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Photochemical & Photobiological Sciences

Dmitri V Kazakov, Timur I Nazyrov, Farit E Safarov, Ivan A Yaremenko, Alexander O Terent'ev
The reaction of biologically active bridged 1,2,4,5-tetraoxanes and diperoxide of trifluoroacetone with ferrous ions in the presence of xanthenes, methylene blue and methylene green is accompanied by bright chemiluminescence (CL) caused by the emission from electronically-excited dyes. The promising perspectives for the employment of the CL method for the analytical detection of tetraoxanes were demonstrated. The most convenient CL system was found to be their reaction with ferrous gluconate in the presence of rhodamine 3B, which allowed the detection of up to 10-9 M of diperoxides...
February 13, 2019: Photochemical & Photobiological Sciences
Jose A Lara-Ramos, Katerine Sánchez-Gómez, Daniel Valencia-Rincón, Jennyfer Diaz-Angulo, Miguel Mueses, Fiderman Machuca-Martínez
The present work reports the use of a flotation cell as a prospective reactor for ozonation and the intensification of ozonation (catalytic ozonation and photocatalytic ozonation). The effect of the pH, ozone concentration and loading catalyst was investigated. The performance of the flotation cell was compared with that of conventional reactors used in ozonation through the ozone utilized index (OUI), which was proposed in this work and relates the amount of ozone supplied to the system per milligram of degraded pollutant...
February 13, 2019: Photochemical & Photobiological Sciences
Marina V Rogozina, Svetlana G Matveeva, Evgeni M Glebov, Roman G Fedunov
Quantum chemical calculations (CASSCF and XMCQDPT level of theory, IMCP-SR1 and SBKJC basis sets) of the structures and electronic absorption spectra of the OsIVCl5(H2O)- and OsIVCl5(OH)2- complexes, which are the products of OsIVCl62- photoaquation, were performed. The satisfactory agreement between the experimental and calculated spectra was achieved using both triplet and quintet manifolds. The dissociation of the aquacomplex with the formation of the hydroxocomplex was explained by the thermochemical data...
February 13, 2019: Photochemical & Photobiological Sciences
Prakash Majee, Debal Kanti Singha, Sudip Kumar Mondal, Partha Mahata
We have thoroughly studied the luminescence behaviour of a cadmium based MOF, [Cd(C12N2H8)(C7N1O4H3)] {C12N2H8 = 1,10-phenanthroline, C7N1O4H3 = 2,5-pyridine dicarboxylate}, 1. Both steady-state and time-resolved luminescence spectroscopic experiments were performed to understand the dissimilar responses of compound 1 towards different metal ions in aqueous medium. Upon excitation at 280 nm, compound 1 showed a luminescence spectrum centered at 365 nm, which exhibited a three-fold turn-on in the presence of a trace amount of Zn2+ in aqueous solution, whereas in the presence of Co2+, Hg2+, Ni2+, Fe2+ and Cu2+ the luminescence of compound 1 got largely quenched...
February 12, 2019: Photochemical & Photobiological Sciences
Mengyang Liu, Wolfgang Drexler
Optical coherence tomography angiography (OCTA) is a relatively novel functional extension of the widely accepted ophthalmic imaging tool named optical coherence tomography (OCT). Since OCTA's debut in ophthalmology, researchers have also been trying to expand its translational application in dermatology. The ability of OCTA to resolve microvasculature has shown promising results in imaging skin diseases. Meanwhile, photoacoustic imaging (PAI), which uses laser pulse induced ultrasound waves as the signal, has been studied to differentiate human skin layers and to help in skin disease diagnosis...
February 8, 2019: Photochemical & Photobiological Sciences
Christoph Kurzmann, Jeroen Verheyen, Michael Coto, Ramachandran Vasant Kumar, Giorgio Divitini, Hassan Ali Shokoohi-Tabrizi, Peter Verheyen, Roeland Jozef Gentil De Moor, Andreas Moritz, Hermann Agis
Dental bleaching is an important part of aesthetic dentistry. Various strategies have been created to enhance the bleaching efficacy. As one such strategy, light-activated nanoparticles that enable localized generation of reactive oxygen species have been developed. Here, we evaluated the cellular response to experimental gels containing these materials in in vitro models. L-929 cells, 3T3 cells, and gingival fibroblasts were exposed to the gels at 50%, 10%, 2%, 0.4%, 0.08%, 0.016%, and 0.0032%. The gels contained TiO2/Ag nanoparticles, TiO2 nanoparticles, hydrogen peroxide (6% hydrogen peroxide), or no added component and were tested with and without exposure to light...
February 6, 2019: Photochemical & Photobiological Sciences
A V Zakharov, A G Lvov, I A Rostovtseva, A V Metelitsa, A V Chernyshev, M M Krayushkin, A V Yadykov, V Z Shirinian
We have studied the photoreaction of 1,2-diarylethenes under aerobic conditions in the presence of various amines to prevent side processes promoted by singlet oxygen. It has been found that the most amines quite effectively deactivate processes associated with singlet oxygen, but primary and secondary amines unlike tertiary ones, react with substrates resulting in various side products. Among the studied amines, the most effective additive for preventing side processes, including those associated with singlet oxygen is imidazole, which is practically not consumed in photoreaction...
February 6, 2019: Photochemical & Photobiological Sciences
Kohei Inaba, Ryota Iwai, Masakazu Morimoto, Masahiro Irie
Although diarylethene derivatives are considered to undergo thermally irreversible photochromic reactions, this is not always the case. Here, we report on thermally reversible photochromic diarylethenes having pyrrole-2-carbonitrile aryl groups. The thermal stability of the coloured closed-ring isomer of 1,2-bis(2-alkyl-5-cyano-1-methyl-3-pyrrolyl)perfluorocyclopentene was found to depend on alkyl substituents at the 2- and 2'-positions. The closed-ring isomer of the ethyl-substituted derivative thermally returned back to the open-ring isomer much faster than that of the methyl-substituted derivative...
February 6, 2019: Photochemical & Photobiological Sciences
T Matthew Robson, Pedro J Aphalo, Agnieszka Katarzyna Banaś, Paul W Barnes, Craig C Brelsford, Gareth I Jenkins, Titta K Kotilainen, Justyna Łabuz, Javier Martínez-Abaigar, Luis O Morales, Susanne Neugart, Marta Pieristè, Neha Rai, Filip Vandenbussche, Marcel A K Jansen
Plants perceive ultraviolet-B (UV-B) radiation through the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8), and initiate regulatory responses via associated signalling networks, gene expression and metabolic pathways. Various regulatory adaptations to UV-B radiation enable plants to harvest information about fluctuations in UV-B irradiance and spectral composition in natural environments, and to defend themselves against UV-B exposure. Given that UVR8 is present across plant organs and tissues, knowledge of the systemic signalling involved in its activation and function throughout the plant is important for understanding the context of specific responses...
February 5, 2019: Photochemical & Photobiological Sciences
Love Kumar Dhandole, Young-Seok Seo, Su-Gyeong Kim, Aerin Kim, Min Cho, Jum Suk Jang
This study presents the first report on the photocatalytic inactivation mechanism for a Salmonella typhimurium pathogen by visible-light active CuxO loaded rhodium-antimony co-doped TiO2 nanorods (CuxO/Rh-Sb-TiO2 NRs) under visible light irradiation (cutoff filter, λ ≥ 420 nm). Remarkably higher pathogenic inactivation of 4 log within 40 min by a CuxO supported Rh-Sb-TiO2 NR photocatalyst was observed. The visible light active photocatalyst mainly produced reduced Cu+ in the lattice of CuxO by charge separation...
February 1, 2019: Photochemical & Photobiological Sciences
Ye Wu, Yingcheng Lin, Jian Xu
Development of materials for fluorescence imaging with a wide optical range is important for clinical applications. In this work, a solution synthesis method was used for making Ag-Ho, Ag-Sm, Ag-Zn, Ag-Cu Ag-Cs, Ag-Zr, Ag-Er, Ag-Y and Ag-Co metal organic compound nanoparticles. XRD, XPS and TEM were carried out for sample characterization. They showed broad fluorescence from the UV to NIR region. In particular, they presented near-infrared (NIR) fluorescence (800-1100 nm) when excitation light of 785 nm was used...
January 31, 2019: Photochemical & Photobiological Sciences
Stefano Protti, Davide Ravelli, Maurizio Fagnoni
The concepts of wavelength dependence and wavelength selectivity have been commonly used by organic photochemists for a long time. The aim of the present article is to offer a selection of relevant cases where the choice of the irradiation wavelength played a key role in the outcome of a photochemical path. Wavelength dependence can be related to the variation in the efficiency (but not the fate) of a process. Herein, three cases have been recognized where a wavelength-selectivity paradigm operates. Indeed, a different wavelength may (i) activate a different chromophore in a single molecule, (ii) induce the population of different reactive excited states and (iii) sequentially populate the excited state of a compound and the excited state of an intermediate photogenerated from it, which show a different reactivity...
January 29, 2019: Photochemical & Photobiological Sciences
Martin Dilla, Ahmet E Becerikli, Alina Jakubowski, Robert Schlögl, Simon Ristig
A self-made, low-cost tubular reactor for the gas-phase photocatalytic CO2 reduction was developed. The resulting flow conditions cause an intensive interaction between the reactants in the gas-phase and the fixed bed photocatalyst. This approach is used to test the scalability of tubular reactors for the photocatalytic CO2 reduction.
January 28, 2019: Photochemical & Photobiological Sciences
Matías Exequiel Rodríguez, Daniela Elisa Arévalo, Laura Milla Sanabria, Fernando Darío Cuello Carrión, Mariel Andrea Fanelli, Viviana Alicia Rivarola
Photodynamic therapy (PDT) is a clinically approved treatment that exerts a selective cytotoxic activity toward cancer cells. The procedure involves the administration of a photosensitizer drug followed by its activation by visible light. In the presence of oxygen, a series of events lead to tumor cell death. PDT releases different cell signals, some of these lead to death while others can lead to survival. The surviving or resistant cells contribute to the recurrence of tumors after treatment, from which the necessity to understand this molecular response induced by PDT arises...
January 25, 2019: Photochemical & Photobiological Sciences
Paramanantham Parasuraman, V T Anju, S B Sruthil Lal, Alok Sharan, Siddhardha Busi, K Kaviyarasu, Mohammed Arshad, Turki M S Dawoud, Asad Syed
Correction for 'Synthesis and antimicrobial photodynamic effect of methylene blue conjugated carbon nanotubes on E. coli and S. aureus' by Paramanantham Parasuraman et al., Photochem. Photobiol. Sci., 2019, DOI: 10.1039/c8pp00369f.
January 24, 2019: Photochemical & Photobiological Sciences
Suraj Kumar Panigrahi, Ashok Kumar Mishra
In this study, we report the identification of absorbance value of an analyte at the excitation wavelength that corresponds to the maximum of the observed fluorescence intensity obtainable for a certain instrument operating with right-angle fluorescence measurement (). The value depends on the fluorescence observation field (FOF) dimensions of the concerned spectrofluorometer. As the FOF varies from instrument to instrument, this study presents a simple method for obtaining FOF dimensions. Using the knowledge of FOF, absorbance of analyte at the excitation wavelength (Aλex) and emission wavelength (Aλem), we deduced a derived absorbance spectral parameter (Dabs)...
January 21, 2019: Photochemical & Photobiological Sciences
Xiaohong Shang, Deming Han, Lihui Zhao, Leijiao Li, Shuhui Lv
A DFT/TDDFT (density functional theory/time-dependent density functional theory) investigation on the geometries in the ground and lowest triplet excited states, the frontier molecular orbitals, the absorption spectra and the phosphorescent emission properties of five heteroleptic iridium(iii) complexes have been performed to obtain a better understanding of structure-property relationships. The key aim was to investigate the effect of π-conjugation on the photophysical properties of these studied complexes...
January 18, 2019: Photochemical & Photobiological Sciences
Diana Marcela Cañas-Martínez, Gilles Henri Gauthier, Julio Andrés Pedraza-Avella
Ilmenite-rich black sands from an alluvial deposit of Barbacoas (Nariño, Colombia) were used as a natural source aiming to obtain a low-cost and highly available photocatalyst. Mineral concentrates were obtained by gravimetric concentration in a Wilfley table (deck tilt angle: 11-14°) followed by dry magnetic or wet electromagnetic separation. Afterwards, the particle size was manually reduced down to -325 mesh. Rietveld refinements using X-ray diffraction data showed that the highest purity achieved was 93...
January 18, 2019: Photochemical & Photobiological Sciences
Tae Gyu Hwang, Jeong Yun Kim, Jin Woong Namgoong, Jae Moon Lee, Sim Bum Yuk, Se Hun Kim, Jae Pil Kim
A large number of diketopyrrolopyrrole (DPP) compounds showing aggregation induced emission (AIE) have been reported in the past few years. However, although DPP compounds exhibited AIE and excellent luminescence properties, their luminescence properties in solid or film states were not much focused on. Here we synthesized and characterized a series of DPP compounds with triphenylamine (TPA) moieties to investigate the AIE properties in the solid film state depending on the functional groups (TPA, BTPA, and MTPA) attached to the TPA moieties...
January 18, 2019: Photochemical & Photobiological Sciences
Alistair W R Seddon, Daniela Festi, T Matthew Robson, Boris Zimmermann
Ultraviolet-B radiation (UV-B, 280-315 nm) constitutes less than 1% of the total solar radiation that reaches the Earth's surface but has a disproportional impact on biological and ecological processes from the individual to the ecosystem level. Absorption of UV-B by ozone is also one of the primary heat sources to the stratosphere, so variations in UV-B have important relationships to the Earth's radiation budget. Yet despite its importance for understanding atmospheric and ecological processes, there is limited understanding about the changes in UV-B radiation in the geological past...
January 16, 2019: Photochemical & Photobiological Sciences
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