Picosecond studies on the photodissociation dynamics of aromatic endoperoxides

Blumenstock, Th.; Jesse, Klemens; Comes, F. J.; Schmidt, R.; Brauer, H.‐D.

doi:10.1016/0301-0104(89)87058-2

Cited by 19 publications

(9 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Kearn's analysis predicts that excitation of an endoperoxide to the first excited state (long-wavelength photolysis) should lead to the cleavage of oxygen−oxygen bond because an electron is promoted to the O−O antibonding orbital. The excitation to the second excited state (short-wavelength photolysis) would lead to the cleavage of carbon−oxygen bond because this transition from n OO to σ * CO should strengthen the O−O bond while weakening the C−O bond. − Since this was actually observed in the process of photodissociation of 34 , 36 was difficult to obtain in high purity. The irradiation of 34 in chloroform- d at −50 °C with a low pressure mercury lamp gave a very complex mixture which included 39 as the major compound.…”

Section: Resultsmentioning

confidence: 99%

Chemistry of anti-o,o‘-Dibenzene

et al. 1997

View full text Add to dashboard Cite

A new and efficient preparation of anti-o,o‘-dibenzene 1 has been achieved in three steps from cis-3,5-cyclohexadiene-1,2-diol 25. Utilizing a method for deoxygenation of 1,2-diols developed in our laboratory, anti-tetraol 23 was converted to 1 in 65% yield on a 0.5 g scale. This has allowed us to explore the chemistry of anti-dibenzenes extensively. The kinetics for thermal reversion of 1 to benzene have been studied in three different solvents. The direct photolysis of 1 to benzene has been found to form excited benzene in unit efficiency. This high efficiency of adiabatic photon up-conversion in the singlet manifold is unprecedented. No light was detected in the thermal dissociation of 1 in solution using various sensitizers. The chemiluminescence spectrum from the thermolysis of 1 in the presence of perylene has been recorded and found to correspond to the emission of perylene excimer. Although the efficiency of the chemiluminescent process was very low, it has proven to be one of a very few examples of chemiluminescent reactions from pure hydrocarbons. The possible mechanisms were discussed. Benzene 1,4-endoperoxide 36 was formed during the photolysis of monoperoxide 34 at low temperature. Peroxide 36 underwent a quantitative concerted retrocycloaddition to benzene and singlet oxygen. The half-life of 36 was determined to be 29 min at −30 °C.

show abstract

Section: Resultsmentioning

confidence: 99%

Chemistry of anti-o,o‘-Dibenzene

et al. 1997

View full text Add to dashboard Cite

show abstract

“…Cycloreversion quantum yield Q C increases for many nonsymmetrical EPOs stepwise with decreasing λ, indicating that cycloreversion occurs from several excited S n (ππ*) ( n = 2, 3...) states. , Cycloreversion must be very fast to compete efficiently with internal conversion. Several groups, however, measured surprisingly long PAC rise times τ 2 ranging for eight EPOs from 40 ( 24f ) to 95 ps ( 11c ). − These results indicate a two-step reaction with a much faster first step. Experiments with 24f demonstrated that τ 2 does not depend on solvent polarity and viscosity, indicating a fast homolytic cleavage of a C−O bond of the peroxide bridge as first step .…”

Section: Dissociation Of Endoperoxidesmentioning

confidence: 97%

“…Several groups, however, measured surprisingly long PAC rise times τ 2 ranging for eight EPOs from 40 ( 24f ) to 95 ps ( 11c ). − These results indicate a two-step reaction with a much faster first step. Experiments with 24f demonstrated that τ 2 does not depend on solvent polarity and viscosity, indicating a fast homolytic cleavage of a C−O bond of the peroxide bridge as first step . The breakage of the second C−O bond initiating the loss of O 2 requires the same activation enthalpy of 22 kJ mol -1 for the four EPOs 24c to 24f , but only 24d to 24f have similar rise times (55 ≥ τ 2 ≥ 40 ps).…”

Section: Dissociation Of Endoperoxidesmentioning

confidence: 97%

Reversible Binding of Oxygen to Aromatic Compounds

et al. 2003

View full text Add to dashboard Cite

Many polycyclic aromatic hydrocarbons are able to trap singlet oxygen (1)O(2). Some of the endoperoxides, thus obtained, exhibit the exceptional feature of releasing oxygen, frequently in the excited singlet state, under heating or UV irradiation. In this Account, we provide a short summary of the present knowledge on these endoperoxides: preparation and thermal and photolytic decomposition, with a special emphasis on the structural requirements to favor cycloreversion. The profitable use of this property in the development of highly reversible photochromic systems and of specific sources or traps of (1)O(2) in aqueous media is also described.

show abstract

“…Although a real-time study of the photochemistry of APO in the UV-range has never been done before, 17 timeresolved investigations have been reported on a handful of other aromatic endoperoxides. 8,[20][21][22][23][24][25] A femtosecond study by Ernsting et al 20 on the endoperoxide of dimethylhomoeocoerdianthrone (HOCDPO), employing the same experimental method, arrived at a PAH formation time constant of 1.6 ps. For all other investigated aromatic endoperoxides, 8,[21][22][23][24][25] including four derivatives created from anthracene, 8,21 the method of PAH product detection was Laser-induced-fluorescence (LIF), with picosecond time resolution, and the PAH formation times were found to vary from 40 ps to 95 ps.…”

Section: Introductionmentioning

confidence: 99%

“…8,[20][21][22][23][24][25] A femtosecond study by Ernsting et al 20 on the endoperoxide of dimethylhomoeocoerdianthrone (HOCDPO), employing the same experimental method, arrived at a PAH formation time constant of 1.6 ps. For all other investigated aromatic endoperoxides, 8,[21][22][23][24][25] including four derivatives created from anthracene, 8,21 the method of PAH product detection was Laser-induced-fluorescence (LIF), with picosecond time resolution, and the PAH formation times were found to vary from 40 ps to 95 ps. Supercontinuum probing holds the advantage over LIF that the product molecules are not required to fluoresce.…”

Section: Introductionmentioning

confidence: 99%

Dual photochemistry of anthracene-9,10-endoperoxide studied by femtosecond spectroscopy

Lauer

Dobryakov

Kovalenko

et al. 2011

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The dual photochemistry of anthracene-9,10-endoperoxide (APO) was investigated in a fs UV pump-supercontinuum probe experiment, along with anthracene (AC) and anthraquinone (AQ) for comparison. Excitation of APO at 282 nm leads to 100% product formation by two competing photoreaction channels. Cycloreversion generates with a ∼25% quantum yield (QY) (1)O(2) and AC vibrationally excited in the singlet electronic ground state (hot AC). 1-2% of the AC is generated in the lowest triplet state, but no AC is generated in electronically excited singlet states. Generation and cooling of hot AC are modeled using solution phase and broadened gas-phase AC absorption spectra at various temperatures. Results indicate ultrafast generation of hot AC within 3 ps, much faster than reported before for derivatives of anthracene endoperoxide, and subsequent cooling with an 18 ps time constant. The homolytic O-O cleavage pathway generates a biradical, which converts into electronically excited diepoxide (DE). Our data indicate a 1.5 ps time constant that we tentatively assign to the biradical decay and DE formation. Cooling of DE in this electronically excited state takes place with a ∼21 ps time constant. Excitation of AQ at 266 nm is followed by an ultrafast population of the T(1)(nπ*) triplet state of AQ with a time constant of (160 ± 60) fs.

show abstract

Picosecond studies on the photodissociation dynamics of aromatic endoperoxides

Cited by 19 publications

References 16 publications

Chemistry of anti-o,o‘-Dibenzene

Chemistry of anti-o,o‘-Dibenzene

Reversible Binding of Oxygen to Aromatic Compounds

Dual photochemistry of anthracene-9,10-endoperoxide studied by femtosecond spectroscopy

Contact Info

Product

Resources

About