Chiral Redox-Active Metal–Organic Frameworks Based on Benzoquinone-Derived Linkers

Metal–organic frameworks (MOFs) are porous materials formed by the self-assembly of metal nodes and organic linkers. MOFs based on redox-active ligands represent versatile platforms for the design of functional materials, while the inclusion of chiral moieties introduces additional stereochemical complexity. Therefore, the combined influence of chirality and redox activity on framework formation and resulting properties has not yet been comprehensively investigated.

Here, we report the design and synthesis of novel redox-active linker benzoquinone derivatives functionalized at the 2,5-positions with chiral amino acid moieties, with the goal of introducing chirality into the ligand framework. These chiral linkers were employed in the assembly of MOFs with both transition metal and lanthanide ions under solvothermal conditions. Synthetic parameters, i.e., i) solvent choice, ii ) temperature, iii) reaction time, and iv) precursor ratios, were systematically varied to investigate their influence on framework formation, crystallinity and linker incorporation.

The synthesized MOFs were fully characterized by single-crystal and powder X-ray diffraction and spectroscopic and elemental analyses to assess their structural framework and chemical composition.

The obtained results show that both the chirality of the linkers and the choice of metal ion play an important role in the assembly of the frameworks, influencing structural characteristics and coordination environment. The comparison with non-chiral analogues emphasizes the effect of amino acid-derived chirality. These observations outline consistent trends that can support the further design of chiral redox-active MOFs.