keyword
MENU ▼
Read by QxMD icon Read
search

photochemistry

keyword
https://www.readbyqxmd.com/read/28437102/insights-into-the-complex-photophysics-and-photochemistry-of-the-simplest-nitroaromatic-compound-a-caspt2-casscf-study-on-nitrobenzene
#1
Angelo Giussani, Graham A Worth
Nitrobenzene is the simplest nitroaromatic compound and yet is characterized by a challenging and rich photophysics and photochemistry. In the present contribution the main decay paths undertaken by the system after UV absorption from both the brightest 1(La*) and the lowest 1(nA*) singlet excited states have been characterized by means of CASPT2//CASSCF computations. The obtained results match with the main photophysical properties experimentally reported: the lack of fluorescence and phosphorescence emission is justified by the presence of accessible conical intersections and intersystem crossing regions between respectively the 1(nA*) and 3(nA*) states with the ground state, while the high triplet quantum yield is attributable to the strong coupling between the 1(nA*) and 3(O*) states along the main decay path of the former...
April 24, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28432500/walking-over-4-gya-chemical-evolution-from-photochemistry-to-mineral-and-organic-chemistries-leading-to-an-rna-world
#2
REVIEW
Kunio Kawamura, Marie-Christine Maurel
Here we overview the chemical evolution of RNA molecules from inorganic material through mineral-mediated RNA formation compatible with the plausible early Earth environments. Pathways from the gas-phase reaction to the formation of nucleotides, activation and oligomerization of nucleotides, seem to be compatible with specific environments. However, how these steps interacted is not clear since the chemical conditions are frequently different and can be incompatible between them; thus the products would have migrated from one place to another, suitable for further chemical evolution...
April 21, 2017: Origins of Life and Evolution of the Biosphere
https://www.readbyqxmd.com/read/28430422/gauging-donor-acceptor-properties-and-redox-stability-of-chelating-click-derived-triazoles-and-triazolylidenes-a-case-study-with-rhenium-i-complexes
#3
Lisa Suntrup, Sinja Klenk, Johannes Klein, Sebastian Sobottka, Biprajit Sarkar
Bidentate ligands containing at least one triazole or triazolylidene (mesoionic carbene, MIC) unit are extremely popular in contemporary chemistry. One reason for their popularity is the similarities as well as differences in the donor/acceptor properties that these ligands display in comparison to their pyridine or other N-heterocyclic carbene counterparts. We present here seven rhenium(I) carbonyl complexes where the bidentate ligands contain combinations of pyridine/triazole/triazolylidene. These are the first examples of rhenium(I) complexes with bidentate 1,2,3-triazol-5-ylidene-containing ligands...
April 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28430416/a-complimentary-benzophenone-cross-linking-mass-spectrometry-photochemistry
#4
Adam Belsom, Gemma Mudd, Sven H Giese, Manfred Auer, Juri Rappsilber
Use of a heterobifunctional photoactivatable cross-linker, sulfo-SDA (diazirine), has yielded high-density data that facilitated structure modelling of individual proteins. We expand the photoactivatable chemistry toolbox here with a second reagent, sulfo-SBP (benzophenone). This further increases the density of photo-cross-linking to a factor of 20x over conventional cross-linking. Importantly, the two different photoactivatable groups display orthogonal directionality, enabling access to different protein regions, unreachable with a single cross-linker...
April 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28430203/photoredox-activation-of-carbon-dioxide-for-amino-acid-synthesis-in-continuous-flow
#5
Hyowon Seo, Matthew H Katcher, Timothy F Jamison
Although carbon dioxide (CO2) is highly abundant, its low reactivity has limited its use in chemical synthesis. In particular, methods for carbon-carbon bond formation generally rely on two-electron mechanisms for CO2 activation and require highly activated reaction partners. Alternatively, radical pathways accessed via photoredox catalysis could provide new reactivity under milder conditions. Here we demonstrate the direct coupling of CO2 and amines via the single-electron reduction of CO2 for the photoredox-catalysed continuous flow synthesis of α-amino acids...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28421106/the-synergistic-responses-of-different-photoprotective-pathways-in-dwarf-bamboo-fargesia-rufa-to-drought-and-subsequent-rewatering
#6
Chenggang Liu, Yanjie Wang, Kaiwen Pan, Qingwei Wang, Jin Liang, Yanqiang Jin, Akash Tariq
Dwarf bamboo-dominated forests are often subjected to temporary periods of drought due to rising air temperature and decreasing rainfall. Nevertheless, the relationship among CO2 assimilation, photoprotective pathways and metabolism of reactive oxygen species (ROS) remains unexplored in bamboo species. Changes in leaf gas exchange, chlorophyll fluorescence, energy partitioning, antioxidative system and compounds related to ROS metabolism in Fargesia rufa plants subjected to drought and subsequent rewatering were analyzed...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28419758/provenance-effect-on-carbon-assimilation-photochemistry-and-leaf-morphology-in-mediterranean-cistus-species-under-chilling-stress
#7
Giacomo Puglielli, Francisco J Cuevas Román, Rosangela Catoni, José M Moreno Rojas, Loretta Gratani, Laura Varone
The potential resilience of shrub species to environmental change deserves attention in those areas threatened by climate change such as the Mediterranean basin. We asked if leaves produced under climatically different conditions through the winter season up to spring can highlight the leaf traits involved in determining the potential resilience of three Cistus spp. to changing environmental conditions and to what extent intra-specific differences affect such a response. We analyzed carbon assimilation, maximum quantum efficiency of PSII photochemistry (Fv /Fm ) and the leaf morphological control of the photosynthetic process in leaves formed through the winter season up to spring in C...
April 18, 2017: Plant Biology
https://www.readbyqxmd.com/read/28419325/dissecting-molecular-and-physiological-response-mechanisms-to-high-solar-radiation-in-cyanic-and-acyanic-leaves-a-case-study-on-red-and-green-basil
#8
Massimiliano Tattini, Federico Sebastiani, Cecilia Brunetti, Alessio Fini, Sara Torre, Antonella Gori, Mauro Centritto, Francesco Ferrini, Marco Landi, Lucia Guidi
Photosynthetic performance and the expression of genes involved in light signaling and the biosynthesis of isoprenoids and phenylpropanoids were analysed in green ('Tigullio', TIG) and red ('Red Rubin', RR) basil. The aim was to detect the physiological and molecular response mechanisms to high sunlight. The attenuation of blue-green light by epidermal anthocyanins was shown to evoke shade-avoidance responses with consequential effects on leaf morpho-anatomical traits and gas exchange performance. Red basil had a lower mesophyll conductance, partially compensated by the less effective control of stomatal movements, in comparison with TIG...
April 17, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28418680/dual-functional-tamm-dancoff-approximation-a-convenient-density-functional-method-that-correctly-describes-s1-s0-conical-intersections
#9
Yinan Shu, Kelsey Anne Parker, Donald G Truhlar
Time-dependent Kohn-Sham density functional theory has been used successfully to compute vertical excitation energies, especially for large molecular systems. However, the lack of double excitation character in the excited amplitudes produced by linear response in the adiabatic approximation holds it back from broader applications in photochemistry; for example, it shows (3N-7)-dimensional conical intersection seams (where N is the number of atoms) between ground and excited states, although the correct dimensionality is 3N-8...
April 18, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28403551/cyclic-electron-flow-npq-and-photorespiration-are-crucial-for-the-establishment-of-young-plants-of-ricinus-communis-and-jatropha-curcas-exposed-to-drought
#10
Milton Costa Lima Neto, João Victor A Cerqueira, Juliana Ribeiro da Cunha, Rafael Vasconcelos Ribeiro, Joaquim Albenísio G Silveira
Although plant physiological responses to drought have been widely studied, the interaction between photoprotection, photorespiration and antioxidant metabolism in water-stressed plants is scarcely known. This study aimed to evaluate the physiological adjustments preserving photosynthesis and growth in two plant-species with differential tolerance to drought: Jatropha curcas and Ricinus communis. We measured stress indicators, gas exchange, photochemistry of PSII and PSI, antioxidant enzymes, cyclic electron flow and photorespiradion...
April 12, 2017: Plant Biology
https://www.readbyqxmd.com/read/28401765/near-infrared-fluorescent-proteins-biosensors-and-optogenetic-tools-engineered-from-phytochromes
#11
Konstantin G Chernov, Taras A Redchuk, Evgeniya S Omelina, Vladislav V Verkhusha
Phytochrome photoreceptors absorb far-red and near-infrared (NIR) light and regulate light responses in plants, fungi, and bacteria. Their multidomain structure and autocatalytic incorporation of linear tetrapyrrole chromophores make phytochromes attractive molecular templates for the development of light-sensing probes. A subclass of bacterial phytochromes (BphPs) utilizes heme-derived biliverdin tetrapyrrole, which is ubiquitous in mammalian tissues, as a chromophore. Because biliverdin possesses the largest electron-conjugated chromophore system among linear tetrapyrroles, BphPs exhibit the most NIR-shifted spectra that reside within the NIR tissue transparency window...
April 12, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28401228/environmental-photochemistry-of-fenamate-nsaids-and-their-radical-intermediates
#12
Caroline A Davis, Paul R Erickson, Kristopher McNeill, Elisabeth M L Janssen
Fenamates are a class of nonsteroidal anti-inflammatory drugs (NSAIDs) that are not fully removed during wastewater treatment and can be released to surface waters. Here, near-surface photochemical half-lives were evaluated to range from minutes to hours of four fenamates and the closely related diclofenac. While quantum yields for direct photochemical reactions at the water surface vary widely from 0.071 for diclofenac to <0.001 for mefenamic acid, all fenamates showed significant reactivity towards singlet oxygen and hydroxyl radical with bimolecular reaction rate constants of 1...
April 12, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28388049/multiphase-photochemistry-of-pyruvic-acid-under-atmospheric-conditions
#13
Allison E Reed Harris, Aki Pajunoja, Mathieu Cazaunau, Aline Gratien, Edouard Pangui, Anne Monod, Elizabeth C Griffith, Annele Virtanen, Jean-Francois Doussin, Veronica Vaida
Aerosol and molecular processing in the atmosphere occurs in a complex and variable environment consisting of multiple phases and interfacial regions. To explore the effects of such conditions on the reactivity of chemical systems, we employ an environmental simulation chamber to investigate the multiphase photolysis of pyruvic acid, which photoreacts in the troposphere in aqueous particles and in the gas phase. Upon irradiation of nebulized pyruvic acid, acetic acid and carbon dioxide are rapidly generated, which is consistent with previous literature on the bulk phase photolysis reactions...
April 17, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28383895/photochemistry-and-transmission-pump-probe-spectroscopy-of-2-azidobiphenyls-in-aqueous-nanocrystalline-suspensions-simplified-kinetics-in-crystalline-solids
#14
Tim S Chung, Anoklase J-L Ayitou, Jin H Park, Vanessa M Breslin, Miguel A Garcia-Garibay
Aqueous nanocrystalline suspensions provide a simple and efficient medium for performing transmission spectroscopy measurements in the solid state. In this Letter we describe the use of laser flash photolysis methods to analyze the photochemistry of 2-azidobiphenyl and several aryl-substituted derivatives. We show that all the crystalline compounds analyzed in this study transform quantitatively into carbazole products via a crystal-to-crystal reconstructive phase transition. While the initial steps of the reaction cannot be followed within the time resolution of our instrument (ca...
April 20, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28382451/environmental-photocatalysis-and-photochemistry-for-a-sustainable-world-a-big-challenge
#15
EDITORIAL
Didier Robert, Nicolas Keller, Elena Selli
No abstract text is available yet for this article.
April 6, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28374889/targeting-photochemical-scalpels-or-lancets-in-the-pdt-field-the-photochemist-s-role
#16
Stefano Protti, Angelo Albini, Radhika Viswanathan, Alexander Greer
This review covers photochemical approaches aimed at supplementing surgical instruments with hand-held photodynamic therapy (PDT) instruments. PDT is not widely used in hospitals, because of the laser equipment and expertise needed, and because insurance policies often do not cover the procedure. Accordingly, this review focuses on advances in photochemistry, photophysics, nanotechnology and miniaturization techniques that may likely inspire the use of hand-held instruments in PDT. A takeaway point is that the advent of photochemical scalpels or lancets that deliver reactive oxygen species (ROS) on site may better equip medical practitioners and allow for eradication of tumors or infections in general...
April 4, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28374761/solar-eclipse-demonstrating-the-importance-of-photochemistry-in-new-particle-formation
#17
Tuija Jokinen, Jenni Kontkanen, Katrianne Lehtipalo, Hanna E Manninen, Juho Aalto, Albert Porcar-Castell, Olga Garmash, Tuomo Nieminen, Mikael Ehn, Juha Kangasluoma, Heikki Junninen, Janne Levula, Jonathan Duplissy, Lauri R Ahonen, Pekka Rantala, Liine Heikkinen, Chao Yan, Mikko Sipilä, Douglas R Worsnop, Jaana Bäck, Tuukka Petäjä, Veli-Matti Kerminen, Markku Kulmala
Solar eclipses provide unique possibilities to investigate atmospheric processes, such as new particle formation (NPF), important to the global aerosol load and radiative balance. The temporary absence of solar radiation gives particular insight into different oxidation and clustering processes leading to NPF. This is crucial because our mechanistic understanding on how NPF is related to photochemistry is still rather limited. During a partial solar eclipse over Finland in 2015, we found that this phenomenon had prominent effects on atmospheric on-going NPF...
April 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28373695/catalyzed-synthesis-of-zinc-clays-by-prebiotic-central-metabolites
#18
Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J Matocha, S Kelly Sears, Hojatollah Vali, Marcelo I Guzman
How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism...
April 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28372735/photosynthesis-and-biochemical-responses-to-elevated-o3-in-plantago-major-and-sonchus-oleraceus-growing-in-a-lowland-habitat-of-northern-china
#19
Benying Su, Meihua Zhou, Hong Xu, Xiujie Zhang, Yonggeng Li, Hua Su, Bao Xiang
A field experiment was carried out to compare the responses to ozone (O3) in two common herbaceous plant species, Plantago major L. and Sonchus oleraceus L., by building open-top growth chambers in situ to simulate O3 stress (+O3, 85±5ppb, 9hr/day for 30days) in a lowland habitat in Inner Mongolia, Northern China. Responses to O3 of gas exchange, chlorophyll a fluorescence, leaf pigment content, antioxidant capability, soluble protein content, membrane lipid peroxidation and dark respiration (Rd) were analyzed...
March 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28370457/photochemistry-of-1-and-2-naphthols-and-their-water-clusters-the-role-of-1%C3%AF-%C3%AF-la-mediated-hydrogen-transfer-to-carbon-atoms
#20
Nađa Došlić, Jurica Novak, Antonio Prlj, Nikola Basarić, Clémence Corminboeuf
The computational analysis of isomer- and conformer- dependent photochemistry of 1- and 2-naphthols and their microsolvated water clusters is motivated by their very different excited state reactivity. We present evidence that 1- and 2-naphthol follow distinct excited state deactivation pathways. The deactivation of 2-naphthols, 2-naphthol water clusters as well as of the anti conformer of 1-naphthol is mediated by the optically dark 1πσ* state. The dynamics on the 1πσ* surface leads to the homolytic cleavage of the OH bond...
March 30, 2017: Chemistry: a European Journal
keyword
keyword
46954
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"