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Photochemical & Photobiological Sciences

Shivraj, B Siddlingeshwar, Elena M Kirilova, Sergey V Belyakov, Darshan Devang Divakar, Abdulaziz Abdullah Alkheraif
Benzanthrone derivatives are potential fluorescent probes for various chemical and biological environments. A mechanistic understanding of their photophysical properties is pivotal for designing an efficient fluorescence sensor based on the benzanthrone framework. In this study, we report on the effect of chemical substitution on the photophysical properties of two benzanthrone derivatives, namely, 3-(N'-methyl)-piperazino-7H-benzo[de]anthracen-7-one [Me-PBA] and 3-(N'-phenyl)-piperazino-7H-benzo[de]anthracen-7-one [Ph-PBA] in different solvents and solvent mixtures of varying polarities and proticities...
March 21, 2018: Photochemical & Photobiological Sciences
Ji Hye Kang, Cheal Kim
Chemosensor 1 was synthesized by the reaction of octopamine with 2,3-dihydroxybenzaldehyde. Sensor 1 determined iron with an obvious color change from pale yellow to brown in nearly-pure water. The detection limits (0.55 and 0.25 μM) for Fe2+ and Fe3+, respectively, were far lower than the EPA (Environmental Protection Agency) guideline concentration for drinking water (5.37 μM). In addition, 1 could be employed to quantify iron in environmental water samples. Moreover, sensor 1 exhibited different fluorescence emissions in response to zinc (green) and cadmium (blue)...
March 20, 2018: Photochemical & Photobiological Sciences
M Crawford Andrews, Ping Peng, Amit Rajput, Anthony F Cozzolino
Carboxamidines functionalized with either a spiropyran or fulgimide photoswitch were prepared on multigram scales. The thermal, electrochemical, and photochemical ring isomerizations of these compounds were studied and the results compared with related systems. The photochemical isomerisations were found to be reversible and could be followed by1 H NMR and UV-vis spectroscopy. The spiropyran/merocyanine couple was thermally active and an activation enthalpy of 116 kJ mol-1 was measured for ring-opening. These measurements yielded an enthalpy difference of 25 kJ mol-1 between the open and closed states which is consistent with DFT calculations...
March 12, 2018: Photochemical & Photobiological Sciences
Yan Xie, Jianrong Gao, Shaozheng Zhang, Liang Wu
Four novel metal-free organic dyes (CFB1, CFB2, CFT1 and CFT2) based on indeno[2,1-b]carbazole donors were synthesized and their absorption spectra, photovoltaic performances, and electrochemical properties were evaluated. The differences in linking mode and the number of thiophene units led to variations in absorptivity, electron injection efficiency, and charge recombination. Among the four dyes, CFT1 with a π-bridge at the indeno[2,1-b]carbazole ring and a bridge of thiophene showed the best photovoltaic performance with a JSC of 12...
March 7, 2018: Photochemical & Photobiological Sciences
Thangaraj Anand, Ashok S K Kumar, Suban K Sahoo
An easy to prepare novel vitamin B6 cofactor derivative 3-hydroxy-N'-((3 hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene)-2-naphthohydrazide (NPY) was synthesized by a one pot condensation reaction of pyridoxal with 3-hydroxy-2-naphthoic hydrazide and applied for the optical detection of Zn2+ and cysteine in the aqueous DMSO medium. The addition of Zn2+ ions leads to a selective blue-shift in the fluorescence emission spectrum of NPY from 530 nm to 475 nm, which allowed ratiometric detection of Zn2+ ions down to 8...
March 5, 2018: Photochemical & Photobiological Sciences
Pouriya Faraj Tabrizi, Sara Wennige, Mark Berneburg, Tim Maisch
Photodynamic antimicrobial chemotherapy (PACT) is a multi-target method to inactivate pathogenic microorganisms by exciting a photosensitizer (PS) with visible light of appropriate wavelength in the presence of molecular oxygen (3 O2 ). There are two major pathways by which reactive oxygen species (ROS) are produced. In type I (TI )-reactions, radicals such as superoxide (O2 ˙- ) and hydroxyl radicals (˙OH) are generated by electron transfer. In type II (TII )-reactions, highly reactive singlet oxygen (1 O2 ) is produced by direct energy transfer...
February 28, 2018: Photochemical & Photobiological Sciences
Mariana de Almeida Torres, Marcus Vinicius de Liz, Lucia Regina Rocha Martins, Adriane Martins Freitas
Increased concentrations of nutrients in water bodies caused by effluent discharge, fertilizers and other inputs can lead to artificial eutrophication, increasing the primary productivity, bringing well-known and serious consequences to the environment (such as excessive macrophyte and microalgae growth). Most strategies for phytoplankton control in aquatic ecosystems result in metal accumulation or toxic by-product formation after chlorination. Concerning this matter, the photo-Fenton process (usually applied in wastewater treatment and degradation of a variety of contaminants) has been studied for water and effluent disinfection...
February 26, 2018: Photochemical & Photobiological Sciences
V Otero, M Vilarigues, L Carlyle, M Cotte, W De Nolf, M J Melo
By means of synchrotron based techniques, we propose an integrated mechanism for the degradation of 19th century chrome yellow oil paints based on pigment reconstructions from historical recipes. We show that for certain paint formulations the darkening of these colours is triggered by the binder photodegradation which leads to the formation of calcium oxalate at the expense of the filler CaCO3 , and the reduction of the chrome yellow pigment (Cr6+ /Cr3+ ). Considering that calcium oxalate is formed as a thin superficial layer, that may prevent light absorption by the paint bulk, we discuss its role as protective patina...
February 22, 2018: Photochemical & Photobiological Sciences
Hironobu Ikehata, Toshio Mori, Thierry Douki, Jean Cadet, Masayuki Yamamoto
The amount of photolesions produced in DNA after exposure to physiological doses of ultraviolet radiation (UVR) can be estimated with high sensitivity and at low cost through an immunological assay, ELISA, which, however, provides only a relative estimate that cannot be used for comparisons between different photolesions such as cyclobutane pyrimidine dimer (CPD) and pyrimidine(6-4)pyrimidone photoproduct (64PP) or for analysis of the genotoxicity of photolesions on a molecular basis. To solve this drawback of ELISA, we introduced a set of UVR-exposed, calibration DNA whose photolesion amounts were predetermined and estimated the absolute molecular amounts of CPDs and 64PPs produced in mouse skin exposed to UVC and UVB...
February 21, 2018: Photochemical & Photobiological Sciences
Xiang Li, Yongmei He, Chunmei Xie, Yanqun Zu, Fangdong Zhan, Xinyue Mei, Yang Xia, Yuan Li
Correction for 'Effects of UV-B radiation on the infectivity of Magnaporthe oryzae and rice disease-resistant physiology in Yuanyang terraces' by Xiang Li et al., Photochem. Photobiol. Sci., 2018, 17, 8-17.
February 20, 2018: Photochemical & Photobiological Sciences
Sarah Keller, Alessandro Prescimone, Edwin C Constable, Catherine E Housecroft
The heteroleptic complexes [Cu(tBu-xantphos)(bpy)][PF6 ] and [Ag(tBu-xantphos)(bpy)][PF6 ], where tBu-xantphos = 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene and bpy = 2,2'-bipyridine have been synthesized and their photophysical properties investigated. Single crystal X-ray diffraction studies of the compounds under ambient and increased pressure are presented; increase in pressure results in little structural perturbation. For the copper(i) complexes, the effects of changing the N^N ligand from bpy to 6-methyl-2,2'-bipyridine (6-Mebpy), 6-bromo-2,2'-bipyridine (6-Brbpy), and 4,4'-di(tert-butyl)-2,2'-bipyridine (4,4'-tBu2 bpy) were also investigated...
February 19, 2018: Photochemical & Photobiological Sciences
N Kaerkitcha, T Sagawa
Nanofibers with the cationic fluorescent molecules, 1-pyrenemethylamine hydrochloride (PyrMA) and α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP), in the presence of complementary anionic chiral polysaccharide, hyaluronic acid (HA) and transparent polymer, polyethylene oxide (PEO) were successfully prepared using an electrospinning technique. The results showed that the fluorescence spectra of electrospun nanofibers (ENFs) of PEO-HA-PyrMA exhibit a higher amount of pyrene excimer emission when the [PyrMA]/[HA] ratio was increased from 0...
February 15, 2018: Photochemical & Photobiological Sciences
Praveen Naik, Rui Su, Mohamed R Elmorsy, Ahmed El-Shafei, Airody Vasudeva Adhikari
Correction for 'New di-anchoring A-π-D-π-A configured organic chromophores for DSSC application: sensitization and co-sensitization studies' by Praveen Naik et al., Photochem. Photobiol. Sci., 2018, DOI: 10.1039/c7pp00351j.
February 8, 2018: Photochemical & Photobiological Sciences
Jagadish Katla, Akshay J M Nair, Abhijeet Ojha, Sriram Kanvah
A series of α-cyanostyrenes bearing anthracene and electron withdrawing trifluoromethyl units were designed and synthesized. The α-cyanostyrene skeleton favors aggregation induced enhanced emission behavior due to the restriction of intramolecular rotations. Remarkably, the anthryl cyanostyrenes bearing simple trifluoromethyl (CF3) substituents form stable organogels with enhanced fluorescence emission compared to their solution state. In water, the CF3 substituted anthrylstyrenes self-assemble into entangled fibrous nano/microstructures through intermolecular H-bonding, π-π stacking and cyano substituent interactions...
February 7, 2018: Photochemical & Photobiological Sciences
Jean Cadet, Thierry Douki
UV-induced DNA damage plays a key role in the initiation phase of skin cancer. When left unrepaired or when damaged cells are not eliminated by apoptosis, DNA lesions express their mutagneic properties, leading to the activation of proto-oncogene or the inactivation of tumor suppression genes. The chemical nature and the amount of DNA damage strongly depend on the wavelength of the incident photons. The most energetic part of the solar spectrum at the Earth's surface (UVB, 280-320 nm) leads to the formation of cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (64PPs)...
February 6, 2018: Photochemical & Photobiological Sciences
A F Bais, R M Lucas, J F Bornman, C E Williamson, B Sulzberger, A T Austin, S R Wilson, A L Andrady, G Bernhard, R L McKenzie, P J Aucamp, S Madronich, R E Neale, S Yazar, A R Young, F R de Gruijl, M Norval, Y Takizawa, P W Barnes, T M Robson, S A Robinson, C L Ballaré, S D Flint, P J Neale, S Hylander, K C Rose, S-Å Wängberg, D-P Häder, R C Worrest, R G Zepp, N D Paul, R M Cory, K R Solomon, J Longstreth, K K Pandey, H H Redhwi, A Torikai, A M Heikkilä
The Environmental Effects Assessment Panel (EEAP) is one of three Panels of experts that inform the Parties to the Montreal Protocol. The EEAP focuses on the effects of UV radiation on human health, terrestrial and aquatic ecosystems, air quality, and materials, as well as on the interactive effects of UV radiation and global climate change. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously held. Because of the Montreal Protocol, there are now indications of the beginnings of a recovery of stratospheric ozone, although the time required to reach levels like those before the 1960s is still uncertain, particularly as the effects of stratospheric ozone on climate change and vice versa, are not yet fully understood...
February 6, 2018: Photochemical & Photobiological Sciences
Qinghe Meng, Yuzheng Lian, Jianjun Jiang, Wei Wang, Xiaohong Hou, Yao Pan, Hongqian Chu, Lanqin Shang, Xuetao Wei, Weidong Hao
OBJECTIVES: Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants...
February 6, 2018: Photochemical & Photobiological Sciences
Yu Lei, Chengzhu Zhu, Jun Lu, Rong Chen, Jun Xiao, Shuchuan Peng
The photochemical transformation of dimethyl phthalate (DMP) with N(iii)(NO2-/HONO/H2ONO+) was investigated using 365 nm steady-state irradiation and 355 nm laser flash photolysis (LFP) techniques. The results showed that N(iii) concentration, DMP initial concentration and pH values all strongly affected the oxidation efficiency of DMP. The primary step of the reaction was the attack of ˙OH radicals on the aromatic ring to form a DMP-OH adduct, and the bimolecular rate constant was determined to be (5.5 ± 0...
January 31, 2018: Photochemical & Photobiological Sciences
Elena Zvereva, Javier Segarra-Martí, Marco Marazzi, Johanna Brazard, Artur Nenov, Oliver Weingart, Jérémie Léonard, Marco Garavelli, Ivan Rivalta, Elise Dumont, Xavier Assfeld, Stefan Haacke, Antonio Monari
Benzophenone (BP) despite its relatively simple molecular structure is a paradigmatic sensitizer, featuring both photocatalytic and photobiological effects due to its rather complex photophysical properties. In this contribution we report an original theoretical approach to model realistic, ultra-fast spectroscopy data, which requires describing intra- and intermolecular energy and structural relaxation. In particular we explicitly simulate time-resolved pump-probe spectra using a combination of state-of-the art hybrid quantum mechanics/molecular mechanics dynamics to treat relaxation and vibrational effects...
January 31, 2018: Photochemical & Photobiological Sciences
Yoriko Sonoda, Midori Goto, Kunihiro Ichimura
Higher order derivative spectra were applied at first to one-way ZEZ-to-EEE photoisomerisation of dimethyl ester (ZEZ-DPH1) of the titled compound in a methylcyclohexane solution. Many common crossing points emerged in UV-induced derivative-spectral changes to reveal the direct ZEZ-to-EEE photoisomerisation without the transient formation of an intermediate to suggest the bicycle-pedal mechanism. The solid-state photoisomerisation was subsequently monitored by tracing changes in the fourth-order derivatives of absorption spectra of a thin crystalline layer of ZEZ-DPH1 prepared by the drop-casting method, because the distortion of absorption spectra due to light scattering is cancelled...
January 24, 2018: Photochemical & Photobiological Sciences
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