MOF-74(Mg) Metal Organic Frameworks (MOFs) Powder for Gas Absorption and Separation, CGASMOF74Mg

MOF-74(Mg) (also designated as Mg-MOF-74 or CPO-27-Mg, with chemical formula Mg2(DOBDC), where DOBDC = 2,5-dioxido-1,4-benzenedicarboxylate) is a honeycomb-topology metal-organic framework with an exceptionally high density of coordinatively unsaturated metal sites (open metal sites, OMS). Built from infinite helical chains of edge-sharing MgO6 octahedra cross-linked by 2,5-dihydroxyterephthalate linkers, it features 1D hexagonal channels with open Mg^{2+} cations that provide benchmark performance for low-pressure gas capture.

The critical structural and functional features of the MOF-74(Mg) are shown below: (1) 1D Hexagonal Honeycomb Channels: Channel Diameter: ~11.0–12.0 Å (accessible pore aperture ~ 10.5 Å. Open Metal Site Density: Every Mg^{2+} ion in the coordination backbone points an open coordination site directly into the channel interior upon solvent removal, yielding a theoretical active site density of ~ 7.6 mmol/g. (2) Electrostatic Charge Density of Mg^{2+}: The lightweight Mg^{2+} cation has a high charge-to-radius ratio (z/r), generating intense localized electrostatic field gradients that polarize guest molecules more strongly than heavier transition-metal analogues (Co^{2+}, Ni^{2+}, Zn^{2+}, Fe^{2+}).

References:

1. X. Wu, et al., Microwave synthesis and characterization of MOF-74 (M = Ni, Mg) for gas separation, Microporous and Mesoporous Materials, 2013, 180, 114-120.
2. R. Sharma, et al., An ultra-permeable hybrid Mg-MOF-74-Melamine sponge composite for fast dynamic gas separation, Microporous and Mesoporous Materials, 2022, 343, 112146