Structure investigation of challenging organic and hybrid compounds by single crystal synchrotron microdiffraction

Organic and hybrid organic-inorganic semiconductors have recently attracted increasing interest due to the growing demand of new materials with remarkable and tunable optoelectronic properties. A crystallographic study of this kind of compounds is the obliged step to be carried out for attaining a deep knowledge of the structure-property relationships, via the identification of the main intermolecular interactions determining the crystal packing, i.e., the p-p interactions, that favor stacking arrangements, and all the non-covalent interactions influencing the physical properties of the materials. Due to the difficulties in growing single crystals with size and diffraction power suitable for a successful investigation by conventional single crystal diffraction data, powerful X-ray microsources available at synchrotron beamlines revealed themselves an unavoidable tool to be exploited for obtaining high quality diffraction data whose completeness and accuracy are essential for a successful structure solution process. Some examples of recent structure characterization by synchrotron microdiffraction data in case of organic semiconductors [1] (see Fig. 1) and hybrid organic-inorganic two-dimensional (2D) perovskites [2] (see Fig. 2) are here presented. Synchrotron data were collected at the Swiss Light Source (SLS), Villigen, Switzerland, at the beamline X06DA-PXIII [3]. Structure solution was carried out by Direct Methods using SIR2019 [4] and refined by SHELXL2014/7 [5]. All non-hydrogen atoms were refined anisotropically; the carbon-bound H atoms were placed on geometrically calculated positions and refined using a riding-model approximation. The crystallographic study, supported by the optical investigation, has enabled to explore and understand the intricate relationships between physical properties and synthesis, material composition and crystal structure. The authors thank John E. Anthony (JEA), Andrea Camposeo (AC), Dario Pisignano (DP), and Luisa De Marco (LDM) for providing the crystalline samples, i.e., the anthracene derivatives compounds (JEA, AC and DP) and the hybrid organic-inorganic perovskites (LDM).