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Analysis of Complexation of Silver and Co-recovered Metals with Novel Aza-Crown Ether Macrocycles by Electrospray Ionization Mass Spectrometry Sheldon M. Williams † , Jennifer S. Brodbelt † , Zilin Huang ‡ , Huiguo Lai ‡ And Alan P. Marchand ‡ † Department of Chemistry and Biochemistry
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Analysis of Complexation of Silver and Co-recovered Metals with Novel Aza-Crown Ether Macrocycles by Electrospray Ionization Mass Spectrometry Sheldon M. Williams†, Jennifer S. Brodbelt†, Zilin Huang‡, Huiguo Lai‡ And Alan P. Marchand‡ †Department of Chemistry and Biochemistry University of Texas at Austin, Austin, TX ‡Department of Chemistry University of North Texas, Denton, Texas
Objective • Evaluate relative Ag+ binding affinities of crown ethers with O and N heteroatoms, aromatic groups, and cage groups • Determine avidities for extracting Ag+ from aqueous solution. • Applications • Developing and evaluating new ion sensors and affinity columns • Rapid, efficient screening of waste remediation agents • More efficient, environmentally beneficial mining of precious metals • Enhanced detection methods for metal ion binding analytes • Understanding interactions of natural products and biomolecules with metal ions
Customized ESI - Quadrupole Ion Trap Mass Spectrometer
Evaluation of Size Selectivities of Macrocycles Based on Alkali Metal Complexation
Ionic Diameters of Ions and Estimated Diameters of Macrocycle Cavities
(3 + Ag)+ Ag+ (4 + Ag)+ Ag+ Models of Macrocycle 2 and 3 With Ag+ Determined by Density Functional Theory Calculations Gray = Carbon, Red = Oxygen, Blue = Nitrogen
Relative Percentages of Alkali Metal Complexes Detected Compared to Silver Ion Complex Error is 20% RSD
Relative Percentages of Transition Metal Complexes Detected Compared to Silver Ion Complex Error is 20% RSD
Determination of Extraction Selectivities and Avidities by ESI-MS
Conclusions • ESI-MS allows rapid screening of metal binding properties of novel ligands • Five of the six novel macrocycles are highly Ag+ selective • Appropriate ring diameter, at least one nitrogen atom, aromatic group(s), and cage group all enhance silver selectivity • Macrocycle 3 shows greatest resistance to protonation and performs the best at extracting Ag+ from aqueous to chloroform organic phase
Acknowledgments Advisor & Principle Investigator Prof. Jennifer Brodbelt Collaborator Prof. Alan Marchand, University of North Texas Support Welch Foundation Texas Advanced Technology Program