Author:

Keywords:

Science & Technology, Physical Sciences, Chemistry, Multidisciplinary, Chemistry, Direct C-H borylation, Electron Diffraction, Green Chemistry, Metal-organic Frameworks, Zirconium, AUTOMATED DIFFRACTION TOMOGRAPHY, CATALYZED BORYLATION, HIGHLY EFFICIENT, GREEN SYNTHESIS, ZR-MOF, ARENES, CLUSTERS, ORGANOSILICA, STABILITY, TOXICITY, Direct C−H borylation, 03 Chemical Sciences, Organic Chemistry, 34 Chemical sciences

Abstract:

Two new zirconium-based metal-organic frameworks with the composition [Zr6 O4 (OH)4 (OAc)6 (BDC)3 ] (CAU-26) and [Zr5 O4 (OH)4 (OAc)4 (BDC)2 ] (CAU-27) are reported, which were synthesized from acetic acid, a rarely utilized but green and sustainable solvent (BDC2- : 1,4-benzenedicarboxylate). Structure determination aided by automated electron diffraction tomography revealed that CAU-26 is composed of layers of well-known {Zr6 O8 } clusters interconnected by terephthalate ions. In contrast CAU-27 exhibits a three-dimensional structure with a so far unknown type of one-dimensional inorganic building unit (IBU), which can be rationalized as condensed polyhedron-sharing chains of {Zr6 O8 } clusters. CAU-26 occurs as an intermediate of the CAU-27 synthesis and can be isolated easily, when reaction temperature and time are decreased. We were also able to synthesize two isoreticular derivatives of CAU-27 with extended linker molecules by implementing 4,4'-biphenyldicarboxylic acid (H2 BPDC) and 5,5'-dicarboxy-2,2'-bipyridine (H2 BIPY). All materials show high thermal and chemical stability as well as permanent microporosity. The excellent stability of CAU-27-BIPY was exploited to synthesize a performant iridium-supported heterogeneous MOF-based catalyst for the direct C-H borylation of arenes.