Photoionization of chlorophyll a in rapidly frozen phospholipid vesicle solutions: Effects of phospholipid headgroup variation and addition of synthetic charged surfactants

Journal Article · Thu Mar 09 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100342a071· OSTI ID:5115187

Hiff, T; Kevan, L ^[1]

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1. Univ. of Houston, TX (USA)

Electron spin resonance (ESR) has been applied to measure the photoionization yield of chlorophyll a (Chla) after red-light irradiation with or without electron scavengers in frozen phospholipid vesicles differing in the nature of their headgroups. Along with the Chla monomeric cation, oligomeric cations have been detected. For anionic headgroups the photoionization yield is found to be half or less than that observed with the zwitterionic choline headgroup. A decrease of the yield is also observed when increasing amounts of anionic sodium dihexadecyl phosphate (DHP) are added to vary the surface charge of mixed vesicles. Electron spin echo (ESE) experiments in samples prepared with tetrabromo-P-benzoquinone (TBBQ) showed that the average location of the TBBQ radical anion is not sensitive to DHP addition. At low Chla concentration, the photoionization yield is increased more than 2-fold in dioctadecyldimethylammonium chloride (DODAC) cationic vesicles, prepared in pure water without electron scavengers, compared to the yield in similar dipalmitoylphosphatidylcholine (DPPC), vesicles. An increase in yield is also seen in mixed DPPC/DODAC vesicles at low Chla concentration. The results are discussed in terms of electrostatic barriers influencing electron transfer.

• OSTI ID: 5115187
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:5; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
CARBOXYLIC ACIDS
CHEMICAL REACTION YIELD
CHLOROPHYLL
DATA
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
ESTERS
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IONIZATION
LIPIDS
LOW TEMPERATURE
MAGNETIC RESONANCE
MICELLAR SYSTEMS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PHOTOIONIZATION
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RADIATIONS
RESONANCE
TEMPERATURE DEPENDENCE
VISIBLE RADIATION
YIELDS