A 3D metal-organic framework with a pcu net constructed from lead(II) and thiophene-2, 5-dicarboxylic acid: Synthesis, structure and ferroelectric property

Self-assembly reaction of Pb(NO3)2 with thiophene-2, 5-dicarboxylic acid (H2TDC) led to an acentric three-dimensional (3D) metal-organic framework under solvothermal conditions, namely, Pb(TDC) (1). The 3D framework of 1 is a pillared-layer structure with the I2O1 type which is composed of a 2D inorganic Pb–O–Pb substructural layer and two independent μ6-TDC2- anions pillars. This 3D framework shows a six-connected pcu topological net according to the topological analysis. Compound 1 crystallizes in an acentric space group and displays potential ferroelectric property which could be due to the swing of the thiophene rings. The remnant polarization (Pr), coercive field (Ec) and saturation spontaneous polarization (Ps) of 1 are ca. 0.034μCcm−2, 15.7kVcm−1 and 0.0997μCcm−2, respectively. Among the H2TDC-based MOFs, the present compound is the first example which shows ferroelectric property. In addition, 1 also exhibits photoluminescent property which can be attributed to ligand-to-metal charge transfer.