Topologies of Metal-Organic Frameworks Based on Pyrimidine-5-carboxylate and Unexpected Gas-Sorption Selectivity for CO2

A simple and multitopic ligand, pyrimidine-5-carboxylate (pmc), has been used to obtain a series of metal organic frameworks (MOFs) based on Co2+, Cd2+, and Cu2+. The networks possess well-defined topologies of body-centered-cubic, rutile, and interpenetrated NbO structures, respectively. Among those, [Cu(pmc)(2)] possesses a permanent porosity resulting from straight one-dimensional channels of 5.5 angstrom free passages. Unexpectedly, this porous MOF displays a highly selective sorption behavior for CO2, and the sorptions of N-2, Ar, O-2, H-2, and CH4 at two different temperatures are found to be negligible. The results of diffraction and spectroscopic analyses exclude framework dynamics or incomplete evacuation as the origin of the gas-sorption selectivity.