Irreversible Crystal to Crystal Transformation of Nano Lead(ll) Coordination Polymer by Solid State Anion-replacement

摘要

Irreversible crystal-to-crystal transformation of 3D lead(II) coordination polymer with the ligand 1H-1,2,4-triazole-3-carboxylic acid (HL), [Pb(L)((μ_(1,1)-NCS)(H_2O)]_n (1) to 3D supramalecular compound [Pb(L)(μ2-I)]_n (2) by solid state anion-replacement have been studied. Structural determination of compound 2 reveals the Pb(II) ion is five coordinated with hemidirected geometry, bonded to one nitrogen atom, two oxygen atoms from the L~- ligand and two iodide ions. The irreversible solid state structural transformation of compound 1 to compound 2, by anion-replacement processes under mechanochemical reaction have been verified by PXRD measurements. Nanoparticles of compound 1 was synthesized by sonochemical process and characterized by scanning electron microscopy (SEM), powder X-ray diffraction, IR spectroscopy and elemental analyses. The SEM images showed that no morphology change occur during this solid state anion-replacement.