Two lead(II) 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate complexes exhibiting different topologies and fluorescent properties

Abstract

The reactions of PbCl 2 with 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid (H 3iso) gave two complexes [Pb(H 2iso) 2(H 2O)] n ( 1) and [Pb(Hiso)(H 2O)] n ( 2), which were characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and single crystal X-ray diffraction analysis. The two complexes display different topologies. 1 shows a three-dimensional framework with the Schläfli symbol (4.8 5)(4.8 2) no matter if the weak Pb–O bonds are included or not. However, 2 presents a 3,3-connected two-dimensional sheet with the Schläfli symbol (4.8 2)(4.8 2) based on the calculation of only the normal Pb–O bonds and a 5,5-connected 3D network with the Schläfli symbol (4 15.6 4)(4 4.6 8.8 2) when the weak Pb–O bonds are also included. The fluorescent studies reveal an emission attributed to intraligand emission for 1 and an emission assigned to LMCT for 2.