The quantum yield in the photo-decomposition of the alkyl halides in non-polar solvents

Abstract For 4'-acceptor substituted 4-dimethylaminostilbenes 1 the fluorescence quantum yield φf increases in n-heptane and toluene with decreasing acceptor interaction (i.e. with decreasing polarity in the S1-state). At the same time, the lifetimes τfw change with φf so that kfn remains approximately constant. Changes in φf for compounds 1 result from a strong change of the rate constant ktp of radiationless deactivation. This is interpreted in terms of the decreased stabilization of the Si-state occurring with the increase in the polarity of the investigated compounds in non-polar solvents, and remains in good agreement with the calculations carried out previously.

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Fluorescent Whitening Agents

Textile Research Journal ◽

10.1177/004051757604600715 ◽

1976 ◽

Vol 46 (7) ◽

pp. 539-544 ◽

Cited By ~ 9

Author(s):

L. A. Holt ◽

I. H. Leaver ◽

B. Milligan

Keyword(s):

Vinyl Acetate ◽

Polymer Films ◽

Room Temperature ◽

Polar Solvents ◽

Fluorescence Studies ◽

First Order ◽

Absorption And Fluorescence Spectroscopy ◽

Fluorescent Whitening Agents ◽

Kinetics Of ◽

Photo Decomposition

Ultraviolet absorption and fluorescence spectroscopy have been used to determine the nature and extent of photo-decomposition of fluorescent whitening agents in polymer films and in surface-whitened wool. Irradiation of the coumarin (I) in polymer films at 365 nm gives rise to a mixture of photodimers which rapidly revert to I on irradiation at wavelengths less than 320 nm. Irradiation of the stilbene (II) at 365 nm also gives a photodimer which absorbs strongly around 350 nm, but this reverts only slowly to II on irradiation. Fluorescence studies indicate that there is an increase in the degree of aggregation of I in polymer films with increasing whitener concentration, and that the kinetics of whitener photodecomposition change from first-order at low whitener concentration (0.0025%) to second-order at the higher concentration (2.5%) used in surface-whitening. The coumarin (I) is more stable to light in poly(vinyl acetate) film cast from formic acid than in films cast from less polar solvents, probably because of differences in the degree of whitener aggregation. The photostability of I in poly(vinyl acetate) film is also improved if the film is heated for short periods or stored at room temperature for longer periods.

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Einfluß von Substituenten und polaren Lösungsmitteln auf die Deaktivierung des S1Zustandes bei Donator-Akzeptor-substituierten trans-Stilbenen/Influence of Substituents and Polar Solvents on the Deactivation of the First Excited Singlet of Donor-acceptor Substituted Trans-stilbenes

Zeitschrift für Naturforschung A ◽

10.1515/zna-1980-1227 ◽

1980 ◽

Vol 35 (12) ◽

pp. 1411-1414 ◽

Cited By ~ 1

Author(s):

D. Gloyna ◽

A. Kawski ◽

I. Gryczyński

Keyword(s):

Quantum Yield ◽

Fluorescence Quantum Yield ◽

Singlet State ◽

Excited Singlet State ◽

Excited Singlet ◽

Polar Solvents ◽

Effect Of Substituents ◽

Nonpolar Solvents ◽

Donor Acceptor ◽

Influence Of Substituents

AbstractThe effect of substituents on the fluorescence quantum yield φf of trans-stilbenes (1) in dimethylformamide, acetonitrile, and n-propanol, as well as in n-heptane, is mainly due to radiationless deactivation. Contrary to n-heptane, the rate kd of radiationless deactivation in the above mentioned polar solvents for compounds 1 of similar structure is not a monotoneous function of the polarity of the first excited singlet state. The maximum of kd corresponds to compounds with medium polarity (1h, 1i). The effect of substituents on the fluorescence rate kfn in polar and nonpolar solvents is small compared to that on kd. In all solvents kfn drops with increasing polarity of the first excited singlet state.

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Protonation effect on the excited state behaviour of some aza-analogues ofEE-distyrylbenzene

International Journal of Photoenergy ◽

10.1155/s1110662x04000315 ◽

2004 ◽

Vol 6 (4) ◽

pp. 241-250 ◽

Cited By ~ 7

Author(s):

Gabriella Ginocchietti ◽

Ugo Mazzucato ◽

Anna Spalletti

Keyword(s):

Quantum Yield ◽

Conformational Isomerism ◽

Central Ring ◽

Polar Solvents ◽

Experimental Conditions ◽

Acid Media ◽

Order Of Magnitude ◽

State Behaviour ◽

Photochemical Properties ◽

Main Effects

The photobehaviour of four aza-analogues ofEE-distyrylbenzene bearing the heteroatom in the two side rings [1,4-di-(2-pyridylethenyl)benzene] or in the central ring [2,5-di-(phenylethenyl)pyridine, 2,6-di(phenylethenyl)pyridine and the corresponding diene, 2,6-di(phenylbutadienyl)pyridine] has been investigated in aqueous solutions at pH 2 and 9, where the molecules are in mono-protonated and neutral forms, respectively. The type of conjugation, linear for the first two compounds and crossed for the others, is particularly important in determining the spectral and photochemical properties. The main effects of the protic solvent are a reduction of the radiative deactivation, prevalent in the corresponding hydrocarbons, and an increase of the reactive deactivation, very modest in the hydrocarbons. The increase in photoreactivity to detriment of fluorescence, observed in protic medium with respect to non-polar solvents, is drastically emphasized in acid medium where the fluorescence quantum yield decreases by an order of magnitude leading to high values of theEE→ZEphotoisomerization quantum yield. The presence of conformational isomerism (two main conformers were detected) has been observed in both basic and acid media for compounds with crossed conjugation and for the linearly conjugated 2,5 substituted pyridine. The results obtained give a picture of the different photobehaviour of the neutral and protonated species and indicate the experimental conditions to favour a specific relaxation pathway.

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Fluorescence Properties of p-Quaterphenyl and p-Quinquephenyl Derivatives in Liquid Solvents

Zeitschrift für Naturforschung A ◽

10.1515/zna-1996-0804 ◽

1996 ◽

Vol 51 (8) ◽

pp. 905-909 ◽

Cited By ~ 2

Author(s):

A. Kawski ◽

G. Piszczek ◽

A. Kubicki

Keyword(s):

Quantum Yield ◽

Linear Molecule ◽

Quantum Yields ◽

High Quantum Yield ◽

Polar Solvents ◽

Emission Anisotropy ◽

Low Viscosity ◽

Decay Times ◽

Rotational Motions ◽

Anisotropy Spectra

Abstract Absorption, fluorescence and emission anisotropy spectra, as well as quantum yields and fluores-cence decay times of p-quaterphenyl (PQP), 4,4"'-bis-(2-butyloctyloxy)-p-quaterphenyl (BBQ), 2,5,2"",5""-tetramethyl-p-quinquephenyl (TMI) and 3,5,3"",5""-tetra-f-butyl-p-quinquephenyl (QUI) were investigated in several nonpolar and polar solvents. It was found that high quantum yield is accompanied by a short (not exceeding 1 ns) lifetime and considerable emission anisotropy in low viscosity solvents. For TMI and QUI, which incorporate as many as 5 phenyl groups, the quantum yield in dioxane is 0.98 and 0.97, respectively. In the case of molecules with 4 phenyl groups, the quantum yield is slightly lower, amounting to 0.91. Rotational motions of terminal phenyl groups cause a lower deactivation of the excitation energy of the singlet state S p the longer the linear molecule.

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An ESIPT fluorescent dye based on HBI with high quantum yield and large Stokes shift for selective detection of Cys

Journal of Materials Chemistry B ◽

10.1039/c4tb00190g ◽

2014 ◽

Vol 2 (26) ◽

pp. 4159-4166 ◽

Cited By ~ 61

Author(s):

Ying Zhang ◽

Jun-Hao Wang ◽

Wenjie Zheng ◽

Tianfeng Chen ◽

Qing-Xiao Tong ◽

...

Keyword(s):

Quantum Yield ◽

Stokes Shift ◽

Fluorescent Dye ◽

Selective Detection ◽

High Quantum Yield ◽

Polar Solvents ◽

Large Stokes Shift ◽

High Quantum

DPIN shows prominent ESIPT emission even in protic/polar solvents, and is further employed as a sensor for selective detection of Cys.

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Controlled synthesis and photostability of blue emitting Cs3Bi2Br9 perovskite nanocrystals by employing weak polar solvents at room temperature

Journal of Materials Chemistry C ◽

10.1039/c9tc00400a ◽

2019 ◽

Vol 7 (12) ◽

pp. 3688-3695 ◽

Cited By ~ 16

Author(s):

Mingyang Gao ◽

Chi Zhang ◽

Linyuan Lian ◽

Jianwei Guo ◽

Yong Xia ◽

...

Keyword(s):

Quantum Yield ◽

Room Temperature ◽

Controlled Synthesis ◽

Polar Solvents ◽

Dual Emission ◽

Perovskite Nanocrystals ◽

Photoluminescence Quantum Yield

All inorganic Cs3Bi2Br9 perovskite NCs were synthesized at room temperature, demonstrating blue dual-emission peaks and high photoluminescence quantum yield.

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