Zr6O8 core cluster with formula unit [Zr6O4(OH)4(OH2)8(CH3COO)4(SO4)4]·nH2O obtained under mild conditions

Abstract

During attempts to synthesize zirconium-based MOFs, we have obtained a new crystal structure of the cluster with Zr₆O₈ core and formula unit [Zr₆O₄(OH)₄(OH₂)₈(CH₃COO)₄(SO₄)₄]·nH₂O. Unlike other systems, mild conditions were employed in this case; no strong acids or hydrothermal conditions were required. The molecular assembly in the crystal is characterized by strong O–H⋯O hydrogen bonds connecting neighboring molecules, allowing the formation of a three-dimensional maze of tunnels with H₂O molecules stabilizing the framework. Noteworthy, at 100 °C, the strong Zr₆O₈ core and the O–H⋯O hydrogen bonds help form a system where the molecular cluster is conserved, but the long-range order is lost. FT-IR, Raman, TGA, DSC, and X-ray diffraction techniques were used to characterize the title compound.