Thermally Resolved in Situ Dynamic Light Scattering Studies of Zirconium(IV) Complex Formation

New zirconium glycine crystals have been isolated by the reaction between hydrated ZrOCl2 and glycine. The structure was determined by single crystal X-ray diffraction. Employing dynamic light scattering (DLS), the particle size changes in an aqueous zirconium oxychloride octahydrate (ZrOCl2 center dot 8H(2)O) system with and without glycine have been investigated. A preliminary assay of ZrOCl2 center dot 8H(2)O indicated the viability of DLS to perform detailed analysis of species with hydrodynamic radii smaller than 1 nm. Additional time-resolved DLS studies of ZrOCl2 center dot 8H(2)O employing a linear temperature gradient from 0-100 degrees C demonstrated the temperature-dependent formation of oligonuclear aggregates, which was inhibited in the presence of acidic buffer. After glycine was added into aqueous ZrOCl2 center dot 8H(2)O, DLS detected the formation of the newly characterized zirconium-glycine species, CP-2. The results clearly show an equilibrium process, which has at least three distinct phases depending oil the solution temperature.