Cyclen based bis-macrocyclic ligands as phosphates receptors. A potentiometric and NMR study
Abstract
The host-guest interaction between orthophosphate, pyrophosphate and triphosphate anions and four cyclen based bis-macrocycles ligands possessing ortho-(BOC), meta-(BMC), para-xylenyl (BPC) or 2,6-pyridinyl (BPyC) linker was investigated by potentiometric measurements and NMR spectroscopy. Each ligand gave protonated species in aqueous solution that further formed ternary complexes after binding with anions; these complexes were analyzed as a result of hydrogen bond formation and Coulombic attraction between the organic host and the inorganic guest. The equilibrium constants for all the detected species are reported and the selectivity, illustrated with species distribution diagrams, is discussed. The results unambiguously showed the importance of the distance between the two cyclen cores and underlined, especially for the triphosphate species, the contribution of the nitrogen atom of the pyridinyl spacer as a supplementary anchoring point in acidic medium. © The Royal Society of Chemistry 2005.
Keywords
Bond formation
Macrocycles
Orthophosphates
Hydrogen bonds
Phase equilibria
Phosphates
1
7
10 tetraazacyclododecane
anion
heterocyclic compound
ligand
macrocyclic compound
phosphate
article
chemical structure
chemistry
methodology
nuclear magnetic resonance spectroscopy
pH
potentiometry
Anions
Heterocyclic Compounds
Hydrogen-Ion Concentration
Ligands
Macrocyclic Compounds
Magnetic Resonance Spectroscopy
Models
Molecular
Molecular Structure
Sensitivity and Specificity