Homochiral Eu<sup>3+</sup>@MOF Composite for the Enantioselective Detection and Separation of (<i>R</i>/<i>S</i>)-Ornidazole
Mingyuan Lei, Xiaohe Wang, Tianjun Zhang, Yang Shi, Jinghong Wen, Qingfu Zhang
Abstract
The development of homochiral materials for the enantioselective detection and separation of chiral drugs is in high demand for the pharmaceutical industry. Herein, an anionic homochiral metal–organic framework (HMOF) with in situ generated [Me2NH2]+ counterions, {[Me2NH2]2[Zn2(d-L)2(HCO2)(OH)]·5H2O}n (HMOF-1), was synthesized using a d-camphorate-derived enantiopure dicarboxylate ligand, 4,4′-[[(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarbonyl]bis(azanediyl)]dibenzoic acid (d-H2L) via a simple solvothermal method. Interestingly, HMOF-1 could be used as a parent framework to encapsulate Eu3+ cations via an ion-exchange process, yielding an Eu3+@HMOF-1 composite with dual-luminescent centers. The obtained Eu3+@HMOF-1 has high chemical stability and good luminescence stability in water. Importantly, Eu3+@HMOF-1 exhibits enhanced enantioselectivity and sensitivity in the detection of an important chiral nitroimidazole antibiotic, (R/S)-ornidazole (ONZ) in comparison to HMOF-1 under the same aqueous conditions. The enantiomeric excess (ee) value of the ONZ enantiomers can be accurately determined by the ratio of dual emission from the ligand and Eu3+. In addition, Eu3+@HMOF-1 shows the enantioselective separation of racemic ONZ enantiomers with an ee value of 86.6%. This work provides a simple strategy for the preparation of LnIII-incorporated HMOF composite materials for the simultaneous enantioselective detection and separation of chiral drugs.