Electrical characteristics of chlorophyll a films

Reucroft, P. J.; Simpson, William H.

doi:10.1039/df9715100202

Cited by 12 publications

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“…A number of studies on the functions of Chl- a LB films have been carried out extensively, aiming at developing new molecular devices such as photoelectric cells based upon the Chl- a assemblies. − Most of the studies suggested that Chl- a is not a suitable organic semiconductor and a sufficient photoelectric conversion effect has not been observed. Some research groups investigated energy transfer from/to Chl- a in LB films containing another molecule as well as Chl- a .…”

Section: Introductionmentioning

confidence: 99%

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,

Sato¹,

Ozaki²,

Oishi³

et al. 1997

Langmuir

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Attenuated total reflection (ATR)/Fourier-transform infrared (FT-IR) spectra were measured for one-monolayer Langmuir−Blodgett (LB) films of chlorophyll a (Chl-a) fabricated in an argon (Ar) atmosphere. The frequencies of CO stretching bands and marker bands for the coordination number of the central Mg atom suggest that Chl-a takes a five-coordinated dimer in the films prepared in the Ar atmosphere. Ultraviolet−visible (UV−vis) as well as IR spectra were obtained for multilayer LB films of Chl-a prepared in air, Ar, nitrogen (N2), and oxygen (O2) atmospheres. In the cases of the multilayer LB films, spectral features in the CO stretching band region suggest that Chl-a exists as a monomer in the film prepared in air while it assumes a dimer in the films prepared in the Ar, N2, and O2 atmospheres. The marker bands for the coordination number of the Mg atom in the IR spectra indicate that Chl-a is in a five-coordinated state. These results imply that one can control the molecular arrangement in the LB films of Chl-a by changing the atmosphere in which they are prepared. Both the UV−vis and IR spectra of the LB films fabricated in the Ar, N2, and O2 atmospheres are almost identical to each other. This means that O2 does not affect the stability and structure of Chl-a in the monolayer on the aqueous subphase. On the basis of the postulate that CO2, which exists only in air, caused a change in pH of the aqueous subphase, we investigated pH-dependent IR spectral changes for the LB films. The results indicate that the dimer of Chl-a changes into pheophytine a (Phe-a) below pH 6.0 and that the monomer species do not exist through pH 6.0−4.0; therefore, it is unlikely that CO2 changes the pH. Probably CO2 coordinates to the central Mg atom as a fifth ligand in the LB films prepared in air, preventing the keto carbonyl group of another Chl-a molecule from coordinating to it.

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Section: Introductionmentioning

confidence: 99%

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,

Sato¹,

Ozaki²,

Oishi³

et al. 1997

Langmuir

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Multiplikationseffekt bei der Sensibilisierung organischer Molekülkristalle durch induzierte Feldemission

Killesreiter

1973

Ber Bunsenges Phys Chem

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Ein sandwichartiger Aufbau aus einem p‐Chloranilkristall und monomolekularen Schichten von Cyaninfarbstoff‐ und Fettsäuremolekülen wurde mit aufgedampften Aluminiumelektroden kontaktiert. Die Quantenausbeute für den sensibilisierten Photostrom ist bis zu mehreren Größenordnungen höher als eins. Die Strom‐Spannungsabhängigkeit, die Temperaturabhängigkeit und die Intensitätsabhängigkeit wurden untersucht. Die Deutung der Ergebnisse ist konsistent mit einem Modell, das durch eine lichtinduzierte Potentialbergänderung zwischen dem Kristall und der Elektrode eine zusätzliche Elektronenemission aus dem Metall erklärt

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Laser Photoinduced Changes in the High Frequency Dielectric Constant of Chloroplasts and Dyes

Anitoff¹

1979

Electro-Optics and Dielectrics of Macromolecules and Colloids

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Electrical characteristics of chlorophyll a films

Cited by 12 publications

References 0 publications

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,

Multiplikationseffekt bei der Sensibilisierung organischer Molekülkristalle durch induzierte Feldemission

Laser Photoinduced Changes in the High Frequency Dielectric Constant of Chloroplasts and Dyes

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Electrical characteristics of chlorophyll a films

Cited by 12 publications

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Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy,

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy,

Multiplikationseffekt bei der Sensibilisierung organischer Molekülkristalle durch induzierte Feldemission

Laser Photoinduced Changes in the High Frequency Dielectric Constant of Chloroplasts and Dyes

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Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,

Control of Molecular Arrangement in Langmuir−Blodgett Films of Chlorophyll a Prepared in Various Gas Phases Studied by Ultraviolet−Visible and Infrared Spectroscopies and Atomic Force Microscopy^,