Mineral neogenesis as an inspiration for mild, solvent-free synthesis of bulk microporous metal–organic frameworks from metal (Zn, Co) oxides
作者:Cristina Mottillo、Yuneng Lu、Minh-Hao Pham、Matthew J. Cliffe、Trong-On Do、Tomislav Friščić
DOI:10.1039/c3gc40520f
日期:——
âAccelerated agingâ is a simple and conceptually novel methodology for the synthesis of functional metalâorganic materials, which seeks to provide a scalable, mild and environmentally-friendly alternative to solution-based or mechanochemical syntheses. Accelerated aging draws inspiration from slow processes of geological biomineralization and mineral neogenesis, and adapts them for the low-energy and solvent-free synthesis of modern metalâorganic materials. This systematic study outlines the development of an accelerated aging synthesis of microporous frameworks from metal oxides CoO and ZnO. Whereas metal oxides often require high temperatures or aggressive reagents, accelerated aging allows their spontaneous transformation into porous materials under surprisingly mild conditions, akin to those of molecular self-assembly (humid air, up to 45 °C). Here, we describe how accelerated aging can be optimized for the one-step synthesis of multi-gram amounts of microporous solids. As targets, we selected popular zeolitic imidazolate frameworks (ZIFs): the sodalite-topology ZIF-8, its cobalt analogue ZIF-67, and a related zeolite RHO framework. Unlike conventional solution or mechanochemical syntheses, accelerated aging is diffusion-controlled and does not require continuous agitation, bulk solvent or high temperature. The syntheses of ZIF-8 and ZIF-67 contrast the conventional paradigm of metalâorganic framework synthesis, by demonstrating that microporous materials can be spontaneously and efficiently assembled from a close-packed metal oxide without using solvents, high temperature or other activation (e.g. microwave, sonochemical, mechanochemical).
加速老化是合成功能性金属有机材料的一种简单而概念新颖的方法,旨在提供一种可扩展、温和且环保的方法,以替代基于溶液或机械化学的合成方法。加速老化从地质生物成矿和矿物新生的缓慢过程中汲取灵感,并将其应用于现代金属有机材料的低能耗、无溶剂合成。本系统研究概述了从金属氧化物 CoO 和 ZnO 加速老化合成微孔框架的发展过程。金属氧化物通常需要高温或侵蚀性试剂,而加速老化却能让它们在类似分子自组装(潮湿空气,最高 45 °C)的惊人温和条件下自发转化为多孔材料。在此,我们介绍了如何优化加速老化,以一步合成多克量的微孔固体。我们选择了常用的沸石咪唑啉框架(ZIF)作为目标:钠钙基结构的 ZIF-8、其钴类似物 ZIF-67 以及相关的沸石 RHO 框架。与传统的溶液或机械化学合成不同,加速老化是由扩散控制的,不需要持续搅拌、大量溶剂或高温。ZIF-8 和 ZIF-67 的合成与传统的金属有机框架合成模式形成了鲜明对比,证明了微孔材料可以在不使用溶剂、高温或其他活化(如微波、声化学、机械化学)的情况下,由紧密堆积的金属氧化物自发、高效地组装而成。