Large-Pore Apertures in a Series of Metal-Organic Frameworks

Abstract

We report a strategy to expand the pore aperture of metal-organic frameworks (MOFs) into a previously unattained size regime (>32 angstroms). Specifically, the systematic expansion of a well-known MOF structure, MOF-74, from its original link of one phenylene ring (I) to two, three, four, five, six, seven, nine, and eleven (II to XI, respectively), afforded an isoreticular series of MOF-74 structures (termed IRMOF-74-I to XI) with pore apertures ranging from 14 to 98 angstroms. All members of this series have noninterpenetrating structures and exhibit robust architectures, as evidenced by their permanent porosity and high thermal stability (up to 300°C). The pore apertures of an oligoethylene glycol-functionalized IRMOF-74-VII and IRMOF-74-IX are large enough for natural proteins to enter the pores.

Stable metal-organic frameworks containing single-molecule traps for enzyme encapsulation

“…In addition, cages usually have small windows, which can efficiently encapsulate enzymes, diminishing aggregation, eliminating leaching and optimizing the catalytic environment. Unfortunately, there are very few reported MOFs with enzyme compatible cages, and even fewer can survive in aqueous media 3,11,12 . Thus, MOFs with larger cages and better stability are highly desired for enzyme encapsulation.…”

“…The largest pore reported in MOFs was based on a 1D hexagonal channel structure, which requires a complicated synthetic process to make an extremely long organic linker to reach enzymatic size 3 . Considering the structural feature of the 1D channel, it can only partially interact with immobilized enzymes even if the size is very compatible.…”

“…The extension of organic linkers, which mostly serve as the faces or edges of pores in MOFs, is the main approach to achieve large pores in MOFs 3,[13][14][15][16][17][18][19] . However, the pore shape or symmetry plays a very important role in determining the overall pore size.…”

“…M etal-organic frameworks (MOFs) with large pores or channels are considered to be promising candidates for the immobilization of many catalysts, such as metal complexes, nanoparticles and enzymes [1][2][3][4] . Immobilization is particularly valuable for enzymes, since they are costly and can be difficult to reuse and recover 5 .…”

Series of Highly Stable Isoreticular Lanthanide Metal–Organic Frameworks with Expanding Pore Size and Tunable Luminescent Properties

“…Interpenetration may be avoided so that pores can be extended. 21 Isoreticular MOFs built from inorganic chains and ditopic linkers have been synthesized, such as in the series of IRMOF-74 with Mg, Zn, or Al chains, 22 and in the series of STA-12 and STA-16 with Co phosphonate spiral chains 23 and in the MIL-140 series with Zr chains. 24 Although MOFs built from inorganic chains and tritopic linkers have been reported, 25,26 to the best of our knowledge, there is no report on isoreticular MOFs with expanding pore sizes based on tritopic linkers.…”