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RESEARCH PRODUCT
Synthesis, Characterization, and X-ray Crystal Structures of Cyclam Derivatives. 8. Thermodynamic and Kinetic Appraisal of Lead(II) Chelation by Octadentate Carbamoyl-Armed Macrocycles1
Michel MeyerFrançois CuenotEnrique EspinosaRoger Guilardsubject
Aqueous solutionHydrogen bondInorganic chemistryProtonationCrystal structureCarbon-13 NMRInorganic Chemistrychemistry.chemical_compoundCrystallographychemistryIntramolecular forceCyclamPhysical and Theoretical ChemistryLone pairdescription
En route toward the development of hybrid organic−inorganic extracting materials incorporating lead-selective chelators and their implementation in water purification processes, the lead(II) binding properties of three N-carbamoylmethyl-substituted 1,4,8,11-tetraazacyclotetradecanes (cyclams) have been fully investigated by spectroscopic (IR, UV−vis, MALDI-TOF MS, 1H and 13C NMR), X-ray crystallographic, potentiometric, and kinetic methods. Solution NMR studies revealed that the Pb2+ ion is entrapped in a molecular cage constituted by the four macrocyclic nitrogen and four amidic oxygen atoms. Protonation and lead binding constants determined in aqueous solution were shown to be linearly dependent, so that all three derivatives possess a similar affinity at any pH value. Thermodynamic and kinetic parameters revealed the crucial role played by the intramolecular hydrogen bonds also evidenced in the crystal structure of the tetraacetamide derivative L1, which involve the lone pair of each macrocyclic tertia...
year | journal | country | edition | language |
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2005-10-01 | Inorganic Chemistry |