Fluorescence spectroscopy for a polymer monolayer at the air-water interface

Ito, Shinzaburo; Oki, Satoshi; Hayashi, Takanori; Yamamoto, Masahide

doi:10.1016/0040-6090(94)90632-7

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…All the sample solutions were purged with Ar before UV-absorption and fluorescence emission measurements. Fluorescence lifetimes were measured by a time-resolved equipment described before (35).…”

Section: Methodsmentioning

confidence: 99%

Conformational Effects on Photophysical Characteristics of C5–C5′-linked Dihydrothymine Dimers in Solution¶

Ito¹,

Shinohara²,

Nishimoto³

2000

Photochem Photobiol

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Photophysical characteristics of N-substituted C5-C5'-linked dihydrothymine dimers (1a,b[meso], meso compounds of [5R,5'S]-bi-5,6-dihydrothymines; 1a,b[rac], racemic compounds of [5R,5'R]-bi-5,6-dihydrothymines and [5S,5'S]-bi-5,6-dihydrothymines) in aqueous solution with varying contents of less-polar aprotic solvent such as tetrahydrofuran or dioxane have been investigated by UV-absorption, and steady-state and time-resolved fluorescence spectroscopies. Among the C5-C5'-linked dimers, (5R,5'S)-bi-5,6-dihydro-1-methylthymine (1a[meso]) showed a red-shifted weak UV-absorption band at 270-350 nm and excimer fluorescence emission at lambda max = 370 nm with a quantum yield (phi F) of approximately 0.1 in phosphate buffer (pH < 10) at 293 K. Racemic compound of 5,6-dihydro-1-methylthymine dimer (1a[rac]), meso and racemic compounds of 5,6-dihydro-1,3-dimethylthymine dimers (1b[meso] and 1b[rac]) in phosphate buffer were nonfluorescent under similar conditions. The UV-absorption and fluorescence spectral characteristics of 1a[meso] in aqueous solution were interpreted in terms of intramolecular stacking interactions between the dihydropyrimidine chromophores leading to a preferential "closed-shell" conformation both in the ground state and the excited singlet state. In basic solutions at pH > pKa = 11.7, the fluorescence quantum yield of 1a[meso] decreased due to a dominant "open-shell" conformation resulting from the electrostatic repulsion between the deprotonated dihydrothymine chromophores of 1a[meso] in a dianion form.

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Section: Methodsmentioning

confidence: 99%

Conformational Effects on Photophysical Characteristics of C5–C5′-linked Dihydrothymine Dimers in Solution¶

Ito¹,

Shinohara²,

Nishimoto³

2000

Photochem Photobiol

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“…Measurements. The details of the apparatus used in this study have been described elsewhere . We employed a pair of quartz optical fibers 3 mm in diameter.…”

Section: Methodsmentioning

confidence: 99%

“…The details of the apparatus used in this study have been described elsewhere. 11 We employed a pair of quartz optical fibers 3 mm in diameter. One was used as a light guide for excitation and its one end was positioned in the middle of trough at a distance of 5 mm above the water surface and at an angle of 45°by the surface plane.…”

Section: Preparation Of Monolayermentioning

confidence: 99%

Micro-Brownian Motion of Polymer Segments in a Monolayer at the Air−Water Interface: A Time-Resolved Study of Intralayer Energy Transfer

et al. 1996

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This work is concerned with micro-Brownian motion of polymer segments on a water surface, which is observed as the lateral diffusion of fluorescence probes attached to the polymer chains. Poly(vinyl octanal acetal)s labeled with phenanthrene (P: energy donor) and anthracene (A: energy acceptor) are spread on water, yielding a stable monolayer in which the probes are able to take statistically random distributions in the two-dimensional plane. The time-resolved fluorescence analysis of the energy transfer between the P and A probes allows us to evaluate the acceptor densities and lateral diffusion coefficients of polymer segments on the water surface. The result is obtained by fitting the fluorescence decay data with the theoretical prediction by the Monte Carlo simulation. It is found that this polymer forms a viscous monolayer, in which the lateral diffusion of polymer segments takes place with a diffusion coefficient of ca. 8 × 10-8 cm2 s-1.

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