Dual fluorescence of diphenylpolyenes

Itoh, Takaò; Kohler, Bryan E.

doi:10.1021/j100291a017

Cited by 103 publications

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“…5 While water does not shift the wavelength of the emission bands, its low polarizability, a S, water = 0.206, compared to 0.222 of ethanol and 0.284 of DMSO at 30 °C, destabilizes the S 2 orbital and reduces the S 2 -S 1 coupling, which are reflected as a weak fluorescence emission (low F F ). 9,15 However, the large decrease in the fluorescence intensity for such low water percentage in the solvent cannot be attributed to a simple solvent polarizability effect, as demonstrated by the fluorescence intensity decay of 27% for the addition of 10% water in methanol. 2 The a S of methanol is even smaller than that of water (a S, methanol = 0.203).…”

Section: Resultsmentioning

confidence: 99%

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Unusual 1,6-diphenyl-1,3,5-hexatriene (DPH) spectrophotometric behavior in water/ethanol and water/DMSO mixtures

Gracetto

Batistela

Santos

et al. 2010

J. Braz. Chem. Soc.

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O espectro de absorção de DPH, em concentração fixa, não varia com o teor de água em solvente orgânico. Tem-se a banda de monômeros igual àquela em etanol puro. A absorção não muda até o limite de 54 e 46% de água em etanol e DMSO, respectivamente, para [DPH] = 5,0 × 10 -6 mol L -1 a 30 °C. Entretanto, em misturas com água muito abaixo desses conteúdos críticos, observou-se um decaimento intenso de fluorescência enquanto a absorção manteve-se constante. Propõe-se que moléculas de água atuam como supressores dos estados excitados e a constante de supressão de Stern-Volmer através de intensidade relativas, resultou em 7,4 × 10 -2 (água/etanol) e 2,6 × 10 -2 L mol -1 (água/DMSO). Os tempos de vida do DPH na ausência e presença do supressor forneceram constantes de 7,1 × 10 -2 L mol -1 em água/etanol, indicando supressão dinâmica. Em investigações de ambientes com esta sonda, este processo deve ser considerado tendo em vista o risco de erros de interpretação.The absorption spectra of DPH at fixed concentration do not change with water content in organic solvents. It exhibits monomer bands, such as those obtained in ethanol. The absorption did not change for solutions up to 54 and 46% of water in ethanol and DMSO, respectively, for [DPH] = 5.0 × 10 -6 mol L -1 at 30 °C. However, at the same experimental conditions, a gradual sharp decay of the DPH fluorescence is observed. It is proposed that water molecules below these water concentration limits act as quenchers of the excited states of DPH. Stern-Volmer quenching constants by intensities measurements are 7.4 × 10 -2 (water/ethanol) and 2.6 × 10 -2 L mol -1 (water/DMSO). DPH lifetime measurements in the absence and presence of water resulted in 7.1 × 10 -2 L mol -1 in water/ethanol, which pointed out that the process is a dynamic quenching by water molecules. For experiments using DPH as probe, this process can affect data, leading to misunderstanding interpretation.Keywords: diphenylhexatriene, DPH, DPH fluorescence, dynamic quenching, lifetime 3,, which is used as a fluorescence probe, has a rod-like structure that absorbs and emits light with a high quantum efficiency, although it is not a large conjugative p-electron system. Introduction 1,2The spectrophotometric properties of DPH are very sensitive to the experimental conditions, which allows using this compound and its derivatives as environmental probes in colloidal systems to determine the critical micellar concentration of surfactants 3 and in biological cell membranes. 4,5 The measurement of the fluorescence anisotropy of DPH is extensively used for membranes, particularly in studies of microviscosities, 6 due to the non-polar characteristic, the low water solubility, and the suitable geometric design, which maintains the molecule aligned parallel to the phospholipids chains of the membranes. 7 Although the DPH molecule remains inserted in the membrane layer, it stays in contact with water molecules. 2,5The majority of DPH spectrophotometric studies on electronic transitions are performed in organic solven...

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Section: Resultsmentioning

confidence: 99%

“…Additionally, a solvent with high polarizability stabilizes the S 2 orbital and favors the S 2 -S 1 coupling, leading to a high fluorescence yield. 9,15 The slightly decrease in the polarizability of organic solvents with the increase in the temperature destabilizes the 1 B u * state. The resulting decrease of the S 1 -S 2 coupling promotes a decrease of F F .…”

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confidence: 99%

Unusual 1,6-diphenyl-1,3,5-hexatriene (DPH) spectrophotometric behavior in water/ethanol and water/DMSO mixtures

Gracetto

Batistela

Santos

et al. 2010

J. Braz. Chem. Soc.

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“…The S1 state of DPA is nonfluorescent, while many diphenylpolyenes emit fluorescence from the S1 state and the S2 fluorescence appears on the higher-energy side of the S1 --> S0 fluorescence [13,15]. Such difference may be partially due to the rapid S1 → Τ1 intersystem crossing of DPA but the more strict forbidden factor of the Si-S0 dipole transition of DPA compared with that of diphenylpolyenes should be responsible for the nonfluorescent character of the S 1 state of DPA.…”

Section: Discussionmentioning

confidence: 99%

Photophysical Properties of Diphenylacetylene and Diphenylbutadiyne Derivatives in Solution Phase

1998

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By using the femtosecond and picosecond transient absorption measurement techniques, we have investigated diphenylatetylene, diphenylbutadiyne, and their methoxy and cyano derivatives in the solution phase.Both the rapid S2 → S1 internal conversion in the subpicosecond time scale and the triplet formation in the tens of picosecond region were observed for diphenylbutadiyne and its methoxy derivatives, while the dynamic behavior of dimethoxy-diphenylacetylene was quite similar to that of diphenylacetylene. The level inversion of the lowest excited singlet states of dicyano-diphenylbutadiyne was observed. The thermally activated S2 <-S1 internal conversion was not negligible and the sum of the rate constants of 52 → S1 and S2 ←S1 internal conversions was estimated to be about Recently, characters of the low lying excited singlet states of diphenylacetylene (DPA) and its derivatives have been studied in the solution phase [1][2][3][4][5][6][7]. The absorption band of DPA observed at 290 mn was assigned to the 1B1u state, while the lowest excited singlet state was predicted to be 2 1Αg state [8]. Recent INDO/S calculation predicted that the S1 state has Au symmetry [6]. Under the supersonic beam conditions, the energy gap between the 1Β1u and 2 1Αg states is less *The results of this paper were initially presented at

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“…For the 1 ^ <-1 1 A g transition the converse applies. Since the l 1 B u -2 1 A g energy gap in DPH is sufficiently small for thermal repopulation to occur to the ^B,, state, which is reflected by the delayed fluorescence from the state observed by Alford and Palmer [12,13] and others [14,15] in the form of a shoulder at the onset of DPH fluorescence spectra, the fluorescence can be emitted from both the lower 2 1 A g state (S t ) and 1 1 B U state (S 2 ) with a slightly higher energy. The investigations of Felder et al [16] of the transient behaviour of DPH and DPO carried out using picosecond time-resolved fluorescence spectroscopy have shown that, contrary to DPO, the prompt fluorescence of DPH from the 1 state is weak, exhibiting an abormally long decay time (> 30 ps).…”

Section: Introductionmentioning

confidence: 99%

Isomerization of Diphenyl Polyenes. Part V. The Origin of Fluorescence of l,6-Diphenyl-1,3,5-hexatriene in Poly (vinyl alcohol) Films

Kawski

Kubicki

Kukliński

et al. 1993

Zeitschrift Für Naturforschung A

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The effect of temperature on the absorption and fluorescence spectra of l,6-diphenyl-l,3,5-hexatriene (DPH) was investigated in three different polymer films: polyvinyl chloride) (PVCh), polyvinyl formal) (PVF) and polyvinyl alcohol) (PVA) in the temperature range 296-423 K. Anomalous behaviour of the fluorescence intensity was observed only for DPH in non-heated PVA film. The intensity distribution in the fluorescence band of DPH in both non-heated and heated PVCh and PVF films was found to be independent of the excitation light wavelength, A exc . The behaviour of DPH is similar in the PVA film heated to 423 K. For these samples, single exponential fluorescence decay was observed. The behaviour of non-heated DPH samples in PVA is quite different, the intensity distribution and the fluorescence band position depending strongly on ^. exc and the fluorescence decay being double exponential. It can be inferred that the fluorescence of DPH in a non-heated PVA sample consists of two components, the first originating from the all-trans conformer and the second from the ground-state s-eis conformer.

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Dual fluorescence of diphenylpolyenes

Cited by 103 publications

References 0 publications

Unusual 1,6-diphenyl-1,3,5-hexatriene (DPH) spectrophotometric behavior in water/ethanol and water/DMSO mixtures

Unusual 1,6-diphenyl-1,3,5-hexatriene (DPH) spectrophotometric behavior in water/ethanol and water/DMSO mixtures

Photophysical Properties of Diphenylacetylene and Diphenylbutadiyne Derivatives in Solution Phase

Isomerization of Diphenyl Polyenes. Part V. The Origin of Fluorescence of l,6-Diphenyl-1,3,5-hexatriene in Poly (vinyl alcohol) Films

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