A Two-Dimensional Terrace-Like N-heterocyclic-Pb(II) Coordination Compound: Structure and Photoluminescence Property

Abstract

The first example of lead compound from <TEX>$Pb(NO_3)_2$</TEX> and <TEX>$H_3L$</TEX> N-heterocyclic ligand <TEX>$(H_3L\;=\;(HO_2C)_2(C_3N_2)(C_3H_7)CH_2(C_6H_4)(C_6H_3)CO_2H)$</TEX>, <TEX>$[Pb_4(L')_4]{\cdot}5H_2O$</TEX> 1 (L' = OOC<TEX>$(C_3H_7)(C_3N_2)CH_2(C_6H_4)(C_6H_3)COO)$</TEX>, has been obtained under hydrothermal condition by decarboxylation, and characterized by elemental analysis, IR, TGDTA, and single-crystal X-ray diffraction. Compound 1 possesses a rare two-dimensional upper-lower offset terrace-like layer structure. In 1, crystallographic distinct Pb(II) ion adopts five-coordination geometry, and two lattice water molecules occupy the voids between 2-D layers. Results of solid state fluorescence measurement indicate that the emission band 458 nm may be assigned to <TEX>$\pi^*-n$</TEX> and <TEX>$\pi^*-\pi$</TEX> electronic transitions within the aromatic systems of the ligand L', however, the emission bands centred at 555 nm, 600 nm and 719 nm may be derived from phosphorescent emission (<TEX>$\lambda_{excitation}$</TEX> = 390 nm).