Search results for "Butane"
showing 10 items of 184 documents
On the Intrinsically Low Quantum Yields of Pyrimidine DNA Photodamages: Evaluating the Reactivity of the Corresponding Minimum Energy Crossing Points
2020
The low quantum yield of photoformation of cyclobutane pyrimidine dimers and pyrimidine-pyrimidone (6-4) adducts in DNA bases is usually associated with the presence of more favorable nonreactive decay paths and with the unlikeliness of exciting the system in a favorable conformation. Here, we prove that the ability of the reactive conical intersection to bring the system either back to the absorbing conformation or to the photoproduct must be considered as a fundamental factor in the low quantum yields of the mentioned photodamage. In support of the proposed model, the one order of magnitude difference in the quantum yield of formation of the cyclobutane thymine dimer with respect to the t…
Molecular Basis of DNA Photodimerization: Intrinsic Production of Cyclobutane Cytosine Dimers
2008
Based on CASPT2 results, the present contribution establishes for the first time that cytosine photodimer formation (CC) is mediated along the triplet and singlet manifold by a singlet-triplet crossing, (T1/S0)X, and by a conical intersection, (S1/S0)CI, respectively. The former can be accessed in a barrierless way from a great variety of photochemical avenues and exhibits a covalent single bond between the ethene C6-C6' carbon atoms of each monomer. The efficiency of the stepwise triplet mechanism, however, would be modulated by the effectiveness of the intersystem crossing mechanism. The results provide the grounds for the understanding of the potential photogenotoxicity of endogenous and…
Kinetic Study of the Oxidation of n-Butane on Vanadium Oxide Supported on Al/Mg Mixed Oxide
1997
The reaction kinetics of the oxidative dehydrogenation (ODH) of n-butane over vanadia supported on a heat-treated Mg/Al hydrotalcite (37.3 wt % of V2O5) was investigated by both linear and nonlinear regression techniques. A reaction network including the formation of butenes (1-, 2-cis-, and 2-trans-butene), butadiene, and carbon oxides by parallel and consecutive reactions, at low and high n-butane conversions, has been proposed. Langmuir−Hinshelwood (LH) models can be used as suitable models which allows reproduction of the global kinetic behavior, although differences between oxydehydrogenation and deep oxidation reactions have been observed. Thus, the formation of oxydehydrogenation pro…
Squaraine Dyes for Photodynamic Therapy: Study of Their Cytotoxicity and Genotoxicity in Bacteria and Mammalian Cells¶‡
2007
Halogenated squaraine dyes are characterized by long wavelength absorption (>600 nm) and high triplet yields and therefore represent new types of photosensitizers that could be useful for photodynamic therapy. We have analyzed the cytotoxicity and genotoxicity of the bromo derivative 1, the iodo derivative 2 and the corresponding nonhalogenated dye 3 in the absence and presence of visible light. At concentrations of 1-2 microM, 1 and 2 reduced the cloning efficiency of AS52 Chinese hamster ovary cells to less than 1% under conditions that were well tolerated in the dark. Similarly, the proliferation of L5178Y mouse lymphoma cells was inhibited by photoexcited 1 and 2 with high selectivity. …
Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide
2014
International audience; The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10−3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, prop…
CCDC 1469018: Experimental Crystal Structure Determination
2016
Related Article: Filip Topić and Kari Rissanen|2016|J.Am.Chem.Soc.|138|6610|doi:10.1021/jacs.6b02854
CCDC 1469009: Experimental Crystal Structure Determination
2016
Related Article: Filip Topić and Kari Rissanen|2016|J.Am.Chem.Soc.|138|6610|doi:10.1021/jacs.6b02854
CCDC 2100781: Experimental Crystal Structure Determination
2021
Related Article: Yuewei Wu, Jing Xi, Tongtong Xiao, Jes��s Ferrando-Soria, Zhong-Wen Ouyang, Zhenxing Wang, Shuchang Luo, Xiangyu Liu, Emilio Pardo|2020|Inorg.Chem.Front.|8|5158|doi:10.1039/D1QI01208H
CCDC 2100780: Experimental Crystal Structure Determination
2021
Related Article: Yuewei Wu, Jing Xi, Tongtong Xiao, Jes��s Ferrando-Soria, Zhong-Wen Ouyang, Zhenxing Wang, Shuchang Luo, Xiangyu Liu, Emilio Pardo|2020|Inorg.Chem.Front.|8|5158|doi:10.1039/D1QI01208H
CCDC 2058519: Experimental Crystal Structure Determination
2021
Related Article: Esa Kukkonen, Elmeri Lahtinen, Pasi Myllyperkiö, Matti Haukka, Jari Konu|2021|New J.Chem.|45|6640|doi:10.1039/D1NJ00456E