Chapter 14
Bimetallic Lanthanide Supramolecular Edifices with Calixarenes 1
Jean-Claude G. Bünzli , Frédéric Besançon, and Frédéric Ihringer
Downloaded by UNIV OF ROCHESTER on June 4, 2014 | http://pubs.acs.org Publication Date: July 20, 2000 | doi: 10.1021/bk-2000-0757.ch014
Institute of Inorganic and Analytical Chemistry, University of Lausanne, BCH 1402,CH-1015Lausanne, Switzerland
The structural, kinetic and photophysical properties of bimetallic lanthanide complexes with simple calix[n]arenes (n = 5 and 8) are discussed. The intensity of the f-f transitions of the Eu(III)-containingedifices strongly depends on the mixing between 4f and ligand-to-metal charge-transfer ( L M C T ) wave functions. In particular, the D F transition, which is unique for a given Eu(III) chemical environment, upon mixing the lanthanide salt and the ligand in the presence of an excess of triethylamine, points to a very fast formation of the 1:1 complex (half-life in the ms range) which then slowly transforms into the bimetallic 2:1 assembly with a half-life of 5,500 s in the presence of an 18-fold excess of triemylamine. It is noteworthy that this second reaction is 6 times slower in the presence of a 4-fold excess of Et N and becomes incomplete when only one equivalent of base per Eu(III) ion is added (32). 8
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In Calixarenes for Separations; Lumetta, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2000.
Downloaded by UNIV OF ROCHESTER on June 4, 2014 | http://pubs.acs.org Publication Date: July 20, 2000 | doi: 10.1021/bk-2000-0757.ch014
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Figure 5. Absorption spectra (10 cm cells) at 298 K. Left: [Eu2(b-LH2)(DMF) j] and [Eu(NOs) s(DMSO)4] 3.8x10^ M in DMF. Right: Do
