Liu Hualin, Li Yanan, Zi Min, Chen Zheng, Duan Aihong, Yuan Liming
School of Chemistry and Chemical Engineering，Yunnan Normal University，Kunming 650500，China.
Se Pu. 2023 Feb;41(2):187-194. doi: 10.3724/SP.J.1123.2022.06012.
Covalent organic frameworks （COFs） are an emerging class of porous crystalline materials composed of multidentate organic units connected by covalent bonds. COFs have been demonstrated to exhibit great potential and research value in many fields， including gas storage and separation， photoelectric devices， fluorescence sensors， catalysis， drug delivery， dye and pollutant adsorption， and electronic devices， and so on. The COFs obtained by post-synthesis modification tend to exhibit high crystallinities and porosities， thereby rendering them suitable materials for use in the fields of chiral resolution， asymmetric catalysis， and chromatography. In this work， TpPa-NO was synthesized from 1，3，5-tricarbaldehyde phloroglucinol and 2-nitro-1，4-phenylenediamine， which was then reduced to TpPa-NH. Subsequently， this material was modified with D-glucose via a post-synthesis modification strategy to obtain the TpPa-NH-Glu. TpPa-NH-Glu were characterized by nuclear magnetic resonance （NMR） spectroscopy， Fourier transform-infrared （FT-IR） spectroscopy， X-ray powder diffraction （XRD） analysis， etc. In the XRD pattern， the peaks observed at 4.7°， 8.1°， 11.1°， and 27° were attributed to the TpPa-NH-Glu， and these peaks are consistent with previous reports， thereby confirming the successful synthesis of this derivative. In addition， circular dichroism experiments indicated that the TpPa-NH-Glu exhibited a Cotton effect， further confirming the chiral COF was prepared. Subsequently， this material was immobilized on the surface of spherical silica gel particles via the net-wrapping method to prepare a stationary phase for high performance liquid chromatographic column. Using -hexane-isopropanol （9∶1， v/v） or methanol-water （9∶1， v/v） as mobile phases at a flow rate of 0.5 mL/min， 16 racemates and two benzene-based positional isomers （，，-nitroaniline and ，，-Iodoaniline） were successfully resolved by this chiral column. In addition， under methanol-water （9∶1， v/v） mobile phase conditions， five racemates were separated， among which propranolol hydrochloride， warfarin， and metoprolol reached baseline separation. Furthermore， under -hexane-isopropanol （9∶1， v/v） mobile phase conditions， 11 racemates were resolved， among which ethyl 2-bromopropionate and 3-butyn-2-ol reached baseline separation. Meanwhile， the effect of temperature on the TpPa-NH-Glu liquid chromatography column and the repeatability of the TpPa-NH-Glu liquid chromatography column were also explored. The HPLC column prepared by TpPa-NH-Glu had good repeatability， and its relative standard deviation （RSD） was 1.55% and 1.46%， respectively. It is demonstrated that the TpPa-NH-Glu material has good resolution ability for chiral compounds.
共价有机框架（COFs）是一类新兴的多孔晶体材料，由通过共价键连接的多齿有机单元组成。COFs已被证明在许多领域具有巨大的潜力和研究价值，包括气体存储与分离、光电器件、荧光传感器、催化、药物递送、染料和污染物吸附以及电子器件等。通过后合成修饰获得的COFs往往具有高结晶度和孔隙率，因此使其成为适用于手性拆分、不对称催化和色谱等领域的材料。在本工作中，由间苯三酚三甲醛和2-硝基-1,4-苯二胺合成了TpPa-NO，然后将其还原为TpPa-NH。随后，通过后合成修饰策略用D-葡萄糖对该材料进行修饰，得到TpPa-NH-Glu。通过核磁共振（NMR）光谱、傅里叶变换红外（FT-IR）光谱、X射线粉末衍射（XRD）分析等对TpPa-NH-Glu进行了表征。在XRD图谱中，在4.7°、8.1°、11.1°和27°处观察到的峰归属于TpPa-NH-Glu，这些峰与先前的报道一致，从而证实了该衍生物的成功合成。此外，圆二色性实验表明TpPa-NH-Glu表现出科顿效应，进一步证实了手性COF的制备。随后，通过净包裹法将该材料固定在球形硅胶颗粒表面，制备了用于高效液相色谱柱的固定相。以正己烷 - 异丙醇（9∶1，v/v）或甲醇 - 水（9∶1，v/v）为流动相，流速为0.5 mL/min，该手性柱成功拆分了16种外消旋体和两种苯系位置异构体（间硝基苯胺和间碘苯胺）。此外，在甲醇 - 水（9∶1，v/v）流动相条件下，分离了5种外消旋体，其中盐酸普萘洛尔、华法林和美托洛尔达到了基线分离。此外，在正己烷 - 异丙醇（9∶1，v/v）流动相条件下，拆分了11种外消旋体，其中2-溴丙酸乙酯和3-丁炔-2-醇达到了基线分离。同时，还探讨了温度对TpPa-NH-Glu液相色谱柱的影响以及TpPa-NH-Glu液相色谱柱的重复性。由TpPa-NH-Glu制备的HPLC柱具有良好的重复性，其相对标准偏差（RSD）分别为1.55%和1.46%。结果表明，TpPa-NH-Glu材料对手性化合物具有良好的拆分能力。
