Mechanochemical solid-state transformations from a 3D lead(ii) chloride triazole carboxylate coordination polymer to its bromide/thiocyanate analogs via anion-replacements: precursors for the preparation of lead(ii) chloride/bromide/sulfide nanoparticles

Abstract

Irreversible crystal-to-crystal transformations of 3D lead(II) coordination polymers with the ligand 1H-1,2,4-triazole-3-carboxylic acid (HL), from [Pb(L)(μ₂-Cl)(H₂O)]_n (1) to [Pb(L)(μ₂-Br)(H₂O)]_n (2) and [Pb(L)(μ_1,1-NCS)(H₂O)]_n (3) by solid-state anion-replacement processes under mechanochemical reactions, have been studied. The thermal stabilities of compounds 1–3 were studied by thermogravimetric and differential thermal analyses. These irreversible solid-state structural transformations of compound 1 to compounds 2 and 3, have been verified by PXRD measurements. PbCl₂, PbBr₂ and PbS nanoparticles were obtained by thermal decomposition of compounds 1, 2 and 3 in oleic acid as surfactant at 200 °C under air atmosphere, respectively. These nanoparticles were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM).