Journal of The Chilean Chemical Society 

About: Journal of The Chilean Chemical Society is an academic journal published by Sociedad Chilena de Química. The journal publishes majorly in the area(s): Catalysis & Adsorption. It has an ISSN identifier of 0717-9324. It is also open access. Over the lifetime, 1571 publications have been published receiving 13364 citations.

Organic photovoltaic cells: history, principle and techniques

Abstract: In this review we present an overview of the different organic solar cells families. After recalling shortly the specificities of organic materials, the band structure, the electronic properties and the charge separation process in organic materials are shortly described. Then the new organic solar cell concepts are presented. Plastic organic solar cells consist either of two organic layers or a homogeneous mixture of two organic materials. One of them - either an organic dye or a semiconducting polymer - donates the electrons. The other component serves as the electron acceptor. Principies of these multi-layers and bulk heterojunctions are presented and discussed. Then some typical examples are presented, showing the fast evolution of the cells performances. Finally, a specific attention is devoted to the interfaces electrodes/organics. Indeed recent results show that, at least in the case of multi-layers cells, the introduction of thin buffer layers at the interfaces cathode/organic acceptor and/or anode/organic donor, can strongly improve the efficiency of the organic solar cells. About the interface organic acceptor/cathode, we report the influence of an exciton-blocking layer and/or an A1203 thin layer on the efficiency of CuPc/C60 based photovoltaic cells. The presence, or not, of a thin A1203 layer depends on the encapsulating process of the devices. In the case of glass/ITO/CuPc/C60/Al cells, the presence of an A1203 thin layer at the interface "organic acceptor/aluminium" increases strongly the open circuit voltage of the cells but decreases slightly their short circuit current and fill factor. In the case of glass/ITO/CuPc/C60/Alq3/Al cells, the open circuit voltage is systematically higher than without Alq3. However, in that case, the presence of A1203 does not improve significantly the cell performances. All these results are discussed in terms of series and shunt resistance values related to possible oxygen contamination and organic covalent action with the Al films. The effectiveness of these different phenomena depends on the presence, or not, of Alq3 and/or A1203 layers. About the interface anode/organic donor, it is shown that an ultra thin metallic film improves significantly the short circuit current and the cell performances. The anode in plastic solar cells, which is a transparent conductive oxide (TCO), is usually an indium tin oxide film (ITO). Indeed, when a ZnO anode is used, cells performances are far from those achieved with ITO. However, strong improvement of the cells efficiency is encountered when an ultra thin buffer layer is introduced between the ZnO and the organic film. The presence of this ultra thin buffer layer at the surface of the TCO allows decreasing the performance difference between the cells using ITO and those using ZnO. More generally such ultra thin buffer layer improves the solar cells performances

Ftir and tga studies of chitosan composite films

Abstract: The synthesis of chitosan and resulting chitosan composite films was carried out using glycerol, tween, and beeswax as additives to prepare the composites films, after which a complete study by FTIR was carried out for all the chitosan composite films. Several differences in the absorption bands were seen for each composite, confirming the presence of the material incorporated therein. Thermal stability was studied by thermogravimetric analysis, which further verified the differences between pure chitosan films and the series of composite films. The composite films are good alternatives to existing food storage materials due to important similarities with commercial polypropylenes, not to mention their environmental advantages as regards improved degradability

Structure and thermal properties of lignins: characterization by infrared spectroscopy and differential scanning calorimetry

Abstract: After cellulose, lignin is, the second most abundant component in wood. In the pulping industry, the introduction of modern Kraft pulping technologies could produce chemical modification in lignin’s functional groups. Kraft lignins from Eucaliptus nitens and Pinus radiata industrial black liquors were isolated by acid precipitation. An organosolv lignin was obtained from spent liquor from the P.radiata wood pulping process.All lignins were acetylated with acetic anhydride and characterized by Fourier-transformed infrared spectroscopy (FT-IR) .Analysis based on the IR-fingerprint spectral region indicates several differences in the functional groups of the different types of lignins.The thermal behaviour of unmodified and acetylated lignins were studied by differential scanning calorimetry (DSC) and the glass transition temperatures (Tg) were determined and compared with values reported in the literature.The acetylated lignins show a decrease in the Tg values which is probably due, to the at plasticization effect of the acetylation reaction.

SECONDARY METABOLITES FROM FOUR MEDICINAL PLANTS FROM NORTHERN CHILE: ANTIMICROBIAL ACTIVITY AND BIOTOXICITY AGAINST Artemia salina

Abstract: Antibacterial activity and biotoxicity against Artemia salina of chloroform and alcohol extracts and isolated products from four plants used in ethnomedicine in northern Chile is reported. Nine compounds already identified were isolated from aerial parts of Artemisia copa Phil., Acantholippia punensis Botta, Ephedra andina Poepp. ex C. A . Mey and Haplopappus rigidus Phil : 3,5 ­ dihydroxy ­ 6, 7, 3', 4' ­ tetramethoxyflavone, lupeol, b ­ amyrine , b ­ sitosterol, ephedrine, 2 ­ ethylhexanol phthalate , 18 ­ acetoxy ­ cis ­ cleroda ­ 3,13 Z ­ dien ­ 15 ­ oic acid, 5,4' ­ dihydroxy ­7­ methoxyflavanone and 3,5,7 ­ trihydroxy ­ 6, 4' ­ dimethoxyflavone

Fenton reaction driven by iron ligands

Abstract: One of the most important sources of reactive oxygen species (ROS) in biological systems is the Fenton reaction. In this, the Fe 2+ or Fe 3+ reacts with H 2 O 2 to produce ROS as the hydroxyl radical (∙OH), superoxide radical (O 2∙- ) and singlet oxygen ( 1 O 2 ).The main ROS, responsible for the high oxidizing power of the Fenton reaction, is not clear. Some authors claim that the principal reactive species is ∙OH, while others propose a ferryl specie (Fe 4+ or [FeO] 2+ ) ( 1, 2 ) . Recently, have been proposed that the kind of reaction species produced depends mainly of pH and the iron composition of the coordination sphere. This is highlighted for Fe 3+ , because in mono and (some) bis-complexes Fe is reduced to Fe 2+ and there are some positions occupied by water or hydroxide ligands, readily to be exchanged by H 2 O 2 . On the other hand, in tris-complexes there are not any positions occupied by water or hydroxide, avoiding the formation of peroxo-complexes, necessary for Fenton or Fenton like reaction.The 1,2-dihydroxybenzenes (DHBs) have been described as modulators of Fenton reaction. The DHBs driven Fenton reaction have been used for environmental applications as an advanced oxidation process. Furthermore, these systems participate in different biological process, as the wood biodegradation by fungi and oxidative stress in neurodegenerative diseases.In this review, the effect of 1,2-dihydroxybenzenes on the activated species production by the Fenton and Fenton like reaction will be discussed and its participation in different systems.