More Like this

1. 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. 

   more » « less
2. 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. 

   more » « less
3. “Orthogonal‐Twisted‐Arm” Ligands for The Construction of Metal–Organic Frameworks (MOFs): New Topology and Catalytic Reactivity

   https://doi.org/10.1002/chem.202003878  

   Zhao, Kai ; He, Ying ; Shan, Chuan ; Ren, Junyu ; Wojtas, Lukasz ; Wang, Li ; Li, Guanghua ; Song, Zhiguang ; Shi, Xiaodong ( November 2020 , Chemistry – A European Journal)

   Extended tetratopic benzoic acid ligands with “orthogonal‐twisted‐arms” conformations were designed and synthesized for the construction of new MOF structures (OTA‐MOF). Upon coordination with Cd²⁺and Cu²⁺cations, two well‐defined new MOFs were prepared. X‐ray single crystal structures were successfully obtained, demonstrating the formation of a new topology (4,4,4‐c). The OTA2‐MOF‐Cu gave moderate stability in organic solvents and good gas sorption ability toward CO₂. This new MOF showed superior catalytic reactivity toward the epoxide‐CO₂cycloaddition, giving >50 folds yield enhancement over the controlled reaction without MOF. It is expected that this new ligand design, porous structure, and excellent CO₂catalytic reactivity will make OTA‐MOF promising new materials for applications in catalysis and separation.

    

   more » « less
4. Expanding the “library” of Metal-Organic Frameworks (MOFs) for enzyme biomineralization

   Jordahl, Drew Jordahl ; Armstrong, Zoe ; Li, Qiaobin ; Gao, Runxiang ; Liu, Wei ; Johnson, Kelley ; Brown, William ; Scheiwiller, Allison ; Feng, Li ; Ugrinov, Angel ; et al ( October 2022 , ACS applied materials interfaces)

   Farha, Omar (Ed.)

   Metal-Organic Frameworks (MOFs) are advanced platforms for enzyme immobilization. Enzymes can be entrapped via either diffusion (into pre-formed MOFs) or co-crystallization. Enzyme co-crystallization with specific metals/ligands in the aqueous phase, also known as biomineralization, minimizes the enzyme loss as compared to organic phase co-crystallization, removes the size limitation on enzymes and substrates, and can potentially broaden the application of enzyme@MOF composites. However, not all enzymes are stable/functional in the presence of excess metal ions and/or ligands currently available for co-crystallization. Furthermore, most current biomineralization-based MOFs have limited (acid-) pH stability, making it necessary to explore other metal-ligand combinations that can also immobilize enzymes. Here, we report our discovery on the combination of five metal ions and two ligands that can form biocomposites with two model enzymes differing in size and hydrophobicity in the aqueous phase under ambient conditions. Surprisingly, most of the formed composites are single- or multi- phase crystals even though the reaction phase is aqueous, with the rest as amorphous powders. All 20 enzyme@MOF composites showed good to excellent reusability, and were stable under weakly acidic pHs. The stability under weakly basic conditions depended on the selection of enzyme and metal-ligand combinations, yet for both enzymes, 3-4 MOFs offered decent stability under basic conditions. This work initiates the expansion of the current “library” of metal-ligand selection for encapsulating/biomineralizing large enzymes/enzyme clusters, leading to customized encapsulation of enzymes according to enzymes stability, functionality, and optimal pH. 

   more » « less
5. Cooperative Cluster Metalation and Ligand Migration in Zirconium Metal–Organic Frameworks

   https://doi.org/10.1002/anie.201505625  

   Yuan, Shuai ; Chen, Ying‐Pin ; Qin, Junsheng ; Lu, Weigang ; Wang, Xuan ; Zhang, Qiang ; Bosch, Mathieu ; Liu, Tian‐Fu ; Lian, Xizhen ; Zhou, Hong‐Cai ( October 2015 , Angewandte Chemie International Edition)

   Cooperative cluster metalation and ligand migration were performed on a Zr‐MOF, leading to the isolation of unique bimetallic MOFs based on decanuclear Zr₆M₄(M=Ni, Co) clusters. The M²⁺reacts with the μ₃‐OH and terminal H₂O ligands on an 8‐connected [Zr₆O₄(OH)₈(H₂O)₄] cluster to form a bimetallic [Zr₆M₄O₈(OH)₈(H₂O)₈] cluster. Along with the metalation of Zr₆cluster, ligand migration is observed in which a Zr–carboxylate bond dissociates to form a M–carboxylate bond. Single‐crystal to single‐crystal transformation is realized so that snapshots for cooperative cluster metalation and ligand migration processes are captured by successive single‐crystal X‐ray structures. In³⁺was metalated into the same Zr‐MOF which showed excellent catalytic activity in the acetaldehyde cyclotrimerization reaction. This work not only provides a powerful tool to functionalize Zr‐MOFs with other metals, but also structurally elucidates the formation mechanism of the resulting heterometallic MOFs.

    

   more » « less