Resonance Raman spectra of the anion and cation radicals of bacterial photosynthetic pigments

Journal Article · Thu Dec 08 04:00:00 EST 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100100a013· OSTI ID:6669755

Diers, J R; Bocian, D F ^[1]

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1. Univ. of California, Riverside, CA (United States)

Resonance Raman (RR) spectra are reported for the radical ions of the bacterial photosynthetic pigments bacteriochlorophyll a (BCh) and its metal-free analog bacteriopheophytin a (BPh). The radical anions, BCh[sup [minus]] and BPh[sup [minus]], were the primary focus of the RR study; however, the radical cation, BCh[sup +], was also examined. The RR data for all the radical species were acquired by using a variety of excitation wavelengths in the UV-violet region. Data were also obtained for BCh[sup +] and BCh[sup [minus]] in solvents in which the MG(II) ion axially coordinates either one or two solvent molecules. The RR data for the radical ions suggest that oxidation/reduction results in characteristic frequency shifts for the carbonyl and ring skeletal modes of the bacteriochlorin macrocycles. These frequency shifts provide benchmarks for the characterization of transient radicals in vivo via time-resolved vibrational spectroscopy. The oxidation/reduction-induced frequency shifts observed for BPh and BCh are indicative of significant structural and/or electronic perturbations of the bacteriochlorin macrocycle. 39 refs., 9 figs., 2 tabs.

• OSTI ID: 6669755
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:49; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

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ABSORPTION SPECTRA
BACTERIA
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHLOROPHYLL
COMPILED DATA
DATA
EIGENVECTORS
ELECTROLYSIS
ENERGY LEVELS
EXCITED STATES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IONS
LYSIS
MAGNESIUM IONS
MICROORGANISMS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC BACTERIA
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RADICALS
RAMAN SPECTRA
REDOX PROCESS
REPROCESSING
SEPARATION PROCESSES
SPECTRA
ULTRAVIOLET SPECTRA
VIBRATIONAL STATES
VOLTAMETRY