Artificial Photosynthesis Empowered by PSII-Inspired Supramolecular Quantasomes with Chiral Architectures

Being the natural-born photoelectrolyzer for oxygen delivery, Photosystem II (PSII) is hardly replicated with man-made constructs. In particular, the PSII organization in natural thylakoids sets key guidelines to rethink the molecular design of groundbreaking artificial photo-electrolysers. Building on the early “quantasome” hypothesis (<i>Science 1964, 144, 1009-1011</i>), PSII mimicry can be pared down to essentials by shaping a photocatalytic ensemble (from the Greek term ”soma”= body) where light-quanta trigger water oxidation. We have recently reported on PSII-inspired nanodimensional quantasomes (QS) that readily self-assemble into hierarchical photosynthetic nano-stacks, made of bis-cationic perylenebisimides (PBI²⁺) as chromophores and deca-anionic tetraruthenate polyoxometalates (Ru4POM) as water oxidation catalysts (<i>Nature Chem.</i> 2019, 11, 146–153). A combined supramolecular and click-chemistry strategy allows to interlock the multi-lamellar architecture emerging from the perylene aromatic stacking in water, while installing tetraethylene glycol (TEG) cross-linkers thus enhancing water harvesting and transport in proximity of the oxygen evolving center (<i>J. Am. Chem. Soc.</i> 2022, 144, 14021-14025). <i>Our breaking new results deal with the introduction of sugar-based substituents as asymmetry effectors for the assembly of chiral quantasomes</i> evolving oxygen using low energy green photons (λ &gt; 450 nm, FEO₂ &gt; 95 %). Action spectra, mass-activity, light-management, photoelectrochemical impedance spectros-copy (PEIS) together with Raman mapping of hydration shells, point to a key role of the supramolecular structure nano-arrays, where the interplay of hydrophilic, hydrophobic and chiral domains is reminiscent of PSII-rich natural thylakoids.<br/>References<br/>[1] Scheuring, S., Sturgis, J. N. Chromatic Adaptation of Photosynthetic Membranes. Science 309, 484–487 (2005); Sartorel, A., Carraro, M., Toma, F. M., Prato, M., Bonchio, M. Shaping the beating heart of artificial photosynthesis: oxygenic metal oxide nano-clusters. Energy Environ. Sci. 5, 5592 (2012);<br/>[2] Piccinin, S.; Sartorel, A.; Aquilanti, G.; Goldoni, A.; Bonchio, M.; Fabris, S. Water oxidation surface mechanisms replicated by a totally inorganic tetraruthenium-oxo molecular complex. Proc. Natl. Acad. Sci. 110, 4917–4922 (2013)<br/>[3] Toma, F. M.; Prato, M.; Bonchio, M. et al. Efficient water oxidation at carbon nanotube–polyoxometalate electrocatalytic interfaces. Nature Chemistry 2, 826-831 (2010).<br/>[4] Bonchio, M.; Sartorel, A.; Prato, M. et al. Hierarchical organization of perylene bisimides and polyoxometalates for photo-assisted water oxidation. Nature Chemistry 11, 146-153 (2019).<br/>[5] Gobbo, P.; Bonchio, M.; Mann, S. et al. Catalytic processing in ruthenium-based polyoxometalate coacervate protocells Nature Commun 11, 41 (2020);<br/>[6] GobbatoT.; Rigodanza F.; Benazzi, E.; Prato, M.; Bonchio M. et al. J. Am. Chem. Soc.144,14021-14025 (2022).