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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, 5, 6] In fact we have recently shown that we can translate this concept to all-organic nanocages. [7] 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 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 Advances 2019, 5, 2, eaav4806.
[5] S. Paul, A. Das and J. Dasgupta*; submitted
[6] S. Ghoshal, A. Das, D. Roy, and J. Dasgupta*; under revision
[7] D. Roy, S. Paul, and J. Dasgupta*; submitted

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