Degradation of Pharmaceuticals through Sequential Photon Absorption and Photoionization in Amiloride Derivatives

Jorner, Kjell; Rabten, Wangchuk; Slanina, Tomáš; Vedin, Nathalie Proos; Sillén, Sara; Ludvigsson, Jufang Wu; Ottosson, Henrik; Norrby, Per‐Ola

doi:10.1016/j.xcrp.2020.100274

Cited by 8 publications

(15 citation statements)

References 61 publications

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“…Traditionally, the driving force for photoinduced electron transfer has been explained by the Rehm–Weller model, where Gibbs free energy for charge separation is estimated by oxidation/reduction potentials of the electron donor/acceptor. Here, we show that a more complete picture emerges when the effects of excited-state (anti)aromaticity − are considered. Even though all photoexcited molecules can be thought to be “unstable,” Baird antiaromaticity is a useful effect for tuning the energy levels of ππ* states and the many reactions that proceed through these bright states.…”

mentioning

confidence: 79%

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

Karas

2021

J. Am. Chem. Soc.

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Many popular organic chromophores that catalyze photoinduced proton-coupled electron transfer (PCET) reactions are aromatic in the ground state but become excited-state antiaromatic in the lowest ππ* state. We show that excited-state antiaromaticity makes electron transfer easier. Two representative photoinduced electron transfer processes are investigated: (1) the photolysis of phenol and (2) solar water splitting of a pyridine–water complex. In the selected reactions, the directions of electron transfer are opposite, but the net result is proton transfer following the direction of electron transfer. Nucleus-independent chemical shifts (NICS), ionization energies, electron affinities, and PCET energy profiles of selected [4n] and [4n + 2] π-systems are presented, and important mechanistic implications are discussed.

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confidence: 79%

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

Karas

2021

J. Am. Chem. Soc.

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“…Finally, photoinduced intermolecular electron transfer triggered by ESAA can also go to the surrounding medium as observed for amiloride derivatives 140 (Scheme 11), [215] a class of diuretic drug compounds. Upon irradiation, amilorides undergo photosubstitution in various protic solvents [216–220] .…”

Section: Relief Of Esaamentioning

confidence: 97%

“…Biphotonic mechanism of photosubstitution of amiloride analogue 140 in protic solvents. [215] Chemistry-A European Journal…”

Section: Esaa Relief Through Electron Transfermentioning

confidence: 99%

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Photochemistry Driven by Excited‐State Aromaticity Gain or Antiaromaticity Relief

Yan

Slanina

Bergman

et al. 2023

Chemistry A European J

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Gain of aromaticity or relief of antiaromaticity along a reaction path are important factors to consider in mechanism studies. Analysis of such changes along potential energy surfaces has historically focused on reactions in the electronic ground state (S 0 ), but can also be used for excited states. In the lowest ππ* states, the electron counts for aromaticity and antiaromaticity follow Baird's rule where 4n π-electrons indicate aromaticity and 4n + 2 π-electrons antiaromaticity. Yet, there are also cases where Hückel's rule plays a role in the excited state. The electron count reversals of Baird's rule compared to Hückel's rule explain many altered physicochemical properties upon excitation of (hetero)annulene derivatives. Here we illustrate how the gain of excited-state aromaticity (ESA) and relief of excited-state antiaromaticity (ESAA) have an impact on photoreactivity and photostability. Emphasis is placed on recent findings supported by the results of quantum chemical calculations, and photoreactions in a wide variety of areas are covered.

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“…But here, we show that a more complete picture emerges when the effects of excited-state (anti)aromaticity are considered. A number of works have recognized the role of excited-state antiaromaticity in organic photoreactions (e.g., the photoionization of haloaromatic compounds, 16 phototriggered bond breaking, 17,18 photodeactivation of DNA base pairs, 19 photoreaction of benzene, 20 and excited-state proton transfer 21,22 ).…”

mentioning

confidence: 99%

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

Karas

Wu²,

Wu³

2021

Preprint

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Baird antiaromaticity plays a central role in the photochemistry of proton-coupled electron transfer (PCET) reactions. We recognize that many popular organic chromophores that catalyze photoinduced PCET reactions are Hückel aromatic in the ground state, but gain significant Baird antiaromatic character in the lowest ππ* state, having important barrier-lowering effects for electron transfer. Two examples, 1) the photolytic O–H bond dissociation of phenol and 2) solar water splitting in the pyridine-water complex, are discussed. Contrary to an assumed homolytic O–H bond dissociation, both reactions proceed through loss (and gain) of an electron in the π-system (i.e., antiaromaticity relief), followed by heterolytic cleavage of the polar O–H bond near barrierlessly. Nucleus-independent chemical shifts (NICS), ionization energies (IE), electron affinities (EA), and excited-state PCET energy profiles of selected [4n] and [4n+2] π-systems are presented.

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Degradation of Pharmaceuticals through Sequential Photon Absorption and Photoionization in Amiloride Derivatives

Cited by 8 publications

References 61 publications

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

Photochemistry Driven by Excited‐State Aromaticity Gain or Antiaromaticity Relief

Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions

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