...Mainly with Metal Organic Frameworks (MOFs)

Due to Covid-19, the lab was closed from 24-Mar-2020 to 31-Mar-2021. The lab reopened from 01-April-2021 with one student.   

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Gas Storage and Separation:

To isolate the pure and purer component from the gas mixture, separation and purification processes are critically important for the modern chemical industry. As MOFs are capable to capture targeted gas molecules selectively via physisorption methods, they are employed towards several gas sorption and separation directions, especially flue and biogas separation, hydrocarbon separations, noble gas separations, and so on. Even though the involvement of MOFs towards this gas sorption and separation direction is the maximum one, the excellent trade-off between sorption capacity, separation selectivity, easy regenerability, and recyclability is not yet achieved at the necessary level. We are actively working on these aspects particularly focusing on designing strategies on the water and/or moisture stability of the synthesized MOFs. Our target is to achieve the trade-off between the aforementioned parameters along with ultra-high stability of the developed MOFs so that they can be suitable for practical industrial entanglement.

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Representative Review:

1) "C2s/C1 Hydrocarbon Separation: The Major Step towards Natural Gas Purification by Metal-Organic Frameworks (MOFs)"

Coord. Chem. Rev.  2021442, 213998.

Selected Articles:

1) "A ‘Thermodynamically Stable’ 2D Ni‐MOF over a Wide pH Range with Scalable Preparation for Efficient C2s over C1 Hydrocarbon Separations" Chem. Eur. J. 2020, 26, 12624-12631.

2) "Immobilization of a Polar Sulfone Moiety onto the Pore Surface of a Humid Stable MOF for Highly Efficient CO2 Separation under Dry and Wet Environment through Direct CO2-Sulfone Interactions" ACS Appl. Mater. Interface. 202012, 41177-41184.

3) "Two Closely Related Zn(II)-MOFs for Their Large Difference in CO2 Uptake Capacities and Selective CO2 Sorption" Inorg. Chem. 202059, 7056–7066.

4) "A Microporous Co-MOF for Highly Selective CO2 Sorption in High Loadings Involving Aryl C–H...O=C=O Interactions: Combined Simulation and Breakthrough Studies'' Inorg. Chem. 201958, 11553-11560.

5) "A Moisture‐Stable 3D Microporous Co(II)‐Metal–Organic Framework with Potential for Highly Selective CO2 Separation under Ambient Conditions'' Chem. Eur. J. 201824, 5982-5986.​

6) "A Water Stable Two-Fold Interpenetrating Microporous MOF for Selective CO2 Adsorption and Separation'' Inorg. Chem. 201756, 13991-13997.

Proton Conduction:

Proton conduction (PC) having the paramount property for biological organisms and energy conversion in electrochemical systems such as polymer electrolyte fuel cells, Nafion and Nafion-like polymer membranes are also efficient proton conductors; however, the high costs and temperature limitations have driven a number of strategies towards the design of alternative materials, such as coordination polymers (CPs) and/or metal-organic frameworks (MOFs) and covalent organic polymers (COFs). Our target is to design and develop a simple yet powerful proton-conducting CPs/MOFs/COFs which not only will display exceptional ultra-high superprotonic conductivity with its excellent framework robustness but also will retain its potentiality for a longer time. For example, we have proposed a simple yet powerful template-assisted strategy for synthesizing proton-conducting MOFs where the templates remained in the frameworks with charge assist proportions which show exceptional proton conductivity in the order 10-1 S cm-1. This study reports one of the highest proton conductivity by MOFs thus far (Angew. Chem., Int. Ed. 2018, 57, 6662-6666).

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Representative Reviews:

1) "Covalent-Organic Frameworks (COFs) as Proton Conductors" Adv. Energy Mater.  2021, 2102300.

2) "Superprotonic Conductivity of MOFs and Other Crystalline Platforms beyond 10-1 S cm-1" Adv. Funct. Mater.  202131, 2101584.

3) "Metal-Organic Frameworks and Other Crystalline Materials for Ultrahigh Superprotonic Conductivities of 10-2 S cm-1 or Higher" Chem. Eur. J. 201925, 6259-6269.

Selected Articles:

1) "A 2D Mg(II)-MOF with High Density of Coordinated Waters as Sole Intrinsic Proton Sources for Ultrahigh Superprotonic Conduction" ACS Materials Lett. 20202, 1343-1350.

2) "A Co(II)-Coordination Polymer for Ultrahigh Superprotonic Conduction: An atomistic Insight through Molecular Simulations and QENS Experiments" J. Mater. Chem. A 20208, 7847 - 7853.

3) "A Phosphate-based Silver-bipyridine 1D Coordination Polymer with Crystallized Phosphoric acid as Superprotonic Conductor" Chem. Eur. J. 202026, 4607-4612.

4) "Polycarboxylates Templated Coordination Polymers: Role of Templates for Superprotonic Conductivities up to 10-1 S cm-1'' Angew. Chem., Int. Ed. 201857, 6662-6666.

Luminescence & Sensing:

On account of the crucial role of metal ions in environmental and biological systems, the design and synthesis of metal-ion sensors have attracted considerable attention from researchers across the globe. Most important and essential elements such as Fe(III) in the human body, play vital functions in many biochemical processes. Similarly, the gradual gathering of Al(III) in human body with a high dose has the direct influence on the nervous system causing many symptoms of Al(III) toxicity for instance Alzheimer’s disease, Parkinson’s syndrome, and osteoporosis. On the other hand, large amounts of toxic organic small molecules and hazardous heavy metal ions are released into the environment with serious adverse effects on the environment and human health. Thus, it is very important to develop novel systems that have the ability to detect exclusively desired ions and toxic small organic molecules like nitromethane by convenient methods that are easy to apply, such as luminescence quenching by exploiting the luminescence nature of MOFs.

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Selected Articles:

1) "Porous Anionic Co(II) Metal-Organic Framework, with a High Density of Amino Groups, as a Superior Luminescent Sensor for Turn-on Al(III) Detection" Chem. Eur. J.  202127, 11804-11810.

2) "A Trifunctional Luminescent 3D Microporous MOF with Potential for CO2 Separation, Selective Sensing of a Metal Ion, and Recognition of a Small Organic Molecule" Eur. J. Inorg. Chem. 2018, 2785-2792.

3) "Two Azo-functionalized Luminescent 3D Cd(II)-MOFs for Highly Selective Detection of Fe3+ and Al3+" New J. Chem. 201842, 12865-12871.

4) "Three Isostructural Azo-functionalized 3D Cd(II)-Coordination Polymers for Solvent Dependent Photoluminescence Study'' Polyhedron 2018153, 115-121.

Heterogeneous Catalysis:

In recent years, MOFs having well-defined crystal structures, modifiable pore topology, excellent tailorability, high surface areas have presented huge potential, especially in the field of heterogeneous catalysis. The catalytic property of MOFs can be readily controlled by the proper selection of metal ion and organic ligands. Based on the literature reports, there are different types of the active sites in the MOF which can catalyze the heterogeneous catalysis reactions (structural defect site, Lewis acid center, open metal site, and MOFs with a functional linker). Our target is to design and develop finely tuned robust MOFs suitable to display excellent catalytic activity with high yield and most desirable recyclability.

Selected Article:

1) "3D Co(II)-MOFs with Varying Porosity and Open Metal Sites toward Multipurpose Heterogeneous Catalysis under Mild Conditions" Cryst. Growth Des. 201919, 5343-5353.

Metalo Hydrogen-Bonded Organic Frameworks (MHOFs):

Proton conductivity has long been investigated as a desirable property in a variety of materials, whether organic, inorganic or crystalline materials to construct proton exchange membranes (PEMs) for hydrogen fuel-cell applications. Among these, crystalline materials that include metal-organic frameworks (MOFs), coordination polymers (CPs), polyoxometalates (POMs), H-bonded organic frameworks (HOFs), and covalent organic frameworks (COFs) have attracted immense attention to the field of proton conducting materials, and have received great development in recent years.   

     The heart of the design and synthesis of new proton-conducting crystalline materials is the thoughtful selection of reaction substrates. In order to search for new crystalline materials as super-protonic conductors, we explored for the first time metalo hydrogen-bonded organic frameworks (MHOFs) as a new class of promising conducting materials.


Selected Article:

1) "Metalo Hydrogen-Bonded Organic Frameworks (MHOFs) as New Class of Crystalline Materials for Protonic Conduction" Chem. Eur. J. 2019, 25, 1691-1695.