Unusual Zn5(μ3-OH)2(COO−)8 secondary building units for the construction of a metal–organic framework

A new three-dimensional (3D) metal–organic framework (MOF) {Zn5(μ3-OH)2(obb)4[(CH3)2NH]2}·2DMF (1; H2obb = 4,4′-oxybisbenzoic acid; DMF = N,N′-dimethyl formamide) with unusual Zn5(μ3-OH)2(COO−)8 secondary building units (SBUs) has been solvothermally synthesized and structurally characterized by the aid of single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Elemental analysis (EA) and Infrared Spectroscopy (IR). The unprecedented pentanuclear Zn5(μ3-OH)2(COO−)8 SBU was formed by two trimeric Zn3(μ3-OH)(COO−)6 SBUs, which can be simplified as 4-connected node. Correspondingly, compound 1 exhibits dia structural topology.

Graphical abstractPresented here is a new 4-connected dia zinc–organic framework with unusual Zn5(μ3-OH)2(COO−)8 SBUs.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new zinc–organic framework with unusual pentanuclear Zn5(μ3-OH)2(COO−)8 SBUs ► Pentanuclear Zn5(μ3-OH)2(COO−)8 SBU formed by two trimeric Zn3(μ3-OH)(COO−)6 SBUs by sharing the Zn2 atom ► The observation of interesting double helix chain and 4-connected dia topology based on Zn5(μ3-OH)2(COO−)8 SBUs.