Carotenoid radical ions: A laser flash photolysis study.

Laser excitation of a single precursor, namely 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HHEMP), has been used for generating the radical cations and radical anions of various carotenoids in methanol. In the presence of oxygen, laser excitation of HHEMP undergoes an efficient α-cleavage reaction (Norrish type I) to form acyl radicals, which react with O, in a nearly diffusion-controlled reaction, to form their corresponding strong oxidizing acylperoxyl radicals (RO) (E = ~1.1 V (v SHE)), which are capable of oxidizing almost all carotenoids.

Exploring the reactivity of retinol radical cation toward organic and biological molecules: A laser flash photolysis study.

Vitamin A (retinol) and various natural retinoids are essential for life. Under oxidative conditions, vitamin A radical cation (RET) can be formed. Many deleterious effects were reported about the formation of carotenoid radical cations in biological environments, on the other hand, little is known about the consequences of the RET formation in these environments.

Peroxyl radical reactions with carotenoids in microemulsions: Influence of microemulsion composition and the nature of peroxyl radical precursor.

The reactions of acetylperoxyl radicals with different carotenoids (7,7'-dihydro-β-carotene and ζ-carotene) in SDS and CTAC microemulsions of different compositions were investigated using laser flash photolysis (LFP) coupled with kinetic absorption spectroscopy. The primary objective of this study was to explore the influence of microemulsion composition and the type of surfactant used on the yields and kinetics of various transients formed from the reaction of acetylperoxyl radicals with carotenoids. Also, the influence of the site (hydrocarbon phases or aqueous phase) of generation of the peroxyl radical precursor was examined by using 4-acetyl-4-phenylpiperidine hydrochloride (APPHCl) and 1,1-diphenylacetone (11DPA) as water-soluble and lipid-soluble peroxyl radical precursors, respectively.

Influence of pH on the decay of β-carotene radical cation in aqueous Triton X-100: A laser flash photolysis study.

The identification of the spectral information of carotenoid neutral radicals is essential for studying their reactivities towards O2 and thereby evaluating their role in the antioxidant-prooxidant properties of the corresponding carotenoid. Recently, it was reported that β-carotene neutral radical (β-CAR) has an absorption maximum at 750 nm. This contradicts the results of many reports that show carotenoid neutral radicals (CAR) absorb in the same or near to the spectral region as their parent carotenoids.

Synthesis, crystal structure and thin-film-optical properties of 3-amino-2-(2-nitrophenyl)diazinyl-3-(morpholin-1-yl)acrylonitrile.

3-Amino-2-(2-nitrophenyl)diazinyl-3-(morpholin-1-yl)acrylonitrile (ANMA) has been successfully synthesized via conventional solvent method, and its molecular structure has been identified by using various techniques including FTIR, (1)H NMR, MS and elemental analysis. The crystal structure of ANMA is characterized by single crystal X-ray crystallography. Crystallographic data revealed that the spatial structure of ANMA belongs to monoclinic, P21 a space group.