The observation of drastic change of metal cluster in metal-organic frameworks by transmetalation

Abstract

Metal-organic frameworks (MOF) as crystalline porous material are composed of metal ion or cluster and coordinative organic ligands. MOF are utilized for gas storage or separation, catalyst, sensing due to porosity, diversity and additional tunability to specific purpose. Post-synthetic modification (PSM) method provides an extension of applicability of MOF. PSM can lead to change of its properties or enhancement of quality of MOF with known structures. PSM is also able to induce new materials from existing framework, for example, as attachment of new functional groups, partial exchange of ligands and alternation in metal ion or cluster. Those modification methods give chance to variability, however, the analysis of structural environment about amended product is not easy because deteriorated crystallinity or limitation of analysis condition even though some properties are improved by PSM. So many of PSMMOF were difficult to investigate structure analysis directly. In this work, we carried out transmetalation of Zn-MOF to Fe3+ under ferric chloride solution, then performed single crystal x-ray structure determination about transmetalated Fe-MOF single crystal. This structure determination supplied the observation of change of metal clusters from Zn4O(COO)6 to Fe3O(COO)6 (with one chloride for charge balance) following Zn2+ to Fe3+ ion. And we will discuss change of property in those experimental results.