A Method for the Preparation of Highly Porous, Nanosized Crystals of Isoreticular Metal−Organic Frameworks

In this paper, we describe a general method for the controlled synthesis of nanosized isoreticular metal−organic framework (IRMOF-n) crystals, which for the first time combine good monodispersity and crystallinity. Nano-IRMOF-1 and -3 crystals are produced as examples. TEM and SEM micrographs show nanocrystals with regular shape and uniform size of 200−300 nm. While powder X-ray diffraction data show a high degree of crystallinity, the BET surface area of the nano-IRMOF-1 crystals of ca. 3000 m2/g demonstrates the large internal pore volume. The nanocrystal growth mechanism under the assistance of hexadecyltrimethylammonium bromide (CTAB) as surfactant was studied by systematically changing the parameters of the preparation. The influence of each step in the preparation could be explained, and a rational synthesis protocol was thus obtained. Thereby, this work provides access to much-desired but difficult to obtain high-quality nano-MOF crystals through an optimized and rational synthesis. Moreover, the synthesis principles outlined herein should be transferable to other nanoporous materials with related growth mechanisms.