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1. Design and synthesis of photoluminescent active interpenetrating metal–organic frameworks using N -2-aryl-1,2,3-triazole ligands

   https://doi.org/10.1039/d0dt00933d  

   Li, Jingyang; He, Ying; Wang, Li; Pan, Qinhe; Song, Zhiguang; Shi, Xiaodong (May 2020, Dalton Transactions)

   N -2-aryl-1,2,3-triazole derivatives were synthesized as new ligand systems for the construction of photoluminescent active metal–organic frameworks (MOFs). Crystal structures revealed that the five-membered triazoles show an unsymmetrical conformation with the two C4,C5-substituted benzenes adopting a “twisted-planar” geometry. As a result, a MOF constructed from this ligand exhibited cross-layer interactions with improved water stability (at 100 °C for 24 hours). Furthermore, enhanced photoluminescence emissions were observed upon the formation of MOF structures ( Φ up to 30%), suggesting the potential applications of these photoactive porous materials through this new ligand design. 

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2. A New Electrically Conducting Metal–Organic Framework Featuring U-Shaped cis-Dipyridyl Tetrathiafulvalene Ligands

   https://doi.org/10.3389/fchem.2021.726544  

   Gordillo, Monica A.; Benavides, Paola A.; Spalding, Kaybriana; Saha, Sourav (October 2021, Frontiers in Chemistry)

   null (Ed.)

   A new electrically conducting 3D metal-organic framework (MOF) with a unique architecture was synthesized using 1,2,4,5-tetrakis-(4-carboxyphenyl)benzene (TCPB) a redox-active cis -dipyridyl-tetrathiafulvalene ( Z -DPTTF) ligand. While TCPB formed Zn 2 (COO) 4 secondary building units (SBUs), instead of connecting the Zn 2 -paddlewheel SBUs located in different planes and forming a traditional pillared paddlewheel MOF, the U-shaped Z -DPTTF ligands bridged the neighboring SBUs formed by the same TCPB ligand like a sine-curve along the b axis that created a new sine -MOF architecture. The pristine sine -MOF displayed an intrinsic electrical conductivity of 1 × 10 −8  S/m, which surged to 5 × 10 −7  S/m after I 2 doping due to partial oxidation of electron rich Z -DPTTF ligands that raised the charge-carrier concentration inside the framework. However, the conductivities of the pristine and I 2 -treated sine -MOFs were modest possibly because of large spatial distances between the ligands that prevented π-donor/acceptor charge-transfer interactions needed for effective through-space charge movement in 3D MOFs that lack through coordination-bond charge transport pathways. 

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3. PolyMOF Nanoparticles: Dual Roles of a Multivalent polyMOF Ligand in Size Control and Surface Functionalization

   https://doi.org/10.1002/anie.201910542  

   Gu, Yuwei; Huang, Mingjun; Zhang, Wenxu; Pearson, Matthew A.; Johnson, Jeremiah A. (September 2019, Angewandte Chemie International Edition)

   Abstract Metal–organic framework nanoparticles (MOF NPs) have emerged as an important class of materials that display significantly enhanced performance in many applications compared to bulk MOF materials; their synthesis, however, commonly involves a tedious sequence that controls particle size and surface properties in separate steps. Now, a simple strategy to access functional MOF NPs in one pot is reported that uses a polyMOF ligand possessing a polymer block for surface functionalization and a coordination block with tunable multivalency for size control. This strategy produces uniform polyMOF‐5 NPs with sizes down to 20 nm, displaying exceptional structural and colloidal stability upon exposure to ambient conditions. A detailed time‐dependent study revealed that the polyMOF NPs were formed following an aggregation‐confined crystallization mechanism. Generality was demonstrated through the synthesis of well‐defined polyUiO‐66 NPs. 

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4. An ionic Fe-based metal–organic-framework with 4′-pyridyl-2,2′:6′,2′′-terpyridine for catalytic hydroboration of alkynes

   https://doi.org/10.1039/D2RA08040K  

   Zhang, Guoqi; Zheng, Shengping; Neary, Michelle C. (January 2023, RSC Advances)

   An ionic metal–organic-framework (MOF) containing nanoscale channels was readily assembled from ditopic 4′-pyridyl-2,2′:6′,2′′-terpyridine (pytpy) and a simple iron( ii ) salt. X-ray structural analysis revealed a two-dimensional grid-like framework assembled by classic octahedral (pytpy) 2 Fe II cations as linkers (with pytpy as a new ditopic pyridyl ligand) and octa-coordinate FeCl 2 centers as nodes. The layer-by-layer assembly of the 2-D framework resulted in the formation of 3-D porous materials consisting of nano-scale channels. The charges of the cationic framework were balanced with anionic Cl 3 FeOFeCl 3 in its void channels. The new Fe-based MOF material was employed as a precatalyst for syn -selective hydroboration of alkynes under mild, solvent-free conditions in the presence of an activator, leading to the synthesis of a range of trans -alkenylboronates in good yields. The larger scale applicability and recyclability of the new MOF catalyst was further explored. This represents a rare example of an ionic MOF material that can be utilized in hydroboration catalysis. 

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5. Switchable electrical conductivity in a three-dimensional metal–organic framework via reversible ligand n-doping

   https://doi.org/10.1039/C9SC06150A  

   Wentz, Hanna C.; Skorupskii, Grigorii; Bonfim, Ana B.; Mancuso, Jenna L.; Hendon, Christopher H.; Oriel, Evan H.; Sazama, Graham T.; Campbell, Michael G. (February 2020, Chemical Science)

   Redox-active metal–organic frameworks (MOFs) are promising materials for a number of next-generation technologies, and recent work has shown that redox manipulation can dramatically enhance electrical conductivity in MOFs. However, ligand-based strategies for controlling conductivity remain under-developed, particularly those that make use of reversible redox processes. Here we report the first use of ligand n-doping to engender electrical conductivity in a porous 3D MOF, leading to tunable conductivity values that span over six orders of magnitude. Moreover, this work represents the first example of redox switching leading to reversible conductivity changes in a 3D MOF. 

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