Intense greenish phosphorescence emission under ambient conditions in a two-dimensional lead(ii) coordination polymer with a 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylate ligand.

In this study, a new two-dimensional Pb-based coordination polymer (CP), [Pb(EBTC)(DMSO)] (1), where HEBTC is 1,1'-ethynebenzene 3,3',5,5'-tetracarboxylic acid, was synthesized under solvothermal conditions. Structural analysis reveals that 1 crystallizes in the monoclinic space group C2/m, where two crystallographically different Pb ions show a coordination geometry of bicapped trigonal prisms that are connected to a double-chain by the EBTC ligands through carboxylate groups along the b-axis direction, and where successive double chains are held together to form a 2D layer via the Pb1 and Pb2 bicapped trigonal prisms sharing one edge or a triangle face along the c-axis direction. Interestingly, CP 1 emitted intense and long-lived greenish phosphorescence in the solid state at ambient conditions, with a quantum yield of 1.5% and a phosphorescence lifetime of 4.17 ms, and the emission mainly arose from the electron transition within the π-type orbitals of the EBTC ligand. The emission bands assignment and photophysical process were further discussed according to the calculation of both the electronic band structures and density of states. This study gives a fresh impetus to achieve coordination polymer-based long-lived phosphorescence materials under ambient conditions.