Ultrafast Pump−Probe Studies of<i>tert</i>-Butyl Aroylperbenzoates and Triplet Energy Interception by the O−O Bond

Shah, Bela; Gusev, Alex; Rodgers, Michael A. J.; Neckers, Douglas C.

doi:10.1021/jp049588c

Cited by 12 publications

(4 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite relatively few reports, [ 49–51 ] the sensitized homolysis of an organic peroxide is used here to provide a facile source of alkoxy radicals. In our case, cumyloxy and ethoxy radicals are generated and react with ( p ‐F‐C 6 H 4 ‐O) 3 P and to a lesser extent ( p ‐Cl‐C 6 H 4 ‐O) 3 P suggesting that these alkoxy radicals do not efficiently acquire H‐atoms from surface SiOH groups or surface‐adsorbed water.…”

Section: Resultsmentioning

confidence: 99%

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Ghosh

Greer

2020

J of Physical Organic Chem

View full text Add to dashboard Cite

With interests in alkoxy radical formation on natural and artificial surfaces, a physical‐organic study was carried out with a Hammett series of triaryl phosphites (p‐MeO, H, p‐F, and p‐Cl) to trap adsorbed alkoxy radicals on silica nanoparticles. A mechanism which involves PhC (Me)2O• and EtO• trapping in a cumylethyl peroxide sensitized homolysis reaction is consistent with the results. The p‐F phosphite was able to indirectly monitor the alkoxy radical formation, and 31P NMR readily enabled this exploration, but other phosphites of the series such as the p‐MeO phosphite were limited by hydrolysis reactions catalyzed by surface silanol groups. Fluorinated silica nanoparticles helped to suppress the hydrolysis reaction although adventitious water also plays a role in hindering efficient capture of the alkoxy radicals by the phosphite traps.

show abstract

Section: Resultsmentioning

confidence: 99%

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Ghosh

Greer

2020

J of Physical Organic Chem

View full text Add to dashboard Cite

show abstract

“…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. Our work is also part of a growing body of work, ,− examining sensitization reactions by peroxide O–O bond homolysis, where the reaction is also relevant to the more commonly studied sensitization of 3 O 2 to 1 O 2 .…”

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

View full text Add to dashboard Cite

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.

show abstract

“…Transient Absorption Spectroscopy. The transient absorption measurements were performed at the Ohio Laboratory for Kinetic Spectroscopy at Bowling Green State University, and the experimental setup has been detailed elsewhere …”

Section: Methodsmentioning

confidence: 99%

Competitive 1,2- and 1,5-Hydrogen Shifts Following 2-Vinylbiphenyl Photocyclization

et al. 2005

View full text Add to dashboard Cite

[reaction: see text] The photocyclization of 2-vinylbiphenyl and its derivatives has been proposed to occur via a two-step mechanism: photocyclization to form an unstable 8a,9-dihydro-phenanthrene intermediate, followed by exothermic unimolecular isomerization to a 9,10-dihydrophenanthrene. The mechanism of the hydrogen shift process has been investigated using deuterated derivatives of 2-isopropenylbiphenyl and 2,6-diphenylstyrene. 1H NMR analysis of the photoproducts indicates that the thermally allowed 1,5-hydrogen or deuterium shift is a minor product-forming pathway and that an unusual double 1,2-hydrogen or deuterium shift is the major product-forming pathway. The potential energy surface for photocyclization and hydrogen shift processes has been explored computationally. The calculated barrier for the 1,5-shift is predicted to be significantly lower than that for the 1,2-shift. Alternative mechanisms for the occurrence of 1,2-hydrogen or deuterium migration are presented.

show abstract

Ultrafast Pump−Probe Studies oftert-Butyl Aroylperbenzoates and Triplet Energy Interception by the O−O Bond

Cited by 12 publications

References 39 publications

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

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

Competitive 1,2- and 1,5-Hydrogen Shifts Following 2-Vinylbiphenyl Photocyclization

Contact Info

Product

Resources

About