Jyotishman Dasgupta

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 1995, 378, 469–471.
[2] R. Gera, A. Das, A. Jha and J. Dasgupta*; J. Am. Chem. Soc. 2014, 136, 15909.
[3] A. Das, A. Jha, R. Gera and J. Dasgupta*; J. Phys. Chem. C 2015, 119, 21234–21242.
[4] A. Das, I. Mandal, R. Venkatramani, J. Dasgupta*; Science Adv. 2019, 5, 2, eaav4806.
[5] S. Ghosal, A. Das, D. Roy and J. Dasgupta*; Nature Comm 2024, 15, 1810
[6] D. Roy, S. Paul, and J. Dasgupta*; Angew. Chem. 2023, doi.org/10.1002/anie.202312500
[7] R. Gera and P. De et al.; J. Am. Chem. Soc. 2024, accepted
[8] S. Paul, A. Das and J. Dasgupta*; submitted