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Photochemical & Photobiological Sciences

S A R Shahamirifard, M Ghaedi, M Montazerozohori, A Masoudiasl
In this work, the use of carbon dots (CDs) as a complexing agent and sensitizer in a polymeric matrix for determination of copper(ii) by UV-vis spectroscopy is reported for the first time. A new and highly selective Schiff base, namely, (N',N'''E,N',N'''E)-N',N'''-((((2-hydroxypropane-1,3-diyl)bis(oxy))bis(2,1-phenylene))bis(methan-ylylidene))di(isonicotinohydrazide) (NHBMDI), was also incorporated in the polymeric matrix. For the first time, the membrane composition of the proposed optical sensor including NHBMDI as the ionophore, tetraphenylborate (NaTPB) as the anionic additive, dibutyl phthalate (DBP) as the plasticizer and polyvinyl chloride (PVC) as the immobilizer was optimized through central composite design combined with the desirability function approach (DFA) because this method saves material and time consumption and is therefore cost effective...
January 12, 2018: Photochemical & Photobiological Sciences
G Balamurugan, S Velmathi
New benzimidazole and benzothiazole derivatives (S1-S3) derived from thiophene-2,5-dicarboxaldehyde and 5,5'-bipyridyldicarboxaldehyde with NSN/SSS/NN binding sites were tested against various cations and anions. S3 showed selectivity toward copper(ii) ions among other cations under consideration with the colour change to pale yellow from colourless under aqueous medium. In the cases of S1 and S2, no colour change was observed. S1 alone showed selective fluorescence turn on for Cr(iii) ions among other cations...
January 10, 2018: Photochemical & Photobiological Sciences
Luís Gustavo Teixeira Alves Duarte, José Carlos Germino, Cláudia de Ávila Braga, Cristina Aparecida Barboza, Teresa Dib Zambon Atvars, Fabiano da Silveira Santos, Fabiano Severo Rodembusch
This work presents the determination of acidic strengths at the electronic ground and excited states (pKa and ) of three flavonol derivatives using electronic absorption and fluorescence emission spectroscopy. The differences of the pKa and values were successfully correlated with the molecular structures according to the substitution pattern at the flavonol structure (hydrogen, diethylamino or fluoro moieties). In order to obtain more information about the observed photoacidity of these superacids, geometry optimizations and excitation energy calculations were performed at the CAM-B3LYP/6-311++G(d,p) level for their neutral, protonated and deprotonated species...
January 9, 2018: Photochemical & Photobiological Sciences
M S A Abdel-Mottaleb, M Saif, M S Attia, M M Abo-Aly, Sarah N Mobarez
A number of novel lanthanide (Gd3+, Sm3+, and Tb3+) complexes of the 1',3'-dihydro-8-methoxy-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indole] (spiropyran; SP), a widely studied molecular photoswitch, were investigated. Comparative spectroscopic (absorption and fluorescence) and kinetic investigations of the stimulated photochromic and solvatochromic behavior were carried out in different media. SP embedded in a rigid thin film of poly(methylmethacrylate) might be exploited profitably as an optical sensor for the identification of a solvent's nature...
January 8, 2018: Photochemical & Photobiological Sciences
Mikhail F Budyka, Vitalii M Li
Diarylethylenes with large π-systems often lose their photochemical activity (the size effect). 1-(1-Pyrenyl)-2-(2-quinolyl)ethylene (1P2QE), despite having a large conjugated π-system of 28 electrons, undergoes two-way reversible trans-cis photoisomerization both in the neutral and protonated forms with quantum yields as high as 0.13-0.83. For the neutral 1P2QE, experimental data and quantum-chemical calculations indicate a diabatic (nonadiabatic) reaction mechanism. Due to high photoisomerization quantum yields and the long-wavelength absorption band at 340-460 nm and 390-560 nm for the neutral and protonated compounds, respectively, 1P2QE can be used as a molecular photoswitch that is sensitive to visible light...
December 22, 2017: Photochemical & Photobiological Sciences
Paula García Calavia, María J Marín, Isabelle Chambrier, Michael J Cook, David A Russell
Gold nanoparticles (AuNPs; ca. 4 nm) were synthesised and functionalised with a mixed monolayer of polyethylene glycol (PEG) and one of two zinc phthalocyanines (ZnPcs), the difference between the two molecules was the length of the carbon chain that connects the Pc to the gold core. The chain was composed of either three (C3Pc) or eleven (C11Pc) carbon atoms. The C11Pc photosensitiser displayed higher fluorescence emission intensity than the C3Pc in solution. By contrast, the C3Pc photosensitiser exhibited higher fluorescence when bound to the surface of the AuNPs than the C11Pc, despite the shorter carbon chain which was expected to quench the fluorescence...
December 21, 2017: Photochemical & Photobiological Sciences
Hasan Mohammad, Abu Saleh Musha Islam, Chandraday Prodhan, Keya Chaudhuri, Mahammad Ali
A hydrazone-based conjugate Nap-hyz-pyz (H3L3) with potential N2O2 donor atoms was found to act as a dual channel (colori- and fluori-metric) sensor towards Al3+ and PPi in H2O-MeOH (6 : 4, v/v) at pH 7.2 (40 mM HEPES buffer) at 25 °C. The formation constants, Kf = (3.49 ± 1.77) × 104 and (3.78 ± 0.1) × 104 M-1, of the sensor towards Al3+ were determined by absorption and fluorescence titrations, respectively. The 1 : 1 stoichiometry of the reaction was determined by Job's method and confirmed by ESI-MS+ (m/z) studies...
December 20, 2017: Photochemical & Photobiological Sciences
Aleksandra A Ageeva, Ekaterina A Khramtsova, Viktor F Plyusnin, Aleksandr A Stepanov, Tatyana V Leshina
Lappaconitine (LC) is a natural diterpenoid alkaloid (DTA), acting as a human heart sodium channel blocker and possessing a wide range of biological activities, the cellular and molecular mechanisms of which are widely studied. This interest is due to the fact that various representatives of this DTA class show opposite biological activities. The possible reasons for this difference seem to be related to the peculiarities of the substituent effect on the drug-receptor binding process. In this work, the influence of substituents on the reactivity of LC and its derivatives has been studied by using elementary processes of photodecomposition...
December 19, 2017: Photochemical & Photobiological Sciences
Vânia Jesus, Diana Martins, Tatiana Branco, Nádia Valério, Maria G P M S Neves, Maria A F Faustino, Luís Reis, Esther Barreal, Pedro P Gallego, Adelaide Almeida
In the last decade, the worldwide production of kiwi fruit has been highly affected by Pseudomonas syringae pv. actinidiae (Psa), a phytopathogenic bacterium; this has led to severe economic losses that are seriously affecting the kiwi fruit trade. The available treatments for this disease are still scarce, with the most common involving frequently spraying the orchards with copper derivatives, in particular cuprous oxide (Cu2O). However, these copper formulations should be avoided due to their high toxicity; therefore, it is essential to search for new approaches for controlling Psa...
December 15, 2017: Photochemical & Photobiological Sciences
Carlotta Raviola, Maurizio Fagnoni
The site-selective cleavage of an Ar-X bond in polyhalogenated aromatics is an important tool in synthetic planning especially when more than one identical halogen atom is present. An alternative to the usual metal-catalyzed cleavage is represented by photochemistry although only a few examples have been reported. We then investigated the feasibility of the site-selective photodechlorination of some dichloroanisoles through a combined experimental and computational study. In the case of 2,4-dichloroanisole, selective detachment of the chlorine atom at the ortho position with respect to the OMe group was observed upon photohomolysis (in cyclohexane) or photoheterolysis (in MeOH) of the Ar-Cl bond...
December 14, 2017: Photochemical & Photobiological Sciences
Sarah M Greening, Katherine N Robertson, Alison Thompson
A series of synthetic analogs of the tripyrrolic natural product prodigiosin were complexed with boron trifluoride to generate the corresponding F-BODIPYs. The maximum wavelengths of absorption and emission of the pyrrolyldipyrrin F-BODIPYs were tuned through variation of the substituents about the pyrrolyldipyrrinato core. The limited variation of substituents on the C-ring did not significantly affect absorption and emission. However, variation of substituents on the B-ring and A-ring resulted in a corresponding red-shift in absorption and emission reaching maximum wavelengths of 600 nm...
December 8, 2017: Photochemical & Photobiological Sciences
Joshua K G Karlsson, Owen J Woodford, Heinz Mustroph, Anthony Harriman
Most quantitative fluorescence measurements report emission quantum yields by referring the integrated fluorescence profile to that of a well-known standard compound measured under carefully controlled conditions. This simple protocol works well provided an appropriate standard fluorophore is available and that the experimental conditions used for reference and unknown are closely comparable. Commercial fluorescence spectrophotometers tend to perform very well at wavelengths between 250 and 650 nm but are less responsive at longer wavelengths...
December 8, 2017: Photochemical & Photobiological Sciences
Domenica Farci, Chavdar Slavov, Dario Piano
Deinococcus radiodurans is well known for its unusual resistance to different environmental stresses. Recently, we have described a novel complex composed of the surface (S)-layer protein DR_2577 and the carotenoid deinoxanthin. We also showed a role of this complex in the UV resistance under desiccation. Both these properties, UV and desiccation resistance, suggest a selective pressure generated by Sun irradiation. In order to confirm this hypothesis we checked whether this S-layer Deinoxanthin Binding Complex (SDBC) has features of thermo-resistance, a property also expected in proteins evolved under solar irradiative pressure...
December 8, 2017: Photochemical & Photobiological Sciences
Marcelo Hernando, Melina Celeste Crettaz Minaglia, Gabriela Malanga, Christian Houghton, Darío Andrinolo, Daniela Sedan, Lorena Rosso, Leda Giannuzzi
The aim of this study was to evaluate the effects of short-term (hours) exposure to solar UV radiation (UVR, 280-400 nm) on the physiology of Microcystis aeruginosa. Three solar radiation treatments were implemented: (i) PAR (PAR, 400-700 nm), (ii) TUVA (PAR + UVAR, 315-700 nm) and (iii) TUVR (PAR + UVAR + UVBR, 280-700 nm). Differential responses of antioxidant enzymes and the reactive oxygen species (ROS) production to UVR were observed. Antioxidant enzymes were more active at high UVR doses. However, different responses were observed depending on the exposure to UVAR or UVBR and the dose level...
November 30, 2017: Photochemical & Photobiological Sciences
S Ikeyama, Y Amao
The effect of the functional ionic group of 4,4'-bipyridinium salt derivatives (4,4'-BPs) as the electron carrier on the visible-light driven conversion of CO2 to formic acid with the system consisting of water-soluble zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS) and formate dehydrogenase (FDH) in the presence of triethanolamine (TEOA) as an electron donor was investigated. 1,1'-Diaminoethyl- (DAV), 1-aminoethyl-1'-methyl- (AMV), 1-carboxymethyl-1'-methyl- (CMV) and 1,1'-dicarboxymethyl-4,4'-bipyridinium salt (DCV) were prepared as the 4,4'-BPs with the functional ionic group...
November 28, 2017: Photochemical & Photobiological Sciences
Zengzeng Hu, Huanhuan Quan, Zhen Chen, Yu Shao, Danzhen Li
Selective transformation of organics by visible-light-driven photocatalysis has been considered as a green and efficient strategy for the synthesis of fine chemicals. Herein, we fabricated mesoporous structured TiO2 with CdS nanoparticles successfully by a photodeposition method. The photocatalytic selective oxidation of benzyl alcohols and reduction of 4-nitroaniline were demonstrated over the as-prepared samples under visible-light irradiation. The CdS-decorated TiO2 with the photodeposition time of 90 min exhibited highest activity, which was higher than that of the commercial CdS, bare TiO2, CdS/P25, and CdS/SiO2...
November 27, 2017: Photochemical & Photobiological Sciences
Ľubica Vetráková, Vít Ladányi, Jamaludin Al Anshori, Pavel Dvořák, Jakob Wirz, Dominik Heger
Azobenzene is a prototypical photochromic molecule existing in two isomeric forms, which has numerous photochemical applications that rely on a precise knowledge of the molar absorption coefficients (ε). Careful analysis revealed that the previously reported absorption spectra of the "pure" isomers were in fact mutually contaminated by small amounts of the other isomer. Therefore, the absorption spectra of both trans- and cis-azobenzene in methanol were re-determined at temperatures of 5-45 °C. The thermodynamically more stable trans-azobenzene was prepared by warming the solution in the dark...
November 24, 2017: Photochemical & Photobiological Sciences
Vít Ladányi, Pavel Dvořák, Jamaludin Al Anshori, Ľubica Vetráková, Jakob Wirz, Dominik Heger
The quantum yields of azobenzene photoisomerization in methanol solution were redetermined using newly obtained molar absorption coefficients of its cis- and trans-isomers. The results differ substantially from those published previously, especially in the range of the nπ* absorption band. Besides actinometry, these findings are relevant for applications of azobenzene derivatives in optical switching.
November 24, 2017: Photochemical & Photobiological Sciences
Jagadish Katla, Sriram Kanvah
Styrylisoxazoles bearing a nitro group linked to bulky aromatic rings have been synthesized and examined for their absorption and emission studies in organic solvents and water. The molecules showed emission in the visible region with significant solvatochromic emission shifts influenced by the extended conjugation of aromatic rings and intramolecular charge transfer. These absorption and emission changes were used for the efficient and sensitive detection of trace concentrations of hydrogen sulfide (H2S) through the reduction of the nitro group to the amine group in the presence of aqueous sodium sulfide...
November 23, 2017: Photochemical & Photobiological Sciences
Feyza Icoglu Aksakal, Abdulkadir Ciltas
Ultraviolet B (UV-B) radiation is an environmental stressor with detrimental effects on many aquatic organisms including fish. In addition, UV-B exposure combined with other environmental factors could have even more negative effects. The purpose of this study was to investigate the effect of UV-B radiation exposure on zebrafish embryos/larvae in terms of survival, developmental toxicity and the mRNA levels of the genes related to oxidative stress and innate immune response at different temperatures (24 °C, 28 °C and 30 °C)...
November 17, 2017: Photochemical & Photobiological Sciences
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