Zirconium-Based Metal–Organic Framework with 9-Connected Nodes for Ammonia Capture

Construction of multifunctional metal–organic frameworks (MOFs) with asymmetric connectivity have the potential to expand the scope of their utilization. Herein, we report a robust microporous Zr-based MOF with 9-connected Zr6 nodes, NU-300, assembled from low symmetry tricarboxylate ligands and Zr6 nodes. As indicated by single-crystal X-ray diffraction analysis, there exist uncoordinated carboxylate groups in the structure of NU-300 that can participate in ammonia (NH3) sorption through acid–base interactions which yield high uptake of NH3 at low pressure regions (<0.01 bar). In situ infrared (IR) spectroscopy shows the interactions between Brønsted acidic sites and NH3, which suggests that NU-300 can be used as a sorbent for NH3 capture at low pressures.