A series of metal-organic frameworks based on 5-(4-pyridyl)-isophthalic acid: selective sorption and fluorescence sensing

Solvothermal reactions of 5-(4-pyridyl)-isophthalic acid (H(2)pbdc) and transition-metal centers (Ni2+/Co2+/Zn2+) in the presence (or absence) of N-auxiliary 4,4'-bis(1-imidazolyl) biphenyl (bimb) ligand produce [Ni-2(pbdc)(2)(mu(2)-H2O)(H2O)2 center dot(DMA)(2.7)](n) (DMA=N, N'-dimethylacetamide, 1), [Ni-12(pbdc)(12)(mu 2-H2O) 6(py)(2)(H2O)(8)(DMA)(2)center dot(H2O)(5)center dot(DMA)(9)](n) (2), [Co-2(pbdc)(2)(bimb)(2)center dot(bimb)(0.5)center dot(H2O)(4)center dot(DMF)(0.25)](n) (3) and [Zn(pbdc)(bimb)center dot(H2O)](n) (4), which exhibit structural diversity. Both compounds 1 and 2 display a uninodal 8-connected 3D tsi net, but feature different crystal systems and space groups from each other. Compound 3 adopts a 2-fold interpenetrating binodal (3,5)-connected 3D hms net and compound 4 features a rare 2-fold interpenetrating binodal (3,4)-connected 3D fsx architecture. In particular, activated 3 shows high-efficiency for the selective sorption of small molecules, including CO2 over N-2 and CH4, H-2 over N-2, as well as alcohols from water. More importantly, 4 represents the first report on a MOF as a promising luminescent probe for detecting pesticides, and also the very first example for detecting both pesticides and solvent molecules simultaneously.