Novel alkaline earth metal-organic frameworks with thiophene group for selective detection of Fe3+
Three new alkaline earth metal-organic frameworks (MOFs), namely [Mg2(DMTDC)2(DMF)3(H2O)2]•2DMF•2H2O (1), [Ca(DMTDC)(DMF)] (2) and [Sr(DMTDC)(DMF)] (3), have been synthesized under solvothermal conditions by using a thiophene-functionalized dicarboxylate ligand, 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid (H2DMTDC). Single-crystal X-ray diffraction analyses demonstrate that the metal ion radii plays an important role in coordination number and topologies, i.e., the hexa-coordinated Mg2+ in 1 gives a two-dimensional layered framework with a sql net, while the octa-coordinated Ca2+/Sr2+ in 2/3 exhibit a three-dimensional framework with lvt nets. All frameworks show a one-dimensional rhombus-shaped channel that occupied by DMF and/or water molecules. Photoluminescence studies reveal that 1-3 can be used as the fast-response fluorescence sensors for the sensitive detection of Fe3+ ions with favorable recyclability through fluorescence quenching.