Structural modulation of heterometallic metal–organic framework via a facile metal-ion-assisted surface etching and structural transformation

Abstract

Rational control of the morphology and ingredients of metal–organic frameworks (MOFs) is vital to extend their applications. Herein, we present a convenient metal-ion-assisted etching and transformation method to reshape the morphology of zeolitic imidazolate framework-8 (ZIF-8) and to simultaneously introduce new functional metal sites. The regulation was performed in solutions with deferent pHs depending on the Cu(Ⅱ) dose. Under a weak acidic condition created by a finite amount of Cu(Ⅱ), the structures of ZIF-8 could be etched along their corners, edges and faces, while the parent crystalline structures were retained. When sufficient Cu(Ⅱ) was introduced, an unexpected anisotropic structure was obtained via a complete crystalline transformation process. What is more, the Cu(Ⅱ) ions, not only as the pH modulator but also as the coordinative site, anchored in the frameworks, endowing the MOFs with multifunctionality. Benefiting from their superiority of composition and topological structure, the bimetallic organic frameworks can mimic the performance of peroxidase and provide outstanding adsorption capacity toward glucose oxidase.