Exploring Photoinduced Decarboxylation Mechanism of o-Acetylphenylacetic Acid from the Combined CASSCF and DFT Studies

Water-assisted self-photoredox of 2-(1-hydroxyethyl)-9,10-anthraquinone through a triplet excited state intra-molecular proton transfer pathway

A novel self-photoredox reaction for 2-(1-hydroxyethyl)-9,10-anthraquinone has been theoretically rationalized to take place through two steps of triplet excited state intra-molecular proton transfer aided by water wires.

Reaction mechanism of photoinduced decarboxylation of the photoactivatable green fluorescent protein: an ONIOM(QM:MM) study

Photoactivatable (PA) fluorescent proteins are a new class of fluorescent proteins in which the intensity of fluorescence is dramatically enhanced through photoinduced decarboxylation process. In the present study, the reaction mechanism of the photoinduced decarboxylation in PA-GFP was investigated by the ONIOM(QM:MM) method. The decarboxylation process starts from the first excited state (IntraCT state) and then proceeds along an InterCT state after the first crossing (or an approximate transition state). Relative to an equilibrium structure in S(0), a barrier of ~94 kcal/mol to reach this approximate transition state is the rate-determining step for the entire decarboxylation process. The InterCT state becomes the open-shell ground state in the product, after the subsequent crossing with a closed-shell state that holds an extra electron on the dissociated CO(2). The present study elucidated for the first time the mechanism of the photoinduced decarboxylation of PA-GFP and supports the widely accepted Kolbe pathway, which could be a common mechanism for the irreversible photoinduced decarboxylation in different fluorescent proteins.

Organic aspects. Oxygen-containing functions

In this chapter, most of the reported work deals with the photochemistry of carbonyl compounds; however, the photoreactions of other functions, such as the photo-Claisen rearrangement or the photocleavage of cyclic ethers, are also included. In the present volume, time coverage is 2010–2011, and only original research articles are quoted. In general, reviews or purely theoretical calculations are not systematically included. As usually, the material is organized according to established types of reactions (e.g., Norrish I/II, hydrogen abstraction, Paternò-Büchi, photoelimination, photo-Fries/photo-Claisen, etc.). After presenting the basic photochemical aspects, more specific findings are reported. They include synthetic applications, stereoselectivity, and biological or technological implications. Next, the attention is focused on photochemical reactions in anisotropic media, including (micro)heterogeneous or supramolecular systems, solid matrixes or fully organized crystals. Finally, mechanistic studies based on direct experimental evidence are highlighted, especially when transient absorption spectroscopy or related ultrafast detection are employed.