 1.2 x 10(4) M(-1) cm(-1)) allows for the   excitation of infrared luminescence with visible light up to 600   nm. Remarkable features of these complexes include (i)   quantitative ligand-to-Yb(III) energy transfer resulting in high   overall efficiency of the ytterbium luminescence, (ii) unusually   short radiative lifetime of the Yb(III) ion, 706-745 mu s for   solutions in CH(3)Cl(2), calculated from the f-f absorption   spectra, and 513-635 mu s estimated for solid state samples from   quantum yield and lifetime data, and (iii) the unexpected large   influence of second-sphere composition on the radiative lifetime   of ytterbium

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