Static disorder and local structure in zinc(II) isonicotinate, a quartzlike metal-organic framework

TL;DR

This study reveals static disorder and local structural flexibility in zinc(II) isonicotinate MOF at 10 K, using neutron scattering and advanced refinement techniques, highlighting the material's multiple low-energy configurations.

Contribution

It introduces a combined Rietveld and RMC refinement approach to analyze static disorder and local structure in MOFs, emphasizing the role of structural flexibility.

Findings

Evidence of static disorder at 10 K in zinc(II) isonicotinate

Disorder manifests as transverse ligand displacements

Structural flexibility leads to multiple low-energy states

Abstract

Using a combination of Rietveld and RMC refinement of neutron total scattering data, we find that the 10 K structure of zinc(II) isonicotinate shows strong evidence of static disorder. This disorder takes the form of transverse displacements of the isonicotinate ligand and results in elongated atomic displacement parameters and dampened oscillations of the experimental G(r). We analyse the RMC configurations using an approach derived from geometric algebra. Complications regarding the inclusion of hydrogenous guest molecules within the pore structure are discussed. This study highlights the way in which structural flexibility can give rise to multiple low-energy ground states in MOF-type materials.