(63l) A Pyrogallate-Based Metal-Organic Framework with a Two-Dimensional Secondary Building Unit

The topology of MOFs is an essential feature governing their properties. Increasing the dimensionality of the secondary building units (SBUs) can enable enhanced electronic interactions between the atoms comprising them. In this direction, we used the unexplored ligand 3,3’,4,4’,5,5’-hexahydroxybiphenyl (HHBP) as a strategy to design a MOF with a two-dimensional SBU. The SBU comprises mixed-valent Fe²⁺ and Fe³⁺ metal ions bridged by oxygen atoms pertaining to the polytopic HHBP ligand, which also define the iron-oxide 2D layers. Overall, the anionic framework exhibits a rare topology and evidences strong electronic communication between the mixed-valence iron sites. These results highlight the advantage of designing MOFs encompassing high dimensional SBUs and can serve as a blueprint for the design of novel framework structures with properties distinctive to inorganic layered materials.