Original scientific paper

Low-Frequency Vibrational Spectra of Chlorophylls a and b in Solution: Effects ofAxial Coordination

Masao Fujiwara ; Department of Chemistry, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Hidenori Hayashi ; Department of Chemistry, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Mitsuo Tasumi ; Department of Chemistry, Faculty of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan

Abstract

The far-infrared spectra (500--100 cm-I) of chlorophyll a were
observed in three solvent systems (benzene-pyridine, benzene-tetrahydrofuran, and benzene-acetone). The observed spectra could
be classified into three types corresponding to the aggregate state,
the five-coordinate monomeric state, and the six-coordinate state.
The far-infrared spectra of I5N_and 26lV[g-substitutedspecies and
the polarized resonance Raman spectra of chlorophyll a and pheophytin a in the region of 500~100 cm-I were studied. These experimental results indicate that bands characteristic of the three
states are due to modes to which deformations of the macrocycle
make major contributions and vibrations around the Mg atom
make some contributions, and that no band observed in the far-
-infrared and Raman spectra is attributable to a vibrational mode
associated predominantly with the Mg atom and the coordinating
atoms. The spectral behavior of chlorophyll b in the benzene-pyridine
system was similar to that of chlorophyll a.

Keywords

Hrčak ID:

175922

URI

https://hrcak.srce.hr/175922

Publication date:

30.9.1988.

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