T. Oshima et al., SELECTIVE CATION-BINDING OF CROWN-ETHER ACETALS IN ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY, Perkin transactions. 2, (1), 1998, pp. 145-148
Diphenyl-substituted 11- to 20-membered ring crown ether acetals 1a-d
exhibit selective cation complexation with alkali metal ions and NH4in electrospray ionization mass spectrometry (ESI-MS), In addition, ca
tion-bound crown ether dimers (sandwiches) and trimers have also been
observed, especially for the smaller crown ethers, However, their bind
ing ability is completely lost upon acetal hydrolysis, It has been fou
nd that these crown ether acetals tend to preferentially bind smaller
ions as compared with the corresponding simple crown ethers possessing
the same number of ring oxygen atoms, These results are discussed on
the basis of ring-contracted deformation, hydrophobic effects of the d
iphenyl group and the reduced solvation energies of the complexes.