Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin

Mohamad, Samsun Baharin; Yousef, Y.A.; Melø, Thor-Bernt; Jávorfí, Tamás; Partali, Vassilia; Sliwka, Hans‐Richard; Naqvi, K. Razi

doi:10.1016/j.jphotobiol.2006.02.006

Cited by 10 publications

(9 citation statements)

References 13 publications

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“…However, the pragmatic rule "the higher the absorption the better the antioxidant" is not valid for polyenes with heteroatoms, as previously verified for 1 O 2 quenching with carotenoid thiones. [34] Compound 3C + absorbs at a higher wavelength than 6C + , and even higher than 7C + and 4C + (see Table 2 and Figure 4). Compound 3 went from a high ground-state energy level to a low energy level after electron release.…”

Section: Wwwchemeurjorgmentioning

confidence: 96%

“…[11,33] Other groups directly attached to the carotenoid scaffold (e.g., thione, oxime, and Se ether functionalities) have limited or no impact on the antioxidant activity. [3,34] In water, antioxidant properties have occasionally been determined by incorporating hydrophobic carotenoids into micelles prepared with xenobiotic detergents. Extraneous surfactants, however, can obscure the experimental results.…”

Section: Introductionmentioning

confidence: 99%

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Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids

Sliwka

Melø

Foss

et al. 2007

Chemistry A European J

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The antioxidant activities-expressed as the electron-donating properties-of five hydrophilic carotenoids (carotenoid surfactants) and three related hydrophobic carotenoids were investigated by flash photolysis. The electron-transfer rates of the carotenoids to the triplet state of the sensitizer 2-nitronaphthalene and the energy transfer rates of triplet 2-nitronaphthalene to the carotenoids were determined. The results demonstrate that the electron-donating effects of the hydrophilic and hydrophobic carotenoids were comparable when evaluated in acetonitrile. In the presence of water, however, electron transfer (i.e., antioxidant efficiency) was enhanced by a factor of four for the hydrophilic carotenoids. The increased hydrophilicity of carotenoids, therefore, could expand their antioxidant properties, thus facilitating their use as aqueous-phase radical scavengers. At the same time, it was shown that supramolecular assembly ("aggregation") of the amphiphilic carotenoids prevented electron transfer, thus deactivating the antioxidant function. Modulation of the biophysical properties of carotenoids through synthetic modification is capable of increasing the biological and medical utility of this natural class of predominantly hydrophobic antioxidant compound.

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Section: Wwwchemeurjorgmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids

Sliwka

Melø

Foss

et al. 2007

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

show abstract

“…33 Other groups directly attached to the carotenoid scaffold (e.g., thione, oxime, and Se ether functionalities) have limited or no impact on the antioxidant activity 3. 34 In water, antioxidant properties have occasionally been determined by incorporating hydrophobic carotenoids into micelles prepared with xenobiotic detergents. Extraneous surfactants, however, can obscure the experimental results 23.…”

Section: Introductionmentioning

confidence: 99%

Salinity alters the protein composition of rice endosperm and the physicochemical properties of rice flour

Baxter

Zhao

Blanchard

2011

J. Sci. Food Agric.

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Salinity can significantly affect the pasting and textural characteristics of rice flour. Although some of the effects could be attributed to changes in protein content of the rice flour, especially the increased glutelin level, the impact of salinity on the physicochemical properties of rice is rather complex and may involve the interrelated effects of other rice components such as starch and lipids.

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“…In addition, it has also been previously reported that compounds containing thiones usually exhibit a absorption bands in the visible region that are broader and considerably red-shifted compared to those of simple carbonyls 140 .…”

Section: Resultsmentioning

confidence: 82%

Low optical gap materials for organic solar cells - research and application

Chandrasekharan¹

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In spite of the cost of silicon solar cells decreasing in recent years, there is considerable interest in solar cells with lightweight and flexible forms. Organic semiconductor-based photovoltaic cells (OPVs) have the potential to offer low cost, lightweight and flexible devices. At this stage there is still much to be improved for OPVs as the efficiencies are still lower than their inorganic counterparts. Polymeric materials have been more widely studied than their non-polymeric counterparts. In recent years OPVs polymeric donor materials have emerged with efficiencies reaching 10% with quite a range of materials now providing efficiencies of around 7%. However, the problem with semiconducting polymers is that control of the regioregularity, poly(dispersity), and molecular weight from batch-to-batch is not a simple process. Solution-processable nonpolymeric semiconductors are attractive for opto-electronic applications as they are simpler to synthesise, purify, characterise, and the optical properties can be more easily fine-tuned. In this context, diketopyrrolopyrrole (DPP) based small molecules have shown promising results with devices efficiencies reaching around 5-6%. Key properties of the DPP unit are strong π-π interactions, and suitable and tunable energy levels. These properties have been the main drivers in their use in OPVs.This thesis consist of the synthesis, characterisation, and bulk hetrojunction (BHJ) devices properties of novel DPP(ThAr) 2 non-polymeric materials. Accordingly, a first series of compounds was synthesized with different electron affinity groups such as fluorenone (Fl) [EhDPP(ThFl) 2 and OddDPP(ThFl) 2 ] and benzothiadiazole (Bt) [OddDPP(ThBt) 2 ] attached to the distal ends of a bisthienyl-diketopyrrolopyrrole unit DPP(Th) 2 unit. The 'DPP(ThAr) 2 ' derivatives were synthesised under standard Suzuki-Miyaura cross-coupling or by direct arylation reaction conditions and the rate of the direct arylation reaction was found to be faster than for the Suzuki-Miyaura crosscoupling reactions. The solubility of the compounds was poor when the 2-ethylhexyl (Eh) moiety was used as the solubilising group for DPP(ThFl) 2 . 2-Octyldodecyl (Odd) solubilising groups gave better solubility in chlorinated solvents, which are typically used in OPV fabrication. The three nonpolymeric DPP materials exhibited bipolar charge transport in organic field effect transistors (OFETs), with hole and electron mobility in the order of 10 -2 −10 -3 cm 2 V -1 s -1 , and in a diode architecture OddDPP(ThFl) 2 and OddDPP(ThBt) 2 exhibited mobilities of the order of 10 -4 cm 2 V -1 s -1 for pristine films. In BHJ devices using [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM)as the acceptor, different solvent mixtures were used for device fabrication to achieve the maximum efficiency. The EQE spectra of the blend film suggested that charge generation due to absorption at iii wavelengths longer than 750 nm occurred through the Channel I pathway, and at wavelengths shorter than 750 nm, both Channel I and II ...

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Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin

Cited by 10 publications

References 13 publications

Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids

Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids

Salinity alters the protein composition of rice endosperm and the physicochemical properties of rice flour

Low optical gap materials for organic solar cells - research and application

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