Autoxidation and Photooxidation of 1,3-Diphenylisobenzofuran: A Kinetic and Product Study

Abstract

Photooxidation of 1,3-diphenylisobenzofuran (DPBF) in aromatic solvents at 30° gives a monomeric peroxide along with minor amounts of o-benzylphenyl benzoate, whereas in CCl4o-dibenzoylbenzene is the principal reaction product. 1,3-Diphenylisobenzofuran is very susceptible to autoxidation at this temperature (kp/(2kt)1/2 = 4 M−1/2 s−1/2, kp ∼ 105 M−1s−1 2kt ∼ 5 × 108 M−1s−1) yielding a polyperoxide (50%) and o-dibenzoylbenzene (35%). Clearly, in the absence of appropriate control experiments, neither rapid disappearance of DPBF nor production of o-dibenzoylbenzene are sufficient to prove the intermediacy of singlet delta oxygen during molecular oxygen oxidations.

Porous Silicon Nanoparticle Photosensitizers for Singlet Oxygen and Their Phototoxicity against Cancer Cells

“…DPBF reacts with 1 O 2 irreversibly, undergoing a 1,4-cycloaddition that is detected as a decrease in the intensity of the DPBF absorption band at 410 nm. 36,37 As shown in Figure 1a, the absorption intensity of the solution containing porous Si nanoparticles and DPBF decreases gradually as a function of time under light irradiation (halogen lamp fitted with an IR filter and a 454–500 nm bandpass filter), while the change is negligibly small in the absence of light (Figure 1b). DPBF was observed to undergo slight decomposition under the irradiation conditions (in air), even in the absence of porous Si nanoparticles (Supporting Information, Figure S2).…”

Strong Influence of the Ancillary Ligand over the Photodynamic Anticancer Properties of Neutral Biscyclometalated IrIII Complexes Bearing 2‐Benzoazole‐Phenolates

“…Determination of singlet oxygen generation : The 1 O 2 generation was verified by monitoring the photooxidation of 1,3‐diphenylisobenzofuran (DPBF, 97 %, Sigma Aldrich, USA) by absorbance measurements as a function of the irradiation time. The irreversible interaction of DPBF with 1 O 2 leads to a decrease in the absorbance of the DPBF band centered at 410 nm as a consequence of the 1,4‐cycloaddition . Stock solutions of all the compounds, methylene blue (MB) used as standard, and DPBF were freshly prepared in DMSO.…”

“…The irreversible interaction of DPBF with 1 O 2 leads to ad ecrease in the absorbance of the DPBF band centered at 410 nm as ac onsequence of the 1,4-cycloaddition. [83] Stock solutions of all the compounds, methylene blue (MB) used as standard, and DPBF were freshly prepared in DMSO. The final concentration of all the compounds including the standard in the cuvette was 10 mm,a nd that of DPBF 50 mm in DMSO:H 2 O( 60:40).…”

Covalent Dimers of 1,3-Diphenylisobenzofuran for Singlet Fission: Synthesis and Electrochemistry

“…1 It originally elicited our interest because theoretical considerations led to the suggestion 2 that it should be efficient as a model chromophore for singlet fission, 3 a photophysical process in which a singlet excited chromophore shares its energy with a ground-state neighbor and both end up in their excited triplet states.…”

“…The mixture was stirred for 30 min. A light yellow solid 12 formed and was collected by filtration (3.9 g, 97%) 1. H NMR (300 MHz): ä 7.89 (d, 2H, J = 8.46 Hz), 7.79 (t, 1H, J = 1.71 Hz), 7.73 (d, 1H, J = 15.7 Hz), 7.66 (d, 2H, J = 8.34 Hz), 7.54 (m, 2H), 7.46 (d, 1H, J = 15.66 Hz), 7.30 (t, 1H, J = 7.83 Hz).…”