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We report on the novel series of (CH3)3SPbI3−xBrx and (CH3)3SPbI3−xClx (x = 0, 1, 2, 3) perovskite compounds. X-ray diffraction analysis shows that the solid solutions of (CH3)3SPbI3−xBrx (x = 0, 1, 2, 3) and (CH3)3SPbI3−xClx (x = 0, 1, 2) crystallize in hexagonal symmetry (space group P63mc, No. 186) with 1D columns of face-sharing [PbX6] octahedra. (CH3)3SPbCl3 crystallizes in orthorhombic symmetry (space group Pnma, No. 62) forming 3D network of vertex- and face-sharing [PbCl6] octahedra. Optical and vibrational properties were investigated using UV–vis reflectance, photoluminescence and Raman spectroscopy at room temperature. The compounds show high chemical stability in ambient air at temperatures up to 80 °C and under solar simulator, in contrast to the hygroscopic CH3NH3PbI3 or CH(NH2)2PbI3 that are commonly used in perovskite solar cells. First principles theoretical ab initio and efficient semiempirical extended Huckel calculations were performed to evaluate the energy band gap values, whose results are in good agreement with the experimentally determined values.

5',8-Cyclo-2'-deoxyadenosine (cdA) and 5',8-cyclo-2'-deoxyguanosine (cdG) in their two diastereomeric forms, 5'S and 5'R, are tandem lesions produced by the attack of hydroxyl radicals to the purine moieties of DNA. Their formation has been found to challenge the cells' repair machinery, initiating the nucleotide excision repair (NER) for restoring the genome integrity. The involvement of oxidatively induced DNA damage in carcinogenesis and the reduced capacity of some cancer cell lines to repair oxidised DNA base lesions, intrigued us to investigate the implication of these lesions in breast cancer, the most frequently occurring cancer in women. Using liquid chromatography tandem mass spectrometry (LC-MS/MS), we measured the levels of diastereomeric cdA's and cdG's in estrogen receptor-alpha positive (ER-alpha) MCF-7 and triple negative MDA-MB-231 breast cancer cell lines before and after exposure to two different conditions: ionising radiations and hydrogen peroxide, followed by an interval period to allow DNA repair. An increase at the measured levels of all four lesions, i.e. 5'S-cdA, 5'R-cdA, 5'S-cdG and 5'R-cdG, was observed either after gamma-irradiation (5Gy dose) or hydrogen peroxide treatment (300muM) compared to the untreated cells (control), independently from the length of the interval period for repair. For comparison reasons, we also measured the levels of 8-oxo-2'-deoxyadenosine (8-oxo-dA), a well-known oxidatively induced DNA damage lesion and base excision repair (BER) substrate. The collected data indicate that MCF-7 and MDA-MB-231 breast cancer cells are highly susceptible to radiation-induced DNA damage, being mainly defective in the repair of these lesions.

Having their position gained among the smallest bulky DNA lesions recognized by the nucleotide excision repair (NER) enzyme, purine 5′,8-cyclo-2′-deoxynucleosides (5′,8-cPu) are increasingly attracting the interest in the field of genome integrity in health and diseases. Exclusively generated by one of the most harmful of the reactive oxygen species, the hydroxyl radical, 5′,8-cPu can be utilized also for highly valuable information regarding the oxidative status nearby the area where the genetic information is stored. Herein, we have collected the most recently reported biological studies, focusing on the repair mechanism of these lesions and their biological significance particularly in transcription. The LC-MS/MS quantification protocols that appeared in the literature are discussed in details, along with the reported values for the four 5′,8-cPu produced by in vitro γ-radiolysis experiments with calf thymus DNA. Mechanistic insights in the formation of the purine 5′,8-cyclo-2′-deoxynucleosides and their chemical stability are also given in the light of their potential to be utilized as DNA biomarkers of oxidative stress.

The antioxidant activity of oils is an important parameter that determines oils' nutritional value and quality. To date, the methods for the determination of the antioxidant activity of oils are performed under batch conditions, therefore, they have large turnaround times and are labor-intensive. In this work, we describe the first automated method for the determination of the antioxidant activity of edible oils by resorting to the benefits of Flow Injection Analysis (FIA) and the high sensitivity of chemiluminescence (CL) detection. In the developed method, we used the chemiluminescent reaction of bis(2,4, 6-trichlorophenyl) oxalate with the reactive oxygen species produced by the catalytic decomposition of H2O2 by Mn(II) ions. The antioxidants present in the sample scavenge the reactive oxygen species and inhibit the light reaction. 1-Amino-pyrene was used as fluorophore and 1-methyl-imidazole as base catalyst in the reaction. Method validation and application to real samples showed that the analytical features of the method are very satisfactory in terms of linearity of response-lines of standard antioxidant compounds (R2 = 0.98–0.999), precision (%RSD = 0.85–1.9%) and accuracy (%recovery = 91–109%), suggesting that the developed assay could serve as an efficient tool to the routine screening of antioxidant properties in edible oils.

We report on the synthesis, characterization, and optoelectronic properties of the novel trimethylsulfonium lead triiodide perovskite, (CH3)3SPbI3. At room temperature, the air-stable compound adopts a hexagonal crystal structure with a 1D network of face-sharing [PbI6] octahedra along the c axis. UV–vis reflectance spectroscopy on a pressed pellet revealed a band gap of 3.1 eV, in agreement with first-principles calculations, which show a small separation between direct and indirect band gaps. Electrical resistivity measurements on single crystals indicated that the compound behaves as a semiconductor. According to multi-temperature single-crystal X-ray diffraction, synchrotron powder X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry, two fully reversible structural phase transitions occur at −5 and ca. −100 °C with reduction of the unit cell symmetry to monoclinic as temperature decreases. The role of the trimethylsulfonium cation regarding the chemical stability and optoelect...

The lipophilicity of untreated edible oils narrows the application of most published methods for the determination of antioxidant activity to hydrophilic extracts of oils. This research addresses the issue of the estimation of the total antioxidant properties of untreated edible oils by modifying two widely applied analytical methods, the Fe-Phenanthroline and the CUPRAC assays, to be used in untreated oils. The modifications pertain to the selection of mixture of solvents (ethanol-butanol in 3:1 v/v ratio), and the optimization of the reaction conditions (reagents concentration and reaction time). The developed methods were applied to a number of hydrophilic and lipophilic standard compounds and different types of commercial edible oils, as well as their corresponding aqueous or organic extracts. This implementation elucidated the differences in the antioxidant content of edible oils. All the results were compared to those of the DPPH and Folin-Ciocalteu methods and the analytical figures of merit for the methods have been estimated. Lastly, it was concluded that the modified CUPRAC assay has higher sensitivity compared to the Fe-Phenanthroline assay.

This research dwells on two widely used spectrophotometric methods, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, which assess the free radical scavenging activity (RSA) of natural samples and standard compounds. In particular, these assays were modified in order to simplify the evaluation of RSA of untreated edible oils, as well as to assess the antioxidant profile of oils’ hydrophilic and lipophilic extracts with the same analytical procedure. A thorough study highlighted the effect of solvents on the DPPH and ABTS methods and resulted in selecting 2-propanol and an ethanol/1-butanol solvent mixture as the reaction solvent for the DPPH method and the ABTS method, respectively. The developed methods were used to evaluate the RSA of 12 antioxidant compounds and 8 edible oils. Then, the contribution of lipophilic and hydrophilic extracts to the total RSA of oils was estimated. The obtained results demonstrate the applicability of the method to routine edible oil analysis.

The anticancer activity of acridone derivatives has attracted increasing interest, therefore, a variety of substituted analogs belonging to this family have been developed and evaluated for their anti-cancer properties. A series of N-alkyl-acridones 1&ndash, 6 and N,N&prime, dialkyl-9,9&prime, biacridylidenes 7&ndash, 12 with variable alkyl chains were examined for their topoisomerase I activity at neutral and acidic conditions as well as for their binding capacity to calf thymus and possible radical trapping antioxidant activity. It was found that at a neutral pH, topoisomerase I activity of both classes of compounds was similar, while under acidic conditions, enhanced intercalation was observed. N-alkyl-acridone derivatives 1&ndash, 6 exhibited stronger, dose-dependent, cytotoxic activity against MCF-7 human breast epithelial cancer cells than N,N&prime, 12, revealing that conjugation of the heteroaromatic system plays a significant role on the effective distribution of the compound in the intracellular environment. Cellular investigation of long alkyl derivatives against cell migration exhibited 40&ndash, 50% wound healing effects and cytoplasm diffusion, while compounds with shorter alkyl chains were accumulated both in the nucleus and cytoplasm. All N,N&prime, biacridylidenes showed unexpected high scavenging activity towards DPPH or ABTS radicals which may be explained by higher stabilization of radical cations by the extended conjugation of heteroaromatic ring system.

Increased rates of reactive oxygen/nitrogen species (ROS/RNS) are involved in almost all cancer types, associated with tumor development and progression, causing damage to biomolecules such as proteins, nucleic acids and membrane lipids, in different biological compartments. We used a human tumor xenograft mouse model to evaluate for the first time in parallel the remodeling of fatty acid moieties in erythrocyte membrane phospholipids and the level of ROS-induced DNA lesions in liver and kidney tissues. Using liquid chromatography tandem mass spectrometry the 5&rsquo, R and 5&rsquo, S diastereoisomers of 5&rsquo, 8-cyclo-2&rsquo, deoxyadenosine and 5&rsquo, deoxyguanosine, together with 8-oxo-7,8-dihydro-2&rsquo, deoxyadenosine, were determined in mice at young (4- and 5-weeks) and old (17-weeks) ages and compared with control SCID mice without tumor implantation. Tumor-bearing mice showed a higher level of ROS-damaged nucleosides in genomic DNA as the age and tumor progress, compared to controls (1.07&ndash, 1.53-fold in liver and 1.1&ndash, 1.4-fold in kidney, respectively). The parallel fatty acid profile of erythrocyte membranes showed a profound lipid remodeling during tumor and age progression consisting of PUFA consumption and SFA enrichment (ca 28% and 58%, respectively, in late stage tumor-bearing mice), markers of enhanced oxidative and proliferative processes, respectively. Membrane lipid remodeling and ROS-induced DNA lesions may be combined to afford an integrated scenario of cancer progression and ageing, reinforcing a holistic vision among molecular markers rather than the biomarker identification in a single compartment.

Chiral β-amino alcohol-derived N-borane catalysts, namely noncyclic (2S)- and (2R)-2-amino-2-phenylethanol N-borane and their corresponding cyclic trimeric borazine derivatives, were synthesized and their catalytic activities in the asymmetric reduction of prochiral ketones were examined. Both the noncyclic and cyclic catalysts successfully catalyzed this reaction, giving the desired secondary alcohols in up to 82% isolated yield and with up to 80% enantioselectivity. The noncyclic catalyst was stable in aqueous and organic solvents, whereas the polycyclic borazine was stable only in nonprotic dry organic solvents.

A series of RuII-based photosensitizers were synthesized and extensively characterized. The ligand utilized to coordinate ruthenium was a pyridine–quinoline hybrid bearing an anthracene moiety, and it was combined with commercially available 2,2′-bipyridine (bpy) for the heteroleptic complexes. The produced bichromophoric complexes show very strong and wide UV/Vis absorption bands. The ability of these complexes to act as triplet photosensitizers in the production of singlet oxygen was thoroughly studied by utilizing the photooxidation of 1,3-diphenylisobenzofuran as the test reaction. The most efficient photosensitizer in this new family of RuII complexes affords singlet oxygen quantum yields and production-rate efficiencies up to two times higher than those of the benchmark [Ru(bpy)3]2+ parent complex.

Electrolysis of ultrapure water in a two-electrode cell with silver anode and conductive substrate (Si wafer) as a cathode leads to the formation of nanostructured silver layers deposited on cathode. In the process, the silver anode is electrochemically dissolved to silver cations, which react with water (or OH• radicals derived from water electrolysis) forming silver oxide nanoparticles, which fill the interelectrode space by electrophoretic movement, diffusion and convection induced by temperature effects of electrolysis. During the process the silver oxide nanoparticles are partially transformed into silver nanoparticles. On the cathode, silver cations and silver / silver oxide nanoparticles undergo reduction to form nanostructured silver film. The results of the present study open a new, extremely simple and ultra-low cost way to prepare nanostructured silver films on conducting and semiconducting substrates. The prepared nanosilver coated silicon substrates exhibit high performances as amperometric sensors for hydrogen peroxide and also as SERS substrates.

The ability of chiral β-amino alcohols to catalyze the direct asymmetric aldol reaction was evaluated for the first time in aqueous micellar media. A family of cheap and easily accessible β-amino alcohols, obtained in one step from naturally occurring amino acids, was shown to successfully catalyze the asymmetric aldol reaction between a series of ketones and aromatic aldehydes. These aldol reactions furnished the corresponding β-hydroxy ketones with up to 93% isolated yield and 89% ee. (S)-2-phenylglycinol and Triton X-100 proved to be the best organocatalyst and surfactant, respectively. Chirality 25:119–125, 2013. © 2012 Wiley Periodicals, Inc.

Six well established spectrophotometric assays (Folin-Ciocalteu, DPPH, ABTS•+, FRAP, CUPRAC, and the o-diphenols method) have been complementary implemented in order to estimate the total phenolic and o-diphenolic content as well as the free radical scavenging and reducing antioxidant capacities of 40 white and 10 red wines of different varieties and geographic origin. In white wines, the results were weakly correlated; whereas, the results in red wines were strongly correlated, therefore, postulating their separate use in order to estimate efficiently the correlation between results of these methods. The results were subjected to the unsupervised PCA pattern recognition method to investigate the possible classification of white wines. PC analysis framed the wine samples in clear clusters, when the extracted PCA model was based on the results of all six spectrophotometric assays. The usefulness of implementing assays based on different antioxidant mechanisms is discussed. To our knowledge, this is the fir...

The present review describes the application of luminescent methods in the analysis of edible oils without any pretreatment such as extraction prior to analysis. Emphasis has been given to applications of chemiluminescence and fluorescence assays for determining quality parameters of edible oils, such as oxidative stability, antioxidant activity, and lipid hydroperoxides content, as well as classification or adulteration of vegetable oils.

A sensitive and simple method is described for the evaluation of total antioxidant activity of olive and seed oils and their corresponding aqueous and organic extracts based on the chemiluminescent reaction of lucigenin with hydrogen peroxide. The method was fully validated for precision, trueness, robustness, additivity, and uncertainty. Validation results demonstrated that the method is able to measure the antioxidant activity of untreated edible oils as well as their hydrophilic and lipophilic extracts and posses all necessary quality factors required for routine analysis. Comparison of results with those obtained by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and Folin–Ciocalteu methods has indicated a significant correlation between them. Furthermore, it was found that extra virgin olive oils exhibit two to three times higher total antioxidant activity than refined olive oils and seed oils, and the contribution of antioxidant activity of organic and aqueous extracts of oils to the corresponding total antioxidant activity is significantly different in olive oils than seed oils.

This paper presents an overview of flow-based methods in food and environmental analysis using chemiluminescence (CL) detection covering the period from 2005 to the present. The review discussses both automated flow methods of analysis [such as flow-injection analysis (FIA), sequential-injection analysis (SIA) and their variants] and separation techniques [liquid chromatography (LC) and capillary electrophoresis (CE) coupled to CL detection]. The most widely used CL reactions are presented together with representative applications in food and environmental analysis (determination of naturally occurring compounds, contaminants, additives as well as determination of inorganic and organic compounds).

Cylindrical carbon fiber microelectrode coated with a silver layer electrodeposited from silver nitrate solution containing Pluronic F127, a surface active agent, and also a Nafion layer prepared using a dip-dry method forms a sensitive, selective and stable amperometric hydrogen peroxide sensor, operating in the cathodic region of potential. The layer formed at the electrode is composed of porous, partially crystalline silver deposits with a significant fraction of attached silver nanoparticles. Using amperometry in stirred solution at 0 mV (vs. Ag/AgCl), the electrode is capable to monitor hydrogen peroxide over its wide concentration range (1 × 10−5 up to 0.1 M). The response of the electrode is sufficiently time-stable to enable the monitoring of hydrogen peroxide heterogeneous decomposition over manganese dioxide catalyst including the conditions where higher decomposition rates are observed, impossible to be monitored using batch titration.

Two new ruthenium(II) complexes bearing terpyridine- or 2,6-dipyrazinylpyridine ligands have been prepared and characterized by one- and two-dimensional NMR techniques, ESI mass spectrometry, as well as by UV–vis, emission, FTIR, Raman, and cyclic voltammetry studies. The structure of the terpyridine-coordinated complex resembles that of black dye (tris(thiocyanato)(2,2′:6′,2″-terpyridyl-4,4′,4″-tricarboxylato)ruthenium(II) tris(tetra butylammonium) salt), while the spectral data of the 2,6-dipyrazinylpyridine-coordinated complex are consistent with an unanticipated, unsymmetrical binuclear structure. The ruthenium(II)/(III) oxidation potential of the terpyridine-coordinated dye was measured at +0.87 V (vs. Ag/AgCl), about 200 mV higher than the oxidation potential of black dye. According to a series of desorption experiments, both new dyes were found to adsorb on TiO 2 to a greater extent than black dye. The photo-electrochemical properties of both dyes were investigated and compared to that of black dye; while the 2,6-dipyrazinylpyridine-coordinated complex was found to be a very poor sensitizer, the cells obtained from the terpyridine-coordinated dye show power-conversion efficiencies which are more than half of that attained by black dye. Finally, preliminary electron dynamics studies of the cells constructed with the terpyridine dye were carried out and the results are compared to that of black dye cells.

The influence of interfacial structure on interfacial properties between activated carbon filler and surrounding organic matrix of composites has been studied by infrared and NMR spectroscopy. Urea, semicarbazide and ethylurethane, component parts of polyurethane, have been used as organic model compounds in order to predict the interactions between the activated carbon surface and polar groups of real polyurethane molecule. It was shown that organic matrix/activated carbon interphase presented a region where the filler and matrix phases were chemically and/or physically combined. The spectra of the organic matrix undergo significant changes with increase of carbon content. Due to the surface reactive functionalities the activated carbon is considered not only as filler, influenced on the sorption properties of the composition, but also as a physicochemical modifier of the polyurethane matrix.

Novel functionalized organo-inorganic chiral catalysts have been prepared in two steps from activated silica gel and chiral organic auxiliaries, such as (+)-cinchonine or (S)-(−)-nicotine. These new catalysts have been tested in a solid–liquid–liquid three-phase system for the asymmetric epoxidation of α,β-enones and the asymmetric alkylation reactions of glycine derivatives. The obtained stereoselectivities are negligible for the first case (ee

In this study we show that nanoparticles of various ferric oxides (hematite, maghemite, amorphous Fe2O3, β-Fe2O3 and ferrihydrite) incorporated into carbon paste exhibit electro-catalytic properties towards hydrogen peroxide reduction. The modified paste electrode performances were evaluated and compared with those obtained with Prussian Blue-modified carbon paste electrode, which represents an excellent chemical mediator towards the H2O2 redox reaction (as widely described in literature). The best catalytic activity was found for carbon paste modified by amorphous ferric oxide with 2–4 nm particle size, which was further tested for possible application as hydrogen peroxide sensor. At pH 7, the limit of detection was 2×10−5 M H2O2 (S/N=3), the calibration curves were linear upto 8.5 mM H2O2 (R2=0.998), the measurement reproducibility (RSD=97%, n=4), the interelectrode reproducibility (RSD=16%, nelectrodes=5) and

A new family of Ru(II)-based photosensitizers was synthesized and systematically characterized. The ligands employed to coordinate the ruthenium metal center were the commercially available 2,2'-bipyridine and a pyridine-quinoline hybrid bearing an anthracene moiety. The complexes obtained carry either PF6- or Cl(-) counterions. These counterions determine the complexes' hydrophobic or hydrophilic character, respectively, therefore dictating their solubility in biologically related media. All photosensitizers exhibit characteristic, relatively strong and wide UV-Vis absorption spectral profiles. Their high efficiency in generating cytotoxic singlet oxygen was established (up to ΦΔ ~0.8). Moreover, the interaction of these photosensitizers with double-stranded DNA was studied fluoro- and photospectroscopically and their binding affinities were found to be of the order of 3 × 10(7) M(-1) . All complexes are photocytotoxic to DU145 human prostate cancer cells. The highest light-induced toxicity was conferred by the photosensitizers bearing Cl(-) counterions, probably due to the looser ionic "chaperoning" of Cl(-) , in comparison to PF6-, leading to higher cell internalization.

A novel biotinylated fluorophore, 10-(2-biotinyloxyethyl)-9-acridone 3 has been synthesized and its fluorescent properties were examined in the presence and absence of avidin or streptavidin. In aqueous solutions the novel fluorophore 3 , as well as its precursor 10-(2-hydroxyethyl)-9-acridone 2 exhibit intense fluorescence and can be detected down to 8.62 × 10 −10 and 1.90 × 10 −10 M, respectively. A short spacer was chosen in order to minimize steric repulsion between the adjacently bound to avidin or streptavidin residues of acridone. The novel biotinylated fluorophore 3 exhibits rapid, specific and stoichiometric binding to the four biotin binding sites in avidin or streptavidin tetramers, even at low concentrations (20 nM). Preliminary measurements showed that the new conjugate can be applied for the fluorimetric determination of solid-phase immobilized mouse IgG with detection limits down to 1.3 ng per assay.

A series of new isonicotinylhydrazones and thiosemicarbazones of various ketosteroids was synthesized. The structures of the compounds were confirmed by NMR and IR spectroscopy and mass spectrometry.

Background The favorable properties of acridinium derivatives over conventional fluorescent probes have attracted considerable interest. These conjugates have found wide utility in tests developed for medical diagnosis providing at least comparable sensitivity to radioimmunoassay (RIA) and enzyme immunoassay (EIA) procedures. Methods In this paper we describe the synthesis, luminescent properties and immunoassay applications of two novel biotinylated acridinium derivatives, 9-(2-biotinyl-oxyethyl)-carboxylate-10-methyl-acridinium triflate, BOCMAT and 9-(2-biotinyl-amidoethyl)-carboxylate-10-methyl-acridinium triflate, BACMAT. Results The chemiluminescence efficiency of the novel reagents is high in polar aprotic solvents and attains detection limits down to 7.28 × 10 − 8 M, while the fluorescence efficiency has its maximum in aqueous solutions with detection limits down to 1.94 × 10 − 10 M. The above novel compounds were applied in the fluorimetric determination of solid phase-immobilized biotinylated mouse IgG and the detection limit was found to be ∼ 1 μg/assay (∼ 7 pmol/assay). Conclusions The new streptavidin-based detection reagents were synthesized can be used for the development of highly sensitive solid-phase fluorescence-based immunoassays and may find important applications in proteomics.

Two novel biotinylated fluorophores, (2-biotinyloxyethyl) acridine-9-carboxylate (4a) and (2-biotinylamidoethyl) acridine-9-carboxamide (4b) have been synthesized and their fluorescent properties examined, in the presence and absence of avidin. In aqueous solutions the biotinylated conjugates 4, as well as their precursors 3, exhibit intense fluorescence and can be detected down to nanomolar concentrations. A four-atom spacer, ethylene glycol, in the case of 4a and ethylene diamine, in the case of 4b was chosen in order to minimize steric repulsion between two biotin-acridine conjugates adjacently bound on avidin. In the presence of avidin, they show fast and stoichiometric binding to the tetrameric protein. In contrast to most known biotin-fluorophore conjugates, the novel fluorescent labels 4a and 4b not only retain their fluorescence after binding to avidin but fluorescence is also enhanced by 37 and 16.5%, respectively, even when four ligands are bound per avidin tetramer. Consequently, these novel biotin-fluorophore conjugates are prospective fluorescent labels in bioanalytical applications.

A sensitive and simple method for measuring antioxidant activity was developed, based on antioxidant-dependant quenching of the chemiluminescence (CL) generated from 9-benzylacridine and potassium superoxide. This method was used to evaluate the antioxidant activity of fruit and vegetable aqueous extracts as well as of some pure phenolic compounds contained in fruits and vegetables. Coumaric, chlorogenic, caffeic, vanillic and ascorbic acids as well as (±)catechin, and 2-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) were employed as antioxidants. It was found that the antioxidant activity of all fruit extracts is almost one order of magnitude higher than that of vegetables. Among the fruits, grapefruits show the highest antioxidant activity and pears the lowest. From the pure phenolic antioxidants, caffeic acid has the highest antioxidant activity (AA). The calculated antioxidant activities of fruit and vegetable extracts produced by the CL method are compared with other methods such as the ORAC, TEAC or DPPH method.

A simplified quantitative model of chemiluminescence intramicellar sensitization is proposed, based on the analytical solution of Forster’s energy transfer function for donor–acceptor pairs residing on micellar spherical surface. To test the usability of the model, the intramicellar sensitization of phthalhydrazide chemiluminescent oxidation by energy transfer to several xanthene as well as non-xanthene dyes has been investigated. The reactions were initiated using three different initiation systems: copper sulphate–hydrogen peroxide system, sodium hypochlorite and hydrogen peroxide–sodium hypochlorite. In this work, we bring an experimental evidence that different transfer mechanisms operate, if phthalhydrazide-sensitized chemiluminescence reactions are initiated by copper sulphate–hydrogen peroxide, sodium hypochlorite or sodium hypochlorite–hydrogen peroxide. Only the latter system is selective enough to oxidize phthalic hydrazide much more rapidly than dyes employed as acceptors. This fact enables the application of the proposed model to achieve the quantitative description of the sensitization process.

A sensitive and simple procedure is described for measuring the antioxidant activity (AA) of olive oil and seed oil aqueous extracts using the chemiluminescence of N , N ′-dimethyl-9,9′-biacridinium dinitrate (lucigenin). It was found that olive oil aqueous extracts showed 2–10 times higher AA than seed oils. This impressive difference is attributed to the higher content of phenolic compounds present in olive oils. Spectrophotometric and fluorimetric measurements affirmed this hypothesis. As shown in this paper, the reported method could also be used for the quantitation of total phenols in aqueous oil extracts. It was found that commercial and non-commercial Greek olive oil aqueous extracts contain 55.3–125.9 mg caffeic acid equivalents per kilogram, while seed oils, only 0.6–3.2 mg kg −1 .

It is believed that chemiluminescence (CL) of photolyzed aromatic compounds proceeds in alkaline media and in the presence of oxygen, with various reactive oxygen species (ROS). In order to prove this hypothesis we have investigated the contribution of chemically produced ROS, such as hydroxyl radicals, singlet oxygen as well as superoxide radical anions on CL reactions of photolyzed aromatic compounds. The results of this investigation show, indeed, that the light emission (CL) is due to the reaction of photoproducts of aromatic ketones with singlet oxygen or superoxide radical anion. The contribution of hydroxyl radicals in this CL reaction is insignificant. Although, the CL light efficiency of the above reactions is not high, the results of this study can be used for the quantitative determination of some of these ROS as well as for the aromatic compounds down to few parts per billion.

A weak chemiluminescence (CL) emission was observed in commercial Greek extra virgin olive oils (Knossos, Spitiko, Ananias, Altis, Minerva, Xenia) and in refined seed oils such as sunflower oils (Marata, Sanola, Sun, Mana, Sol, Minerva) as well as in corn oils (Flora, Minerva, Marata Sun and Sol) with potassium superoxide in the aprotic solvent dimethoxyethylene. On measuring the CL of mixtures of extra virgin olive oils with the cheaper refined seed oils, calibrations were produced which can be used for the determination of the adulteration of olive oils with seed oils down to 3%. Furthermore, depending on the kind of oils, “low” authenticity-CL-factors for olive oils (0.8–2.15 μmol l−1 gallic acid) and “high” for seed oils (4.5–11.2 μmol l−1 gallic acid) were calculated.

Buckminsterfullerene, C 60 , exhibits photo-, radio- and sonostoragechemiluminescence. Photolysis, radiolysis or sonolysis results in stable products, while subsequent oxidation of the reaction mixtures, constitutes the chemiluminescence step. Besides being an energy storage system in the sense that light, ionizing radiation or ultrasound is absorbed, stored and light is emitted at will, the radiostoragechemiluminescence of C 60 of the present work has the prospects of forming the basis of novel radiation dosemeters up to 500 Gy. Also, novel analytical applications for said fullerenes based on the photo-, radio- or sonostoragechemiluminescence promise detection limits as low as 7.2 ppb of sample.

A sensitive and simple method for measuring antioxidant activity was developed, based on antioxidant-dependant quenching of the chemiluminescence (CL) generated from photolyzed acridine and methanolic potassium hydroxide. This method was used to evaluate the antioxidant activity of food additives by measuring the inhibition of CL at a gradient of antioxidant concentrations. Adipic, tartaric, citric, ascorbic, malic, fumaric and 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid (Trolox) were employed as antioxidants. The method is more suitable for lipophilic compounds.

Acridone and 9-benzylacridine in dialkylated amides are radiolyzed to novel acridan derivatives which emit light upon addition of strong bases regenerating acridone. The chemiluminescence quantum yields are as high as 2.4 × 10 −2 for acridone, while for the 9-benzylacridine 3.1 × 10 −3 einstein mol −1 . The acridone quantum yield is higher than those of most classical chemiluminescent reactions. The radiolysis and chemiluminescence mechanisms are discussed. The radiochemiluminescence reactions constitute prospective radiation dosemeters.

Asymmetric Michael addition of lithiated SAMP hydrazones ( S )- 2 to a variety of alkenylphosphonates ( E )- 3 followed by oxidative cleavage of the 1,4-adducts 4 afforded 2,3-disubstituted 4-oxophosphonates 5 with good to very good yields (58–80%), low to moderate diastereomeric ( de = 6–74%) and excellent enantiomeric excesses ( ee = >93%). Pure anti -diastereomers ( ee = >93%) of 5 were obtained by separation of the stereoisomers by H PLC. In addition, the lithiated SAMP hydrazone ( S )- 2a was added to alkenylphosphonates ( E )- 3 , and the lithio phosphonate anions were trapped with alkyl halides or sulfates, yielding 1,2-disubstituted 4-oxophosphonates 8 with moderate to good yields (38–69%), low to good diastereomeric ( de = 10–77%) and high enantiomeric excesses ( ee = >90%) after oxidative cleavage.

Heteroleptic ruthenium(II) sensitizers DV42 and DV51, encompassing a novel unsymmetrical pyridine-quinoline hybrid ligand with extended π-conjugation, were synthesized, characterized, and utilized in nanocrystalline dye-sensitized solar cells. Due to the extended conjugation of DV42 and DV51, the absorption of the corresponding sensitized TiO2 films extends into the red spectral range, shifted by 30-40 nm relative to the absorption of TiO2 films sensitized with the standard Z907 ruthenium(II) dye. Contact angle measurements of DV42- and DV51-sensitized TiO2 films suggest that these films are hydrophilic with contact angle values commonly observed upon sensitization with the standard N3 ruthenium(II) dye. Electrochemical studies of the novel ruthenium(II) dyes show that their first oxidation potentials lie well below the I(-)/I3(-) redox potential allowing easy regeneration. The excited-state oxidation potentials of both dyes lie above the TiO2 conduction band, permitting efficient electron injection from the excited dye molecules into the semiconductor conduction band. Liquid electrolyte dye-sensitized solar cells incorporating DV42- or DV51-sensitized TiO2 photoelectrodes afford overall power conversion efficiencies of 3.24 or 4.36% respectively. These efficiencies are up to 56% of the power conversion efficiencies attained by TiO2 photoelectrodes sensitized by the benchmark Z907 ruthenium(II) dye under similar experimental conditions.

Asymmetric Michael addition of lithiated methyl ketone SAMP hydrazones (S)-3 to a variety of alkenylphosphonates (E)-2 followed by oxidative cleavage of the 1,4-adducts (S,S)-4 by ozonolysis afforded 2-substituted 4-oxophosphonates (S)-5 in usually moderate to very good overall yields (14–77%) and with mostly high enantiomeric excesses (ee = 20–>95%). In addition, asymmetric Michael Michael tandem additions were carried out in good overall yields by trapping the intermediate lithio phosphonate anions with alkenylphosphonate or enoate Michael acceptors.

The light reaction of protected hemiaminal 3 (N-methoxymethyl-′-methyl-9,9′-biacridylidene) with singlet oxygen and alkaline hydrogen peroxide in homogeneous and micellar media is reported. The chemiluminescence and fluorescence quantum yields and light intensities in those media are also reported. Hemiaminal 3 is suitable for competition reactions in the presence of organic reductants for analytical applications.

The light reactions of six N, N′ -diakyl-9,9′ -biacridylidenes (Cl, C4, C6, C7, C10 and C12) with singlet oxygen in homogeneous and micellar media are reported. The chemiluminescence and fluorescence quantum yields and spectra in these media are also reported, together with the fluorescence quantum yields of the long-alkyl-chain N-alkylacridones, the primary emitters. The longer alkyl-chain homologues can be used for competitive reactions in the presence of reductants for analytical applications.

The chemiluminescent reaction of five N,N ′-dilakyl-9,9′-biacridinium nitrates, C 1 , C 4 , C 6 , C 10 and C 12 , with hydrogen peroxide in alkaline aqueous and micellar solutions is reported. The chemiluminescence and chemiexcitation yields in these media are reported together with the chemical yields and the fluorescence quantum yields of the long chain N -alkylacridones, the primary emitters, in cationic, anionic and non-ionic micellar media. Based on the chemiluminescence profiles the reaction rate constants and chemiluminescence intensities are reported.

A simple and efficient enantioselective synthesis of 2-substituted 4-oxosulfones 5 in 40 – 71% overall chemical yield and enantiomeric excesses of 86->97% is described. The key step is an asymmetric Michael-addition of lithiated methylketone -SAMP-/RAMP-hydrazones 3 to α,β-unsaturated phenylsulfones 2. The absolute configuration is determined by X-ray structure analysis of a crystalline hydrazone Michael adduct (4k) and through chemical correlation by polarimetry.

Asymmetric Michael addition of lithiated SAMP hydrazones ( S )- 2 to a variety of alkenylphosphonates ( E )- 3 followed by oxidative cleavage of the 1,4-adducts 4 afforded 2,3-disubstituted 4-oxophosphonates 5 with good to very good yields (58–80%), low to moderate diastereomeric ( de = 6–74%) and excellent enantiomeric excesses ( ee = >93%). Pure anti -diastereomers ( ee = >93%) of 5 were obtained by separation of the stereoisomers by H PLC. In addition, the lithiated SAMP hydrazone ( S )- 2a was added to alkenylphosphonates ( E )- 3 , and the lithio phosphonate anions were trapped with alkyl halides or sulfates, yielding 1,2-disubstituted 4-oxophosphonates 8 with moderate to good yields (38–69%), low to good diastereomeric ( de = 10–77%) and high enantiomeric excesses ( ee = >90%) after oxidative cleavage.

The racemic and enantioselective synthesis of a novel glyceric acid derivative, namely, 2,3-dihydroxy-3-(3,4-dihydroxyphenyl)-propionic acid as well as the antioxidant activities is described. The virtually pure enantiomers, (+)-(2R,3S)-2,3-dihydroxy-3-(3,4-dihydroxyphenyl)-propionic acid and (-)-(2S,3R)-2,3-dihydroxy-3-(3,4-dihydroxyphenyl)-propionic acid were synthesized for the first time via Sharpless asymmetric dihydroxylation of trans-caffeic acid derivatives using the enantiocomplementary catalysts, (DHQD)(2)-PHAL and (DHQ)(2)-PHAL. The determination of enantiomeric purity of the novel chiral glyceric acid derivatives was performed by high-performance liquid chromatographic techniques on the stage of their alkylated precursors. The novel glyceric acid derivatives show strong antioxidant activity against hypochlorite and N,N-diphenyl-N-picryl-hydrazyl free radical. Their antioxidant activity is about 40-fold higher than that of the corresponding natural polyether and three-fold higher of trans-caffeic acid itself.

A sensitive and simple procedure is described for evaluating the antioxidant activity of 21 known hydrophilic and hydrophobic compounds by using the chemiluminogenic reaction of lucigenin with hydrogen peroxide. The method was validated for linearity, limit of detection, precision, additivity and ruggedness and compared to the DPPH method. Furthermore, the IC(50) values of all compounds were calculated and compared by both methods and results are discussed on the basis of structure-antioxidant activity relationship. Among hydrophilic antioxidants, phenolic compounds with adjacent hydroxyl groups (gallic acid, caffeic acid, pyrocatechol, (+/-)-catechin, oleuropein) were found to be efficient antioxidants in chemiluminescence method with IC(50) values at the sub-micromolar range, while phenolic compounds without adjacent hydroxyl groups (p-coumaric acid, BHT, BHA, resorcinol) exhibited weak activity with IC(50) values>10microM. Alpha-tocopherol was the most efficient hydrophobic antioxidant (IC(50)=6.7microM) while oleic and linoleic acids were found to be very poor antioxidants (IC(50)>300microM). Finally the method was applied to the estimation of antioxidant activity of complex samples such as olive oils. To the best of our knowledge, this is the first time that total antioxidant activity can be determined directly in olive oil and not in aqueous extracts.