Ordered Cationic Mixing in a 1D Organic-Inorganic Hybrid

Hybrid metal halides are a remarkably dynamic family of materials that offer a flexible platform for exploring the novel crystal chemistry that emerges at the intersection of organic and inorganic solids. Herein, we report the discovery of a hybrid that contains two molecules effectively adopting isostructural geometry, (1-NA)PbI₃ and (1-MQ)PbI₃, and our attempts to create solid solutions of the two beyond the 1:1 ratio. Single-crystal X-ray diffraction, combined with solid-state NMR measurements, clearly show that despite having nearly identical steric geometry, the only mixed phase attained was the composition (1-MQ)(1-NA)Pb₂I₆, which exhibits a high degree of order between the two molecules. We propose that this ordering is primarily driven by local molecular dipoles, which ultimately creates a band structure in the blended phase that is highly characteristic of the end members, with little sign of rehybridization between the organic or inorganic components.