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Adam D Smith, Emily M Warne, Darren Bellshaw, Daniel A Horke, Maria Tudorovskya, Emma Springate, Alfred J H Jones, Cephise Cacho, Richard T Chapman, Adam Kirrander, Russell S Minns
We probe the dynamics of dissociating CS_{2} molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that, despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield...
May 4, 2018: Physical Review Letters
Wen-Jing Xiao, Quan-Quan Zhou, You-Quan Zou, Liang-Qiu Lu
Visible-light photocatalysis is a rapidly developing and powerful strategy to initiate organic transformations as it closely adheres to the tenants of green and sustainable chemistry. Generally, most visible-light-induced photochemical reactions occur through single-electron transfer (SET) pathways. Recently, visible-light-induced energy transfer (EnT) reactions have received considerable attentions from the synthetic community as this strategy provides a distinct reaction pathway, and remarkable achievements have been made in this field...
May 18, 2018: Angewandte Chemie
Kevin M Burridge, Thaiesha A Wright, Richard C Page, Dominik Konkolewicz
This review article highlights recent developments in the field of photochemistry and photochemical reversible deactivation radical polymerization applied to aqueous polymerizations. Photochemistry is a topic of significant interest in the fields of organic, polymer, and materials chemistry because it allows challenging reactions to be performed under mild conditions. Aqueous polymerization is of significant interest because water is an environmentally benign solvent, and the use of water enables complex polymer self-assembly and bioconjugation processes to occur...
May 17, 2018: Macromolecular Rapid Communications
Lucilla Taddei, Volha Chukhutsina, Bernard Lepetit, Giulio R Stella, Roberto Bassi, Herbert van Amerongen, Jean-Pierre Bouly, Marianne Jaubert, Giovanni Finazzi, Angela Falciatore
Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extremely variable environments. Diatoms possess a strong ability to dissipate excess absorbed energy as heat via non-photochemical quenching (NPQ). This process relies on changes in carotenoid pigment composition (xanthophyll cycle) and on specific members of the light-harvesting complex (LHC) family specialized in photoprotection (LHCX), which potentially act as NPQ effectors. However, the link between light stress, NPQ, and the existence of different LHCX isoforms is not understood in these organisms...
May 17, 2018: Plant Physiology
Andrew J Clark, Paul Yang, Khizer R Khaderi, Andrew A Moshfeghi
Electronic displays have become an integral part of life in the developed world since the revolution of mobile computing a decade ago. With the release of multiple consumer-grade virtual reality (VR) and augmented reality (AR) products in the past 2 years utilizing head-mounted displays (HMDs), as well as the development of low-cost, smartphone-based HMDs, the ability to intimately interact with electronic screens is greater than ever. VR/AR HMDs also place the display at much closer ocular proximity than traditional electronic devices while also isolating the user from the ambient environment to create a "closed" system between the user's eyes and the display...
May 1, 2018: Ophthalmic Surgery, Lasers & Imaging Retina
Xiong Ding, Pengfei Wang
We have demonstrated that the 3-diethylaminobenzyl (DEABn) photolabile protecting group (PPG) is an effective and structurally simple PPG for releasing molecules in aqueous environment. In general, the photoreaction is clean, and the released substrate and the PPG product, i.e., 3-diethylaminobenzyl alcohol, are obtained in high yield. The clean photoreaction can also be achieved under mild ambient conditions with sunlight while the reactant is stable under indoor lighting. Release of two substrates from one PPG chromophore in aqueous solution has been demonstrated to be feasible...
May 17, 2018: Journal of Organic Chemistry
Felix Schneck, Florian Schendzielorz, Nareh Hatami, Markus Finger, Christian Würtele, Sven Schneider
The endothermic reverse water-gas shift reaction (rWGS) for direct CO2 hydrogenation to CO is an attractive approach to carbon utilization. However, direct CO2 hydrogenation with molecular catalysts generally gives formic acid instead of CO as a result of the selectivity of CO2 insertion into M-H bonds. Based on the photochemical inversion of this selectivity, several synthetic pathways are presented for CO selective CO2 reduction with a nickel pincer platform including the first example of a photodriven rWGS cycle at ambient conditions...
May 17, 2018: Angewandte Chemie
D Salazar-Tortosa, J Castro, P Villar-Salvador, B Viñegla, L Matías, A Michelsen, R Rubio de Casas, J I Querejeta
Climatic dryness imposes limitations on vascular plant growth by reducing stomatal conductance, thereby decreasing CO2 uptake and transpiration. Given that transpiration-driven water flow is required for nutrient uptake, climatic stress-induced nutrient deficit could be a key mechanism for decreased plant performance under prolonged drought. We propose the existence of an "isohydric trap", a dryness-induced detrimental feedback leading to nutrient deficit and stoichiometry imbalance in strict isohydric species...
May 16, 2018: Global Change Biology
Thivyah Munisparan, Evyan Chia Yan Yang, Ragul Paramasivam, Nuraina Anisa Dahlan, Janarthanan Pushpamalar
Ultrafine titanium dioxide (TiO2 ) nanowires were synthesised using a hydrothermal method with different volumes of ethylene glycol (EG) and annealing temperatures. It shows that sodium titanate nanowires synthesised using 5 and 10 ml EG, which annealed at 400°C produced TiO2 nanowires that correspond to a photochemically active phase, which is anatase. The influences of annealing temperatures (400-600°C) on the morphological arrangement of TiO2 nanowires were evident in the field emission scanning electron microscopy...
June 2018: IET Nanobiotechnology
H Sophia Stark, Philipp J Altmann, Stephen Sproules, Corinna R Hess
We present a series of monometallic ([Cu(Mabiq)OTf] (1) and [Cu(Mabiq)] (2)) and bimetallic copper-Mabiq complexes ([Cu2 (Mabiq)(PPh3 )2 (OTf)2 ] (3) and [Cu2 (Mabiq)(PPh3 )2 ]PF6 (4)). The latter compounds contain an additional CuI center that binds in a tetrahedral fashion to the external bipyrimidine nitrogens of the macrocyclic ligand. Compounds 3 and 4 represent the first examples of bimetallic transition metal Mabiq complexes, stable both in solution and in the solid state. The structural and electronic properties of compounds 1-4 were analyzed by means of X-ray crystallography, cyclic voltammetry, and spectroscopic methods...
May 16, 2018: Inorganic Chemistry
JiHyeon Hwang, Dong G Lee, Hyunki Yeo, Jingyi Rao, Zhiyuan Zhu, Jawon Shin, Keunsoo Jeong, Sehoon Kim, Hyun Wook Jung, Anzar Khan
Proton transfer polymerization between thiol and epoxide groups is shown to be an adaptable and utilitarian method for the synthesis of hydrogels. For instance, the polymerization catalyst can be organic or inorganic, and the polymerization medium can be pure water, buffer solutions, or organic solvents. The gelation mechanism can be triggered at ambient conditions, at a physiological temperature of 37 °C, or through using light as an external stimulus. The ambient and photochemical methods both allow for nanoimprint lithography to produce freestanding patterned thick films...
May 16, 2018: Journal of the American Chemical Society
Nianbing Zhong, Ming Chen, Zhengkun Wang, Xin Xin, Bingxin Li
We demonstrate that a lab-on-a-chip device (hereafter termed a photochemical phenol sensor) that integrates a photocatalytic long-period fiber grating (PLPFG), fiber Bragg grating (FBG), polymer membrane, ultraviolet (UV) visible light, and microchannels can be exploited to selectively detect phenol in aqueous solutions. The novel PLPFG consisted of a thinned long-period fiber grating (LPFG) and a UV-visible-light-driven Er3+:YAlO3/SiO2/TiO2 (EYST) coating. The polymer membrane with high phenol permselectivity was synthesized using PEBA2533 doped with β-cyclodextrin and was wrapped around the EYST surface, thus forming a microchannel between the membrane and PLPFG to enable the injection and outflow of standard analytes...
May 16, 2018: Lab on a Chip
Saeed Jafarirad, Ebrahim Hammami Torghabe, Seyed Hosseyn Rasta, Roya Salehi
In the present research, an effective drug-free approach was developed to kill MCF7 breast cancer cells using low-level laser therapy (LLLT) combined with reduced graphene oxide (rGO)-based hybrid nanocomposites (NCs). Here, fruit extract of Rosa canina was used for the first time to obtain the rGO/ZnO, Ag-ZnO/rGO and Nd-ZnO/rGO NCs by green synthesis. Physico/photochemical properties of these NCs were evaluated using FTIR, XRD, Raman, XPS, SEM/EDX, UV-Vis, DLS and AFM. The potential of the as-synthesized NCs on ROS generating and antioxidant activity were assessed by DPPH...
May 15, 2018: Artificial Cells, Nanomedicine, and Biotechnology
N Antonopoulou-Athera, E Chatzitheodoridis, A Terlixi, M Doulgerides, A A Serafetinides
This case study focuses on the reconstruction of the colour palette and the possibility of laser cleaning of burnt paintings. The paintings ORPHEUS IN THE UNDERWORLD and CONCORDIA, composed by the Greek artist Konstantinos Parthenis (1878-1967), have been severely damaged by fire. The colour palette of Parthenis is thoroughly investigated for the first time, and to perform this, a multi-analytical spectroscopic approach was employed. Non-destructive in situ analysis was performed on multiple areas of the paintings by portable XRF...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Laíse Midori Tokubo, Pedro Luiz Rosalen, Janaina de Cássia Orlandi Sardi, Irlan Almeida Freires, Mitsue Fujimaki, Josely Emiko Umeda, Patricia Magalhães Barbosa, Gabriela Ortolan Tecchio, Noboru Hioka, Camila Fabiano de Freitas, Raquel Sano Suga Terada
BACKGROUND: Photodynamic therapy (PDT) has demonstrated promising results in the treatment of several clinical pathologies through the photochemical reaction caused by the combination of a photosensitizer and a light source. The objective of this study was to evaluate the antimicrobial effect of the combination of the photosensitizers (PSs) erythrosine/methylene blue activated by a white halogen light device on Streptococcus mutans biofilm. METHODS: Two separate experiments were conducted, the first using the PSs at the concentration of 100 μM, and the second 250 μM...
May 12, 2018: Photodiagnosis and Photodynamic Therapy
Jianfeng Xu, Dougal J Ritson, Sukrit Ranjan, Zoe R Todd, Dimitar D Sasselov, John D Sutherland
Photoredox cycling during UV irradiation of ferrocyanide ([FeII(CN)6]4-) in the presence of stoichiometric sulfite (SO32-) is shown to be an extremely effective way to drive the reductive homologation of hydrogen cyanide (HCN) to simple sugars and precursors of hydroxy acids and amino acids.
May 15, 2018: Chemical Communications: Chem Comm
Nikoleta Vohradská, Esther M Sánchez-Carnerero, Tomáš Pastierik, Ctibor Mazal, Petr Klán
A controlled photorelease of alkynoic acids from the meso-methyl BODIPY photoremovable protecting group facilitates their subsequent efficient decarboxylation to give terminal alkynes for a CuI-catalyzed azide/alkyne cycloaddition. The quantum efficiencies of the photochemical step and the kinetics of the click reaction step are reported.
May 15, 2018: Chemical Communications: Chem Comm
Linke Ge, Crispin Halsall, Chang-Er Chen, Peng Zhang, Qianqian Dong, Ziwei Yao
Fluoroquinolone antibiotics (FQs) are ubiquitous and ionisable in surface waters. Here we investigate gatifloxacin (GAT) and balofloxacin (BAL), two widely used FQs, and determine the photochemical reactivity of their respective dissociation species that arise at different pH to understand the relevance and pathways of phototransformation reactions. Simulated-sunlight experiments and matrix calculations showed that neutral forms (HFQs0 ) of the two antibiotics had the highest apparent photolytic efficiency and hydroxyl-radical oxidation reactivity...
August 15, 2018: Science of the Total Environment
Abeer N Al-Romaizan, Mahmoud A Hussein
A new candidate laser dye based 1,4-bis[β-(2-naphthothisolyl) vinyl] benzene (BNTVB) were prepared, and characterized in various organic solvents. The center polarity is less sensitive than electronic absorption. A red shift was noticed in the fluorescence spectra (ca. 40 nm) with increment in the solvent's polarity, this means that BNTVB's polarity appreciates upon excitation. The dipole moment of ground state (μg ) and the excited singlet state dipole moment (μe ) are determined from Kawski - Chamma and Bakshiev-Viallet equations using the disparity of Stokes shift with solvent polarity function of ε (dielectric constant) and n (refractive index) of the solvent...
May 12, 2018: Journal of Fluorescence
Riho Takayama, Akimasa Kaneko, Takashi Okitsu, Satoshi P Tsunoda, Kazumi Shimono, Misao Mizuno, Keiichi Kojima, Takashi Tsukamoto, Hideki Kandori, Yasuhisa Mizutani, Akimori Wada, Yuki Sudo
Rhodopsin is widely distributed in organisms as a membrane-embedded photoreceptor protein, consisting of the apoprotein opsin and vitamin-A aldehyde retinal, A1-retinal and A2-retinal being the natural chromophores. Modifications of opsin (e.g., by mutations) have provided insights into the molecular mechanism of the light-induced functions of rhodopsins as well as providing tools in chemical biology to control cellular activity by light. Instead of the apoprotein opsin, in this study, we focused on the retinal chromophore and synthesized three vinylene derivatives of A2-retinal...
May 11, 2018: Journal of Physical Chemistry Letters
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