Mechanochemical solid state anion-exchange of lead(ii) coordination polymers via an intermediate coordination polymer; new precursors for the preparation of PbBr2/Pb3O2Br2, PbBr(OH) and PbO nanoparticles

Abstract

The reversible crystal-to-crystal transformations of a 1D lead(II) coordination polymer with the ligand 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (4-bpdh), from [Pb(4-bpdh)Br₂]_n (1) to intermediate [Pb(4-bpdh)(Br)(NO₃)]_n (2) and [Pb(4-bpdh)(NO₃)₂(H₂O)]_n (3) by a solid state anion-replacement processes under mechanochemical reactions, have been studied. The reversible solid state structural transformation of compound 1 to compound 2 and then 3 by anion replacement have been verified by PXRD and IR measurements. PbBr₂, PbBr(OH), Pb₃O₂Br₂ and PbO nanoparticles were obtained by the thermal decomposition of compounds 1, 2 and 3 in oleic acid at 180 °C in an air atmosphere, respectively. These nanoparticles were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM).