Fine-Tuning the Pressure Response and Mechanical Properties of Azobenzene- and Stilbene-Based Zr-Metal–Organic Frameworks through Multivariate Design

Abstract

The rich chemistry of molecular framework materials enables precise control of physico-chemical properties through structural design of framework topology and underlying building blocks. Here, we demonstrate the tuning of mechanical properties in a series of mixed-linker Zr-based MOFs incorporating azobenzene- and stilbene-based linkers. We synthesized a series of highly porous mixed-linker MOFs and confirmed formation of solid-solutions with random linker mixing using hyperspectral Raman imaging and powder X-ray diffraction (PXRD). We further investigate the linker disorder in a mixed-linker system by single-crystal X-ray diffraction (SCXRD). Using high-pressure PXRD and molecular simulations, we probed the pressure response across this series and show that the bulk modulus can be finely tuned between 9 and 5 GPa by varying linker composition. This multivariate design strategy offers a versatile route to tailor the pressure response of framework materials and may enable counterintuitive mechanical properties in future systems.