Sterically tuned photoreactivity of an aromatic α-diketone family

Malval, Jean‐Pierre; Dietlin, Céline; Allonas, Xavier; Fouassier, Jean‐Pierre

doi:10.1016/j.jphotochem.2007.05.005

Cited by 19 publications

(18 citation statements)

References 41 publications

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“…The chelation of (MeO) 3 P to the dione likely alters the electronic transition of the dicarbonyl group. The experimental results show that α-diketones bear a strong n ,π* character, 16 which is reduced in the phosphorane 5 . Next, we present experimental evidence for a cyclization of dione 1 with (MeO) 3 P to reach phosphorane 4 .…”

Section: Resultsmentioning

confidence: 96%

“…Dione 1 is not likely to photoreduce in the presence of water but would be susceptible to photoreduction with H-atom donors such as triethylamine or a phenol substituted with an electron-donating substituent. 16 In terms of product formation, produced acetophenone ( E T = 74 kcal/mol) may also serve as a photosensitizer, although 4,4′-dimethylbenzil 1 has a fairly low-lying triple state ( E T = ∼51 kcal/mol) is expected to be the main photosensitizer over the course of the peroxide 3 homolysis reaction. Also, for comparison, O 2 degassed conditions were used; otherwise, a competing process would include dione sensitization to O 2 and formation of singlet oxygen.…”

Section: Resultsmentioning

confidence: 99%

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Dark-Binding Process Relevant to Preventing Photosensitized Oxidation: Conformation-Dependent Light and Dark Mechanisms by a Dual-Functioning Diketone

et al. 2019

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Few photosensitizers function in both light and dark processes as they usually have no function when the lights are turned off. We hypothesized that light and dark mechanisms in an α-diketone will be decoupled by dihedral rotation in a conformation-dependent binding process. Successful decoupling of these two functions is now shown. Namely, anti- and syn-skewed conformations of 4,4′-dimethylbenzil promote photosensitized alkoxy radical production, whereas the syn conformation promotes a binding shutoff reaction with trimethyl phosphite. Less rotation of the diketone is better suited to the photosensitizing function since phosphite binding arises through the syn conformer of lower stability. The dual function seen here with the α-diketone is generally not available to sensitizers of limited conformational flexibility, such as porphyrins, phthalocyanines, and fullerenes.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Dark-Binding Process Relevant to Preventing Photosensitized Oxidation: Conformation-Dependent Light and Dark Mechanisms by a Dual-Functioning Diketone

et al. 2019

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“…The photochemistry of ␣-diketones (and the closely related ortho-quinones) has been a subject of interest for a long time and this field of investigation has continued to be very active [6]. Several ortho-quinones have been found to be photoreactive in the presence of hydrogen and electron donors [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

A combined laser flash photolysis, density functional theory and atoms in molecules study of the photochemical hydrogen abstraction by pyrene-4,5-dione

Lucas

Elias

Firme

et al. 2009

Journal of Photochemistry and Photobiology A: Chemistry

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“…As noted, the conformational twist angle about the −CO−CO− bond influences the triplet state energy of BZ as well as the degree of conjugation of the carbonyl groups with their adjacent phenyl moieties [ 63 ]. Therefore, the conformation and energy of the lowest excited triplet state may also influence the reactivity of BZ and diacylperoxide formation.…”

Section: Photoperoxidation Of Benzil In Glassy Polymer Matrices In the Presence Of Molecular Oxygenmentioning

confidence: 99%

Benzil Photoperoxidations in Polymer Films and Crosslinking by the Resultant Benzoyl Peroxides in Polystyrene and Other Polymers

et al. 2021

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Benzil (BZ) can be converted almost quantitatively to benzoyl peroxide (BP) in aerated polymer films upon irradiation at >400 nm (i.e., the long-wavelength edge of the n→π* absorption band of BZ, where BP does not absorb). Here, we summarize results for the photoperoxidation of BZ structures with molecular oxygen, principally in glassy polymer matrices. Some of the polymers are doped directly with BZ or its derivatives, and others, contain covalently attached BZ pendant groups from which BP groups are derived. While the decomposition of low-molecular-weight BP doped into polymer films (such as those of polystyrene (PS)) results in a net decrease in polymer molecular weight, thermal decomposition of pendant BP groups is an efficient method for chain crosslinking. Crosslinking of PS films doped with a molecule containing two covalently linked BZ or BP groups proceeds in a similar fashion. Free radicals from the covalently attached BP allow grafting of new monomers, as well. Additionally, the use of radiation filtered through masks has been used to create patterns of polymers on solid surfaces. Crosslinking of photodegradable poly(phenyl vinyl ketone) with BP structures obtained by photoperoxidation of BZ structures for the preparation of photodegradable polymer networks is described as well. In sum, the use of BZ and BP and their derivatives offers simple and convenient routes for modifying polymer chains and, especially, for crosslinking them. Specific applications of each use and process are provided. Although applications with PS are featured here, the methodologies described are amenable to a wide variety of other polymers.

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Sterically tuned photoreactivity of an aromatic α-diketone family

Cited by 19 publications

References 41 publications

Dark-Binding Process Relevant to Preventing Photosensitized Oxidation: Conformation-Dependent Light and Dark Mechanisms by a Dual-Functioning Diketone

Dark-Binding Process Relevant to Preventing Photosensitized Oxidation: Conformation-Dependent Light and Dark Mechanisms by a Dual-Functioning Diketone

A combined laser flash photolysis, density functional theory and atoms in molecules study of the photochemical hydrogen abstraction by pyrene-4,5-dione

Benzil Photoperoxidations in Polymer Films and Crosslinking by the Resultant Benzoyl Peroxides in Polystyrene and Other Polymers

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