Design, synthesis and fluorescence of two-dimensional pillared layers by connecting infinite one-dimensional chains via 4,4′-bipyridine

Two novel coordination polymers Zn(m-BDC)(4,4′-bipy)·C2H5OH 1 and Cd(m-BDC)(4,4′-bipy)·C2H5OH 2 (m-BDC=1,3-benzenedicarboxylic) have been synthesized under mild conditions and structurally characterized. Crystal data for 1: monoclinic P2/c, a=10.058 (11) Å, b=11.401 (13) Å, c=16.107 (2) Å, β=103.43(3)°, Z=2. Crystal data for 2: monoclinic P2/c, a=10.282 (15) Å, b=11.716 (18) Å, c=16.170 (2) Å, β=103.21 (3)°, Z=2. In the structures, the m-BDC ligands bridge the metal centers to form infinite 1D chains, and the 4,4′-bipyridine ligands act as a pillar to link the adjacent chains to form an extended infinite 2D layer, which exhibit an interesting prismatic topology. The weak π–π stacking interactions extend the 2D layers into a 3D supermolecular framework. Additionally, these two compounds exhibit strong fluorescence at room temperature in the solid state.