–
October 2, 2025
Speaker: Jyotishman Dasgupta (TIFR Mumbai, IND)
Host: Rafal Klain
Abstract
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 stra-
tegy [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,
sp C–H functionalization [5] and C–C bond formation [6] was demonstrated recently along2
with usage of aqueous reactivity by a 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 [8,9].
The success of our designed artificial photoenzyme hints at the crucial role of electric fields
in driving reactions within nanospaces.
[1] M. Fujita, Nature 1995, 378, 469–471.
[2] R. Gera, A. Das, A. Jha, J. Dasgupta, J. Am. Chem. Soc. 2014, 136, 15909–15912.
[3] A. Das, A. Jha, R. Gera, J. Dasgupta, J. Phys. Chem. C 2015, 119, 21234–21242.
[4] A. Das, I. Mandal, R. Venkatramani, J. Dasgupta, Sci. Adv. 2019, 5, eaav4806.
[5] S. Ghosal, A. Das, D. Roy, J. Dasgupta, Nat. Commun. 2024, 15, 1810.
[6] D. Roy, S. Paul, J. Dasgupta, Angew. Chem. 2023, 62, e202312500.
[7] R. Gera, P. De et al., J. Am. Chem. Soc. 2024, 146, 21729–21741.
[8] S. Paul, A. Das, J. Dasgupta, to be submitted.
[9] D. Roy, K. Yadav, J. Dasgupta, Acc. Chem. Res. 2025, under revision.