Photolysis of the endoperoxide of heterocoerdianthrone. A concerted, adiabatic cycloreversion originating from an upper excited singlet state

Schmidt, R.; Drews, W.; Brauer, H.‐D.

doi:10.1021/ja00528a046

“…(bl&+) and the parent hydrocarbon (87,92). Although it has been known for some time that 02(a1Ag) is formed upon photoinduced decomposition of aromatic endoperoxides (93), it was uncertain if this 02(a1A,) was formed directly or if it indeed was a decay product of the expected nascent 02(b1B,+) population. To our knowledge, the only experiments that have thus far addressed this issue were performed by Chou and Frei (10) in which attempts were made to monitor the b + a fluorescence during the photoinduced decomposition of 1,4-dimethylnaphthalene endoperoxide over a wide temperature range.…”

Section: Endoperoxide Decompositionmentioning

confidence: 99%

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Weldon

¹

,

Poulsen

²

,

Mikkelsen

³

et al. 1999

Photochem & Photobiology

View full text Add to dashboard Cite

The lowest excited electronic state of molecular oxygen, 02(a1Ag), is often called simply singlet oxygen. This singlet delta state is an acknowledged and well-studied intermediate in many solution-phase photosystems. However, the second excited electronic state of oxygen, O,(b'X,+), is also a singlet. It has recently become possible to monitor this singlet sigma state in solution, which, in combination with studies of the singlet delta state, contributes to a better understanding of a variety of general problems in chemistry.

show abstract

“…(bl&+) and the parent hydrocarbon (87,92). Although it has been known for some time that 02(a1Ag) is formed upon photoinduced decomposition of aromatic endoperoxides (93), it was uncertain if this 02(a1A,) was formed directly or if it indeed was a decay product of the expected nascent 02(b1B,+) population. To our knowledge, the only experiments that have thus far addressed this issue were performed by Chou and Frei (10) in which attempts were made to monitor the b + a fluorescence during the photoinduced decomposition of 1,4-dimethylnaphthalene endoperoxide over a wide temperature range.…”

Section: Endoperoxide Decompositionmentioning

confidence: 99%

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Weldon¹,

Poulsen²,

Mikkelsen³

et al. 1999

View full text Add to dashboard Cite

The lowest excited electronic state of molecular oxygen, 02(a1Ag), is often called simply singlet oxygen. This singlet delta state is an acknowledged and well-studied intermediate in many solution-phase photosystems. However, the second excited electronic state of oxygen, O,(b'X,+), is also a singlet. It has recently become possible to monitor this singlet sigma state in solution, which, in combination with studies of the singlet delta state, contributes to a better understanding of a variety of general problems in chemistry.

show abstract

“…HCDs are able to regenerate from HCDPO through UV irradiation and heating [20]. Considering this feature, it is expected that the SWNTs which has precipitated once, can be redispersed using this dispersant.…”

Section: Re-dispersion Of Swnts Using Photochromic Reaction Of Dphcdmentioning

confidence: 99%

“…They are capable of forming endoperoxides (HCDPOs), which have significant thermal stability [18,19]. In this photochromic reaction, singlet oxygen ( 1 O 2 ) is initially generated by the triplet sensitization reaction of HCD [20]. The addition of 1 O 2 to HCD produces a colorless endoperoxide product.…”

Section: Introductionmentioning

confidence: 99%

Photo-induced Aggregation of Single-walled Carbon Nanotubes from Dispersion by Using a Photochromic Dispersant

Seki

¹

,

Matsunaga

²

,

Ke

³

et al. 2019

J. Photopol. Sci. Technol.

0

View full text Add to dashboard Cite

Dipropylheterocoerdianthrone (DPHCD) was found to be a potential photo-reactive dispersant of single-walled carbon nanotubes (SWNTs). DPHCD was able to well disperse SWNTs in chloroform. DPHCD is easily photo-oxidized by the irradiation of visible light to form the endoperoxide with a bent structure under oxygen or air atmosphere. Then, SWNTs were photo-precipitated from the DPHCD/SWNTs dispersion. The precipitation was able to disperse again after the photochromic reaction to turn back DPHCD from the endoperoxide and sonication. Such photo-induced precipitation was also observed in DPHCD/SWNTs complex film. The SWNTs precipitates were analyzed by FT-IR and Raman spectra measurements, and discussed about selectivity of DPHCD on chirality, and elimination of the dispersant.

show abstract

Photolysis of the endoperoxide of heterocoerdianthrone. A concerted, adiabatic cycloreversion originating from an upper excited singlet state

Abstract: 21) This observation shows that the cis keto isomer Q1 does not have the same conformation as the excited cis keto isomer produced by excitation of the enol. As shown in reference 17, a large number of keto and enol conformations of 1 are actually possible.

Cited by 64 publications

References 1 publication

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Singlet Sigma: The “Other” Singlet Oxygen in Solution

Photo-induced Aggregation of Single-walled Carbon Nanotubes from Dispersion by Using a Photochromic Dispersant

Contact Info

Product

Resources

About