Synthesis of spherical amorphous metal‒organic frameworks via an in situ hydrolysis strategy for chiral HPLC separation

Abstract

To obtain metal-organic frameworks (MOFs) that are more suitable for applications in liquid chromatography separation, the synthesis of spherical MOF particles of micrometer size is of great importance. Herein, by using an in situ hydrolysis strategy, the reactions of zirconium tetrachloride with terephthalonitrile under optimized water content and temperature give rise to Zr(IV)-carboxylic amorphous metal-organic frameworks (aMOFs) with spherical shapes at the micrometer scale. The aMOF particles can be used as a matrix to fabricate a chiral stationary phase (CSP) after coating cellulose derivative, cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC), on it. The resulting CSP, namely, CDMPC@aMOF, was further applied to separate enantiomers under high-performance liquid chromatography (HPLC). The results showed that six racemic compounds, including metalaxyl, prothioconazole, trans-stilbene oxide, 1-(1-naphthalenyl)ethanol, 1-phenylethanol and atropine sulfate, were well separated by a CDMPC@aMOF packed column.