Triptycene-based 2.5D Metal-Organic Frameworks: Atomically Ac-curate Structures and One-Dimensional Antiferromagnetism from Hydrogen-Bonding Bridged Protonated Building Units

Recent advances in two-dimensional π-d conjugated conductive metal-organic frameworks (2D cMOFs) have highlighted their potential as sophisticated, active materials in electrochemical energy storage devices, electrocatalysis, and sensors. However, a lack of high-quality structural characterization severely limits understanding their physical properties. Specifically, rapid and irre-versible nucleation and aggregation, induced by strong interlayer π-π interactions, have hindered crystal growth in these cMOFs. In this study, by utilizing triptycene-based ligands, 2,3,6,7,14,15-hexahydroxy triptycene (HHTripH2) and 9,10-dimethyl-2,3,6,7,14,15-hexahydroxy triptycene (HHTripMe2), we successfully mitigated interlayer π-π interactions and achieved SCXRD quality crystals of two triptycene-based 2D MOFs: Cu3(TripH2)2 and Cu3(TripMe2)2. The crystal structures reveal a protonated catechol ligand and an interlayer hydrogen-bonding-guided stacking motif. Notably, the steric effect of the two axial methyl groups in the TripMe2 ligand modifies the structure of Cu3(TripMe2)2 from regular AB stacking to interpenetration, significantly enhancing the stability of the crystals. ESR and susceptibility measurements indicate that these modifications facilitate hydrogen-bonding-guided 1D antiferromagnetic behavior in the Cu(cat)2 secondary building units (SBUs). This study reveals the critical roles of high-quality crystal structures and protonation/deprotonation of coordinating atoms in understanding the properties of 2D MOFs.