A resonance Raman investigation of the cation radical of chlorophyll a and several derivatives

Journal Article · Thu May 17 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100373a019· OSTI ID:6510950

Heald, R L ^[1]; Cotton, T M ^[2]

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1. Univ. of Nebraska, Lincoln (USA)
2. Iowa State Univ., Ames (USA)

Soret excitation resonance Raman (RR) spectra of the electrochemically generated cation radical of chlorophyll a and several of its derivatives, including copper- and zinc-substituted pheophytin a, pyrochlorophyll a, and 10-hydroxychlorophyll a, have been obtained. An examination of the RR spectra of the ring five derivatives clearly shows that the band at 1,717 cm{sup {minus}1} in the chlorophyll a cation radical spectrum is due to the C{sub 9} keto stretching mode. This band experiences the largest shift (from 1,685 cm{sup {minus}1} in the neutral to 1,717 cm{sup {minus}1} in the cation radical) following one-electron oxidation. The 32-cm{sup {minus}1} upshift is attributed to a decrease din the conjugation between the C{sub 9} keto group and the macrocycle as a result of the one-electron oxidation. Thus, the C{sub 9} keto group may play a role in the chlorophyll redox reactions in vivo.

• OSTI ID: 6510950
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:10; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

550500* -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLOROPHYLL
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
LASER SPECTROSCOPY
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RADICALS
RAMAN SPECTROSCOPY
SPECTROSCOPY
SYNTHESIS