Solid state syntheses of nano lead(II) iodide triazole carboxylate coordination polymer from its bromide/thiocyanate/chloride analogs via mechanochemical crystal to crystal transformations

Irreversible crystal-to-crystal transformations of 3D lead(II) coordination polymers with the ligand 1H-1,2,4-triazole-3-carboxylic acid (HL), [Pb(L)(μ2-Br)(H2O)]n (1), [Pb(L)(μ1,1-NCS)(H2O)]n (2) and [Pb(L)(μ2-Cl)(H2O)]n (3) to 3D supramolecular compound [Pb(L)(μ2-I)]n (4) by solid state anion-replacement processes under mechanochemical reactions, have been studied. The thermal stabilities of compounds 1–4 were studied by thermogravimetric and differential thermal analyses. The irreversible solid state structural transformations of compounds 1–4, by anion-replacement processes under mechanochemical reaction, have been verified by PXRD measurements. Nanoparticles of compounds 1 and 2 were synthesized by sonochemical process and characterized by scanning electron microscopy (SEM), powder X-ray diffraction, IR spectroscopy, elemental analyses, thermogravimetric and differential thermal analyses. The SEM images showed that no morphology change occurs during solid state anion-replacements of nanocrystals.