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

## TL;DR

Multi-crystal X-ray diffraction (MCXRD) enables accurate structure determination of small crystals, like metal-organic frameworks, that are too tiny for traditional methods and avoids radiation damage.

## Contribution

MCXRD is adapted for MOFs with small crystals, enabling structural characterization where conventional methods fail.

## Key findings

- MCXRD successfully determined crystal structures of six MOFs with crystal sizes as small as 0.5 µm³.
- The method mitigates radiation-induced degradation and chemical changes during X-ray analysis.
- MCXRD bridges the gap between single-crystal and electron diffraction methods for challenging materials.

## Abstract

Structure determination by X‐ray diffraction is limited by crystal size and can be compromised by radiation damage when using very intense X‐ray radiation. X‐ray structure determination from partial diffraction data sets combined from multiple crystals is a potential solution, but its exploitation in chemistry and materials science is largely unrealized. 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 radiation‐induced chemical changes and degradation of diffraction quality can be alleviated. Our approach encompasses both rotation‐ and stationary‐MCXRD measurements for 10 to 1000s of crystals with software‐optimized 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. This approach can address 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 can provide accurate atomic‐resolution structure determination for some of the most challenging cases in chemistry and materials science.

Multi‐crystal X‐ray diffraction (MCXRD) methods allow accurate structural characterisation with crystals too small for single‐crystal X‐ray diffraction and too large for electron diffraction, as demonstrated here for metal‐organic frameworks, and alleviate the radiation‐induced chemical changes that can result from using high‐intensity X‐ray sources to study very small crystals.