Geometry of Zn(II) complexes with dissolved organic matter: X-ray studies at variable pH

作者：Mousavi Aliyar; Marts Amy R; Tierney David L; Cabaniss Stephen E^*

来源：Toxicological and Environmental Chemistry, 2013, 95(1): 38-44.

DOI：10.1080/02772248.2012.734620

• Zn(II)
• dissolved organic matter
• DOM
• XANES
• EXAFS

The structure of Zn(II) complexes with dissolved organic matter (DOM) is an important consideration in developing molecular-level models of Zn(II) speciation, but recent reports favoring the tetrahedral geometry differ from earlier findings that geometry was largely octahedral. In general, the presence of thiolate ligands favors the tetrahedral geometry, while O and N ligands favor the octahedral geometry. This work presents extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectroscopic results, indicating an octahedral geometry over the pH range of 59 for a freshwater DOM isolate. Changes in XANES derivatives as a function of pH can be explained in terms of ligand protonation and/or changing ligand groups. Tetrahedral Zn(II)DOM geometry may be restricted to binding environments containing thiol groups.

• 出版日期2013-1-1