| Abstract
| - Electrospray ionization (ESI)/quadrupole ion trap massspectrometry is used to evaluate the heavy metal bindingselectivities of five caged crown ethers and two polyetherreference compounds in methanol solution. The bindingpreferences for Hg2+, Pb2+, Cd2+, and Cu2+ were analyzedby comparison of ESI mass spectral intensities with theaim of developing this method for the rapid screening ofbinding selectivities of new synthetic ligands. The cagecompounds preferentially bind Hg2+, except for the cagecryptand derivative, which favors Pb2+. The preferencefor Hg2+ stems from the favorable positioning of thenitrogen or sulfur atoms for linear coordination of Hg2+,whereas the cryptand derivative favors Pb2+ because ofits larger cavity size. The counterions of the metal saltsinfluence the type of complexes observed in the ESI massspectra because the strengths of the metal−anion bondsaffect retention of the anion in the complexes.
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