Structural Analysis of Molecular Materials Using the Pair Distribution Function

This is a review of atomic pair distribution function (PDF) analysis as applied to the study of molecular materials. The PDF method is a powerful approach to study short- and intermediate-range order in materials on the nanoscale. It may be obtained from total scattering measurements using X-rays, neutrons, or electrons, and it provides structural details when defects, disorder, or structural ambiguities obscure their elucidation directly in reciprocal space. While its uses in the study of inorganic crystals, glasses, and nanomaterials have been recently highlighted, significant progress has also been made in its application to molecular materials such as carbons, pharmaceuticals, polymers, liquids, coordination compounds, composites, and more. Here, an overview of applications toward a wide variety of molecular compounds (organic and inorganic) and systems with molecular components is presented. We then present pedagogical descriptions and tips for further implementation. Successful utilization of the method requires an interdisciplinary consolidation of material preparation, high quality scattering experimentation, data processing, model formulation, and attentive scrutiny of the results. It is hoped that this article will provide a useful reference to practitioners for PDF applications in a wide realm of molecular sciences, and help new practitioners to get started with this technique.

Automated summary

This article reviews the application of atomic pair distribution function (PDF) analysis in the study of molecular materials. The PDF method is a powerful tool for investigating short- and intermediate-range order in nanoscale materials. It can provide structural details that are obscured in reciprocal space by defects, disorder, or structural ambiguities. While its use in inorganic and nanomaterials research has been highlighted, significant progress has also been made in applying PDF analysis to molecular materials such as carbon, pharmaceuticals, polymers, liquids, coordination compounds, and composites. The article provides an overview of applications in a wide variety of molecular compounds and systems, and offers pedagogical descriptions and tips for implementation.