Photophysical behavior of norharmane related to proximity effect

Olba, A.; Tomás, F.; Zabala, I.

doi:10.1016/0022-2313(90)90055-g

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…Therefore, we conclude that the influence of the temperature in the emission spectra of BC in non-polar aprotic solvents, is not due, as proposed by Olba et al, 1 to a change in the nature of the emitting state, but rather to the formation of intermolecular hydrogen bond BC aggregates. We have shown that, in the temperature range analysed by the mentioned authors, 1 the formation of dimeric hydrogen bonded BC adducts, with a proton transfer structure, satisfactorily explains the modifications suffered by the absorption and emission bands upon decreasing temperature.…”

Section: Methodssupporting

confidence: 69%

“…Some years ago, Olba et al 1 studied the solvent and temperature effect on the fluorescence properties of betacarboline, 9Hpyrido [3,4-b]indole, BC, Scheme 1. These studies were carried out in two solvents, a mixture of 5 : 5 : 2 by volume of ethyl ether, 2-methylbutane and ethanol, EPA, and methylcyclohexane, MCY, at different decreasing temperatures from room temperature.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dual emission of temperature-induced betacarboline self-associated hydrogen bond aggregates

Hidalgo

Sánchez‐Coronilla

Balón

et al. 2009

Photochem Photobiol Sci

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A systematic study of the influence of the gradual temperature decrease on the UV-vis absorption and fluorescence emission spectra of betacarboline, 9H-pyrido[3,4-b]indole, BC, and other model systems, such as BC plus N(9)-methyl-9H-pyrido[3,4-b]indole, MBC, and BC plus pyridine, PY, has been carried out in 2-methylbutane, 2MB. These studies have allowed the conclusion that the temperature decrease favours the formation of hydrogen-bonded self-associated BC aggregates. The initial red shifts of the absorption and emission bands and the fluorescence quenching have been ascribed to the formation of hydrogen bond BC dimers with a proton transfer structure, PTC. In these adducts, the fluorescence is quenched by an electron-driven proton transfer process. However, because the quenching rate constant decreases upon decreasing the temperature, the emission intensity later increases without modification of the wavelength maxima. At the lowest temperatures, these dimeric PTC complexes further aggregate. We propose that they form ground state cyclic tetrameric adducts in which both nitrogen atoms of each BC unit are hydrogen bonded. The tautomeric forms of these tetrameric complexes, generated by a quadruple proton transfer, emit dual fluorescence, from its locally excited state, LE, and its intramolecular charge transfer state, ICT.

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