Function-Topology Relationship in the Catalytic Hydrolysis of a Chemical Warfare Simulant in Two Zr-MOFs.

Abstract

Owing to their high surface area, high concentration of active metal sites, and water stability, zirconium(VI)-based metal-organic frameworks (Zr-MOFs) have shown excellent activity in the hydrolysis of organophosphorus nerve agents (OPNs). In this regard, for the first time, two topologically different Zr-MOFs (Zr-fcu-tmuc and Zr-bcu-tmuc, constructed from the same organic and inorganic building blocks; fcu=face-centered cubic, bcu=body-centered cubic) have been rationally chosen to investigate the effect of network topology on the catalytic hydrolysis of the nerve agent simulant, dimethyl 4-nitrophenyl phosphate (DMNP). A remarkable enhancement in the hydrolysis rate of DMNP was observed with Zr-bcu-tmuc, reducing the half-life more than three-fold compared with Zr-fcu-tmuc. Greater accessibility of the active ZrVI sites in the 8-connected bcu net compared with the 12-connected fcu leads to a faster hydrolysis of DMNP on Zr-bcu-tmuc. Interestingly, the higher activity of Zr-bcu-tmuc was also confirmed by its higher fluorescence sensitivity towards DMNP (limit of detection (LOD)=0.557 μm) compared with Zr-fcu-tmuc (LOD=1.09 μm). The results show that controlling the desired topology of Zr-MOFs is a useful strategy for improving their performance in the detection and catalytic detoxification of OPNs.