Homochiral metal-organic framework for HPLC separation of enantiomers

In recent years, homochiral metal-organic frameworks (MOFs) have been widely used as novel media for separation of chiral compounds. Herein, we report a homochiral MOF [Cu(S-mal)(bpe)]n (S-mal = S-malic acid, bpe = trans-1,2-bis(4-pyridyl)ethylene) packed column for HPLC separation of racemates. A variety of different types of racemic compounds such as alcohols, acids, ketones and phenols can be separated on the homochiral MOF column with high enantioselectivity. Compared with the chiral recognition ability of another homochiral MOF [Cu(S-mal)(bpy)]n column previously reported by our group, the results show that the chiral microenvironment and pore sizes of homochiral MOFs play a vital role in chiral recognition process. The repeatability of homochiral MOF [Cu(S-mal)(bpe)]n column was investigated. The relative standard deviation (RSD) for the retention time of DNB-leucine was less than 1.1% (n = 5), indicating the good stability and repeatability of the homochiral MOF [Cu(S-mal)(bpe)]n column for HPLC enantioseparation. These results demonstrated that the homochiral MOF [Cu(S-mal)(bpe)]n is promising for enantioseparation, which can be complementary to the currently reported homochiral MOFs columns in HPLC.