Research Interest

Inorganic Chemistry
Metal-Organic Frameworks (MOFs)
Coordination Polymers (CPs)
Fluorescence Sensing
Heterogeneous Catalysis
Photo-Physical Chemistry

Mechanochemical Synthesis
Pollutant Sensing/Encapsulation
CO2 Capture and Conversion
Electrocatalysis (OER, HER)
Triplet-Fusion; Singlet-Fission
Quantum Information Science

Design and Fabrication of coordination polymers (CPs)/metal-organic frameworks (MOFs) and their composites.
Application of MOF-based Materials as an Environmental Remediation Probes towards Chemical Sensing and Adsorptive Removal of Hazardous Organic/Inorganic Pollutants.
Application of MOF-based Materials as Heterogeneous Catalysts towards CO2 Sequestration, Small Organic Transformation and Water Splitting.
Application of MOFs/CPs materials for Triplet Fusion (TTA), Singlet Fission (SF), Quantum bits (Qubits) and Quantum Information Science (QIS).

Research Experience

MOFs/CPs Chemistry: Design, synthesis and characterization of mixed-linker coordination polymers (metal-organic frameworks) and MOF-derived nanomaterials. Application of these materials towards chemical/fluorescence sensing, heterogeneous catalysis, pollutant encapsulation/degradation, gas adsorption, CO2 capture/conversion, electrocatalytic water splitting, and photonics for quantum information science.
Crystallization: Hydrothermal/Solvothermal, Diffusion techniques, and non-ambient crystallization.
Mechanochemistry: Mechanochemical (Neat grinding and LAG) synthesis of MOFs/CPs.
Instruments Operating Skills: Experience in handling Single Crystal X-ray Diffractometer (SXRD), Powder X-ray Diffractometer (PXRD), UV-Vis spectrophotometer, Fluorescence spectrophotometer with Time-resolved photoluminescence and lifetime, Circular Dichroism, Rotary evaporator, surface area and gas adsorption analyser and high-pressure gas reactors for catalysis. Basic handling knowledge and advanced data interpretation skills for thermal analytical techniques (TGA, DSC), CHN analyser, FT-IR, FT-NMR, FE-SEM, TEM, EDX, XPS, light/fluorescence microscopes, LC-MS, GC, ICP, zeta analyser instruments.

Research Summary

I am an “Experimental Inorganic Chemist” specializing in the design, synthesis, and characterization of sustainable hybrid materials for, (I) environmental remediation and (II) quantum bits (qubits) development. My research focuses on developing novel coordination polymers (CPs) and metal-organic frameworks (MOFs) and macrocycles. These materials are tailored for applications in a) Fluorescence sensing, adsorptive/degradative removal of pollutants like nitroaromatics, organic dyes, solvents, iodine, and heavy metal ions from water; b) Enabling carbon capture and utilization (CCU), small organic transformations (SOT), and electrocatalytic water splitting; c) Exploring photonics applications like singlet fission (SF)-derived quintet qubits, triplet fusion, and quantum manipulation. I employ a variety of synthetic methods, including solvothermal, diffusion, and mechanochemical approaches, to produce high-crystalline, phase-pure materials. My research has contributed to sustainable solutions for environmental challenges and the development of photogenerated quintet qubits. Application-wise, my doctoral/postdoctoral research achievements can be classified in the following three categories:

1) MOFs for fluorescence sensing and encapsulation of hazardous organic/inorganic pollutants:

Despite the vast array of structurally unique MOFs reported in the literature, many lack the stability and functionality required for real-world applications. My doctoral research aimed to address these limitations by developing robust and luminescent MOFs (LMOFs) for practical use. To achieve this, we systematically identified and overcame the key challenges hindering LMOF development, as illustrated in Figure 1a. By strategically combining d10 metal nodes (Zn(II) and Cd(II)) with polycarboxylate and azine/acylhydrazone-based polypyridyl linkers (Figure 1b), we successfully synthesized over 50 structurally diverse and stable LMOFs. These materials were characterized using single-crystal X-ray diffraction and demonstrated exceptional performance in sensing and adsorbing pollutants from aqueous solutions. Our expertise and comprehensive understanding of the field have led to several perspective reviews (Inorg. Chem. Front. 2020; Dalton Trans. 2021) and original research publications. A few representative studies are highlighted below:

Figure 1. (a) Challenges in developing new LMOFs; (b) Explored N-donors; (c) & (d) representative depictions of sensing and adsorption application of CPs/MOFs.

Our pollutant sensors work involved some of outstanding LMOFs candidates, e.g. 2D [Cd(5-bromoisophthalate)(1,3,5-tris(imidazol-1-ylmethyl)benzene)]n which remains chemically stable for 60 days in the aqueous solution of TNP with ppb levels detection capacity; Two pairs of robust Zn and Cd frameworks, {[M(isophthalate)(L2)]}n and {[M(NH2-terephthalate)(L3)]}n those could detect ppm levels of chromates and ppb levels of 2,4,6-trinitrophenol and Fe3+/Pd2+ in aqueous solutions (Figure 1c). These results were achieved in the presence of interfering analytes and have been best at the time of publication (Dalton Trans. 2016; Inorg. Chem. 2017; Inorg. Chem. 2017).
We have also developed a series of multi-functional MOFs, which serves as a pollutant adsorbent (Figure 1d), e.g. {[Zn2(H-trimesate)2(L1)(H2O)2].solvent}n which could reversibly uptake as much as 60 to 97% of cationic dyes from their aqueous solutions; {[Zn or Cd2(5NO2-IP)2(L3)2](solvent)}n, {[Zn or Cd(5OH-IP)(L3)]}n and {[Cd(5-OH-IPA)(L2)]·solvent}n demonstrated excellent reversible dye removal capability from aqueous media. Practical applicability of this results for environmental remediation was further appreciated by the demonstrated dye removal using MOF packed columns (Dalton Trans. 2018; Mater. Chem. Front. 2021; Inorg. Chem. 2021; Dalton Trans. 2024).

2) MOFs for heterogeneous catalysis (CCS; SOT) and electrocatalytic water splitting:

The leaching of heterogeneous catalysts in aqueous, non-aqueous, or organic solvents has been a longstanding challenge for materials scientists. Given the thermal and chemical stability, as well as the presence of supramolecular unsaturated sites on our prepared materials, we were motivated to investigate their potential as heterogeneous catalysts (Figure 2). Some notable results are presented below:

Figure 2. Developed MOFs/CPs as a heterogeneous catalyst for various small organic transformations including CO2 fixation and MOF-derived nanomaterials as electrocatalyst for water splitting.

CO2 sequestration has been achieved in solvent-free and ambient conditions by employing MOFs, {[Zn(terephthalate)(L3)]}n, {[M(1,4-cyclohexanedicarboxylate)(L3)]}n, {[Co(oxybis(benzoate))(L3)]}n, {[Co(terephthalate) (L3)]}n, {[Cd(H or NH2-terephthalate)(L2)] ⋅ solvent}n as heterogeneous catalyst for cycloaddition reaction between organic epoxide and carbon dioxide (Figure 2; ChemCatChem 2018; Chem. Eur. J. 2018; J. Mater. Chem. A 2019; Inorg. Chem. 2019; Appl. Catal. A: Gen. 2020; Eur. J. Inorg. Chem. 2022). Similarly, C-H activation, Knoevenagel/Biginelli reaction, sulfoxidation/ oxidation, biomass conversion and regioselective ring-opening reaction are heterogeneously catalyzed by MOFs, {[M(1,3-adamantanediacetate)(L3)]}n, {[Zn2(5NO2-isophthalate)2(L2)2]}n, {[Zn(NH2-terephthalate)(L3)]}n, {[Zn or Cd(5OH-IP)(L2)]}n {[Zn2(D-camphorate)2(L2)]·solvent}n (Inorg. Chem. Front. 2018; Mater. Chem. Front. 2021; Dalton Trans. 2018; Inorg. Chem. 2021; ACS Appl. Nano Mater. 2022).
Additionally, a Co(II) containing MOF was pyrolyzed to obtain Co-nanoparticle encapsulated N-doped carbon nanomaterial which was utilized as electrocatalyst towards water splitting via oxygen / hydrogen evolution reaction (OER/HER) (Appl. Sur. Sci. 2020; RSC Adv. 2021). The electrocatalytic activity of these materials for OER outperformed the benchmark electrocatalyst such as RuO2 and IrO2 (Appl. Sur. Sci. 2020). Similarly, Ni(II) MOF derived core-shell Ni-nanoparticles as well as bimomass derived Fe-encapsulated N-doped graphitic carbon composites were utilized as capable bi-functional electocatalyst for water splitting and supercapacitor (Appl. Sur. Sci. 2023; Int. J. Hydrog. Energy 2024).

3) MOFs and Macrocycles for Photonic Applications: Singlet Fission, Triplet Fusion and Qubits:

Our primary goal was to develop quantum bits (qubits) with long coherence times in solid-state at mild temperatures, suitable for practical photonics applications in quantum sensing and quantum information science. Metal-Organic Frameworks (MOFs), known for their tunable structures, porosity, and guest accessibility, were considered ideal hosts for molecular qubits.

Figure 3. Schematic representation of acene based MOFs/macrocycles and their photonic properties explored for singlet fission, triplet fusion, quantum bits (qubits) and qunatum information science (QIS).

We designed and synthesized a series of singlet fission (SF)-active acene-MOFs with the UiO-68 topology. The highly crystalline acene-MOFs exhibits the generation of long-lived quintet qubits at room temperature. By carefully controlling the ratio of tetracene and pentacene chromophores in the hetero-linker system, we precisely tuned the quintet dynamics. Even with a small amount of pentacene, we observed quantum coherence in quintet multiexcitons at room temperature, with coherence times (T2) ranging from 175 to 200 ns (Figure 3a; Unpublished). .
We also developed a series of diazatetracene (DAT)-based MOFs with various topologies. Despite their different framework structures, these DAT-MOFs exhibited long-lived photoinduced radicals with extended T1/T2, even at room temperature. One of the robust and highly porous DAT-MOF with the UiO-68 topology demonstrated guest-responsive coherence changes (Figure 3b; Dalton Trans. 2024; Chem. Commun. 2024).
Furthermore, we synthesized acene-based macrocyclic parallel dimers (MPDs) and investigated their photophysical properties. Pentacene-containing MPD-1 exhibited quantum coherence in SF-generated quintet multiexcitons at room temperature with a long T2 of 648 ns. Anthracene-based MPD-2 demonstrated a green-to-blue triplet-triplet annihilation upconversion (TTA-UC) emission in the presence of a PtOEP triplet sensitizer, enhancing the spin statistical factor of TTA (Figure 3a&3c; J. Am. Chem. Soc. 2024; Precis. Chem. 2024).

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