Measurement of Chiral Recognition Properties of Crown Ethers Using Matrix Assisted Laser Desorption Ionization Mass Spectrometry

Abstract

Hydrogen bonding host-guest complex ions between chiral crown ethers and chiral amino acid ester salts, detected by matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) with a DHBA or MSA matrix, were studied on the view point of chiral recognition properties of the chiral crown hosts. The chiral recognition property (I_R/I_S-dn value≅1.0) obtained by the present MALDI-MS is sharply different from the I_R/I_S-dn value obtained by FAB-MS or ESI-MS (≠1.0) in the same host-guest combinations. The direct comparison on the basis of the I_R/I_S-dn values suggests that MALDI-MS is not a suitable measurement tool for chiral host-guest interactions probably because of the particular way of sample preparation involving a crystallization process.