State Key Laboratory of Medicinal Chemical Biology, and Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, China.
Langmuir. 2012 May 1;28(17):6794-802. doi: 10.1021/la300298e. Epub 2012 Apr 19.
Metal-organic frameworks (MOFs) with open metal sites have great potential for enhancing adsorption separation of the molecules with different polarities. However, the elution and separation of polar compounds on such MOFs packed columns using nonpolar solvents is difficult due to too strong interaction between polar compounds and the open metal sites. Here, we report the control of the coordination status of the open metal sites in MOFs by adjusting the content of methanol (MeOH) in the mobile phase for fast and high-resolution separation of polar compounds. To this end, high-performance liquid chromatographic separation of nitroaniline, aminophenol and naphthol isomers, sulfadimidine, and sulfanilamide on the column packed with MIL-101(Cr) possessing open metal sites was performed. The interaction between the open metal sites of MIL-101(Cr) and the polar analytes was adjusted by adding an appropriate amount of MeOH to the mobile phase to achieve the effective separation of the polar analytes due to the competition of MeOH with the analytes for the open metal sites. Fourier transform infrared spectra and X-ray photoelectron spectra confirmed the interaction between MeOH and the open metal sites of MIL-101(Cr). Thermodynamic parameters were measured to evaluate the effect of the content of MeOH in the mobile phase on the separation of polar analytes on MIL-101(Cr) packed column. This approach provides reproducible and high performance separation of polar compounds on the open metal sites-containing MOFs.
具有开放金属位点的金属有机骨架（MOFs）在增强不同极性分子的吸附分离方面具有巨大的潜力。然而，由于极性化合物与开放金属位点之间的相互作用太强，使用非极性溶剂在这种 MOFs 填充柱上洗脱和分离极性化合物是困难的。在这里，我们通过调节流动相中甲醇（MeOH）的含量来控制 MOFs 中开放金属位点的配位状态，从而实现快速和高分辨率的极性化合物分离。为此，在填充有具有开放金属位点的 MIL-101(Cr)的色谱柱上进行了硝基苯胺、氨基酚和萘酚异构体、磺胺嘧啶和磺胺甲恶唑的高效液相色谱分离。通过向流动相中添加适量的 MeOH 来调节 MIL-101(Cr)的开放金属位点与极性分析物之间的相互作用，由于 MeOH 与分析物竞争开放金属位点，因此可以实现对极性分析物的有效分离。傅里叶变换红外光谱和 X 射线光电子能谱证实了 MeOH 与 MIL-101(Cr)的开放金属位点之间的相互作用。测量了热力学参数以评估流动相中 MeOH 含量对在 MIL-101(Cr)填充柱上分离极性分析物的影响。该方法为含开放金属位点的 MOFs 上的极性化合物提供了可重现的高性能分离。
