Structural information of nanosized iron oxide clusters serendipitously poses the solution of long‐standing problems on nanomaterials: Intra/inter surfactant and core–surfactant interaction

Detailed information on the surface structure of surfactant‐protected metal oxide nanoparticles (NPs) is limited due to the difficulties in preparing samples suitable for single‐crystal x‐ray diffraction analysis. Herein, we report the synthesis and x‐ray structural analysis of 4‐biphenylcarboxylic acid‐protected nanosized iron oxide, comprising 11 Fe(III) ions, 6 O atoms, 6 (OH) ions, and 15 biphenylcarboxylates. The carboxylate bridges the adjacent Fe(III) ions in the core and the core form a slightly twisted pentacapped trigonal prism. In addition, widespread intercalation between the phenyl groups on the surface of the nanoparticles is observed. Through the synthesized nanosized iron oxide clusters with surfactants, the understanding of the interaction between the surfactant, the oxide core, and the solvent is extended.