نتایج جستجو برای: halogen
تعداد نتایج: 4763 فیلتر نتایج به سال:
Halogen photoelimination is a critical step in HX-splitting photocatalysis. Herein, we report the photoreduction of a pair of valence-isomeric dirhodium phosphazane complexes, and suggest that a common intermediate is accessed in the photochemistry of both mixed-valent and valence-symmetric complexes. The results of these investigations suggest that halogen photoelimination proceeds by two sequ...
The electronic structures and band gaps of silicene (the Si analogue of graphene) adsorbed with halogen elements are studied using the density functional theory based screened exchange local density approximation method. It is found that the band gaps of silicene adsorbed with F, Cl, Br and I have a nonmonotonic change as the periodic number of the halogen elements increases. This is attributed...
In the 1- (4-fluorophenyl) -2,3-dihydro-1 H-naphto- [1 and 2-e] [1 and 3] oxazine-3-n, there are 4 rings, respectively, rings from the side attached to the halogen They are named C, B, A, and D. Calculations and studies show that the amount of aromatics in the halogen-ring A in all cases has the highest number. In the B loop, the predicted aromatism level is zero, and in the ring C and D, relat...
The reaction of 2-amino-ethanol and iodo-penta-fluoro-benzene in the presence of K(2)CO(3) gave the title compound, C(8)H(6)F(4)INO, in high yield. The structure is characterized by double layers of mol-ecules linked by O-H⋯O and N-H⋯O hydrogen bonds, and linear C-I⋯F [I⋯F = 3.049 (2) Å] and bent C-I⋯I [I⋯I = 3.9388 (7) Å] inter-actions between pairs of nearly parallel iodo-tetra-fluoro-phenyl ...
The revived interest in halogen bonding as a tool in pharmaceutical cocrystals and drug design has indicated that cyano-halogen interactions could play an important role. The crystal structures of four closely related δ-keto esters, which differ only in the substitution at a single C atom (by H, OMe, Cl and Br), are compared, namely ethyl 2-cyano-5-oxo-5-phenyl-3-(piperidin-1-yl)pent-2-enoate, ...
INTRODUCTION In this in-vitro study, we evaluated the temperature changes in the pulp chamber during bracket bonding using 4 different light sources. METHODS Eighty intact extracted maxillary central incisors were used. The teeth were divided into 4 groups of 20 teeth each. Brackets (Mini Twin, Dentaurum, Ispringen, Germany) were bonded with Transbond XT (3M Unitek, Monrovia, Calif) adhesive ...
Analysis of 664 known structures of protein kinase complexes with halogenated ligands revealed 424 short contacts between a halogen atom and a potential protein X-bond acceptor, the topology and geometry of which were analyzed according to the type of a halogen atom (X = Cl, Br, I) and a putative protein X-bond acceptor. Among 236 identified halogen bonds, the most represented ones are directed...
Although halogen radicals are recognized to form as products of hydroxyl radical ((•)OH) scavenging by halides, their contribution to the phototransformation of marine organic compounds has received little attention. We demonstrate that, relative to freshwater conditions, seawater halides can increase photodegradation rates of domoic acid, a marine algal toxin, and dimethyl sulfide, a volatile ...
Halide ions are ubiquitous in natural waters and wastewaters. Halogens play an important and complex role in environmental photochemical processes and in reactions taking place during photochemical water treatment. While inert to solar wavelengths, halides can be converted into radical and non-radical reactive halogen species (RHS) by sensitized photolysis and by reactions with secondary reacti...
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