INFLUENCE OF HETEROATOM DONORS ON THE ORDERS OF RELATIVE GAS-PHASE BINDING AFFINITIES OF MACROCYCLIC POLYETHERS

The effects of the heteroatom donor on the complexation of various met al ions by macrocyclic polyethers were qualitatively examined by appli cation of the ligand exchange technique in a quadruple ion trap mass s pectrometer. The metal ions, including K+, Cs+, Al+, Mg+, Cu+ and Ni+, were generated by laser desorption and allowed to react with 12-crown -4 and its nitrogen and sulfur analogs, cyclen and 1,4,7,10-tetrathiac yclododecane. The orders of gas-phase basicities were established as a comparison. The relative K+ and Cs+ binding affinities of 12-crown-4 are greatest, whereas cyclen has the highest binding affinity for all the other metal ions and also the highest gas-phase basicity.