Lanthanide(III) complexes of amide derivatives of DOTA exhibit an unusual variation in stability across the lanthanide series |
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Authors: | David A Voss Jr William DeW Horrocks Jr |
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Institution: | a Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260, USA b Department of Chemistry, The Pennsylvania State University, College Park, PA 16802, USA |
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Abstract: | Luminescence excitation spectroscopy of the 7F0→5D0 transition of the Eu(III) complex of 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (TCMC, an amide derivative of DOTA) is used to measure the stability constant of the complex (K). A log K value of 10.6 is obtained for Eu(TCMC)]3+ at 25 °C and an ionic strength of 0.1 M. Competition experiments with eleven other members of the lanthanide(III) series give stability constants for their complexes with TCMC. An unusual variation in stability is observed for complexes of Ln(TCMC)]3+ across the lanthanide series with a pronounced optimum for the Sm(III) complex. This variation is quite different from that observed for other Ln(III) macrocyclic complexes, suggesting that the TCMC ligand is uniquely sensitive to Ln(III) ion radius. |
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Keywords: | Luminescence Lanthanide Macrocycle Stability constant |
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