金属有机骨架印迹修饰新材料对杜仲降血压活性化合物的选择机制研究

Metal organic frameworks is a porous crystal material formed by multidentate ligand coordination to transition metal/metal cluster. The super-high specific surface area and highly ordered pose structure in this crystal are responsible for its extremely high molecular-rebinding capacity, however, it can not produce high-precision molecular selectivity. In this aspect, molecular imprinted polymers (MIPs) can highly selectively and even specially rebind target compounds based on imprint sites possessing a perfect complementary to targets molecule in size, shape and chemical functional groups. Grafting MIPs onto the surface of metal organic frameworks material can make imprint sites with high selectivity in MIPs matrix simultaneously locate at the surface of this crystal, resulting in a great improvement in the selectivity of metal organic frameworks. Thus, a metal organic frameworks named MIL-101 will be chosen in present work as the matrix to prepare a novel metal organic frameworks material MIPs@MIL-101 by performing a two-step procedure, i.e. first functional modification of MIL-101 to introduce -NH2 group and then grafting the MIPs to the surface of MIL-101 material. The physical and chemical properties for the materials obtained will be explored by selecting effective methods to perform functional modification and molecular imprint modification of MIL-101 material during the preparation of this novel MIPs@MIL-101 material. Also, the selectivity mechanism for this novel material toward target compounds will be revealed by systematically studying the selectivity recognition and extraction efficiency for this novel MIPs@MIL-101material in the extraction of bioactive compounds with antihypertensive effect from Eucommia ulmodies Oliv.. In addition, research achievement can provide new methods not only for the separation and purification of antihypertensive activity compounds in the topic plant but also for the extraction and separation of other natural products in this plant.

金属有机骨架是一种由过渡金属或金属簇与多齿配体组装而成的多孔晶体材料，其超大的比表面积及高度有序的孔结构赋予其极高的分子结合能力，但不能提供高精度的分子选择。分子印迹聚合物（MIPs）基于印迹位点与目标分子的大小、形状及化学功能基等多重匹配性，可提供高选择分子键合。对金属有机骨架进行印迹修饰可将印迹位点布置在其表面，大幅提高对特定目标化合物的分子选择性。本项目拟以金属有机骨架MIL-101为载体，通过功能化修饰后再表面接枝分子印迹聚合物，制备MIPs@MIL-101新材料；通过筛选MIL-101功能化及表面接枝的有效方法，考察MIL-101表面修饰过程中的物理化学性质；通过系统研究MIPs@MIL-101新材料对杜仲降血压活性化合物的选择识别和萃取效能，揭示新材料对目标物的选择机制。研究成果不仅可为杜仲降血压活性化合物分离纯化提供新的方法，也可为植物其他天然产物的提取分离提供新的路径。

本项目以金属有机骨架为基质，通过表面化学修饰接入活性功能基团后再接枝分子印迹聚合物，制备了一系列金属有机骨架-分子印迹复合功能材料。探究了这些新材料对目标化合物的吸附选择性、吸附热（动）力学性质、色谱分离性能及固相萃取性能。以杜仲降压化合物、酚酸类化合物及生物碱类化合物为研究对象，探究以这些化合物为模板，构建分子印迹复合功能材料高效方法，对复合材料的印迹识别及提取和分离分析等应用研究方面开展了较为深入细致的研究工作。着重开展了环烯醚萜类化合物（如松脂素二糖苷、京尼平苷、桃叶珊瑚苷等）及多酚类化合物（如槲皮素、咖啡酸、香草酸等）印迹修饰材料的合成及应用、温敏印迹材料的制备及其吸附性能与控制释放、复合金属多酚类共配物印迹新材料的制备及应用、生物碱类化合物印迹新材料的制备与应用等。.研究表明，金属有机骨架-环烯醚萜类印迹复合材料在吸附过程中可以高选择结合模板化合物，显示了较高的保留和分离分辨效能。松脂醇二葡萄糖苷印迹材料的选择因子在竞争吸附中达2.48，分辨率达3.95，在固相萃取中单次提取可得较高纯度的产品。金属有机骨架MIL-101@桃叶珊瑚苷印迹聚合物印迹效率为6.812，其对模板分子最大吸附量可达到69.73 mg g-1，可在80 min内逐渐达到吸附平衡，选择因子达2.634。京尼平苷印迹复合功能材料为吸附剂从杜仲提取物中提取京尼平苷时，单次提取可获得含量高于85%的产品。ED-MIL-101@咖啡酸印迹色谱柱对模板分子动态吸附量达37.62 mg/g。保留因子可达10.36，表现出较好的选择保留性能。香草酸介孔硅胶印迹对模板分子最大吸附量为50.7mg g– 1。当用于从白蒿甲醇提取物中分离和富集目标化合物时，具有较高的吸附能力。.这些研究结果表明金属有机骨架材料是一种较为理想的载体，将分子印迹聚合物负载于其表面，可以将二者的优势较充分发挥。这种复合材料在提取及分离分析中展现无可比拟的优越性。