Synthesis, structure, and metalation of two new highly porous zirconium metal-organic frameworks

Three new metal-organic frameworks [MOF-525, Zr ₆O ₄(OH) ₄(TCPP-H ₂) ₃; MOF-535, Zr ₆O ₄(OH) ₄(XF) ₃; MOF-545, Zr ₆O ₈(H ₂O) ₈(TCPP-H ₂) ₂, where porphyrin H ₄-TCPP-H ₂ = (C ₄₈H ₂₄O ₈N ₄) and cruciform H ₄-XF = (C ₄₂O ₈H ₂₂)] based on two new topologies, ftw and csq, have been synthesized and structurally characterized. MOF-525 and -535 are composed of Zr ₆O ₄(OH) ₄ cuboctahedral units linked by either porphyrin (MOF-525) or cruciform (MOF-535). Another zirconium-containing unit, Zr ₆O ₈(H ₂O) ₈, is linked by porphyrin to give the MOF-545 structure. The structure of MOF-525 was obtained by analysis of powder X-ray diffraction data. The structures of MOF-535 and -545 were resolved from synchrotron single-crystal data. MOF-525, -535, and -545 have Brunauer-Emmett-Teller surface areas of 2620, 1120, and 2260 m ²/g, respectively. In addition to their large surface areas, both porphyrin-containing MOFs are exceptionally chemically stable, maintaining their structures under aqueous and organic conditions. MOF-525 and -545 were metalated with iron(III) and copper(II) to yield the metalated analogues without losing their high surface area and chemical stability.