Gas-phase relative stabilities of Tl+-crown ether complexes and Rb+-crown ether complexes

Abstract

The gas-phase stabilities of Tl+-crown ether complexes and Rb+-crown ether complexes were studied using the electrospray ionization-collision-induced dissociation-tandem mass spectrometry. Tl+ and Rb+ have identical ionic radii, thus a comparison of the properties of the crown ether complexes with these two cations seems to be justified. The selected crown ethers were 12C4 (it has a cavity smaller than the cation radius), 18C6 (it has a cavity of size similar to the cation radius), 24C8 (it has a cavity greater than the cation radius) and their conjugates. It has been found that the crown ether complexes of stoichiometry 1:1 with Tl+ are more or equally stable in the gas phase than the crown ether complexes with Rb+. However, 2:1 complexes with Tl+ are less stable than the complexes with Rb+.