Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.
Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300350, China.
J Am Chem Soc. 2020 Mar 11;142(10):4609-4615. doi: 10.1021/jacs.0c00542. Epub 2020 Feb 24.
Zr-based metal-organic frameworks (MOFs) with tetratopic organic linkers have been extensively investigated owing to their versatile structural tunability. While diverse topologies and polymorphism in the resulting MOFs are often encountered with tetratopic linkers and Zr nodes, reports on phase transitions within these systems are rare. Thus, we have a limited understanding of polymorph transformations, hindering the rational development of pure phase materials. In this study, a phase transition from a microporous MOF, scu-NU-906, to a mesoporous MOF, csq-NU-1008, was discovered and monitored through variable temperature liquid-cell transmission electron microscopy (VT-LCTEM), high-resolution transmission electron microscopy (HRTEM), and variable temperature powder X-ray diffraction (VT-PXRD). It was found that the microporous- to-mesoporous transformation in the presence of formic acid occurs via a concomitant dissolution-reprecipitation process.
Zr 基金属-有机骨架（MOFs）具有四齿有机连接体，由于其结构的多功能可调性而得到了广泛的研究。虽然在使用四齿连接体和 Zr 节点时，经常会遇到不同的拓扑结构和多晶型，但关于这些体系内的相转变的报道却很少。因此，我们对多晶型转变的认识有限，阻碍了纯相材料的合理开发。在这项研究中，我们通过变温液体池透射电子显微镜（VT-LCTEM）、高分辨率透射电子显微镜（HRTEM）和变温粉末 X 射线衍射（VT-PXRD），发现并监测了 scu-NU-906 微孔 MOF 向 csq-NU-1008 介孔 MOF 的相转变。结果发现，在甲酸存在的情况下，微孔到介孔的转变是通过同时的溶解-再沉淀过程发生的。
