Complexation of the lanthanides Eu3+, Gd3+, and Tb3+ with 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (dota) has been studied in solution by using potentiometry, luminescence spectrometry, and EXAFS. Three series of successive complexes were characterized by at least two of these methods: the immediate [LnHn(dota)](n-1)+** and intermediate [LnHn(dota)](n-1)+* complexes with 0 = n = 2, and the final [Ln(dota)]- complexes. The formation constants of the intermediate and final complexes were determined by using potentiometry. From the results, a complexation mechanism involving three steps has been proposed. In the [LnHn(dota)](n-1)+** complexes that are instantaneously formed, the lanthanide is bound to four oxygen atoms of the carboxylate groups and to five water molecules. These species evolve rapidly: the lanthanide moves into the macrocycle cavity, two new bonds are formed with two nitrogen atoms diametrically opposed in the tetraaza cycle and only three water molecules remain bound to the lanthanide in the [LnHn(dota)](n-1)+* (0 = n = 2) complexes, which appear after a two-day wait. These compounds are stable for about four days. After 4-8 weeks, a concerted rearrangement occurs which leads to the formation of thermodynamically stable [Ln(dota)]- complexes in which the lanthanide is bound to four nitrogen atoms, four carboxylate oxygen atoms, and one water molecule.
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http://dx.doi.org/10.1002/chem.200400006 | DOI Listing |
Adv Sci (Weinh)
January 2025
Yunnan Key Laboratory of Electromagnetic Materials and Devices, National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming, 650091, China.
Far-red phosphors have emerged as a desirable research hotspot owing to their critical role in promoting plant growth. Especially, Eu ions typically present the D→F (J = 0, 1, 2, 3, 4) transitions, which overlap with the far-red light required for plant photosynthesis. However, achieving high-efficiency far-red emission of Eu remains challenging due to weak D→F transition and concentration quenching.
View Article and Find Full Text PDFRSC Adv
January 2025
Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo 05508-000 São Paulo SP Brazil
J Am Chem Soc
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Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Rare earth elements (REEs) are widely used in various high-tech industries. Developing affinity ligands that can detect and distinguish REEs is at the forefront of analytical chemistry. It is also interesting to understand the limits of natural biomolecules for the recognition of REEs.
View Article and Find Full Text PDFACS Omega
December 2024
Grupo de QuÃmica de Coordenação e Espectroscopia de LantanÃdeos (GQCEL), Instituto de QuÃmica, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ 20550-013, Brazil.
RSC Adv
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Petru Poni Institute of Macromolecular Chemistry, Department of Inorganic Polymers IaÅŸi 700487 Romania
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