Photoreduction of alkylmethylviologens in dipalmitoylphosphatidylcholine vesicles. Effect of the pendent alkyl chain length and the addition of cholesterol on the net photoyield

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00020a020· OSTI ID:6939303

McManus, H J.D.; Kang, Y S; Sakaguchi, Masato; Kevan, L ^[1]

---

1. Univ. of Houston, TX (United States)

A comprehensive electron magnetic resonance investigation was undertaken on a series of alkylmethylviologens which were solubilized into a D[sub 2]O suspension of dipalmitoylphosphatidylcholine vesicles with and without added cholesterol. These samples were photoirradiated at 77 K with ultraviolet light, and the radical yield was determined through electron spin resonance spectroscopy. The location of the photoreduced species was determined by means of both deuterium electron spin-echo modulation (ESEM) spectroscopy at 4 K and proton electron nuclear double resonance (ENDOR) spectroscopy at 140 K. The effect of added cholesterol on the photoyield was correlated with the location of the photoreduced radical within the lipid bilayer. Addition of cholesterol disrupts the interfacial region of the vesicles, allowing increased water penetration which serves to enhance the radical yield. As the pendent alkyl chain length is increased, the photoreduction yield increases and deuterium ESEM and proton ENDOR show that the viologen moiety is [open quotes]pulled[close quotes] deeper into the bilayer. This is consistent with the interpretation that deeper solubilization decreases the rate of electron back-transfer which effects an increased photoreduction yield. 73 refs., 7 figs.

• OSTI ID: 6939303
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 10:8; ISSN LANGD5; ISSN 0743-7463
• 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
400102 -- Chemical & Spectral Procedures
400201 -- Chemical & Physicochemical Properties
400500 -- Photochemistry
CHEMICAL REACTIONS
CHOLESTEROL
COLLOIDS
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
HEAVY WATER
HYDROGEN COMPOUNDS
HYDROLYSIS
HYDROXY COMPOUNDS
INDICATORS
LYSIS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
RADIATIONS
RADICALS
REDUCTION
RESONANCE
SOLVOLYSIS
SPECTROSCOPY
STEROIDS
STEROLS
SYNTHESIS
ULTRAVIOLET RADIATION
WATER