Temperature Dependence of Fluorescence and Photoisomerization in Symmetric Carbocyanines.Influence of Medium Viscosity and Molecular Structure

Aramendı́a, Pedro F.; Negri, R. Martı́n; Román, Enrique San

doi:10.1021/j100063a020

Cited by 181 publications

(153 citation statements)

References 9 publications

(11 reference statements)

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“…On the other hand, the less viscous and highly polar solvents provide TTBC a freedom to rotate and vibrate which can be the possible sources of the non-radiative transitions. These observations are in concert with the other cyanine dyes [1][2][3][4][5][6][7][8][9][10].…”

Section: Resultssupporting

confidence: 66%

“…The photophysics and photochemistry of cyanine dyes have been studied extensively [1][2][3][4][5][6][7][8][9][10]. It has been demonstrated that photoisomerisation and internal conversion, in general, participate in the deactivation of the excited state, and the restriction of these processes enhances fluorescence efficiency of cyanine dyes.…”

Section: Introductionmentioning

confidence: 99%

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Steady state and picosecond time-resolved photophysics of a benzimidazolocarbocyanine dye

Özçelik

2002

Journal of Luminescence

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We report the steady-state and the excited state properties of 1, 3, 1 0 , 3 0 -tetraethyl-5, 6, 5 0 , 6 0 -tetrachlorobenzimidazolocarbocyanine iodide (TTBC) in various solvents. The magnitude of the Stokes shift and the average transition energy proves that the structure of the fluorescent state should be very similar to that of the ground-state structure. The fluorescence lifetimes and quantum yields indicate that non-radiative processes are collectively much more effective than the radiative processes. It is therefore suggested that the non-radiative processes, which are driven by the medium around the TTBC molecule control the excited state dynamics. r

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Section: Resultssupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Steady state and picosecond time-resolved photophysics of a benzimidazolocarbocyanine dye

Özçelik

2002

Journal of Luminescence

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“…29 In earlier studies, this increased viscosity has been found to modify the nonradiative rates ͑k nr ͒ and increase in the excited state lifetime of molecules such as DiA ͑4-di-16-ASP; ͓4-͑4-dihexadecylamino͒styryl͔-N-methylpyridinium iodide͒. 23,30,31 The shape of the absorption spectrum of 2PBI remains unchanged upon addition of sucrose ͓Fig. 1͑a͔͒, but the intensity of cation emission at 380 nm decreases and that of tautomer emission at 460 nm increases concomitantly ͓Fig.…”

Section: Resultsmentioning

confidence: 95%

Early events associated with the excited state proton transfer in 2-(2′-pyridyl)benzimidazole

Burai

Mukherjee²,

Lahiri³

et al. 2009

The Journal of Chemical Physics

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2-͑2Ј-pyridyl͒benzimidazole ͑2PBI͒ undergoes excited state proton transfer ͑ESPT͒ in acidic solutions, leading to a tautomer emission at 460 nm. This photoprocess has been studied using ultrafast fluorescence spectroscopic techniques in acidic neat aqueous solutions, in viscous mixtures of glycerol with water, as well as in sucrose solutions. The tautomer is found to be stabilized in the more viscous medium, leading to a greater relative quantum yield as well as lifetime. The long rise time in tautomer emission is not affected by viscosity though. Rather, it appears to have the same value as the long component of the decay of the cationic excited state ͑C ‫ء‬ ͒. In addition to the subnanosecond lifetime reported earlier, C ‫ء‬ is found to exhibit a decay time of 2 ps. This is assigned to its protonation to form the nonfluorescent dication in its excited state ͑D ‫ء‬ ͒ considering the ground and excited state pK a values reported earlier. An additional rising component of 100 ps is observed in the region of C ‫ء‬ emission. This is likely to arise from a structural change or charge redistribution in C ‫ء‬ immediately after its creation and before the phototautomerization.

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“…Intersystem crossing, triplet formation and related deactivation channels of the first excited singlet state, i.e. the fluorescent state of cyanines are not very effective and have very low quantum yields [24][25][26][27][28][29][30][31][32]. Photoisomerisation and internal conversions leading to picosecond fluorescence lifetimes are considered as the main non-radiative deactivation pathways for cyanines [31,32].…”

Section: Resultsmentioning

confidence: 99%

“…the fluorescent state of cyanines are not very effective and have very low quantum yields [24][25][26][27][28][29][30][31][32]. Photoisomerisation and internal conversions leading to picosecond fluorescence lifetimes are considered as the main non-radiative deactivation pathways for cyanines [31,32]. Krieg et al investigated effects of structural modifications on photophysical properties of thiacarbocyanine dyes in neat solvents and liposomes [33,34].…”

Section: Resultsmentioning

confidence: 99%

Optical transition rates of a meso-substituted thiacarbocyanine in methanol-in-oil reverse micelles

Özçelik

Atay

2005

Journal of Luminescence

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We report the photophysical properties of 3,3 0 -diethyl-5,5 0 -dichloro-9-phenylthiacarbocyanine (DDPT) in methanolin-oil (m/o) reverse micellar systems which form methanol droplets stabilized with anionic surfactant aerosol-OT (AOT) in n-heptane. The fluorescence quantum yield of DDPT is enhanced by a factor of 17 in the methanol droplet in comparison with bulk methanol. The fluorescence lifetimes of DDPT in m/o reverse micelles are prolonged up to 2.2 ns with increasing molar ratio of methanol to surfactant (w 0 =[MeOH]/[AOT]), whereas the fluorescence lifetime of DDPT in bulk methanol is 75 ps. The non-radiative rate constants of DDPT in the droplets are decreased by a factor of 40, resulting in a remarkable enhancement in quantum yields, indicating that internal motions of DDPT in the droplets are significantly reduced due to strong electrostatic interactions between the positively charged DDPT and the negatively charged sulfonate head-groups of AOT and the spatial confinement induced by the reverse micellar structure. r

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Temperature Dependence of Fluorescence and Photoisomerization in Symmetric Carbocyanines.Influence of Medium Viscosity and Molecular Structure

Cited by 181 publications

References 9 publications

Steady state and picosecond time-resolved photophysics of a benzimidazolocarbocyanine dye

Steady state and picosecond time-resolved photophysics of a benzimidazolocarbocyanine dye

Early events associated with the excited state proton transfer in 2-(2′-pyridyl)benzimidazole

Optical transition rates of a meso-substituted thiacarbocyanine in methanol-in-oil reverse micelles

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