The Use of Electrospray Mass Spectrometry to Determine Speciation in a Dynamic Combinatorial Library for Anion Recognition

Hazel I. A. Phillips, Aleksey V. Chernikov, Nicholas C. Fletcher, Alison E. Ashcroft, James R. Ault, Maria H. Filby, Andrew J. Wilson

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The composition of a dynamic mixture of similar 2,2'-bipyridine complexes of iron(II) bearing either an amide (5-benzylamido-2,2'-bipyridine and 5-(2-methoxyethane)amido-2,2'-bipyridine) or an ester (2,2'-bipyridine-5-carboxylic acid benzylester and 2,2'-bipyridine-5-carboxylic acid 2-methoxyethane ester) side chain have been evaluated by electrospray mass spectroscopy in acetonitrile. The time taken for the complexes to come to equilibrium appears to be dependent on the counteranion, with chloride causing a rapid redistribution of two preformed heteroleptic complexes (of the order of 1 hour), whereas the time it takes in the presence of tetrafluoroborate salts is in excess of 24^^h. Similarly the final distribution of products is dependent on the anion present, with the presence of chloride, and to a lesser extent bromide, preferring three amide-functionalized ligands, and a slight preference for an appended benzyl over a methoxyethyl group. Furthermore, for the first time, this study shows that the distribution of a dynamic library of metal complexes monitored by ESI-MS can adapt following the introduction of a different anion, in this case tetrabutylammonium chloride to give the most favoured heteroleptic complex despite the increasing ionic strength of the solution. 

Original languageEnglish
Pages (from-to)13733-13742
Number of pages10
JournalChemistry - A European Journal
Volume18
Issue number43
Early online date20 Sep 2012
DOIs
Publication statusPublished - 22 Oct 2012

Keywords

  • 2,2′-bipyridine
  • anion recognition
  • combinatorial chemistry
  • iron
  • mass spectrometry

ASJC Scopus subject areas

  • Chemistry(all)

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    Phillips, H. I. A., Chernikov, A. V., Fletcher, N. C., Ashcroft, A. E., Ault, J. R., Filby, M. H., & Wilson, A. J. (2012). The Use of Electrospray Mass Spectrometry to Determine Speciation in a Dynamic Combinatorial Library for Anion Recognition. Chemistry - A European Journal, 18(43), 13733-13742. https://doi.org/10.1002/chem.201201302