title: Gadolinium Complex for the Catch and Release of Phosphate from Water.
abstract: The ability of complexes of hard and labile metal ions with one or more open coordination sites to capture phosphates with high affinity and selectivity directly in water at neutral pH and release them under acidic conditions is evaluated with Gadolinium- 2,2',2''-(((nitrilotris(ethane-2,1-diyl))tris(azanediyl))tris(carbonyl))tris(4-oxo-4H-pyran-3-olate) (Gd-TREN-MAM). This model lanthanide complex has two open coordination sites that, at neutral pH, are filled with water molecules. In water at neutral pH, Gd-TREN-MAM binds phosphate with high affinity (Ka= 1.3 × 104) via the formation of a ternary complex in which one phosphate replaces both inner-sphere water molecules. The formation of this complex is highly pH-dependent; the phosphate is completely released from Gd-TREN-MAM below pH 2. Because the GdIIIion remains complexed by its ligand, even under strong acidic conditions, Gd-TREN-MAM can be used at least 10 times in a pH-based recycling scheme that enables the catch and release of one phosphate per cycle. Gd-TREN-MAM is highly selective for phosphate over other anions of environmental concerns, including HCO3-, HCO2-, CH3CO2-, SO42-, NO3-, NO2-, BrO3-, AsO4-, F-, Cl-, and Br-and, to a lesser extent, ClO3-. The development of such receptors that bind phosphate reversibly in a pH-dependent manner opens the possibility to design catch-and-release systems for the purification of surface waters.
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Harris
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Jamie T
authors.initials: JT
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Sylvie L
authors.initials: SL
authors.lastname: Pailloux
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Jarrett P
authors.initials: JP
authors.lastname: Mansergh
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Dresel
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Tran B
authors.initials: TB
authors.lastname: Swanholm
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Tuo
authors.initials: T
authors.lastname: Gao
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Valérie C
authors.identifier: 0000-0002-0907-8395
authors.initials: VC
authors.lastname: Pierre
mesh_terms: D005682:Gadolinium / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry; D008024:Ligands; D010710:Phosphates; D014867:Water / Q000737:chemistry*
chemical_list: D028581:Lanthanoid Series Elements; D008024:Ligands; D010710:Phosphates; D014867:Water; D005682:Gadolinium