Bis(pyrazolato)-Based Metal–Organic Frameworks Fabricated with 4,4′-Bis((3,5-dimethyl‑1<i>H</i>‑pyrazol-4-yl)methyl)biphenyl and Late Transition Metals

The reaction between the flexible, bis­(pyrazolato)-based ligand 4,4′-bis­((3,5-dimethyl-1<i>H</i>-pyrazol-4-yl)­methyl)­biphenyl (H₂DMPMB) and late transition metal ions allowed the isolation of the two series of thermally stable metal–organic frameworks <b>[M­(DMPMB)]</b> (M = Co, Zn, Cd) and <b>[M</b>_<b>2</b><b>(DMPMB)]</b> (M = Cu, Ag). X-ray powder diffraction (XRPD) structure determinations demonstrated that the <i>anti</i> conformation adopted by the ligand, juxtaposed to its <i>exo</i>-tetradentate coordination mode, induces the formation of a 3-D architecture with nonpervious 1-D channels in the three isomorphous species <b>[M­(DMPMB)]</b> and of corrugated 2-D layers in <b>[Cu</b>_<b>2</b><b>(DMPMB)]</b>. Coupling thermogravimetric analyses and variable temperature XRPD highlighted that the five materials are thermally stable at least up to 300 °C, both under nitrogen and in air, the Cd­(II) derivative decomposing only at the remarkably high temperature of 500 °C. No thermal event could be detected; all the materials preserve their structural motifs up to decomposition. The adsorption properties of the five compounds were assayed toward N₂ at 77 K: while no adsorption was observed for <b>[Cd­(DMPMB)]</b>, the other species possess estimated BET and Langmuir specific surface areas in the ranges 64(1)–526(3) m²/g and 142(4)–713(27) m²/g, respectively, thus being an example of the interesting phenomenon known as “porosity without pores”. Finally, the luminescence properties of the Zn­(II), Cd­(II), and Cu­(I) derivatives were investigated.