Selective photobleaching of the long-lived phosphorescence of 1-indanones

Suter, Georg W.; Wild, Urs P.; Schaffner, Kurt

doi:10.1021/j100402a022

Cited by 24 publications

(15 citation statements)

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“…Such a situation is also expected for enones 1 and 2. As previously proposed for indan-1-ones 26 the longer lived emission may arise from molecules H-bonded to the solvent and the short lived emission originates from molecules in a nonpolar solvent cage. Comparison of the fraction of the recorded phosphorescence found in either solvent for 3-phenylcyclohexenone, 3-phenylcyclopentenone and related compounds 1 is consistent with the relative polarity of each compound.…”

Section: Nature Of the Excited State Of Phenyl Substituted Enonessupporting

confidence: 61%

Photochemistry of substituted cyclic enones. Part 12.1 Photocycloaddition of 3-phenylcyclopentenone and 3-phenylcyclohexenone to (E )- and (Z )-1-phenylpropene

Kelly¹,

Kelly²,

McMurry³

1999

J. Chem. Soc., Perkin Trans. 2

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The quantum yields of adduct formation and isomerisation of (E)-and (Z)-1-phenylpropene by 3-phenylcyclopentenone 1 and 3-phenylcyclohexenone 2 have been measured by 1 H-NMR spectroscopy in solutions of d 6 -benzene. The adducts formed for each photoreaction have been shown to be independent of the starting 1-phenylpropene isomer. For 3-phenylcyclopentenone 1, a photostationary state of 32 : 68 (E)-to (Z)-1-phenylpropene is achieved during the course of the reaction. This isomerisation reaction may occur through reversion of triplet 1,4-biradical intermediates to ground state molecules or by an energy transfer process. However for 3-phenylcyclohexenone 2 isomerisation occurs only through reversion of triplet 1,4-biradical intermediates. The mechanism of photoadduct formation and that of the isomerisation reaction are discussed for both phenylenones.Rate constants for quenching of the 3-phenylcyclopentenone 1 and 3-phenylcyclohexenone 2 triplet states by (E)-and (Z)-1-phenylpropene, 3 and 4, in cyclohexane and benzene solutions have been recorded using laser flash photolysis. In cyclohexane at high quencher concentration, complex decay kinetics are observed consistent with observation of both the enone triplet state and either a triplet exciplex or 1,4-biradical intermediates.

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Section: Nature Of the Excited State Of Phenyl Substituted Enonessupporting

confidence: 61%

Photochemistry of substituted cyclic enones. Part 12.1 Photocycloaddition of 3-phenylcyclopentenone and 3-phenylcyclohexenone to (E )- and (Z )-1-phenylpropene

Kelly¹,

Kelly²,

McMurry³

1999

J. Chem. Soc., Perkin Trans. 2

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“…44 The reduction in the rates of bimolecular quenching of 10 and 11 in the presence of water (particularly the latter compound) may be the result of particularly basic lowest triplet states, to an extent that hydrogen bonding to water competes more effectively with that to the phenol. The triplet state behavior of 1-indanone is known to be particularly sensitive to hydrogen-bonding solvents, 37,45 and our experience with 11 suggests that it behaves similarly.…”

Section: Discussionmentioning

confidence: 85%

Photoinduced Hydrogen Abstraction from Phenols by Aromatic Ketones. A New Mechanism for Hydrogen Abstraction by Carbonyl n,π* and π,π* Triplets

1996

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Nanosecond laser flash photolysis studies have been carried out of the kinetics of inter- and intramolecular phenolic hydrogen abstraction by alkoxyacetophenone, 5-alkoxyindanone, and 4-alkoxybenzophenone triplets in acetonitrile and benzene solution. Information on the geometric requirements for abstraction by carbonyl n,π* and π,π* triplets is derived from the results for a series of ketones which contain a para-phenolic moiety attached via a para-oxyethyl linkage. For all of these compounds, the deuterium kinetic isotope effect on the triplet lifetime in acetonitrile solution indicates that triplet decay is determined by the rate of intramolecular abstraction of the remote phenolic hydrogen, which yields the corresponding phenoxyl−hemipinacol biradical. The biradicals have also been detected, and are about an order of magnitude longer-lived than the triplet in each case. For three of the compounds, the rates of the intramolecular process follow the same trend as that observed in the rates of bimolecular quenching of the parent methoxy-substituted ketones by p-cresol. Deviation from this trend is observed for the alkoxyindanone derivative, where an in-plane approach of the phenolic hydrogen to the carbonyl n-orbital is not possible. The trends in the rate constants for bimolecular quenching of a series of substituted benzophenones by p-cresol indicate that for n,π* triplet abstractions, the quenching mechanism is different for electron donor-substituted and electron acceptor-substituted ketones. For π,π* triplets and donor-substituted (n,π* triplet) benzophenones, abstraction is proposed to occur by a mechanism involving the intermediacy of a hydrogen-bonded exciplex, which yields the corresponding radicals by sequential electron- and proton-transfer. The rate constant for quenching by this mechanism thus depends mainly on the basicity of the ketone triplet state and the oxidation potential of the phenol.

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“…Reaction occurs preferentially at the 1 position to provide the benz[e]indole (1), albeit in modest yield. 87 Nuclear magnetic resonance spectra were recorded on a General Electric QE-300 spectrometer at 300 MHz for 1 H and 75 MHz for 13 C, referenced to DMSO-d 6 , and TMS in CDCl 3 . Melting points were recorded on a Thomas Hoover capillary melting point apparatus, and they were uncorrected.…”

Section: Experimental and Computational Detailsmentioning

confidence: 99%

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

et al. 2007

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The photophysical properties of two isomeric 2-(2′-pyridyl)benzindoles depend on the environment. Strong fluorescence is detected in nonpolar and polar aprotic solvents. In the presence of alcohols, the emission reveals an unusual behavior. Upon titration of n-hexane solutions with ethanol, the fluorescence intensity goes through a minimum and then increases with rising alcohol concentration. Transient absorption and timeresolved emission studies combined with ground-and excited-state geometry optimizations lead to the conclusion that two rotameric forms, syn and anti, coexist in alcohols, whereas in nonpolar and aprotic polar media, only the syn conformation is present. The latter can form cyclic complexes with alcohols, which are rapidly depopulated in the excited state. In the presence of excess alcohol, syn f anti rotamerization occurs in the ground state, promoted by the cooperative action of nonspecific and specific effects such as solvent polarity increase and the formation of hydrogen bonds to both donor and acceptor sites of the bifunctional compounds.

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Selective photobleaching of the long-lived phosphorescence of 1-indanones

Cited by 24 publications

References 0 publications

Photochemistry of substituted cyclic enones. Part 12.1 Photocycloaddition of 3-phenylcyclopentenone and 3-phenylcyclohexenone to (E )- and (Z )-1-phenylpropene

Photochemistry of substituted cyclic enones. Part 12.1 Photocycloaddition of 3-phenylcyclopentenone and 3-phenylcyclohexenone to (E )- and (Z )-1-phenylpropene

Photoinduced Hydrogen Abstraction from Phenols by Aromatic Ketones. A New Mechanism for Hydrogen Abstraction by Carbonyl n,π* and π,π* Triplets

Structure and Photophysics of 2-(2‘-Pyridyl)benzindoles: The Role of Intermolecular Hydrogen Bonds

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