Photoredox Transformations in Water using Host-Guest Charge Transfer Chemistry
Tuesday, April 29th, 4 pm
Department of Chemistry of ENS, Salle R
24, rue Lhomond, 75005 Paris
Prof. Jyotishman Dasgupta
Department of Chemical Sciences
Tata Institute of Fundamental Research
Mumbai, India
Contact Number: +91-9967293402
e-Mail: dasgupta@tifr.res.in
Homepage: https://x.com/jd1278
Enzymes are proteins that catalyze non-spontaneous organic reactions in physiological conditions. Remarkably the water-insoluble organic substrates are usually encapsulated in hydrophobic protein cavities, which constitute reaction hotspots in enzymes. We have devised a new catalytic photoredox paradigm using water-soluble cationic nanocages [1] that mimic the enzyme cavity while providing a modular host-guest photoactivation strategy. [2, 3,] Through the potent combination of light activation and substrate pre-organization in water, we demonstrate facile yet selective aerobic oxidation of hydrocarbon C-H bonds under ambient conditions using proton-coupled electron transfer (PCET).[ 2, 4] Additionally sp2 C-H functionalization [5] and C-C bond formation [6] was demonstrated recently along with usage of aqueous reactivity by an novel cage-trapped Fe(IV)-superoxo complex.[7] Using time-resolved Raman spectroscopy, we show that the water cluster around and inside the nanocage plays a crucial role in driving the PCET chemistry leading to C-H activation. [8] The success of our designed artificial photoenzyme hints at the crucial role of electric fields in driving reactions within nanospaces.
References
[1] M. Fujita; Nature 378, 469–471(1995).
[2] R. Gera, A. Das, A. Jha and J. Dasgupta*; J. Am. Chem. Soc. 136, 15909(2014).
[3] A. Das, A. Jha, R. Gera and J. Dasgupta*; J. Phys. Chem. C , 119, 21234–21242 (2015).
[4] A. Das, I. Mandal, R. Venkatramani, J. Dasgupta*; Science Adv. 5, eaav4806 (2019).
[5] S. Ghosal, A. Das, D. Roy and J. Dasgupta*; Nature Comm 15, 1810 (2024).
[6] D. Roy, S. Paul, and J. Dasgupta*; Angew. Chem. 62, e202312500 (2023).
[7] R. Gera and P. De et al.; J. Am. Chem. Soc. 146, 21729–21741 (2024).
[8] S. Paul, A. Das and J. Dasgupta*; to be submitted.
***
Jyotishman Dasgupta received his 5-years Integrated Masters degree in chemistry from Indian Institute of Technology, Kharagpur in 2000. Subsequently he moved to Princeton University as a Hughes Stott Taylor graduate fellow where he carried out his Ph.D. work in the field of oxygenic photosynthesis under the supervision of Prof. G. Charles Dismukes. In 2006, he moved to UC Berkeley where he did his postdoctoral work with Prof. Richard A. Mathies. He joined the Tata Institute of Fundamental Research, Mumbai in 2010, and has been there ever since. The central theme of his research group is to probe dynamical structural events leading to charge generation in molecular materials, in order to fabricate bio-inspired molecule-based devices for photocatalysis and solar electricity generation. He received the 2017 Asian and Oceanian Photochemical Association (APA) Prize for Young Scientist, the 2018 Best Emerging Investigator Award and the 2024 CRS Silver Medal. He has been inducted as a Fellow in the Royal Society of Chemistry as “Leaders in Field”, and has been in the editorial board of the major physical chemistry journals: JPC Letters, Journal Physical Chemistry and Journal of Chemical Physics.
MAJOR CONTRIBUTIONS:
- Devised a new photoredox route to organic transformations in water (JACS 2024, NatComm 2024, AngewChem 2023; Science Advances2019; JACS 2014)
- Developed a new way to think about Singlet Exciton Fission mechanism (Chemical Science 2022; NatComm 2022, JPC Letters 2021; NatureComm 2019)
- Used time-resolved vibrational spectroscopy to watch charge transfer reactions in photoactive materials (JPCB 2023, JPC Letters 2020; NatureComm2017)