Pragya
PMRF RESEARCH SCHOLAR
DEPARTMENT OF CHEMISTRY
IIT KANPUR
Research Interests
Bio-inorganic Chemistry
& Spectroscopic characterization
Active sites of various metalloenzymes contain high valent Metal-oxo's moieties that catalyze several crucial chemical transformations. Taking such designs as our model, we aim to generate mimic to such active sites using simple non-heme ligand designs. Our work is supported via the complete spectroscopic characterization of these high valent Metal-oxo species. Along with that, we do test the generated models for substrate oxidation qualitatively.
My Projects
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PMRF Project
January 2021 - Present
Development of structural and functional models to the Oxygen Evolving Complex in Photosystem-II
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Abstract :
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With the rise in global energy demands and the consequences of extreme dependence on classical energy resources, there is an urgent need to look for greener and renewable resources. Photosystem-II (PS-II), which possesses Mn4CaO5 cluster in the active site, has an exceptional water splitting efficiency. Here, we propose the synthesis and spectroscopic characterization of MnIV/V(O)(µ-O)(LA) species (LA = Lewis acid) as the closest structural, if possible functional models to the active site of the oxygen-evolving complex in PS-II. We aim to understand the working reaction mechanism by characterizing the putative intermediates responsible for their excellent reactivity towards water oxidation, electron transfer, and oxygen atom transfer reactions. We believe that our results may help develop ideal, highly efficient artificial PS-II mimics capable of performing synthetically useful transformations.
Jan 2022 - Dec 2022
Abstract- The reaction of [(L)MnII]2+ (L = neutral polypyridine ligand framework) in the presence of mCPBA (mCPBA = m-Chloroperoxybenzoic acid) generates a putative MnV=O species at RT. The proposed MnV=O species is capable of performing the aromatic hydroxylation of Cl-benzoic acid derived from mCPBA to give [(L)MnIII(m-Cl-salicylate)]+, which in the presence of excess mCPBA generates a metastable [(L)MnV(O)(m-Cl-salicylate)]+, characterized by UV/Vis absorption, EPR, resonance Raman spectroscopy, and ESI-MS studies. The current study highlights the fact that [(L)MnIII(m-Cl-salicylate)]+ formation may not be a dead end for catalysis. Further, a plausible mechanism has been proposed for the formation of [(L)MnV(O)-m-Cl-salicylate)]+ from [(L)MnIII(m-Cl-salicylate)]+. The characterized transient [(L)MnV(O)-m-Cl-salicylate)]+ reported in the current work exhibits high reactivity for oxygen atom transfer reactions, supported by the electrophilic character depicted from Hammett studies using a series of para-substituted thioanisoles. The unprecedented study starting from a non-heme neutral polypyridine ligand framework paves a path for mimicking the natural active site of photosystem II under ambient conditions. Finally, evaluating the intracellular effect of Mn(II) complexes revealed an enhanced intracellular ROS and mitochondrial dysfunction to prevent the proliferation of hepatocellular carcinoma and breast cancer cells.
Facile formation of a Mn-O-Ce species and its electron transfer equilibria with high valent Mn(IV) complexes
Jan 2022- Dec 2023
The manuscript is under revision for Angewandte Chemie International Edition.
Pivotal m-X-salicylates deciphering the fate of high valent Mn(V)=O
Jan 2023 - Dec 2023
This work has been communicated to Chemistry A European Journal.
A closest structural mimic to PS-II using non-heme tetradentate ligand design
Jan 2023 - Dec 2023
This work is under progress and will soon be communicated.
"Believe you can and you're halfway there"
Theodore Roosevelt
