Structural Analysis of Molecular Materials Using the Pair Distribution Function

Abstract

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.

Long‐Life Zn Anode Enabled by Low Volume Concentration of a Benign Electrolyte Additive

“…We observe that PG displays ordering as evident from a more solid‐like distribution at the low concentration (Figure 5a), consisting of rather well‐defined and relatively sharper peaks. [ 41,42 ] This is also evident from the O‐H distance distribution (Figure S14, Supporting Information). Such self‐organization‐mediated additive film formation can alter the electrode‐electrolyte interface properties.…”

Light-driven molecular motors embedded in covalent organic frameworks

“… 73 As this property also depends on the orientation of the building blocks in neighboring layers, we modeled different orientations of the amine building blocks in the framework and additionally assessed the local structure with the help of pair distribution function (PDF) analysis. 74 …”

Controlling desolvation through polymer-assisted grinding

“…PDF analysis in particular is a useful technique for distinguishing structural signals related to changes in local interactions and short-range order in molecular systems. [37][38][39][40] As a reference point for the assessment of materials with known structures, the crystal structure models for 2(thp)•3(2-pyr), (thp)•(2-pyr), and thp were refined to obtain the best match between simulated and experimental PDFs. The fits show very good agreement, Fig.…”