Two microporous metal–organic frameworks with different topologies constructed from linear trinuclear M3(COO)n secondary building units

Abstract

Two new microporous metal–organic frameworks, [Zn₃(NH₂BDC)₃(H₂O)₂]·5DMF (1) and (Me₂NH₂)₂[Cd₃(NH₂BDC)₄]·2DMF·2.5 H₂O (2) (NH₂BDC = 2-amino-1,4-benzenedicarboxylate), based on linear trinuclear secondary building units of Zn₃(COO)₆ or Cd₃(COO)₈ that have different connected numbers, have been synthesized and characterized, which exhibit usual pcu and rare hex-like topologies, respectively. Both 1 and 2 are three-dimensional porous frameworks, having solvent accessible volumes of ca. 53 and 39%, respectively. There are unremovable guest Me₂NH₂⁺ cations clogged in the channels of 2. In contrast, being of good thermo-stability, 1 has a Langmuir surface area about 570 m² g⁻¹ and type I isotherm behaviour for nitrogen gas sorption at 77 K, being typical of microporous material.