My research focuses primarily on quantum chemical calculations and in silico screenings of potential catalysts and functional materials to address real-world issues such as sustainability and energy. Specific research directions include understanding polymerization reaction mechanisms, catalysis utilizing heterogeneous support materials like metal-organic frameworks, C–H functionalization reactions relevant to pharmaceuticals and agrochemicals, as well as metal-halide perovskite materials for solar cells and lighting.
The University of ChicagoPostdoctoral Research AssociateAdvisor: Prof. Laura GagliardiResearch Interests:
Chicago, IL |
Max Planck Institute for Polymer ResearchHumboldt Postdoctoral FellowGroup Leader: Dr. Denis AndrienkoResearch Interests:
Mainz, RP, Germany |
CSIR-National Chemical LaboratoryResearch InternAdvisor: Prof. Debashree GhoshResearch Project:
Pune, India |
MN, USA |
Indian Institute of Technology (IIT) BombayMSc in ChemistryAdvisor: Prof. G. Naresh PatwariMaster's Thesis: Study of Phenylacetylene Analogues in the Gas Phase using Time of Flight Mass Spectrometry Mumbai, India |
Ramakrishna Mission Residential College (Autonomous)BSc in ChemistryNarendrapur, WB, India |
Plastic pollution is a major environmental concern that requires immediate action. One potential solution is to replace petroleum-based plastics with biodegradable or compostable polymers made from biomass-derived monomers. Bioplastics can be synthesized using ring-opening polymerization (ROP), which often requires the use of metal alkoxide catalysts to facilitate the reaction. Our research aims to better understand the mechanisms of ROP and identify ways to optimize the process through the development of faster and more efficient catalysts, with the ultimate goal of making bioplastics more commercially viable.
Metal-halide perovskites (MHPs) are a class of materials that have gained significant attention due to their exceptional performance in a variety of applications, including solar cells and light-emitting diodes (LEDs). These materials have a general formula of ABX3, where X– is an anion that is bonded to both A+ and B2+ cations. Our research involves the study of both bulk perovskite materials and perovskite nanocrystals (PNCs). Our focus is on improving the efficiency of exciton generation in bulk perovskite materials for use in solar cells, and eliminating carrier recombination pathways. Additionally, we are interested in enhancing charge transport between PNCs through the use of virtual screening to identify ligands with extended π-conjugation that can replace the native insulating ligands on the PNCs.
Small-molecule mononuclear copper(III) compounds, such as hydroxo, peroxo, and benzoate, which mimic biological molecules/enzymes, have been found to initiate hydrocarbon oxidation by activating X–H bonds (X = C, O). These reactions can occur through hydrogen-atom transfer (HAT) or concerted proton-coupling electron transfer (cPCET). In our research, we utilize theoretical techniques such as the analysis of the total dipole moment vector oriented along the hydrogen donor-acceptor axis and direct visualization of the localized intrinsic bond orbitals as they evolve along the reaction coordinate to distinguish between HAT and cPCET mechanisms.
Due to their crystalline structure and porosity, Metal–organic frameworks (MOFs) are an appealing choice as support materials for catalytic moieties. To demonstrate this, our synthesis team synthesized two single-site heterogeneous catalysts by immobilizing vanadium oxide (VOx) species on zirconium- and hafnium-based MOFs, Zr-NU-1000 and Hf-MOF-808, respectively. We then used a DFT-based approach to study the structural features of these VOx-incorporated MOFs, or V-MOFs, and probed their reactivity towards selective oxidation of benzyl alcohol to benzaldehyde. Additionally, the structure and reactivity of palladium-based catalysts anchored to acid-functionalized hafnium-based MOFs were examined, and it was found that the acid-functionalized MOF nodes enhanced catalytic activity.
In this collaborative project, copper-catalyzed radical relay chemistry is used to functionalize diverse molecules with benzylic C–H bonds under mild conditions, resulting in the formation of C–X bonds (X = CN, N3, OMe). The mechanism and enantioselectivity of this reaction are of significant interest to organic synthesis and in particular to medicinal and agricultural chemistry. Using density functional theory, we analyzed multiple potential energy surfaces to understand C–X bond formation. Our results indicate that the mechanism of the reaction depends on the nucleophile X, leading to enantioselectivity in certain cases (X = CN) but not in others (X = N3, OMe).
Melanin is a pigment found in human skin that can both protect against and contribute to photodamage. Although photodegradation of melanin has been linked to photoionization processes, little is known about the oxidation potential of melanin and its monomers. In this project, we calculated the ionization energies of eumelanin monomers, dimers, and oligomers to determine the threshold energy for ionization, which we found to be within the UV-B range. Additionally, we examined the charge and spin distributions of ionized monomers to understand which ionization channels might promote eumelanin monomerization.
This research focuses on the use of hybrid nanographene–graphene (NG–Gr) van der Waals heterostructures (vdWHs) as materials for optoelectronic devices. We found that adjusting the size of synthesized NGs can control the strength of van der Waals interactions in NG–Gr vdWHs, which enables control over interfacial charge transfer. The interfacial charge transfer efficiency and rate in NG-Gr vdWHs increased when the size of NGs were increased from 42 to 96 sp2 carbon atoms, despite the reduction in the interfacial energy driving the charge transfer process. These findings suggest that vdW interactions are the primary factor in determining the interfacial charge transfer efficiency in NG–Gr vdWHs, while interfacial energetics and reorganization energy have only a minor influence.
This research aims to develop a molecular probe that can be used to measure temperature in vivo during magnetic resonance imaging (MRI). We used virtual screening to identify organofluorine compounds that could potentially improve the accuracy and sensitivity of 19F MRI-based temperature monitoring. In collaboration with our experimental team, we have developed a perfluoro-sulfane-based compound that showed a nearly 2-fold increase in temperature responsiveness compared to the current standard 19F MRI temperature sensor (perfluoro-tributylamine) and the 1H resonance frequency, a standard parameter used for temperature mapping in MRI. The ultimate goal of this work is to enhance the diagnostic capabilities of 19F MRI and promote the use of fluorine magnetic resonance techniques in clinical practice.
Synopsis: Cu-catalyzed C(sp3)–H functionalization with NFSI utilizes the Cu-bound •NSI radical for selective benzylic C–H bond activation, with the resulting radical functionalization pathways dependent on the copper-bound nucleophile.
Synopsis: Two vanadium oxide catalysts attached to two different MOFs were studied using DFT, revealing that the MOF node architecture significantly affected their catalytic activity towards selective oxidation of benzyl alcohol to benzaldehyde.
Synopsis: The reactivity of LCuIII–Y complexes (Y = OH, OOCm, O2CAr) in activating X–H bonds (X = C, O) varies based on differing oxidizing abilities of the CuIII complexes and X–H bond functionalization mechanisms, with LCuIII–OH showing the highest reactivity.
Synopsis: An efficient {N,N,N,N}-aluminum complex with a bis-indolide Schiff-base ligand for the ring-opening polymerization of ε-caprolactone was identified through computational screening, synthesis, characterization and experimental reactivity evaluation.
Synopsis: The threshold energy for ionization of melanin monomers, dimers, and oligomers has been studied and found to fall within the UV-B range. The charge and spin distributions of ionized monomers were also studied to see which ionization channels promote monomerization.
Synopsis: A distinct odd-even oscillation of the charge carrier transport in 2D Sn-based perovskite semiconductors by incorporating phenylalkylammonium-based organic cations with different alkyl side chain lengths with odd and even carbon atoms is observed.
Key Takeaways:
Synopsis: Cu-catalyzed C(sp3)–H functionalization with NFSI utilizes the Cu-bound •NSI radical for selective benzylic C–H bond activation, with the resulting radical functionalization pathways dependent on the copper-bound nucleophile.
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Synopsis: Insertion of an ultrathin metal-fluoride interlayer at the perovskite/C60 interface in perovskite-silicon tandem solar cells can reduce nonradiative recombination and improve electron extraction, resulting in a higher power conversion efficiency of 29.3%.
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Synopsis: Hot-casting improves charge carrier transport in SnII-based 2D perovskite field-effect transistors containing a thiophene-based organic cation spacer by controlling grain size and boundary density.
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Synopsis: Addition of a small amount of Sr2+ dopant to pristine CsPbBr3 and Mn2+-doped CsPb(Br,Cl)3 perovskite nanocrystals improves the photoluminescence quantum yields and luminous efficiency of white LEDs by reducing defect density.
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Synopsis: Treatment of perovskite nanocrystals (PNCs) with p-dopant LiTFSI, an organic lithium salt, improves optoelectronic properties such as photoluminescence quantum yields, exciton lifetimes, and external quantum efficiencies in PNCs and LEDs derived from them.
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Synopsis: A perfluoro-sulfane-based compound is developed as a molecular probe for in vivo temperature monitoring during magnetic resonance imaging, showing a nearly 2-fold increase in temperature responsiveness compared to the current standard.
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Synopsis: The strength of van der Waals interactions in hybrid nanographene-graphene heterostructures can be controlled by adjusting the size of synthesized nanographenes, with larger nanographenes resulting in increased charge transfer efficiency and rate.
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Synopsis: Minimizing strain during the self-assembly of CsPbX3 perovskite nanocrystal (PNC) supercrystals is crucial to prevent surface defects caused by misaligned PNCs and compressive strain at their edges, which can reduce fluorescence lifetimes.
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Synopsis: Native surface ligands on all-inorganic CsPbBrI2/SiOx perovskite nanocrystals were replaced with exciton delocalizing mono-functionalized porphyrin derivatives, resulting in increased phase stability and improved optoelectronic properties.
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Synopsis: Two vanadium oxide catalysts attached to two different MOFs were studied using DFT, revealing that the MOF node architecture significantly affected their catalytic activity toward selective oxidation of benzyl alcohol to benzaldehyde.
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Synopsis: A radical-polar crossover pathway for benzylic azidation with a CuII-azide species and a benzyl radical coupling partner is presented, showing unique site-selectivity and producing benzyl azides that can be converted to different functional groups.
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Synopsis: A copper-catalyzed oxidative cross-coupling reaction was developed to synthesize diverse benzyl ethers by coupling benzylic C–H bonds with alcohols, using dialkylphosphites as in situ reductants which allowed for the regeneration of catalytically active CuI.
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Synopsis: Aluminum complexes supported by salen-like indolide-imine ligands were found to catalyze stereoselective polymerization of rac-lactide, and it was concluded that the stereochemistry of initiation in these complexes is governed thermodynamically, not kinetically.
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Synopsis: CuIII-carboxylate complexes with varying –R groups revealed a correlation between their redox properties, UV-vis characteristics, and PCET rates and suggested an oxidatively asynchronous PCET mechanism sensitive to the oxidative power of [CuIII(O2CR)]2+.
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Synopsis: The reactivity of LCuIII–Y complexes (Y = OH, OOCm, O2CAr) in activating X–H bonds (X = C, O) varies based on differing oxidizing abilities of the CuIII complexes and X–H bond functionalization mechanisms, with LCuIII–OH showing the highest reactivity.
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Synopsis: Acid functionalization of the MOF node with PO42– and SO42– groups stabilizes PdII site in MOF-supported PdII catalysts and enhances their catalytic activity in the oxidative Heck reaction by preventing catalyst deactivation due to Pd0 aggregation.
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Synopsis: The annulation and subsequent conversion of rigid sugar-derived monomer, isosorbide, into linear or cyclic polymers via cationic and quasi-zwitterionic ring-opening polymerization are discussed, revealing its potential for use in high-performance materials.
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Synopsis: An efficient {N,N,N,N}-aluminum complex with a bis-indolide Schiff-base ligand for the ring-opening polymerization of ε-caprolactone was identified through computational screening, synthesis, characterization and experimental reactivity evaluation.
Key Takeaways:
Synopsis: The effectiveness of aluminum salen catalysts with o-adamantyl and o-tbutyl substituents in initiating the polymerization of ε-caprolactone is compared, revealing that bulky o-substituents improve the reactivity by distorting the precatalyst geometry in a favorable way.
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Synopsis: The rate of polymerization of rac-lactide using LXZn catalysts was found to be less sensitive to electronic effects of ligand substituents. Changing phenol para-substitutions changed Zn partial charge only slightly, suggesting that extensive nitrogen functionality around Zn buffers the effect of phenol substitution.
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Synopsis: Epoxide/anhydride copolymerization using (salph)AlCl/[PPN]Cl catalytic pairs showed a first-order rate of polymerization for epoxide and zero-order for cyclic anhydride. The reaction proceeds via two catalytic cycles that share a common intermediate with carboxylate ligation, preventing possible side reactions.
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Synopsis: The rigidity of the ligand geometry of TMTAA(Al–OR) impairs its catalytic efficiency for the ring-opening polymerization (ROP) of ε-caprolactone, as a high energy input is required to induce deformation of the precatalyst geometry and reach the transition-state. This highlights the significance of ligand flexibility in the design of ROP catalysts.
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Synopsis: The threshold energy for ionization of melanin monomers, dimers, and oligomers has been studied and found to fall within the UV-B range. The charge and spin distributions of ionized monomers were also studied to see which ionization channels promote monomerization.
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