Design and construction of porous metal–organic frameworks based on flexible BPH pillars

Three metal–organic frameworks (MOFs), [Co2(BPDC)2(4-BPH)·3DMF]n (1), [Cd2(BPDC)2(4-BPH)2·2DMF]n (2) and [Ni2(BDC)2(3-BPH)2 (H2O)·4DMF]n (3) (H2BPDC=biphenyl-4,4′-dicarboxylic acid, H2BDC=terephthalic acid, BPH=bis(pyridinylethylidene)hydrazine and DMF=N,N′-dimethylformamide), have been solvothermally synthesized based on the insertion of heterogeneous BPH pillars. Framework 1 has “single-pillared” MOF-5-like motif with inner cage diameters of up to 18.6 Å. Framework 2 has “double pillared” MOF-5-like motif with cage diameters of 19.2 Å while 3 has “double pillared” 8-connected framework with channel diameters of 11.0 Å. Powder X-ray diffraction (PXRD) shows that 3 is a dynamic porous framework.

By insertion of flexible BPH pillars based on “pillaring” strategy, three metal–organic frameworks are obtained showing that the porous frameworks can be constructed in a much greater variety.Figure optionsDownload as PowerPoint slideHighlights
► Frameworks 1 and 2 have MOF-5 like motif.
► The cube-like cages in 1 and 2 are quite large, comparable to the IRMOF-10.
► Framework 1 is “single-pillared” mode while 2 is “double-pillared” mode.
► PXRD and gas adsorption analysis show that 3 is a dynamic porous framework.