Vidya D. Avasare

Bio: Vidya D. Avasare is an academic researcher. The author has contributed to research in topics: Catalysis & Formic acid. The author has co-authored 1 publications.

Ascendancy of Nitrogen Heterocycles in the Computationally Designed Mn(I)PNN Pincer Catalysts on the Hydrogenation of Carbon Dioxide to Methanol.

Abstract: The development of sustainable catalysts to get methanol from CO2 under milder conditions and without any additives is still considered an arduous task. In many instances, transition-metal-catalyzed carbon dioxide to formic acid formation is more facile than methanol formation. This article provides comprehensive density functional theoretic investigations of six new Mn(I)PNN complexes, which are designed to perform CO2 to methanol conversion under milder reaction conditions. All these six catalysts have similar structural features except at terminal nitrogen, -N (1), where adenine-inspired nitrogen heterocycles containing pyridine and pyrimidine moieties are attached to instill an electron withdrawing effect on the central metal and thus to facilitate dihydrogen polarization during the catalyst regeneration. All these computationally modeled Mn(I)PNN complexes demonstrate the promising catalytic activity to get methanol through cascade catalytic cycles at 298.15 K. The metal-ligand cooperative (MLC) as well as noncooperative (NC) pathways are investigated for each catalytic cycle. The NC pathway is the preferred pathway for formic acid and formaldehyde formation, whereas methanol formation proceeds through only the MLC pathway. Different nitrogen heterocycles attached to the -N (1) terminal manifested a considerable amount of impact on the Gibbs free energies, overall activation energies, and computed turnover frequencies (TOFs). Among all the catalysts, SPCAT02 provides excellent TOFs for HCO2H (500 151 h-1), HCHO (11 912 h-1), and CH3OH (2 372 400 h-1) formation at 50 °C. SPCAT04 is found to be a better catalyst for the selective formation of formic acid formation at room temperature than the rest of the catalysts. The computed TOF results are found reliable upon comparison with experimentally established catalysts. To establish the structure-activity relationship, the activation strain model and Fukui function calculations are performed on all the catalysts. Both these studies provide complementary results. The present study revealed a very important finding that a more electrophilic metal center could facilitate the CO2 hydrogenation reaction robustly. All computationally designed catalysts could be cheaper and better alternatives to convert CO2 to methanol under mild reaction conditions in an aqueous medium.

A Shuttle Catalysis: Elucidating a True Reaction Mechanism Involved in the Palladium Xantphos-Assisted Transposition of Aroyl Chloride and Aryl Iodide Functional Groups.

Abstract: A thorough DFT study was performed to unravel the true mechanism involved in the Pd(0)-catalyzed functional group transposition between aroyl chlorides and aryl iodides. Two different experimental groups proposed different mechanisms for the functional group transposition reaction. A careful assessment of experimental findings and thorough computational studies endorsed that the functional group transposition proceeds via phosphonium salt formation and ligand-enabled C-P bond metathesis, leading to the formation of the PhI and the intermediate 2. After the formation of the intermediate 2, the transposition of functional groups takes place through the interpalladium ligand exchange mechanism, where two palladium centers act as shuttle catalysts. In short, both C-P bond metathesis and interpalladium ligand exchange steps are crucial in the functional group transposition mechanism.

Insights into the CO2 Capture Capacity of Covalent Organic Frameworks.

Abstract: An inexpensive computational model is designed to demonstrate the efficacy of the complex COF toward CO2 capture. The interaction energy calculations of small repeating units of COF precisely demonstrate CO2 uptake capacity at high pressure and effective dual descriptors values of these repeating units of COF accurately establish their structure-property relationships under ambient conditions. The computational findings are in consonance with experimental results. Further, the computationally modelled COF confirms that the addition of -NH2 increases the effective dual descriptors values of COF. Whereas an increase in the size of a central aromatic unit of COF6 shows better interactions. Interaction energy and effective dual descriptor calculations demonstrate the CO2 capture abilities of COF at high pressure and 1ow pressure respectively. The method developed by our group would be useful in high throughput designing and screening of a large number of complex COF at different pressure.