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Главная страница Новости науки Journal of Photochemistry and Photobiology A: Chemistry
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ScienceDirect Publication: Journal of Photochemistry and Photobiology A: Chemistry
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ScienceDirect Publication: Journal of Photochemistry and Photobiology A: Chemistry
  • Photocatalyst activity indicating adhesive labels for use in the field
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): A. Mills, D. Hawthorne, D. Hazafy, N. Wells

    The preparation and characterisation of a resazurin-based photocatalyst activity indicator label is described. The label is applied to a number of different TiO2-based, photocatalytic materials, including self-cleaning: glass, tile, paint and awning materials, as well as a thin, sol-gel film, produced in-house. In all cases, the label exhibited a blue to pink colour transition upon irradiation with UV light. In most cases, the time taken to bleach 90% of the red component of the digital image of the ink, ttb(90), was twice that for a traditional Rz ink, produced by the drawdown method, since the former was twice as thick. Although not as fast as a drawdown Rz ink, by a factor of ca. Two, it still only takes minutes to change and the Rz label is much more easily used, stored and does not need the sample to be: very smooth, horizontal or flat. As such it appears ideal for testing samples, both quantitatively and qualitatively in situ, i.e. in the field.

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  • Epigallocatechin gallate (EGCG) activity against UV light-induced photo damages in erythrocytes and serum albumin—theoretical and experimental studies
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Szymon Sekowski, Milena Terebka, Artem Veiko, Elena Lapshina, Urszula Sulkowska, Ilya B. Zavodnik, Nodira Abdulladjanova, Saidmukhtar Mavlyanov, Anna Roszkowska, Maria Zamaraeva

    Ultraviolet (UV) exerts significant toxic effects on such blood components as erythrocytes and serum albumin under the influence of sunlight, during phototherapy, photodynamic therapy and pathogen reduction technology. In this study, we showed that epigallocatechin gallate (EGCG) isolated from Geranium rectum roots at concentrations of 1–20 μM protected erythrocytes against UVB induced damages, preventing ROS (reactive oxygen species) formation, lipid peroxidation (LP), reduced glutathione (GSH) and hemoglobin (Hb) oxidation. Our data on fluorescence anisotropy measurements noted that EGCG significantly increased the fluidity of the outer leaflet layer of erythrocytes membrane and induced a stiffening in the nonpolar region. We demonstrated that UVB irradiation of bovine serum albumin (BSA) induced SS disruption and SH group formation, which was prevented by EGCG in a dose-dependent manner. The analysis of radical-flavonoid interaction’s stoichiometry in the EGCG-DPPH model revealed that one EGCG molecule was consumed for reduction of two DPPH molecules. On the basis of theoretical calculation it was shown that the hydroxyl groups in positions 4′ and 5′ of the ring B could be considered as the most preferable H-atoms donators. Thus, the theoretical and experimental data showed that EGCG can be useful in protection of blood components against oxidative damages induced by UVB.

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  • Optical and electroluminescent performances of dihydrobenzodioxin phenanthroimidazoles based blue-emitting materials
    Publication date: 15 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 357

    Author(s): Jayaraman Jayabharathi, Ramaiyan Ramya, Venugopal Thanikachalam, Pavadai Nethaji

    Blue-emitting 1-(2, 3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-phenyl-1H-phenanthro[9,10-d]imidazole (1), 1-(2, 3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-p-tolyl-1H-phenanthro[9,10-d]imidazole (2), 1-(2, 3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-(4-methoxyphenyl)-1H-phenanthro[9,10-d]imidazole (3), 1-(2, 3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-(3,4-dimethoxyphenyl)-1H phenanthro[9,10-d]imidazole (4) and 1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-(3,4,5-trimethoxyphenyl)-1H −phenanthro[9,10-d]imidazole (5) were synthesized for OLEDs. These dihydrobenzodioxin phenanthroimidazoles exhibit excellent thermal stability with high glass-transition temperature favourable to form thin films under thermal evaporation. Efficient devices have been fabricated with dihydrobenzodioxin phenanthroimidazoles as a emissive layer between NPB (4, 4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl) and Alq3 (tris(8-hydroxyquinoline) aluminium) layers. Device employing 1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-(3,4,5-trimethoxyphenyl)-1H-phenanthro[9,10-d]imidazole as buffer layer exhibit emission at 424 nm with current and power efficiencies of 6.15 cd A−1 and 5.12 lmw−1, respectively, external quantum efficiency (ηex) of 4.11% and luminance of 40132 cd m−2. This outstanding performances reveal that the great potential of dihydrobenzodioxin phenanthroimidazoles as alternative emissive materials for OLEDs.

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  • A novel mitochondria-targeted fluorescent probe for imaging hydrazine in living cells, tissues and animals
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Xiuqi Kong, Baoli Dong, Chao Wang, Nan Zhang, Wenhui Song, Weiying Lin

    The cytotoxicity of hydrazine (N2H4) is closely associated with mitochondria damages, and real-timely detecting mitochondrial N2H4 is of great importance for the in-depth study of the pathophysiological functions of N2H4 in living system. Although some of N2H4 fluorescent probes have been developed, the selective fluorescence imaging of mitochondrial N2H4 has rarely been reported. Herein, we present a novel mitochondria-targeted fluorescent probe (Rho-N2H4 ) for imaging N2H4 in living system. In the Rho-N2H4 system, a rhodamine derivative Rho with red emission was employed as the fluorophore, and acetyl group was utilized as response site for hydrazine. Upon treatment with N2H4, Rho-N2H4 displayed a drastically fluorescent signal at 645 nm. With the aid of Rho-N2H4 , the fluorescence imaging of mitochondrial N2H4 in living cells was achieved. Assisted by high-definition 3D imaging, Rho-N2H4 can be applied for the imaging of N2H4 in living tissues with a penetration depth of about 50 μm with red emission manner. Furthermore, in vivo experiments demonstrated that Rho-N2H4 can be capable of imaging N2H4 in living animals. We expect that Rho-N2H4 could act as a promising tool for in-depthly unveiling the physiological and pathological roles of mitochondrial N2H4 in living system.

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  • Comparative study of the photocatalytic activity for hydrogen evolution of MFe2O4 (M = Cu, Ni) prepared by three different methods
    Publication date: 15 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 357

    Author(s): Aurora Soto-Arreola, Ali M. Huerta-Flores, J.M. Mora-Hernández, Leticia M. Torres-Martínez

    In this work, CuFe2O4 and NiFe2O4 were synthesized by three different methods solid state reaction, polymer precursor method, and hydrothermal synthesis. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer Emmett-Teller method (BET) and electrochemical measurements were employed to study the structural, morphological, optical, textural and electrical properties of the products. In all the cases (solid state, polymer precursor, and hydrothermal method) we confirmed through XRD analysis the obtention of the tetragonal phase for CuFe2O4 and the cubic phase for NiFe2O4. The influence of the preparation routes on the physicochemical properties of the materials was investigated in detail. The catalytic activity of the materials was tested under different irradiation sources: UV light (254 nm and 365 nm) and visible light, exhibiting activity only under 254 nm. The materials prepared by solid state method exhibited the highest activity for hydrogen evolution, due to their higher crystallinity and lower recombination of charges photogenerated. CuFe2O4 showed higher hydrogen evolution rate (336 μmol g−1 h−1) than NiFe2O4 (234 μmol g−1 h−1) attributed to the more negative character of the conduction band and higher photocurrent response of CuFe2O4. The photocatalytic activity of the materials was further analyzed in the presence of a sacrificial agent (0.25 M Na2SO3 – 0.35 Na2S), increasing more than 10 times the activity of the compounds obtained by solid state.

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  • Molecular modeling for the investigation of UV absorbers for sunscreens: Triazine and benzotriazole derivatives
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Bianca A.M.C. Santos, Anne C.P. da Silva, Murilo L. Bello, Arlan S. Gonçalves, Thais A. Gouvêa, Rayane F. Rodrigues, Lucio M. Cabral, Carlos R. Rodrigues

    Investigations on the photoprotection mechanisms of molecular sunscreens is critical to developing more efficacious sunscreen products. Molecular modeling has proved to be very helpful in understanding intrinsic properties of molecules that protect our skin from the harmful rays of the sun and gathering useful features to developing improved sunscreens. Herein the investigation focuses on the stereoelectronic properties related to photoprotection mechanisms of triazine and benzotriazole derivatives, important compound classes based on their physical-chemical properties, such as resonance and ultraviolet (UV) broad spectrum absorption (UVA and UVB). The method proved to be a valuable tool to reproduce the experimental UV absorption of a set of triazine and benzotriazole derivatives with compromise between the accuracy and the computational speed. All calculations were carried out considering only the isolated UV filter (in vacuum) and have provided a qualitative prediction and interpretation of absorption properties. The lowest band gap energy (Ebg), highest chemical potential (μ) and lowest chemical hardness (η) values were observed to the orthohydroxy substituted derivatives that are able to undergo excited-state proton transfer (ESPT), supporting the UVA absorption and resulting in excellent photostability.

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  • Copper iodide-PEDOT:PSS double hole transport layers for improved efficiency and stability in perovskite solar cells
    Publication date: 15 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 357

    Author(s): Wei-Dong Hu, Chunxiang Dall’Agnesel, Xiao-Feng Wang, Gang Chen, Meng-Zhen Li, Jia-Xing Song, Ying-Jin Wei, Tsutomu Miyasaka

    The hole transport layer (HTL) plays an important role in perovskite solar cells (PSCs). We demonstrate the cupper iodide (CuI)/poly (3,4-ethylenedioxythiophene) poly (styrenesulphonate) (PEDOT:PSS) double layers as the anode buffer layer for efficient hole transport in PSCs. An obvious enhancement of open-circuit voltage and power conversion efficiency (PCE) is observed, and a final PCE of 14.3% is achieved. While the single PEDOT:PSS based device’s PCE is 12.9%. The inorganic CuI buffer layer significantly enhanced the hole extraction from the perovskite film, as revealed from the photoluminescence spectra. The average exciton lifetime is reduced to 2.7 ns. Moreover, the devices with double HTLs structure exhibit better long time stability. The PCE remains 88% of the initial value after 720 h’ storage.

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  • Ga-Ti-codoped ZnO embedded silver nanoparticles as an alternative anode in blue and green OLEDs
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Jayabharathi Jayaraman, Sarojpurani Elayaperumal, Thanikachalam Venugopal, Jeeva Palanivel

    Enhancement in electroluminescent performances have been harvested with embedded silver nanoparticles at glass and Ga-Ti-codoped ZnO interface. The blue emitting device exhibit maximum luminance (L) of 40268 cd/m2 (ITO device II-38863 cd/m2), current efficiency (η c) of 38.3 cd/A (ITO device II-36.0 cd/A) and power efficiency (η p) of 41.6 lm w−1 (ITO device II-40.3 lm w−1) with external quantum efficiency (η ex) of 19.2% (ITO device II-17.0%). Newly fabricated green device with emissive layer Ir(fpi)3 show intensified emission at 520 nm and luminance of 44894 cd/m2 (ITO device-IV-41682 cd/m2), current efficiency (η c) of 40.6 cd/A (ITO device IV-39.4 cd/A), power efficiency (η p) of 43.4 lm w−1 (ITO device IV-39.4 lm w−1) and external quantum efficiency (η ex) of 15.6% (ITO device IV-14.1%).

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  • In–situ formation of self-assembled Ag nanoclusters on ct-DNA in the presence of 2-mercaptothioxanthone by using UV–vis light irradiation
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Eyup Metin, Gonul S. Batibay, Nergis Arsu

    Self-assembled silver nanoparticles (Ag NPs) on calf thymus DNA (ct-DNA) chains were synthesized in the presence of 2-mercaptothioxanthone (TX-SH) by use of UV irradiation technique. Thioxanthone itself and its derivatives show interesting photochemical and biological properties. The formation of Ag NPs on the ct-DNA was achieved with and without TX-SH as a thioxanthone derivative photoinitiator which played a photoreducing role for the formation of Ag NPs. The photoreducing reaction of Ag ions to Ag NPs was followed by UV–vis absorption spectroscopy. A new band was observed at 428 nm which was a good sign of the surface plasmon resonance (SPR) of Ag NPs. Fluorescence quenching was effectively observed depending on the irradiation time of the solution, possibly as a result of Ag NPs size. Particle size analysis and Scanning Electron Microscopy (SEM) imaging confirmed the size of the formed Ag NPs and silver nanoclusters (Ag NCs) effectively. In this study, we report for the first time the formation of self–assembled Ag NPs on ct-DNA in the presence of 2-mercaptothioxanthone by photoirradiation technique. TX-SH played two important roles; photoreducing and photostabilizing agent for the formation of Ag NCs on ct-DNA. Fluorophore character of synthesized Ag NPs on DNA may help to develop new techniques for biological and medical aspects.

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  • Molybdenum-substituted polyoxometalate as stable shuttle redox mediator for visible light driven Z-scheme water splitting system
    Publication date: 1 April 2018
    Source:Journal of Photochemistry and Photobiology A: Chemistry, Volume 356

    Author(s): Yukari Iwase, Osamu Tomita, Hiroki Naito, Masanobu Higashi, Ryu Abe

    In this study, a Mo-substituted Keggin-type polyoxometalate [SiW11MoVIO40]4− was examined as a shuttle redox mediator in Z-scheme water splitting, and its electrochemical and chemical stability were also investigated. The redox cycle of [SiW11MoVIO40]4−/[SiW11MoVO40]5−, which corresponds to the valence change between the incorporated MoVI/MoV species, was confirmed to possess appropriate redox potential (+0.58 V vs. SHE at pH 2.7) for use as a shuttle redox (i.e. between water reduction and oxidation potentials). A sufficiently stable redox cycle in acidic (pH 2.7) aqueous solutions was indeed exhibited, whereas slow but obvious degradation was observed under mildly acidic conditions (pH 4.5). Under visible light, the oxidized form, [SiW11MoVIO40]4−, was found to function as an electron acceptor over WO3-based photocatalysts (i.e., an O2-evolving system), and the reduced form, [SiW11MoVO40]5−, was found to function as an electron donor over Ru-loaded SrTiO3 doped with Rh species (i.e., a H2-evolving system). Finally, two-step water-splitting into H2 and O2 was demonstrated under visible light using [SiW11MoVIO40]4−/[SiW11MoVO40]5− couples as a shuttle redox mediator between Ru/SrTiO3:Rh and PtO x /WO3 photocatalyst particles, under acidic conditions with pH 2.7.

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