Comparative study of metal-organic frameworks synthesized imide condensation and coordination assembly.

A series of metal-organic frameworks (1-XDI) have been synthesized by imide condensation reactions between an amine-functionalized pentanuclear zinc cluster, ZnCl(bt-NH), (bt-NH = 5-aminobenzotriazolate), and organic dianhydrides (pyromellitic dianhydride (PMDA), naphthalenetetracarboxylic dianhydride (NDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (HFIPA)). The properties of the 1-XDI MOFs have been compared with analogues (2-XDI) prepared using traditional coordination assembly. The resulting materials have been characterized by ATR-IR spectroscopy, acid-digested H NMR spectroscopy, elemental analysis, and gas adsorption measurements. N adsorption isotherm data reveal modest porosities and BET surface areas (30-552 m g). All of the new 1-XDI and 2-XDI MOFs show selective adsorption of CH over CO while 2-PMDI and 2-BPDI exhibit high selectivity toward CH/CH separation. This study establishes imide condensation of preformed metal-organic clusters with organic linkers as a viable route for MOF design.