Estimation of Selectivities and Relative Cationization Efficiencies of Different[Crown+M]+ by Electrospray Mass Spectrometry

Abstract

The selectivity of the lariat crown ethers toward metal ions can be estimated easily using electrospray mass spectrometry. Two lariat crown ethers in the sym-dibenzo-16-crown-5 series were shown to be more selective towards Li+ than Na+ ions in methanol. Calibration for the relative cationization efficiencies of the metallated crowns [crown+M]+ was shown to be essential for comparison of the selectivities in ligand–metal interactions. The two sym-dibenzo-16-crown-5 ethers show the best selectivity towards Li+ ion in methanol with their Li+ complexes being the most stable among Li+, Na+ and K+ ions. © 1997 by John Wiley & Sons, Ltd.