Two eight-connected self-penetrating porous metal-organic frameworks: configurational isomers caused by different linking modes between terephthalate and binuclear nickel building units

Two novel nanoporous metal-organic frameworks (MOFs) based on the same binuclear nickel secondary building units, {[Ni-2(H2O)(BDC)(2)(BIMB)(2)]center dot 6DMF}(n) (1) and {[Ni-2(H2O)(BDC)(2)(BIMB)(2)]center dot 5DMAc}(n) (2) (H2BDC terephthalic acid, BIMB 1,4-bis(1-imidazolyl) benzene and DMF = N,N'-dimethylformamide, DMAc = N,N'-dimethylacetamide) have been synthesized by self-assembly of Ni(NO3)(2)center dot 6H(2)O, BIMB and H2BDC in different solvents (DMF and DMAc), respectively. Different linking modes between terephthalate and binuclear nickel building units in 1 and 2 lead to an interesting phenomenon that their host frameworks are isomeric to each other and have the same three periodic eight-connected self-penetrating nets with novel 4(20).6(8) topology. Powder X-ray diffraction (PXRD) results indicate that 1 and 2 both have reversible framework transformations in an acetone/guest solvent molecule system.