Enhanced liquid-liquid anion exchange using macrocyclic anion receptors: effect of receptor structure on sulphate-nitrate exchange selectivity

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Supramolecular Chemistry

DOI:https://doi.org/10.1080/10610271003763263· OSTI ID:1081759

Moyer, Bruce A ^[1]; Fowler, Christopher J ^[1]; Haverlock, Tamara ^[1]; Kang, Hyun Ah ^[1]; Delmau, Laetitia Helene ^[1]; Bau, Diadra ^[1]; Hossain, Alamgir ^[2]; Bowman-James, Kristin ^[2]; Shriver, James A. ^[3]; Gross, Mr. Dustin E. ^[4]; Bill, Nathan ^[4]; Marquez, Manuel ^[3]; Lynch, Vincent M. ^[4]; Sessler, Jonathan L. ^[3]

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1. ORNL
2. University of Kansas
3. University of Texas
4. University of Texas, Austin

When certain macrocyclic anion receptors are added to a chloroform solution of the nitrate form of a lipophilic quaternary ammonium salt (methyltri-C8,10-ammonium nitrate, Aliquat 336N), the extraction of sulphate from an aqueous sodium nitrate solution via exchange with the organic-phase nitrate is significantly enhanced. Eight macrocycles were surveyed, including two derivatives of a tetraamide macrocycle, five derivatives of calix[4]pyrrole and -decafluorocalix[5]pyrrole. Under the hypothesis that the enhancement originates from sulphate binding by the anion receptors in the chloroform phase, it was possible to obtain reasonable fits to the sulphate distribution survey data based on the formation of 1:1 and 2:1 receptor:sulphate complexes in the chloroform phase. Apparent 1:1 sulphate-binding constants obtained from the model in this system fell in the range . Comparison of the results for the various anion receptors included in this study reveals that sulphate binding is sensitive to the nature of the substituents on the parent macrocycle scaffolds in a way that does not follow straightforwardly from simple chemical expectations, such as electron-withdrawing effects on hydrogen-bond donor strength.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1081759
• Journal Information: Supramolecular Chemistry, Vol. 22, Issue 11-12; ISSN 1061--0278
• Country of Publication: United States
• Language: English