Incorporation of homochiral metal-organic cage into ionic liquid based monolithic column for capillary...

Metal-organic cages (MOCs) are a novel kind of porous materials which have three dimensional structures with perpetual and well-defined holes. They have attracted wide consideration for relatively simple synthesis and potential applications such as separation, sensing, microreactor and catalysis etc. In this study, a homochiral MOC [Zn₃L₂] was prepared as a novel stereoselective stationary phase and added into poly (ionic liquid-co-ethylene dimethacrylate) (Zn₃L₂@poly(IL-co-EDMA)) monolith for capillary electrochromatography (CEC). The chiral analytes comprising mandelic acid, benzoin and furoin enantiomer were separated perfectly using the monolithic column Zn₃L₂@poly(IL-co-EDMA), and the effects of buffer pH, acetonitrile percentage and buffer concentration on enantiomers separation were confirmed. Moreover, incorporation of MOC [Zn₃L₂] into IL polymer monolith strengthened obviously the stereoselective isolation of some positional isomers (such as nitrophenols, nitrotoluenes, xylenes, and ionones). The relative standard deviations (RSDs) of the retention time for intra-day (n = 5) and inter-day (n = 3) and column-to-column (n = 3) enantioseparations were all below 5.0%. This novel monolithic column combined distinct features of the stereoselective materials with the eminent traits of ionic liquid matrix, it has great application potential in CEC.