Use of transition metals to improve the diastereomers differentiation by ion mobility and mass spectrometry

摘要

Asymmetric synthesis is a growing field of study in organic chemistry because of the role of stereoisomers in biochemistry, particularly for therapeutic applications. It is therefore essential to develop analytical methods for characterization and quantification of diastereomers and enantiomers. The latter must be identified because they are known to develop different behavior in biological systems.~([1]) However, it is relatively difficult to identify and separate enantiomers. Indeed, these molecules have identical chemical and physical properties except in case of interaction with polarized light or with chiral molecules. It is thanks to a chiral environment that enantiomers are most often differentiated. The principle task of chiral separation is to form interactions between enantiomers and chiral selectors in order to form diastereomers.~([2]) For the separation and the identification of stereoisomers, chromatography is the most commonly used technique.~([3]) The supercritical fluid chromatography is a field that has focused a growing interest during recent decades and has become a popular technique for chiral separation.~([4]) Henceforth, coupling of ion mobility and mass spectrometry (IM-MS), known for isomers differentiation~([5,6]) constitutes a new alternative method for stereochemistry study.~([7]) Ion mobility spectrometry (IMS) is a post-ionization separation method, which measures the time taken for an ion to travel through a gas-filled cell under the influence of an electric field. This time on the millisecond range is called drift time. Ion mobility depends on mass (m), charge (z) and collision cross section (CCS: Ω) of the ions. CCS is related to the conformation and size of ions in the gas phase. Ions with different CCS can be separated thanks to IM-MS, although they have the same m/z ratio.