title: Complexation of silver and co-recovered metals with novel aza-crown ether macrocycles by electrospray ionization mass spectrometry.
abstract: Electrospray ionization mass spectrometry (ESI-MS) is used to evaluate the metal binding selectivities of an array of novel caged macrocycles for silver, gold, copper, nickel, zinc, iron, lead, manganese and alkali metal ions. It is found that five of the new compounds display silver selectivity, and their relative affinities for various metals depend on the type, number, and arrangement of heteroatoms (N, O), the cavity size, and the presence of aromatic substituents. Alkali metal cation binding studies are used to evaluate the size-selectivities of the cavities of the macrocycles. Electronic structure calculation by B3LYP density function theory methods were used to model the metal complexes. The presence of nitrogen atoms in the macrocyclic ring is essential for silver selectivity over other transition metals and alkali metal ions, and the presence of aromatic groups also enhances silver avidity. Macrocycle 3, a triaza-18-crown-6 analog modified with two phenyl groups and a cage group, is capable of selective extraction of Ag+ from aqueous solutions in the presence of other transition metal ions and the most common alkali and alkaline earth metal ions.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Sheldon M
authors.initials: SM
authors.lastname: Williams
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brodbelt
authors.forename: Zilin
authors.initials: Z
authors.lastname: Huang
authors.forename: Huiguo
authors.initials: H
authors.lastname: Lai
authors.forename: Alan P
authors.initials: AP
authors.lastname: Marchand
mesh_terms: D043844:Crown Ethers; D004785:Environmental Pollutants / Q000032:analysis*; D017736:Ion-Selective Electrodes; D008672:Metals, Alkali / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis; D012834:Silver / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D043844:Crown Ethers; D004785:Environmental Pollutants; D008672:Metals, Alkali; D019216:Metals, Heavy; D012834:Silver