Bimetallic Rod-Packing Metal-Organic Framework Combining Two Charged Forms of 2-Hydroxyterephthalic Acid.

Although many rod-packing metal-organic frameworks are known, few are based on ordered heterometallic rod building unit. We show here the synthesis of CPM-76 based on an unprecedented Zn-Mg bimetallic rod with crystallographically distinguishable metal sites. The configuration of the rod offers two types of coordination site with trigonal bipyramidal and octahedral sites selectively occupied by Zn and Mg, respectively. Also unusual is the inter-connection mode between the rods, which is based on dual-charged forms (-3 and -2) of the 2-hydroxyterephthalic acid (H3 OBDC) ligand. Interestingly, each metal site in CPM-76 binds one solvent molecule, leading to a high density of solvent binding sites.