The role of central ion in chiral recognition by taking phenylalanine as an example

• DOI: 10.1007/s11426-009-0080-5
• Publication Date: 2009-07-29T07:25:34Z
• Authors: Qing Yu; Jie Cao; Gang Lu; ZhiXiang Wang
• Keywords: 01 natural sciences; 0104 chemical sciences

Chiral recognition of phenylalanine (Phe) was achieved in the gas phase by electrospray ionization Q-TOF tandem mass spectrometry. In this method, two central ions, i.e. proton and divalent copper, were used and chiral crown ether, (+)-2,3,11,12-tetracarboxylic acid-18-crown-6 (18-C-6-TCA), was used as a chiral host. Dimeric complexes were readily formed by electrospray ionization of a methanol/water (50/50, V/V) solution containing central ions, Phe and 18-C-6-TCA. The dimeric complex included proton-bound (18-C-6-TCA)(Phe)H+ and copper-bound deprotonated [Cu2+(18-C-6-TCA)(Phe)-H]+ ions were mass selected and then collided with Ar in the CID experiments. The chiral recognition capability of these complexes was evaluated using the relative abundance of daughter ion to parent ion. A higher degree of chiral recognition ability was observed with Cu2+ compared to that of H+. Different central ions exhibited distinctive dissociation pathways and unique chiral recognition characteristics. The chiral recognition mechanism was also discussed in detail with the help of the structure of copper-bound complex predicted by theoretical calculation.