Photoswitchable imines: aryliminopyrazoles quantitatively convert to long-lived <i>Z</i>-isomers with visible light

Wu, Jiarong; Kreimendahl, Lasse; Tao, Suyuan; Anhalt, Olga; Greenfield, Jake L.

doi:10.1039/d3sc05841g

Cited by 17 publications

(9 citation statements)

References 67 publications

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“…Imine E ‑ 1 was quantitatively formed from the condensation of A and B in CDCl 3 (Figure a) . The addition of aniline C to E ‑ 1 leads to a series of transimination reactions, creating a complex dynamic covalent network as depicted in Figure b.…”

Section: Resultsmentioning

confidence: 99%

“…This indicates that the photochemical E ‑ 1 to Z ‑ 1 pathway is dominant in this part of the cycle. (ii) Given that the 405 nm PSS is obtained for 1 , the impact of the unimolecular thermally induced Z -to- E isomerization on the amount of Z ‑ 1 generated is not significant under continuous photoirradiation . (iii) The E ‑ 2 , Z ‑ 2 , and aminal‑2 cycles can also be omitted (purple-shaded cycle, Figure b): the amount of Z -isomer generated under 405 nm irradiation remains unchanged upon addition of C (50 equiv).…”

Section: Resultsmentioning

confidence: 99%

“…We have recently introduced a new class of imine-based photoswitches, termed as aryliminopyrazoles (AIPs) . These switches can be prepared quantitatively from commercially available precursors and display useful photoswitching properties: achieving over 95% conversion to the metastable Z -isomer with visible light, good fatigue resistance, exhibit negative photochromism, and thermal half-lives ( t 1/2 ) of up to 19 h at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Photoswitchable Imines Drive Dynamic Covalent Systems to Nonequilibrium Steady States

Wu,

Greenfield

2024

J. Am. Chem. Soc.

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Coupling a photochemical reaction to a thermal exchange process can drive the latter to a nonequilibrium steady state (NESS) under photoirradiation. Typically, systems use separate motifs for photoresponse and equilibrium-related processes. Here, we show that photoswitchable imines can fulfill both roles simultaneously, autonomously driving a dynamic covalent system into a NESS under continuous light irradiation. We demonstrate this using transimination reactions, where E-to-Z photoisomerism generates a more kinetically labile species. At the NESS, energy is stored both in the metastable Z-isomer of the imine and in the system’s nonequilibrium constitution; when the light is switched off, this stored energy is released as the system reverts to its equilibrium state. The system operates autonomously under continuous light irradiation and exhibits characteristics of a light-driven information ratchet. This is enabled by the dual-role of the imine linkage as both the photochromic and dynamic covalent bond. This work highlights the ability and application of these imines to drive systems to NESSs, thus offering a novel approach in the field of systems chemistry.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photoswitchable Imines Drive Dynamic Covalent Systems to Nonequilibrium Steady States

Wu,

Greenfield

2024

J. Am. Chem. Soc.

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“…It is only with this additional care that there can be confidence in the structural determination of photoswitchable materials using X-ray radiation. This understanding is vital as the field advances to harness the improved properties of new photoswitches with greater isomerisation control, such as aryliminopyrazoles, [44] and to optimise these systems towards applications in solar energy storage, drug delivery, or catalysis.…”

Section: Discussionmentioning

confidence: 99%

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

Jones,

Blayo,

Greenfield

et al. 2024

Preprint

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Dynamic, responsive materials can be built using photosurfactants (PS) that self-assemble into ordered nanostructures, such as micelles or liquid crystals. These PS contain photoswitchable groups, such as azobenzene (Azo) or, more recently, arylazopyrazoles (AAPs), which change shape and polarity on photoisomerisation between the E and Z states, thus changing the self-assembled structure. Small-angle X-ray scattering (SAXS) is a powerful technique to probe the morphology of PS and can be used to measure the mechanisms of structural changes using in-situ light irradiation with rapid, time-resolved data collection. However, X-ray irradiation has been shown previously to induce Z-to-E isomerisation of Azo-PS, which can lead to inaccuracies in the measured photostationary state. Here, we investigate the effect of light and X-ray irradiation on micelles formed from two different PS, containing either an Azo or AAP photoswitch using SAXS with in-situ light irradiation. The effect of X-ray irradiation on the Z isomer is shown to depend on the photoswitch, solvent, concentration and morphology. We use this to create guidelines for future X-ray experiments using photoswitchable molecules, which can aid more accurate understanding of these materials for application in solar energy storage, catalysis or controlled drug delivery.

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“…Our design considerations appear to be valid for other classes of photoswitches as well, such as imines. [27]…”

Section: Generality Of Molecular Designmentioning

confidence: 99%

Solar Azo‐Switches for Effective E→Z Photoisomerization by Sunlight

Zhang,

Dong,

Bösking

et al. 2024

Angewandte Chemie

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Natural photoactive systems have evolved to harness broad‐spectrum light from solar radiation for critical functions such as light perception and photosynthetic energy conversion. Molecular photoswitches, which undergo structural changes upon light absorption, are artificial photoactive tools widely used for developing photoresponsive systems and converting light energy. However, photoswitches generally need to be activated by light of specific narrow wavelength ranges for effective photoconversion, which limits their ability to directly work under sunlight and to efficiently harvest solar energy. Here, focusing on azo‐switches—the most extensively studied photoswitches, we demonstrate effective solar E→Zphotoisomerization with photoconversions exceeding 80% under unfiltered sunlight. These sunlight‐driven azo‐switches are developed by rendering the absorption of E isomers overwhelmingly stronger than that of Z isomers across a broad ultraviolet to visible spectrum. This unusual type of spectral profile is realized by a simple yet highly adjustable molecular design strategy, enabling the fine‐tuning of spectral window that extends light absorption beyond 600 nm. Notably, back‐photoconversion can be achieved without impairing the forward solar isomerization, resulting in unique light‐reversible solar switches. Such exceptional solar chemistry of photoswitches provides unprecedented opportunities for developing sustainable light‐driven systems and efficient solar energy technologies.

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Photoswitchable imines: aryliminopyrazoles quantitatively convert to long-lived Z-isomers with visible light

Abstract: Arylimines offer promise in dynamic-covalent materials due to their recyclability and ease of synthesis. However, their light-triggered E/Z isomerism has received little attention. This is attributed to challenges that include...

Cited by 17 publications

References 67 publications

Photoswitchable Imines Drive Dynamic Covalent Systems to Nonequilibrium Steady States

Photoswitchable Imines Drive Dynamic Covalent Systems to Nonequilibrium Steady States

Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

Solar Azo‐Switches for Effective E→Z Photoisomerization by Sunlight

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