Syntheses, characterization and luminescent properties of two lead(II) fumarate metal-organic frameworks

• DOI: 10.1016/j.poly.2008.10.074
• Publication Date: 2009-02-10T08:48:19Z
• Authors: Kou-Lin Zhang; Wei Liang; Yan Chang; Li-Min Yuan; Seik Weng Ng
• Keywords: Lone pair; Thermogravimetric analysis; Pyrazine; Coordination complex

Abstract It is of interest that the hydrous 3D metal-organic framework (MOF) {[Pb2(fum)2(H2O)4] · 2H2O}n (1) has been synthesized by the reaction of the fum dianion with the lead(II) ion (fum = fumarate) in the presence of pyrazole, while the anhydrous 3D MOF [Pb(fum)]n (2) is obtained by the reaction of the fum dianion with the lead(II) ion in the presence of pyrazine. These complexes were further characterized by FT-IR spectroscopy, thermogravimetric analysis (TG), X-ray analysis and solid state photoluminescence spectra. The arrangement of the ligands displays a coordination gap around the Pb atom, occupied possibly by a stereoactive lone pair of electrons on lead(II), with the coordination around both the eight-coordinated lead atom in 1 and six-coordinated lead atom in 2 exhibiting a hemidirected geometry. The fum ligand shows different ligation behavior toward the lead(II) ions in these complexes. These compounds exhibit photoluminescence with the maximum emission located in the UV region.