Overcoming the crystallization and designability issues in the ultrastable zirconium phosphonate framework system

• Published in: Nature communications Vol. 8; no. 1; p. 15369
• Main Authors: Zheng, Tao, Yang, Zaixing, Gui, Daxiang, Liu, Zhiyong, Wang, Xiangxiang, Dai, Xing, Liu, Shengtang, Zhang, Linjuan, Gao, Yang, Chen, Lanhua, Sheng, Daopeng, Wang, Yanlong, Diwu, Juan, Wang, Jianqiang, Zhou, Ruhong, Chai, Zhifang, Albrecht-Schmitt, Thomas E., Wang, Shuao
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.05.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/638/263/915; 639/638/298/921; Humanities and Social Sciences; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; metal-organic frameworks; multidisciplinary; Science; Science (multidisciplinary); solid-state chemistry
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15369

Metal-organic frameworks (MOFs) based on zirconium phosphonates exhibit superior chemical stability suitable for applications under harsh conditions. These compounds mostly exist as poorly crystallized precipitates, and precise structural information has therefore remained elusive. Furthermore, a zero-dimensional zirconium phosphonate cluster acting as secondary building unit has been lacking, leading to poor designability in this system. Herein, we overcome these challenges and obtain single crystals of three zirconium phosphonates that are suitable for structural analysis. These compounds are built by previously unknown isolated zirconium phosphonate clusters and exhibit combined high porosity and ultrastability even in fuming acids. SZ-2 possesses the largest void volume recorded in zirconium phosphonates and SZ-3 represents the most porous crystalline zirconium phosphonate and the only porous MOF material reported to survive in aqua regia. SZ-2 and SZ-3 can effectively remove uranyl ions from aqueous solutions over a wide pH range, and we have elucidated the removal mechanism. Zirconium phosphonate based metal-organic frameworks often exhibit superior chemical stabilities, but typically exist as poorly crystalline or amorphous materials. Here the authors exploit an ionothermal method to obtain highly porous and remarkably stable single crystalline zirconium phosphonate frameworks that can efficiently remove uranyl ions from aqueous solutions.