Adsorption of Natural Gas in Metal-Organic Frameworks: Selectivity, Cyclability, and Comparison to Methane Adsorption.

Evaluation of metal-organic frameworks (MOFs) for adsorbed natural gas (ANG) technology employs pure methane as a surrogate for natural gas (NG). This approximation is problematic, as it ignores the impact of other heavier hydrocarbons present in NG, such as ethane and propane, which generally have more favorable adsorption interactions with MOFs compared to methane. Herein, using quantitative Raman spectroscopic analysis and Monte Carlo calculations, we demonstrate the adsorption selectivity of high-performing MOFs, such as MOF-5, MOF-177, and SNU-70, for a methane and ethane mixture (95:5) that mimics the composition of NG. The impact of selectivity on the storage and deliverable capacities of these adsorbents during successive cycles of adsorption and desorption, simulating the filling and emptying of an ANG tank, is also demonstrated. The study reveals a gradual reduction in the storage performance of MOFs, particularly with smaller pore volumes, due to ethane accumulation over long-term cycling, until a steady state is reached with substantially degraded storage performance.

Superior Metal-Organic Framework Activation with Dimethyl Ether.

Metal-organic frameworks (MOFs) are demonstrated to be readily activated by treatment with the low surface tension, low boiling point solvent dimethyl ether (DME). The mildness of the method enables access to high surface areas by avoiding structural changes in the framework that often plague thermal activation methods. A distinction from previous methods is that DME activation succeeds for materials with coordinatively unsaturated sites (CUS) and non-CUS MOFs as well. DME displaces solvent molecules occupying the pores of the MOF as well as those coordinated to metal centers; reducing evacuation temperature by using a coordinating, yet highly volatile guest enables low temperature activation with structural retention as demonstrated surface area measurements that match or exceed existing activation protocols.

Microscale Determination of Binary Gas Adsorption Isotherms in MOFs.

The experimental determination of mixed gas isotherms is challenging and thus rarely performed. Nevertheless, characterizing the performance of adsorbents toward mixtures of gases is critical in most adsorptive separations. Here, the utility of Raman spectroscopy in determining binary gas adsorption isotherms on the microscale with metal-organic framework (MOF) single crystals is demonstrated for quantifying C2H6/CH4 selectivity. The influence of pore size on sorption selectivity is determined experimentally. The technique also allows determination of kinetics of methane adsorption in MOFs, which is critical for refueling times in adsorbed natural gas storage.

Computational Identification and Experimental Demonstration of High-Performance Methane Sorbents.

Remarkable methane uptake is demonstrated experimentally in three metal-organic frameworks (MOFs) identified by computational screening: UTSA-76, UMCM-152 and DUT-23-Cu. These MOFs outperform the benchmark sorbent, HKUST-1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high-affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

Porous Li-MOF as a solid-state electrolyte: exploration of lithium ion conductivity through bio-inspired ionic channels.

A rarely porous Li-MOF (Li-AOIA) with surface area of 605 m2 g-1 was employed for the formation of an emerging class of solid-state lithium ion electrolytes. Infiltration of LiBF4 into Li-AOIA afforded Li-AOIA@BF4 with ionic conductivity of 1.09 × 10-5 S cm-1 at room temperature and an activation energy of 0.18 eV.

Tailoring Coordination Polymers by Substituent Effect: A Bifunctional CoII -Doped 1D-Coordination Network with Electrochemical Water Oxidation and Nitroaromatics Sensing.

Three CdII coordination polymers (CPs) were synthesized with a tripodal ligand N,N',N' '-tris(4-pyridinylmethyl)-1,3,5-benzenetricarboxamide in combination with three different substituted isophthalic acids with general formulas {[Cd2 (L)(NIP)2 (H2 O)2 ].4H2 O}n , (CP-1), {[Cd2 (L)(AIP)2 (H2 O)2 ].4H2 O}n , (CP-2) and {[Cd(L)(BIP) (H2 O)].4H2 O}n , (CP-3). The substituent groups on the co-ligand had profound effect on the network topologies of the corresponding CPs as well as their properties. Out of the three, CP-1 and 2 were found to form 3D networks whereas CP-3 was a 1D linear chain with uncoordinated pyridyl sites. Due to its structural features CP-3 was found to show interesting properties. The 1D CP containing uncoordinated pyridyl site exhibited an excellent ability for doping with CoII which in turn acts as an efficient water oxidation electrocatalyst with required overpotential of 380 mV for an anodic current density of 1 mA cm-2 . The CP also exhibited luminescence-based detection of nitroaromatics (LOD: 0.003 mm) without any significant interference in presence of other organic compounds.

Isoreticular Expansion of Metal-Organic Frameworks via Pillaring of Metal Templated Tunable Building Layers: Hydrogen Storage and Selective CO2 Capture.

The deliberate construction of isoreticular eea-metal-organic frameworks (MOFs) (Cu-eea-1, Cu-eea-2 and Cu-eea-3) and rtl-MOFs (Co-rtl-1 and Co-rtl-2) has been accomplished based on the ligand-to-axial pillaring of supermolecular building layers. The use of different metal ions resulted in two types of supermolecular building layers (SBLs): Kagome (kgm) and square lattices (sql) which further interconnect to form anticipated 3D-MOFs. The isoreticular expansion of (3,6)-connected Cu-MOFs has been achieved with desired eea-topology based on kgm building layers. In addition, two (3,6)-connected Co-rtl-MOFs were also successfully constructed based on sql building layers. The Cu-eea-MOFs were shown to act as hydrogen storage materials with appreciable amount of hydrogen uptake abilities. Moreover Cu-eea-MOFs have also exhibited remarkable CO2 capture ability at ambient condition compared to nitrogen and methane, due to the presence of amide functionalities.

MOF-templated cobalt nanoparticles embedded in nitrogen-doped porous carbon: a bifunctional electrocatalyst for overall water splitting.

Development of cost-effective and efficient non noble metal electrocatalysts has immense importance towards sustainable energy technologies. Herein, a newly constructed porous Co(ii)-metal organic framework (MOF) has been utilized for the synthesis of cobalt nanoparticles embedded in N-doped porous carbon, (Co@NPC), via a facile MOF-annealing strategy, at an optimum temperature of 800 °C under an argon atmosphere. DMF molecules present in the form of solvated guests and cations within the 3D-framework serve as a source for N-doping during the formation of the porous graphitic carbon upon carbonization. The nanocomposite was found to encapsulate homogeneously dispersed cobalt nanoparticles within the N-doped porous carbonaceous matrix. The synergistic effect of cobalt nanoparticles and the heteroatom-doped carbon framework makes Co@NPC electrochemically active towards both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline conditions. Furthermore, Co@NPC exhibits outstanding performance as a bifunctional electrocatalyst towards electrochemical water splitting with remarkable stability and durability. It achieves a current density of 10 mA cm-2 at a low cell voltage of 1.66 V in 1 M NaOH solution which is comparable with that of most of the self-templated ZIF-derived non-noble metal electrocatalysts.

Supramolecular Organic Photocatalyst Containing a Cubanelike Water Cluster and Donor-Acceptor Stacks: Hydrogen Evolution and Dye Degradation under Visible Light.

Supramolecular organic photocatalysts are scarcely explored for the generation of sustainable energy as well as for environmental remediation purposes. An organic photocatalyst, containing a cubanelike water cluster and donor-acceptor stacks, was efficiently developed through a supramolecular approach. The material exhibited remarkable photocatalytic hydrogen generation, in the absence of any cocatalyst, with excellent stability and recyclability. The photoactivity was further assessed through time-resolved photoluminescence and electrochemical impedance spectroscopy. The material also exhibited highly efficient sunlight-driven photocatalytic activity through the degradation of harmful organic dye methylene blue.

Computational Analysis of N-acetyl transferase in Tribolium castaneum.

N-acetyl transferase (NAT) is responsible to catalyze the transfer of acetyl groups to arylamines from acetyl-CoA. Aralkylamine Nacetyl transferase (AANAT), which belongs to GCN5-related N-acetyl transferase member, is a globular 23-kDa cytosolic protein that forms a reversible regulatory complex with 14-3-3 proteins, AANAT regulates the daily cycle of melatonin biosynthesis in mammals, making it an attractive target for therapeutic control of abnormal melatonin production in mood and sleep disorders. There is no evidence available regarding α and ß subunits, active site and their ASA value in Dopamine N-acetyl transferase. Therefore, we describe the development of Dopamine N-acetyl transferase model in Tribolium castaneum. We further document the predicted active sites in the structural model with solvent exposed ASA residues. During this study, the model was built by CPH program and validated through PROCHECK, Verify 3D, ERRAT and ProSA for reliability. The active sites were predicted in the model with further ASA analysis of active site residues. The discussed information thus provides insight to the predicted active site and ASA values of Dopamine N-acetyl transferase model in Tribolium castaneum.