<b>Decay Kinetics of the 1-Naphthaldehyde and Benzophenone Triplet States in Benzene</b>

Bell, J. S.; Linschitz, Henry

doi:10.1021/ja00888a009

Cited by 108 publications

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“…Cu(acac)? and several other transition metal acetylacetonates are known to quench triplet transients generated by flash photolysis of aromatic ketones and hydrocarbons (2)(3)(4)(5). However, the chemical consequences of the quenching has not been investigated s o far, except in our recent report (1).…”

Section: W E Have Shown (1) That Bis(acetylacetonato)copper(ii)mentioning

confidence: 99%

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

Chow¹,

Buono-Core²

1983

Can. J. Chem.

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Triplet-state benzophenone rapidly sensitized the photoreduction of Cu(acac)2 in alcohols to give polymeric Cu(acac) as black precipitates. The binary complexes of Cu(acac) of polypyridines, polysulfide, olefins, acetylenes, and carbon monoxide could be generated in solution under an inert atmosphere when a ligand was present insitu during photoreduction or added after an appropriate photoreduction was completed. Except Cu(acac)—(PPh3)2, the Cu(acac) complexes of various ligands are sensitive to air oxidation, but show a wide range of reactivity towards disproportionation and photolysis. In the presence of terminal acetylenes, amorphous copper(I) acetylides were isolated in good yields.

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Section: W E Have Shown (1) That Bis(acetylacetonato)copper(ii)mentioning

confidence: 99%

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

Chow¹,

Buono-Core²

1983

Can. J. Chem.

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“…Reactions [2] and [3] illustrate the competition that would Several of the quenchers used are excellent h~drogen donors be responsible for the quenching rate constants of (e. g. 2-propanol, c yclohexane, 1,4-c yclohexadiene, phenol). that is, +K is the fraction of quenching events that lead to ketyl radical generation.…”

Section: Kinetics Of Triplet Quenching By Various Substratesmentioning

confidence: 99%

“…The photochemical and photophysical properties of benzophenone have been studied extensively and are rather well understood (1)(2)(3)(4)(5). Benzophenone (as do many other aromatic ketones) undergoes intersystem crossing rapidly and efficiently to populate its lowest triplet state, which is responsible for most of its photochemistry (I).…”

Section: Introductionmentioning

confidence: 99%

A laser flash photolysis study of the behaviour of polyfluorophenyl ketones in solution

Boate¹,

Johnston²,

Scaiano³

1989

Can. J. Chem.

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. Can. J. Chem. 67, 927 (1989).Decafluorobenzophenone triplets, which have a triplet energy very close to that of benzophenone, are much more reactive than benzophenone in quenching reactions that involve hydrogen transfer and/or charge transfer. An excellent correlation has been observed between the rate constants for charge transfer quenching and the oxidation potential of the substrate. In the case of 2-propanol, where the reactivity can be fully accounted for by hydrogen transfer, decafluorobenzophenone is 35 times more reactive than benzophenone. Pentafluorobenzophenone shows intermediate behaviour.

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“…This type of electronic excitation creates significant spin density at the carbonyl oxygen atom, which consequently behaves like a highly-reactive oxygen-centered radical, and is efficiently quenched by hydrogen-donor molecules like benzhydrol, 1,4-cyclohexadiene, or tributylstannane. [2,3] If no sufficiently low-lying empty π*-orbitals are available to accept an electron, electrons can also be promoted to antibonding σ*-type orbitals. Thus, (π,σ*) excited states are observed in the case of certain heteroaromatic compounds.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π) and (n,π) versus (σ,π) States. Substituent-Induced State Switching in Triplet Ketones

Bucher¹

2017

Aust. J. Chem.

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The intramolecular interaction of ketone triplet excited states with nucleophilic substituents is investigated by studying the electronic properties of phenalenone and a range of phenalenones functionalized in position 9 as a model system. In accordance with the literature, a (π,π*) triplet excited state is predicted for phenalenone. Similarly, 9-fluoro-, 9-chloro-, and 9-methoxyphenalenone are calculated to have (π,π*) lowest triplet excited states, whereas the lowest triplet states of 9-bromo-, 9-iodo, 9-methylthio, and 9-dimethylaminophenalenone are predicted to have (σ*,π*) character. As a result of the interaction between halogen and oxygen lone pairs increasing with increasing orbital size, the antibonding linear combination of substituent lone pairs with oxygen lone pairs sufficiently rises in energy to change the character of the lowest triplet excited state of the 9-substituted phenalenones from (π,π*) to (σ*,π*). These unusual triplet excited states or exciplexes should essentially behave like (n,π*) triplets states, but will differ from pure (n,π*) states by showing significant spin densities at the substituent heteroatoms, predicted to reach values of 0.25 for 9-iodophenalenone, and ~0.5 for 9-dimethylaminophenalenone. Vertical T1–T2 excitation energies calculated indicate that the stabilization of the (σ*,π*) relative to the (π,π*) state can reach 1 eV. Preliminary calculations on the triplet excited states of 2-iodobenzophenone, 4-iodo-2-butanone, and iodoacetone indicate that intramolecular triplet exciplex formation should be a general phenomenon, as long as the ring being formed is at least a five-membered ring.

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Decay Kinetics of the 1-Naphthaldehyde and Benzophenone Triplet States in Benzene

Cited by 108 publications

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Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

A laser flash photolysis study of the behaviour of polyfluorophenyl ketones in solution

Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π) and (n,π) versus (σ,π) States. Substituent-Induced State Switching in Triplet Ketones

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Decay Kinetics of the 1-Naphthaldehyde and Benzophenone Triplet States in Benzene

Cited by 108 publications

References 0 publications

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

Triplet-state benzophenone-sensitized photoreduction of bis(acetylacetonato)copper(II): the generation and stability of copper(I) complexes

A laser flash photolysis study of the behaviour of polyfluorophenyl ketones in solution

Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π*) and (n,π*) versus (σ*,π*) States. Substituent-Induced State Switching in Triplet Ketones

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Interaction of Triplet Excited States of Ketones with Nucleophilic Groups: (π,π) and (n,π) versus (σ,π) States. Substituent-Induced State Switching in Triplet Ketones