Aggregate assembly of ferrocene functionalized indium-oxo clusters

In this study, we synthesized multi-nuclear indium oxide clusters (InOCs) using 1,1'-ferrocene dicarboxylic acid (H₂FcDCA) as the chelating and surface protection ligand. The obtained clusters include the cubane-type heptanuclear InOCs ([In₇]) and the sandwich-type thirteen-nuclear InOCs ([In₁₃]). Notably, [In₁₃] represents the highest nuclear number reported within the InOC family. In addition, the presence of labile coordination sites in these clusters allowed for structural modification and self-assembly. A series of [In₇] clusters with adjustable band gaps have been obtained and the self-assembly of [In₇] clusters resulted in the formation of an Fe-doped dimer, [Fe₂In₁₂], and an imidazole-bridged tetramer, [In₂₈]. Similarly, in the case of [In₁₃] clusters, the coordinated water molecules could be replaced by imidazole, methylimidazole, and even a bridged carboxylic acid, allowing the construction of one-dimensional extended structures. Additionally, part of the H₂FcDCA could be substituted by pyrazole. This flexibility in replacing solvent molecules offered diverse possibilities for tailoring the properties and structures of the InOCs to suit specific applications.