An fcu Th-MOF Constructed from In Situ Coupling of Monovalent Ligands

Abstract

Synthetic efforts targeting highly symmetrical metal–organic frameworks (MOFs) have always been relentless, for the symmetry of a MOF’s pore environment and overall crystal structure are relevant to the MOF’s properties and behavior. Herein, we report a novel Th-based MOF constructed from assembling highly symmetrical Th-oxo clusters via in situ reductive coupling of nitroso groups on the cluster surface. Nitroso groups have long been known to dimerize in a reversible fashion. Putting them on the monovalent ligands that decorate the Th-oxo clusters can facilitate a downstream assembly process that link the said clusters in a controllable and predictable manner, preserving the overall symmetry in the MOF product. Moreover, the assembly can be made permanent by reducing the azodioxy moiety to azo, effectively locking the symmetrical MOF form. We believe this process of assembling pre-formed Th-oxo clusters helps the overall MOF adopt a highly symmetrical topology (face-centered cubic, fcu) resembling the well-known UiO series MOFs based on tetravalent Zr/Hf.

Visualizing Pore Packing and Topology in MOFs

“…The CaF 2 (fluorite) structure in Figure is a face-centered cubic arrangement of calcium atoms with an interpenetrating simple cubic arrangement of fluorine atoms such that the cubic set sits in the tetrahedral holes of the face-centered cubic set. MOF-801, SUM-5, and UiO-68 , have two sets of pores with the same arrangement as does UiO-66 shown in the graphical abstract. In the cubic ZnS (zinc blende or sphalerite) structure in Figure , half the tetrahedral positions are vacant.…”

Principles of Design and Synthesis of Metal Derivatives from MOFs

“…Elements reported and inferred for the synthesis of MOFs and their conversion into different MDs. [ 20,32,33,41,49,51,52,54,65–162 ] See Supporting Information for further information.…”