Enhancing Oxygenic Photosynthesis by Cross-Linked Perylenebisimide “Quantasomes”

Abstract

As the natural-born photoelectrolyzer for oxygen delivery, photosystem II (PSII) is hardly replicated with man-made constructs. However, building on the “quantasome” hypothesis ( 17811607 Science 1964 144 1009 1011 ), PSII mimicry can be pared down to essentials by shaping a photocatalytic ensemble (from the Greek term ”soma” = body) where visible-light quanta trigger water oxidation. PSII-inspired quantasomes (QS) readily self-assemble into hierarchical photosynthetic nanostacks, made of bis-cationic perylenebisimides (PBI 2+ ) as chromophores and deca-anionic tetraruthenate polyoxometalates (Ru 4 POM) as water oxidation catalysts ( 30510216 Nat. Chem. 2019 11 146 153 ). A combined supramolecular and click-chemistry strategy is used herein to interlock the PBI-QS with tetraethylene glycol (TEG) cross-linkers, yielding QS-TEG lock with increased water solvation, controlled growth, and up to a 340% enhancement of the oxygenic photocurrent compared to the first generation QS, as probed on 3D-inverse opal indium tin oxide electrodes at 8.5 sun irradiance (λ > 450 nm, 1.28 V vs RHE applied bias, TOF max = 0.096 ± 0.005 s –1 , FE O2 > 95%). Action spectra, catalyst mass-activity, light-management, photoelectrochemical impedance spectroscopy (PEIS) together with Raman mapping of TEG-templated hydration shells point to a key role of the cross-linked PBI/Ru 4 POM nanoarrays, where the interplay of hydrophilic/hydrophobic domains is reminiscent of PSII-rich natural thylakoids.

Photoelectrochemical C−H Activation Through a Quinacridone Dye Enabling Proton‐Coupled Electron Transfer

“…Dye-sensitized photoelectrochemical cells (DS-PECs) constitute an appealing tool for exploiting solar light to drive sustainable chemical processes, such as the conversion of abundant small molecules and raw materials into valuable products. [1,2] Since the seminal work by Mallouk and co-workers, [3] many efforts have been oriented towards the design of dye-sensitized photoelectrodes for the splitting of water into hydrogen and oxygen, [4][5][6][7] combining cathodic water reduction and anodic water oxidation. More recently, oxidation of organic compounds has emerged as an alternative anodic process, [8,9] with the double advantage of i) bypassing the significant thermodynamic and kinetic hurdles of the water oxidation reaction, while ii) targeting valuable reaction products instead of oxygen.…”

Covalent post-assembly modification of π-conjugated supramolecular polymers delivers structurally robust light-harvesting nanoscale objects

“…21 Others have recently capitalized on this methodology to engineer elegant solar energy transduction complexes. 24 Herein, the scope of the two-component stapling method is expanded by elucidating how the monomer structures that comprise model π-SPs in conjunction with tether lengths regulate the photophysical properties of stapled assemblies. To do so, we use novel water-soluble π-SPs built from bay-functionalized perylene bisimide (PBI) units to highlight that the structure of the reactive side chains flanked on PBI building blocks is a structural component to regulate the interactions between π-conjugated cores in the final stapled assemblies.…”

“…21 Others have recently capitalized on this methodology to engineer elegant solar energy transduction complexes. 24…”

A breath of sunshine: oxygenic photosynthesis by functional molecular architectures

“…29 To this end, supramolecular strategies can include electrostatic assemblies favoured by multi-charge interactions, 30,31 as in the case of tetravalent cations (such as Zr IV , vide infra ) binding to carboxylate pendants, 32,33 liposome membranes, 34,35 polymeric coatings, 36 and hierarchical photosynthetic architectures with controlled morphology, optimized for the light-quanta conversion. 37–41…”

“…Fig.18Second-generation quantasomes, exploiting an inter-locked multi-chromophoric antenna system based on PBI photosensitizers bearing hydrophilic tetraethylene glycol chains (TEG). Reprinted from ref 39. with permission from the American Chemical Society, copyright 2022.…”