Mechanisms Of Enantiomer Separation On Modified Cyclodextrin Chiral Stationary Phases In Gas Chromatography

Enantiomer separation techniques are urgently needed not only to separate mixtures of chiral drugs and their optically active metabolites, but also for the quality control of enantiomerically pure drugs and in the development of asymmetric synthesis. Direct gas chromatographic (GC) enantiomer separation on chiral stationary phases (CSPs) is a simple and effective method, and is one of the most suitable techniques for the purpose. Various types of modified cyclodextrins (CDs) have been successfully investigated as CSPs in capillary GC, and these compounds exhibit very broad enantioselectivity for a variety of chiral compounds in GC. However, enantiomer separation mechanisms on CD CSPs are not clear, and a simple and reasonable mechanism is still lack so far. Herewith, we proposed a more effective and simple method to study the chiral recognition mechanisms on CD CSPs. First, combined with statistic analysis, the enthalpy-entropy compensation effects were investigated in each series of the related chiral separation processes. Based on the compensation theory, chiral separation processes can be classified to different groups, in which all the related chiral separation processes are governed by the same chiral recognition mechanism. Secondly, select the typical chiral separation systems from each group and investigate their chiral recognition mechanisms using molecular modeling methods. Using these methods, we successfully investigated the recognition mechanisms of some compounds separated on different CD CSPs.Combined with statistic analysis, the enthalpy-entropy compensation effect in...