Multi-Crystal X-Ray Diffraction (MCXRD) Bridges the Crystallographic Characterisation Gap in Chemistry and Materials Science: Application to MOFs

Structure determination by X-ray diffraction in many forefront areas of chemistry and materials science is limited by available crystal size and can be compromised by radiation damage when using very intense X-ray radiation. X-ray crystal structure determination involving combination of partial diffraction data sets from multiple crystals has been developed for application in structural biology to protein crystals to alleviate similar problems. The potential for adaptation and exploitation in chemistry and materials science, however, is largely unrealised. Here we report the use of synchrotron radiation for multi-crystal X-ray diffraction (MCXRD) adapted for structure determination of metal-organic framework (MOF) materials with crystal dimensions too small for conventional single-crystal diffraction studies. We further show that such methodologies can alleviate the radiation damage that substantially degrades diffraction quality and undermines structure determination. Our approach encompasses both rotation-MCXRD and static-crystal measurements (serial crystallography, SX) for 10s to 1000s of crystals with software-optimised combination of the multiple data sets. We report the crystal structures of six MOFs: MOF-919(Sc/Cu), MET-2, MIL-88B(Cr)-1,4-NDC, PCN-260(Sc), UiO-66 and UiO-66-MoO4 with unit cell dimensions ranging from 18−114 Å and crystal sizes from 0.5−480 μm3. We anticipate that this approach can alleviate the challenges of structure determination in a regime of particle size and sample radiation sensitivity that lies between existing single-crystal X-ray diffraction and the emerging field of electron diffraction. MCXRD has the potential to provide the best option for accurate atomic-resolution structure determination for some of the most challenging cases in chemistry and materials science.