Publication: Development Of Chromium and Molybdenum Complexes for CO₂ Hydrogenation and Biological Application
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Date
2024-12-31
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Indian Institute of Technology, Jodhpur
Abstract
The catalytic hydrogenation of the potent greenhouse gas carbon dioxide to value-added products represents a sought-after methodology in academia and industry. Molecular complexes facilitate the conversion of CO2 into formic acid, which is a beneficial process because formic acid is a versatile feedstock in many industries and can be used as a potential renewable hydrogen storage material. Group VI elements chromium and molybdenum are earth-abundant and low-toxic metals, and their chemistry towards the utilization of CO2 has been sparsely investigated. Therefore, we examined both the direct and indirect hydrogenation of CO2 using low-valent Mo(0) and Cr(0) complexes supported by multidentate phosphine ligands with varied bite angles. We achieved maximum formate TONs of 950 and 2,59000, the highest for any Mo and Cr system reported in the literature thus far. Mechanistic probing revealed that the reaction proceeded via the formation of anionic hydride species in both cases. Based on the initial success with low-valent Cr species, we performed CO2 hydrogenation using high-valent Cr (II) pincer complexes and obtained formate with a TON of 87,00. We also carried out the transfer hydrogenation of CO2 using isopropanol as the hydrogen source under ambient conditions using bidentate DPPP ligand-based low-valent chromium complex. A formate TON of up to 1974 was recorded using 1 bar CO2. This is a state-of-the-art discovery with regard to base metal catalysts. Lastly, we developed a NIR II-emitting low-valent Schiff base-supported chromium complex that is effective as an antibacterial agent against gram-positive pathogenic bacteria selectively. The current study deals with transition metal complexes derived from non-noble earth-abundant metals for catalytic and biological applications, and we believe this research opens new avenues for developing next-generation innovative catalysts and bioactive compounds.
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Tushar (2019).Development Of Chromium and Molybdenum Complexes for CO₂ Hydrogenation and Biological Application (Doctor's thesis).Indian Institute of Technology, Jodhpur