A novel (3,3,6)-connected luminescent metal-organic framework for sensing of nitroaromatic explosives

A novel metal-organic framework [Cd-3(CPEIP)(2)(DMF)(3)].solvent (1) based on a neutral non-oxo triangular [Cd-3(COO)(6)] secondary building unit (SBU), was synthesized under solvothermal conditions by using a rigid unsymmetrical tricarboxylate ligand 5-((4-carboxyphenyl) ethynyl) isophthalic acid (H3CPEIP). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group C2/c. The crystal structure exhibits a rare (3,3,6)-connected three-dimensional (3-D) framework with vertex symbol of (4(2).6)(4(3))(4(5).6(4).8(6)). The incorporation of CPEIP3+ into 1 gives rise to high luminescence in solid state. The emission of micrometer-sized compound 1 (1') dispersed in ethanol could be quenched efficiently by picric acid (PA), indicating that this compound could be utilized as a chemosensor for detection of aromatic explosives.