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Wathsala Liyanage, Paul W Rubeo, Bradley L Nilsson
Peptide and low molecular weight amino acid-based materials that self-assemble in response to environmental triggers are highly desirable candidates in forming functional materials with tunable biophysical properties. In this paper, we explore redox-sensitive self-assembly of cationic phenylalanine derivatives conjugated to naphthalene diimide (NDI). Self-assembly of the cationic Phe-NDI conjugates into nanofibrils was induced in aqueous solvent at high ionic strength. Under reducing conditions, these self-assembled Phe-NDI conjugate fibrils underwent a morphological change to non-fibril aggregates...
December 6, 2017: Interface Focus
Buddhadev Maiti, Alexander Schubert, Sunandan Sarkar, Srijana Bhandari, Kunlun Wang, Zhe Li, Eitan Geva, Robert J Twieg, Barry D Dunietz
Selective fluorination of organic semiconducting molecules is proposed as a means to achieving enhanced hole mobility. Naphthalene is examined here as a root molecular system with fluorination performed at various sites. Our quantum chemical calculations show that selective fluorination can enhance attractive intermolecular interactions while reducing charge trapping. Those observations suggest a design principle whereby fluorination is utilized for achieving high charge mobilities in the crystalline form. The utility of this design principle is demonstrated through an application to perylene, which is an important building block of organic semiconducting materials...
October 1, 2017: Chemical Science
Moghal Zubair Khalid Baig, Prabhat Kumar Sahu, Moloy Sarkar, Manab Chakravarty
Unsymmetrically substituted triarylalkenes as aggregation-induced emission-active fluorogens (AIEgens) are sporadically explored by different researchers. In this paper, naphthalene, biphenyl and haloarene-linked new triarylethenes are conveniently synthesized and presented as unsymmetrically substituted extensive π-conjugates to continue the discovery of small molecules as new AIEgens. Moreover, fluorophores attached to haloarenes are noteworthy but such compounds are barely investigated as AIEgens. The possible mechanism underlying this AIE-behavior has also been addressed by the support of experimental/theoretical outcomes...
November 16, 2017: Journal of Organic Chemistry
K Uematsu, K Noguchi, K Nakano
A series of [7]helicene and [7]helicene-like compounds composed of a cyclopenta[1,2-b:4,3-b']dithiophene or dithieno[2,3-b:3',2'-d]heterole moiety and two naphthalene moieties were successfully synthesized from a common synthetic intermediate, 1,1'-binaphtho[2,1-b]thiophene. Their helical structures were confirmed by X-ray crystallographic analysis. The photophysical properties of them and their benzene analogues were investigated via absorption and fluorescence spectroscopy and theoretical calculations to correlate the effect of the five-membered rings in their π-conjugated skeleton...
November 16, 2017: Physical Chemistry Chemical Physics: PCCP
Charles Heath, Matthew B Myers, Bobby Pejcic
Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy using a polymer coated internal reflection element/waveguide is an established sensor platform for the detection of a range of organic and hydrocarbon molecules dissolved in water. The polymer coating serves two purposes: to concentrate hydrocarbons from the aqueous phase and to exclude water along with other interfering molecules from the surface of the internal reflection element. Crucial to reliable quantification and analytical performance is the calibration of the ATR-FTIR sensor which is commonly performed in water under mild ambient conditions (i...
November 15, 2017: Analytical Chemistry
Guiping Qin, Yong Wang, Hanmin Huang
Higher π-extended naphthalene, contained in methylnaphthalenes, which could capture alkyl radicals via SOMO-LUMO interactions, enabled the development of Cu-catalyzed formal [4 + 2] and [3 + 2] cycloadditions between methylnaphthalenes and electron-deficient alkenes. Under copper catalysis, a series of electron-deficient alkenes and methylnaphthalenes with different substituents were successfully incorporated with di-tert-butyl peroxide (TBP) as an oxidant and radical initiator, providing a wide range of cycloadducts...
November 15, 2017: Organic Letters
Stéphanie Mendes Marinho, Minh-Huong Ha-Thi, Van-Thai Pham, Annamaria Quaranta, Thomas Pino, Christophe Lefumeux, Thierry Chamaillé, Winfried Leibl, Ally Aukauloo
Biomimetic models that contain elements of photosynthesis are fundamental in the development of synthetic systems that can use sunlight to produce fuel. The critical task consists of running several rounds of light-induced charge separation, which is required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur. Long-lived first charge-separated state and distinct electronic signatures for the sequential charge accumulated species are essential features to be able to track these events on a spectroscopic ground...
November 15, 2017: Angewandte Chemie
Nicholas Pearce, E Stephen Davies, Raphael Horvath, Constance R Pfeiffer, Xue-Zhong Sun, William Lewis, Jonathan McMaster, Michael W George, Neil R Champness
Varying the degree of thionation of a series of naphthalene diimide (NDI) and naphthalic imide (NI) phenothiazine dyad systems affords a systematic approach for tuning the system's donor-acceptor energy gap. Each dyad was compared to model NDI/NI systems and fully characterised through single crystal X-ray diffraction, NMR, cyclic voltammetry, electron paramagnetic resonance (EPR), transient absorption spectroscopy (TA), time-resolved infra-red spectroscopy (TRIR) and DFT. The measurements reveal that thionation increases both electron affinity of the NDI/NI acceptor dyad component and accessibility of the singly or doubly reduced states...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
Jiabao Xu, Di Zhu, Aliyu Ibrahim, Christopher C R Allen, Christopher M Gibson, Patrick William Fowler, Yizhi Song, Wei E Huang
We illustrate that single-cell Raman microspectroscopy, coupled with deuterium isotope probing (Raman-DIP), provides a culture-independent and non-destructive approach to probe metabolic pathways of carbon substrates at the single-cell level. We find a clearly distinguishable C-D vibration band at 2070 - 2300 cm-1 in single-cell Raman spectra (SCRS) when Escherichia coli used deuterated glucose and Pseudomonas sp. used deuterated naphthalene as sole carbon sources. The intensity of the C-D band is proportional to the extent of deuteration in carbon source, and as low as 5% deuteration can be distinguished by analysis of SCRS...
November 14, 2017: Analytical Chemistry
Sarah L Skraba-Joiner, Jeffrey W Brulet, Min K Song, Richard P Johnson
In 1 M triflic acid/dichloroethane, anthracene is completely protonated at C9 and the resulting 9-anthracenium ion is easily observed at ambient temperature. When heated at > 84 °C as a dilute (10-3 M) solution in 1 M triflic acid/dichloroethane (DCE), anthracene undergoes conversion to phenanthrene as the major volatile product. Minor dihydro and tetrahydro products are also observed. MALDI analysis supports the simultaneous formation of oligomers, primarily dimeric, which represent 10 - 60% of the product mixture...
November 14, 2017: Journal of Organic Chemistry
Dingyu Hou, Xiaoqing You
Hydrogen abstraction reactions of polycyclic aromatic hydrocarbons (PAH) by H atoms play a very important role in both PAH and soot formation processes. However, large discrepancies up to a few orders of magnitude exist among the literature rate constant values. To increase the reliability of the computed rate constants, it is critical to obtain highly accurate potential energy surfaces. For this purpose, we have investigated the energetics of hydrogen abstraction from benzene and naphthalene using both high level-of-theory quantum chemistry methods and a series of density functional theory (DFT) methods, among which M06-2X/6-311g(d,p) has the best performance with a mean unsigned deviation from the CCSD(T)/CBS calculations of 1...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
Ivan Tavera Busso, Florencia Tames, José Avelino Silva, Sara Ramos, Vera Homem, Nuno Ratola, Hebe Carreras
Polycyclic aromatic hydrocarbons (PAHs) are some of the most studied organic compounds in urban environments, due to their known adverse effects on human health and persistence in environmental matrices. During the last decade, new groups of organic compounds with an intensive use worldwide such as synthetic musks have been raising the interest of the scientific community given their toxicity and health effects. However, literature is still scarce in studies dealing with their concentration in the environment, especially in developing countries, where they are even more rare or non-existing at all...
November 8, 2017: Science of the Total Environment
Moussa Mbaye, Pape Abdoulaye Diaw, Diabou Gaye-Saye, Bernard Le Jeune, Goulven Cavalin, Lydie Denis, Jean-Jacques Aaron, Roger Delmas, Philippe Giamarchi
Permanent online monitoring of water supply pollution by hydrocarbons is needed for various industrial plants, to serve as an alert when thresholds are exceeded. Fluorescence spectroscopy is a suitable technique for this purpose due to its sensitivity and moderate cost. However, fluorescence measurements can be disturbed by the presence of suspended organic matter, which induces beam scattering and absorption, leading to an underestimation of hydrocarbon content. To overcome this problem, we propose an original technique of fluorescence spectra correction, based on a measure of the excitation beam scattering caused by suspended organic matter on the left side of the Rayleigh scattering spectral line...
November 3, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Nathalie Grova, Jean-Philippe Antignac, Emilie M Hardy, Fabrice Monteau, Karine Pouponneau, Bruno Le Bizec, Brice M R Appenzeller
The present study addresses the hypothesis that the concentration of tetrahydroxylated Polycylic Aromatic Hydrocarbons (tetra-OH-PAHs) in hair might be a useful biomarker of human exposure to PAHs, providing quantitative assessment of the internal dose, as well as information on the associated toxicity in relation to individual's specific metabolism. By means of animal models, this work aimed at identifying new tetra-OH-PAHs which can be released from the hydrolysis of DNA-adducts and can also be directly detected in biological matrices usually used in the field of biomonitoring such as hair and urine...
December 1, 2017: Analytica Chimica Acta
Deepak Rawat, Radhey Shyam Sharma, Swagata Karmakar, Lakhbeer Singh Arora, Vandana Mishra
Microbes have potential to convert non-toxic azo dyes into hazardous products in the environment. However, the role of microbes in biotransforming such presumably non-toxic dyes has not been given proper attention, thereby, questions the environmental safety of such compounds. The present study assessed salinity driven microbial degradation of an unregulated azo dye, Acid orange 7 (AO7), under moderately halophilic conditions of textile effluent. The halophilic microbial consortium from effluent decolorized ~97% AO7 (50-500mgL(-1))...
November 7, 2017: Ecotoxicology and Environmental Safety
Wing Y Tuet, Yunle Chen, Shierly Fok, Dong Gao, Rodney J Weber, Julie A Champion, Nga L Ng
Exposure to air pollution is a leading global health risk. Secondary organic aerosol (SOA) constitute a large portion of ambient particulate matter (PM). In this study, the water-soluble oxidative potential (OP) determined by dithiothreitol (DTT) consumption and intracellular reactive oxygen and nitrogen species (ROS/RNS) production was measured for SOA generated from the photooxidation of naphthalene in the presence of iron sulfate and ammonium sulfate seed particles. The measured intrinsic OP varied for aerosol formed using different initial naphthalene concentrations, however, no trends were observed between OP and bulk aerosol composition or seed type...
November 9, 2017: Scientific Reports
Federica Nalin, Lane C Sander, Walter B Wilson, Stephen A Wise
Retention indices (I) for 45 polycyclic aromatic hydrocarbons (PAHs) and 63 methyl-substituted PAHs were determined by gas chromatography - mass spectrometry (GC-MS) using two different stationary phases: a Rxi-PAH phase (a "higher phenyl-content stationary phase") and a 50% (mole fraction) liquid crystalline dimethylpolysiloxane phase. Retention data were obtained for parent PAHs from molecular mass (MM) 128 g/mol (naphthalene) to 328 g/mol (benzo[c]picene) and for 12 sets of methyl-PAHs (methylfluorenes, methylanthracenes, methylphenanthrenes, methylfluoranthenes, methylpyrenes, methylbenz[a]anthracenes, methylbenzo[c]phenanthrenes, methylchrysenes, methyltriphenylenes, methylbenzo[a]pyrenes, methylperylenes, and methylpicenes)...
November 8, 2017: Analytical and Bioanalytical Chemistry
Jakub Kaminský, Jakub Chalupský, Petr Štěpánek, Jan Kříž, Petr Bouř
Absorption and magnetic circular dichroism (MCD) spectroscopies are powerful and simple methods to discriminate among various compounds. Polycyclic aromatic hydrocarbons provide particularly strong signal, which, for example, facilitates their detection in the environment. However, interpretation of the spectra is often based on quantum-chemical simulations, providing a limited precision only. In the present work, we use time-dependent density functional theory and complete active space second-order perturbation theories to understand spectral features observed in a series of naphthalene, anthracene, phenanthrene, and three larger compounds...
November 17, 2017: Journal of Physical Chemistry. A
Edoardo Giovannelli, Matteo Cioni, Piero Procacci, Gianni Cardini, Marco Pagliai, Victor Volkov, Riccardo Chelli
In the companion article (Giovannelli et al., journal, year, volume, pages), we have presented an alchemical approach, based on nonequilibrium molecular dynamics simulations, to compute absolute binding free energies of a generic host-guest system. Two alternative computational routes, called binded-domain and single-point alchemical-path schemes, have been proposed. This study is addressed to furnish numerical validation and illustrative examples of the above-mentioned alchemical schemes. Validation is provided by comparing binding free-energy data relative to two poses of a Zn(II)·anion complex with those recovered from an alternative approach, based on steered molecular dynamics simulations...
November 7, 2017: Journal of Chemical Theory and Computation
Samuel J Hein, Dan Lehnherr, Hasan Arslan, Fernando J Uribe-Romo, William R Dichtel
Aromatic compounds and polymers are integrated into organic field effect transistors, light-emitting diodes, photovoltaic devices, and redox-flow batteries. These compounds and materials feature increasingly complex designs, and substituents influence energy levels, bandgaps, solution conformation, and crystal packing, all of which impact performance. However, many polycyclic aromatic hydrocarbons of interest are difficult to prepare because their substitution patterns lie outside the scope of current synthetic methods, as strategies for functionalizing benzene are often unselective when applied to naphthalene or larger systems...
November 7, 2017: Accounts of Chemical Research
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