Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding

Marlton, Samuel; McKinnon, Benjamin I.; Hill, Nicholas S.; Coote, Michelle L.; Trevitt, Adam J.

doi:10.1021/jacs.0c11978

Cited by 23 publications

(30 citation statements)

References 58 publications

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“…To our knowledge, our study of the effect of alkali metal complexation on oxybenzone is the first to directly probe how cation binding can affect the photodynamics of a sunscreen molecule. However, our results were mirrored by other subsequent studies where metal cation binding has been reported to significantly perturb the excited-state behaviour of an aromatic molecule ( Marlton et al, 2021 ; Robertson et al, 2021 ), indicating that cation coordination may have widespread photochemical importance.…”

Section: Sodium Cation Binding Can Disrupt Sunscreen Actionsupporting

confidence: 85%

Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes

Wong

Dessent

2022

Front. Chem.

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Sunscreens are essential for protecting the skin from UV radiation, but significant questions remain about the fundamental molecular-level processes by which they operate. In this mini review, we provide an overview of recent advanced laser spectroscopic studies that have probed how the local, chemical environment of an organic sunscreen affects its performance. We highlight experiments where UV laser spectroscopy has been performed on isolated gas-phase sunscreen molecules and complexes. These experiments reveal how pH, alkali metal cation binding, and solvation perturb the geometric and hence electronic structures of sunscreen molecules, and hence their non-radiative decay pathways. A better understanding of how these interactions impact on the performance of individual sunscreens will inform the rational design of future sunscreens and their optimum formulations.

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Section: Sodium Cation Binding Can Disrupt Sunscreen Actionsupporting

confidence: 85%

Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes

Wong

Dessent

2022

Front. Chem.

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“…Increasing equivalents of Mg 2+ ions appear to extend the absorption via the 1 ππ* band to longer wavelengths, ultimately eclipsing the 1 nπ* band contribution. Drawing on the gas-phase cluster studies of Marlton et al, we attribute this phenomenon to stabilization of the 1 ππ* state by coordination of a Mg 2+ cation to the ACP carbonyl group. From these observations, the excitation wavelengths (λ exc ) selected for TEAS experiments were 280 and 320 nm to compare excited-state dynamics following UV absorption in the 1 ππ* and 1 nπ* bands and to explore the effects of metal-ion coordination on the ultrafast photochemistry of ACP.…”

mentioning

confidence: 76%

“…They were also able to demonstrate the preferential photoexcitation of benzophenone molecules transiently hydrogen-bonded to phenol co-solute molecules, thereby enhancing the rate of bimolecular reaction beyond the diffusional limit . Coote and co-workers used TD-DFT calculations to show that coordinated Lewis acids can tune excited-state energy levels in Irgacure 2959, a commercially available ACP derivative. ,, This mechanism was validated experimentally by using several different metal ions to establish orientated electric fields (OEFs) in gas-phase complexes . Similarly, externally applied electric fields have been shown to drive reaction pathways that would otherwise be energetically unavailable, , and triplet excited-state reordering has been observed for ACP derivatives embedded within zeolite pores containing metal ions .…”

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confidence: 93%

Tuning the Excited-State Dynamics of Acetophenone Using Metal Ions in Solution

Robertson

Bishop

Orr-Ewing

2021

J. Phys. Chem. Lett.

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The effects of dissolved metal salts on the excited-state dynamics of acetophenone in solution have been explored by using ultrafast transient absorption spectroscopy at two UV excitation wavelengths. In the absence of metal ions, the S1(nπ*) transition of acetophenone is excited at 320 nm, with intersystem crossing (ISC) occurring with a time constant τISC = 5.95 ± 0.47 ps in acetonitrile solution. Excitation at 280 nm accesses the S2(ππ*) state, which internally converts (<0.2 ps) to S1 before undergoing ISC with τISC = 4.36 ± 0.14 ps. Coordination to Mg2+ ions makes the S2 state accessible to excitation at 320 nm, with the rate of S2 → S1 internal conversion reducing 3-fold but the ISC rate increasing. These changes to the excited-state energies and dynamics of this model photosensitizer indicate that dissolved metal salts could modify the photochemistry of synthetically useful homogeneous photocatalytic systems.

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“…Importantly, PDAS yields a powerful assessment of photochemical reactivity of individual components, even in crude mixtures, and is thus potentially compatible with combinatorial chemistry and multicomponent reactions. These synthetic approaches are not readily amenable to analogous solution-phase analyses.…”

Section: Discussionmentioning

confidence: 99%

“…Herein, UV photodissociation action spectroscopy (PDAS) is employed on an ion-trap mass spectrometer coupled to a tunable laser system to evaluate the wavelength dependence of nitrile imine formation from substituted tetrazoles. Combining the analytical benefits of spectroscopy and mass spectrometry, the resulting action spectra reveal absorption events that produce a specified molecular mass change, − which can guide the design of new substrates with desirable photodissociation profiles . We show that the efficiency of nitrile imine formation as a function of irradiation wavelength can be readily surveyed in the gas phase, independent of dipolarophile cycloaddition.…”

Section: Introductionmentioning

confidence: 96%

Laser Photodissociation Action Spectroscopy for the Wavelength-Dependent Evaluation of Photoligation Reactions

et al. 2021

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The nitrile imine-mediated tetrazole–ene cycloaddition is a widely used class of photoligation. Optimizing the reaction outcome requires detailed knowledge of the tetrazole photoactivation profile, which can only partially be ascertained from absorption spectroscopy, or otherwise involves laborious reaction monitoring in solution. Photodissociation action spectroscopy (PDAS) combines the advantages of optical spectroscopy and mass spectrometry in that only absorption events resulting in a mass change are recorded, thus revealing the desired wavelength dependence of product formation. Moreover, the sensitivity and selectivity afforded by the mass spectrometer enable reliable assessment of the photodissociation profile even on small amounts of crude material, thus accelerating the design and synthesis of next-generation substrates. Using this workflow, we demonstrate that the photodissociation onset for nitrile imine formation is red-shifted by ca. 50 nm with a novel N-ethylcarbazole derivative relative to a phenyl-substituted archetype. Benchmarked against solution-phase tunable laser experiments and supported by quantum chemical calculations, these discoveries demonstrate that PDAS is a powerful tool for rapidly screening the efficacy of new substrates in the quest toward efficient visible light-triggered ligation for biological applications.

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Electrostatically Tuning the Photodissociation of the Irgacure 2959 Photoinitiator in the Gas Phase by Cation Binding

Cited by 23 publications

References 58 publications

Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes

Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes

Tuning the Excited-State Dynamics of Acetophenone Using Metal Ions in Solution

Laser Photodissociation Action Spectroscopy for the Wavelength-Dependent Evaluation of Photoligation Reactions

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