Luminescent lead(II) complexes: new three-dimensional mixed ligand MOFs

Two new lead(II) butyrate-based compounds with formulae [Pb-2(but)(4)(4,4'-bipy)(H2O)](n) (1) and [Pb-2(but)(4)(bpe)(H2O)](n) (2) [with but = butyrate; 4,4'-bipy = 4,4'-bipyridine and bpe 1,2-bis(4-pyridyl) ethene] have been synthesized and characterized, with the aim of obtaining different three-dimensional (3D) structures from the typical two-dimensional (2D) lamellar one of most of metal alkanoates, and enhancing the properties of the products synthesized, using these two different N bridging ligands (4,4'-bipy and bpe). Both new complexes show a similar 3D (4(2)6(3)8)-sra network in a monoclinic lattice (C2/c) and present interesting photophysical properties. The two compounds have been fully characterized by single crystal X-ray diffraction (synchrotron radiation), thermogravimetric analysis, differential scanning calorimetry, UV-Vis absorption spectroscopy, and steady-state fluorescence and lifetime measurements.