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Chlorine reactivity

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https://www.readbyqxmd.com/read/28229949/predicting-reactivity-of-model-dom-compounds-towards-chlorine-with-mediated-electrochemical-oxidation
#1
Glen Andrew de Vera, Wolfgang Gernjak, Jelena Radjenovic
Chlorine demand of a water sample depends on the characteristics of dissolved organic matter (DOM). It is an important parameter for water utilities used to assess oxidant and/or disinfectant consumption of source waters during treatment and distribution. In this study, model compounds namely resorcinol, tannic acid, vanillin, cysteine, tyrosine, and tryptophan were used to represent the reactive moieties of complex DOM mixtures. The reactivity of these compounds was evaluated in terms of Cl2 demand and electron donating capacity (EDC)...
January 23, 2017: Water Research
https://www.readbyqxmd.com/read/28222687/a-controlled-survey-of-less-typical-long-term-consequences-after-an-extensive-waterborne-epidemic
#2
Janne Laine, Outi Laine, Jukka Lumio, Jaakko Antonen, Salla Toikkanen, Mikko J Virtanen, Markku Kuusi
BACKGROUND: Extensive backflow of treated wastewater caused household water contamination in a Finnish town in 2007. The drinking water of 9 500 residents became heavily polluted with faecal microbes, resulting in a large gastroenteritis epidemic. Cases of reactive arthritis, milder joint symptoms and prolonged gastrointestinal symptoms were observed after the outbreak. A follow-up survey was performed to study less familiar long-term health consequences within a year from the outbreak...
February 21, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/28210728/self-initiation-of-uv-photopolymerization-reactions-using-tetrahalogenated-bisphenol-a-meth-acrylates
#3
Théophile Pelras, Wolfgang Knolle, Sergej Naumov, Katja Heymann, Olesya Daikos, Tom Scherzer
The potential of tetrachlorinated and tetrabrominated bisphenol A diacrylates and dimethacrylates for self-initiation of a radical photopolymerization was investigated. The kinetics of the photopolymerization of an acrylic model varnish containing halogenated monomers was studied by real-time FTIR spectroscopy, whereas the formation of reactive species and secondary products was elucidated by laser flash photolysis and product analysis by GC-MS after steady-state photolysis. The interpretation of the experimental data and the analysis of possible reaction pathways were assisted by quantum chemical calculations...
February 17, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/28205400/design-features-for-optimization-of-tetrapyrrole-macrocycles-as-antimicrobial-and-anticancer-photosensitizers
#4
EDITORIAL
Alejandra Martinez De Pinillos Bayona, Pawel Mroz, Connor Thunshelle, Michael R Hamblin
Photodynamic therapy (PDT) uses non-toxic dyes called photosensitizers (PS) and harmless visible light that combine to form highly toxic reactive oxygen species that kill cells. Originally, a cancer therapy, PDT, now includes applications for infections. The most widely studied PS are tetrapyrrole macrocycles including porphyrins, chlorins, bacteriochlorins, and phthalocyanines. The present review covers the design features in PS that can work together to maximize the PDT activity for various disease targets...
February 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28191929/stop-frame-filming-and-discovery-of-reactions-at-the-single-molecule-level-by-transmission-electron-microscopy
#5
Thomas W Chamberlain, Johannes Biskupek, Stephen T Skowron, Alexander V Markevich, Simon Kurasch, Oliver Reimer, Kate Walker, Graham A Rance, Xinliang Feng, Klaus Müllen, Andrey Turchanin, Maria A Lebedeva, Alexander Majouga, Valentine Georgievich Nenajdenko, Ute Kaiser, Elena Besley, Andrei N Khlobystov
We report an approach - named chemTEM - to follow chemical transformations at the single-molecule level with the electron beam of a transmission electron microscope (TEM) applied as both a tuneable source of energy and a sub-Angstrom imaging probe. Deposited on graphene, disk-shaped perchlorocoronene molecules are precluded from intermolecular interactions. This allows monomolecular transformations to be studied at the single-molecule level in real time and reveals chlorine elimination and reactive aryne formation as a key initial stage of multi-step reactions initiated by the 80 keV e-beam...
February 13, 2017: ACS Nano
https://www.readbyqxmd.com/read/28187315/reaction-of-tetracycline-with-biologically-relevant-chloramines
#6
J Benavides, P Barrias, N Piro, A Arenas, A Orrego, E Pino, L Villegas, E Dorta, A Aspée, C López-Alarcón
Helicobacter pylori (H. pylori) infection triggers inflammatory processes with the consequent production of hypochlorous acid (HOCl), monochloramine (NH2Cl), and protein-derived chloramines. As the therapy for eradicating H. pylori is partially based on the use of tetracycline, we studied the kinetic of its consumption elicited by HOCl, NH2Cl, N-chloro-n-butylamine (NHCl-But, used as a lysine-derived chloramine model), and lysozyme-derived chloramines. In the micromolar concentration range, tetracycline reacted rapidly with HOCl, generating in the first few seconds intermediates of short half-life...
February 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28167408/thm-and-haa-formation-from-nom-in-raw-and-treated-surface-waters
#7
D M Golea, A Upton, P Jarvis, G Moore, S Sutherland, S A Parsons, S J Judd
The disinfection by-product (DBP) formation potential (FP) of natural organic matter (NOM) in surface water sources has been studied with reference to the key water quality determinants (WQDs) of UV absorption (UV254), colour, and dissolved organic carbon (DOC) concentration. The data set used encompassed raw and treated water sampled over a 30-month period from 30 water treatment works (WTWs) across Scotland, all employing conventional clarification. Both trihalomethane (THM) and haloacetic acid (HAA) FPs were considered...
January 29, 2017: Water Research
https://www.readbyqxmd.com/read/28165179/controlled-covalent-functionalization-of-thermally-reduced-graphene-oxide-to-generate-defined-bifunctional-2d-nanomaterials
#8
Abbas Faghani, Ievgen S Donskyi, Mohammad Fardin Gholami, Benjamin Ziem, Andreas Lippitz, Wolfgang E S Unger, Christoph Böttcher, Jürgen P Rabe, Rainer Haag, Mohsen Adeli
A controlled, reproducible, gram-scale method is reported for the covalent functionalization of graphene sheets by a one-pot nitrene [2+1] cycloaddition reaction under mild conditions. The reaction between commercially available 2,4,6-trichloro-1,3,5-triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine-functionalized sheets. The different reactivities of the chlorine substituents on the functionalized graphene allow stepwise post-modification by manipulating the temperature...
March 1, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28159107/chlorine-triggered-de-alloying-of-auag-carbon-nanodots-towards-fabrication-of-a-dual-signalling-assay-combining-the-plasmonic-property-of-bimetallic-alloy-nanoparticles-and-photoluminescence-of-carbon-nanodots
#9
Zahra Mohammadpour, Afsaneh Safavi, Seyyed Hossein Abdollahi
Integration of Au-Ag alloy and fluorescent carbon nanodots (C-dots) into a single platform resulted in a new dual sensing assay for chlorine. Selective etching of Ag from AuAg@C-dots was transformed into: (i) colorimetric signal by surface plasmon resonance (SPR) tuning of the alloy and (ii) fluorimetric signal by perturbation of fluorescence energy transfer between C-dots and alloy nanoparticles. Fast oxidizing of silver atoms incorporated in the bimetallic structure induced by chlorine resulted in selective de-alloying of bimetallic hybrid nanoparticles and an intense visible change of the colloidal dispersion color...
March 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28133704/studies-on-the-formation-of-formaldehyde-during-2-ethylhexyl-4-dimethylamino-benzoate-demethylation-in-the-presence-of-reactive-oxygen-and-chlorine-species
#10
Waldemar Studziński, Alicja Gackowska, Maciej Przybyłek, Jerzy Gaca
In order to protect the skin from UV radiation, personal care products (PCPS) often contain chemical UV-filters. These compounds can enter the environment causing serious consequences on the water ecosystems. The aim of this study was to examine, the effect of different factors, such as UV light, the presence of NaOCl and H2O2 on the formaldehyde formation during popular UV filter, 2-ethylhexyl 4-(dimethylamino)benzoate (ODPABA) demethylation. The concentration of formaldehyde was determined by VIS spectrophotometry after derivatization...
January 29, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28120123/polymerization-of-chloro-p-xylylenes-quantum-chemical-study
#11
Cezary Czaplewski, Krzysztof Smalara, Artur Giełdoń, Maciej Bobrowski
The p-xylylene monomers of parylene N, C and D have similar high polymerization reactivity. For effective copolymerization processes this fact is basically a drawback and for instance the copolymerization with styrene doesn't go at all (Corley et al. J Pol Sc 13(68):137-156, [15]). Substitution of terminal hydrogen atoms by chlorine atoms reduces reactivity dramatically. 7,7,8,8-tetrachloro-p-xylylene and 2,5,7,7,8,8-hexachloro-p-xylylene can be isolated as yellow crystals. These crystals can be kept without any change in temperature below 0 (∘)C, but they polymerize slowly at room temperature...
February 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28112235/nanoscale-topography-on-black-titanium-imparts-multi-biofunctional-properties-for-orthopedic-applications
#12
Jafar Hasan, Shubham Jain, Kaushik Chatterjee
We have developed a chlorine based reactive ion etching process to yield randomly oriented anisotropic nanostructures that render the titanium metal surface 'black' similar to that of black silicon. The surface appears black due to the nanostructures in contrast to the conventional shiny surface of titanium. The nanostructures were found to kill bacteria on contact by mechanically rupturing the cells as has been observed previously on wings of certain insects. The etching was optimized to yield nanostructures of ≈1 μm height for maximal bactericidal efficiency without compromising cytocompatibility...
January 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28109630/analytical-model-for-the-design-of-in-situ-horizontal-permeable-reactive-barriers-hprbs-for-the-mitigation-of-chlorinated-solvent-vapors-in-the-unsaturated-zone
#13
Iason Verginelli, Oriana Capobianco, Niels Hartog, Renato Baciocchi
In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water...
January 10, 2017: Journal of Contaminant Hydrology
https://www.readbyqxmd.com/read/28106994/enzymatic-halogenation-and-dehalogenation-reactions-pervasive-and-mechanistically-diverse
#14
Vinayak Agarwal, Zachary D Miles, Jaclyn M Winter, Alessandra S Eustáquio, Abrahim A El Gamal, Bradley S Moore
Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution...
January 20, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28098448/new-insights-into-trihalomethane-and-haloacetic-acid-formation-potentials-correlation-with-the-molecular-composition-of-natural-organic-matter-in-source-water
#15
Xin Wang, Haifeng Zhang, Yahe Zhang, Quan Shi, Juan Wang, Jianwei Yu, Min Yang
Natural organic matter (NOM) represents the major source of precursors for disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), formed during disinfection of drinking water, but the molecular composition and reactivity of NOM remain not well understood. In this study, electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize the molecular composition of NOM of 20 source waters taken across China for the purpose of determining the major precursors of THMs and HAAs at molecular level...
February 2, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28095695/frontier-molecular-orbital-contributions-to-chlorination-versus-hydroxylation-selectivity-in-the-non-heme-iron-halogenase-syrb2
#16
Martin Srnec, Edward I Solomon
The ability of an Fe(IV)═O intermediate in SyrB2 to perform chlorination versus hydroxylation was computationally evaluated for different substrates that had been studied experimentally. The π-trajectory for H atom abstraction (Fe(IV)═O oriented perpendicular to the C-H bond of substrate) was found to lead to the S = 2 five-coordinate HO-Fe(III)-Cl complex with the C(•) of the substrate, π-oriented relative to both the Cl(-) and the OH(-) ligands. From this ferric intermediate, hydroxylation is thermodynamically favored, but chlorination is intrinsically more reactive due to the energy splitting between two key redox-active dπ* frontier molecular orbitals (FMOs)...
February 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28087479/synthesis-and-characterization-of-gold-nanostructured-chorin-e6-for-photodynamic-therapy
#17
L Vieira, M L Castilho, I Ferreira, J Ferreira-Strixino, K C Hewitt, L Raniero
Photodynamic therapy is an alternative treatment for cancer based on cellular uptake of a photosensitizer, illuminated with an appropriate wavelength in the presence of oxygen. A cascade of reactions generates reactive oxygen species leading to cell death. Using carbodiimide chemistry, chlorin e6 (Ce6) was covalently bonded to thiourea, and (via the sulphur end group) to gold nanoparticles (AuNPs), forming the Ce6-AuNP complex. Ce6 absorbs in the range 650-680nm, where the coefficient of biological tissue absorption is low (part of the therapeutic window), which is ideal for biological application...
January 10, 2017: Photodiagnosis and Photodynamic Therapy
https://www.readbyqxmd.com/read/28075568/reaction-pathways-and-kinetics-of-a-cyanobacterial-neurotoxin-%C3%AE-n-methylamino-l-alanine-bmaa-during-chlorination
#18
Yi-Ting Chen, Wan-Ru Chen, Zhi-Quan Liu, Tsair-Fuh Lin
β-N-Methylamino-L-alanine (BMAA), a probable cause of the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC), or Alzheimer's disease, has been identified in more than 20 cyanobacterial genera. However, its removal and fate in drinking water has never been reported before. In this study, the reaction of BMAA with chlorine, a common drinking-water oxidant/disinfectant, was investigated. A liquid chromatograph coupled with a triple quadrupole mass spectrometer was employed to quantify BMAA and its intermediates...
January 30, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28070104/comparative-photodynamic-therapy-cytotoxicity-of-mannose-conjugated-chlorin-and-talaporfin-sodium-in-cultured-human-and-rat-cells
#19
Yo Shinoda, Tsutomu Takahashi, Jiro Akimoto, Megumi Ichikawa, Hiromi Yamazaki, Atsushi Narumi, Shigenobu Yano, Yasuyuki Fujiwara
Photodynamic therapy (PDT) is a Food and Drug Administration authorized method for cancer treatment, which uses photosensitizer and laser photo-irradiation to generate reactive oxygen species to induce cell death in tumors. Photosensitizers have been progressively developed, from first to third generation, with improvements in cell specificity, reduced side effects and toxicity, increased sensitivity for irradiation and reduced persistence of photosensitizer in healthy cells. These improvements have been achieved by basic comparative experiments between current and novel photosensitizers using cell lines; however, photosensitizers should be carefully evaluated because they may have cell type specificity...
2017: Journal of Toxicological Sciences
https://www.readbyqxmd.com/read/28067486/photo-cross-linkable-polymer-dots-with-stable-sensitizer-loading-and-amplified-singlet-oxygen-generation-for-photodynamic-therapy
#20
Ying Tang, Haobin Chen, Kaiwen Chang, Zhihe Liu, Yu Wang, Songnan Qu, Hong Xu, Changfeng Wu
Photodynamic therapy (PDT) is a promising treatment modality for clinical cancer therapy. However, the therapeutic effect of PDT is strongly dependent on the property of photosensitizer. Here, we developed photo-cross-linkable semiconductor polymer dots doped with photosensitizer Chlorin e6 (Ce6) to construct a nanoparticle platform for photodynamic therapy. Photoreactive oxetane groups were attached to the side chains of the semiconductor polymer. After photo-cross-linking reaction, the Ce6-doped Pdots formed an interpenetrated structure to prevent Ce6 leaching out from the Pdot matrix...
February 1, 2017: ACS Applied Materials & Interfaces
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