Two New 3-D Lead(II) Coordination Polymers of Glycolic Acid with Luminescent Properties

Abstract

Two new 3-D lead(II) coordination polymers [PbL]n (1, L = glycolic acid) and [Pb4L2L′2CdBr2]n (2, L′ = ethylene glycol) have been solvothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction and single crystal X-ray diffraction. 1 contains 1-D neutral [PbL]n chain with hemidirected tetrahedral geometry, which is further connected by weak Pb···O interactions to produce a 3-D network. 2 contains another 1-D neutral [Pb2LL′]n chain with hemidirected tetrahedral/trigonal–pyramidal geometry that is converted into 2-D neutral [Pb4L2L′2]n layer via weak Pb···O interactions. The layers of 2 are further bridged by unsaturated [CdBr2] complexes to form a 3-D heterobimetallic [Pb4L2L′2CdBr2]n framework. The L ligand of both 1 and 2 resulted from in-situ oxidation of L′ ligand during the solvothermal reaction. 2 represents the rare example of 3-D heterometallic organic framework based on the linkages of 2-D lead(II) carboxylates and cadmium(II) bromides. Their luminescent properties in the solid state and density functional theory calculations have been investigated.