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Novel organometallic chalcones functionalized with a crown ether fragment as optical ion chemosensors 下载免费PDF全文
Fernando Godoy Tamara Maldonado Erick Flores Nicolás Agurto Rodrigo González Guillermo Ferraudi Graham Lappin 《应用有机金属化学》2018,32(3)
We previously reported the synthesis and characterization of new organometallic chalcones derived from ferrocene, cyrhetrene and cymantrene functionalized with a benzo‐15‐crown‐5 fragment. The ferrocene and cyrhetrene chalcones have been investigated as chemosensors for metal ions with optical response in acetonitrile. Several metal ions were selected considering the diameter of the cavity and the charge‐to‐radius ratio of the cation. The stoichiometry of the complexes was determined using Job's method. It was found that Na+ and Ca2+ complexes have a 1:1 stoichiometry while a 2:1 (metaloligand‐to‐cation) stoichiometry was determined for Ba2+ and Pb2+ complexes. The association constants were calculated according to the stoichiometry of the complex and the results showed that they are directly affected by the electron‐withdrawing nature of the organometallic fragment. Moreover, complexes of ferrocenyl chalcone have larger association constants than those of the cyrhetrenyl analogue. This experimental observation is consistent with the electronic properties of the ferrocenyl fragment. 相似文献
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Fabio Briscese Yeinzon Rodríguez Guillermo A. González 《Foundations of Physics》2012,42(11):1444-1451
We argue that the true nature of the renormalizability of Horava-Lifshitz gravity lies in the presence of higher order spatial derivatives and not in the anisotropic Lifshitz scaling of space and time. We discuss the possibility of constructing a higher order spatial derivatives model that has the same renormalization properties of Horava-Lifshitz gravity but that does not make use of the Lifshitz scaling. In addition, the state-of-the-art of the Lorentz symmetry restoration in Horava-Lifshitz-type theories of gravitation is reviewed. 相似文献
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Arnald Grabulosa Alberto Mannu Antonio Mezzetti Guillermo Muller 《Journal of organometallic chemistry》2012,696(26):4221-4228
A family of eight neutral, pseudotetrahedral piano-stool ruthenium complexes C, of the type [RuCl2(p-cymene)(PArPhR)] (Ar = 1-naphthyl, 9-phenanthryl and 2-biphenylyl; R = Me, i-Pr, OMe, –CH2SiMe3 and –CH2SiPh3) have been prepared and characterised, including the X-ray crystal structure for C6 (Ar = 2-biphenylyl; R = i-Pr). These complexes catalyse the asymmetric hydrogen transfer reaction of acetophenone in refluxing 2-propanol in the presence of potassium tert-butoxyde, reaching full conversions and up to 45% ee after 24 h towards the S enantiomer of 1-phenylethanol. Cationic complexes formed upon treatment of C with one equivalent of AgSbF6 or (Et3O)PF6 are active in the cyclopropanation reaction of styrene and α-methylstyrene by ethyl diazoacetate. Low to moderate conversions (up to 58%), diastereoselectivities (up to 40% de), and moderate enantioselectivities (up to 69% ee) have been found. For both reactions, bulky complexes and C6 in particular lead to the best results. 相似文献
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Laila D. Kazimierski Guillermo Abramson Marcelo N. Kuperman 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):232
We study a simple model of a foraging animal that modifies the substrate on which itmoves. This substrate provides its only resource, and the forager manages it by taking alimited portion at each visited site. The resource recovers its value after the visitfollowing a relaxation law. We study different scenarios to analyze the efficiency of themanaging strategy, corresponding to control the bite size. We observe the non trivialemergence of a home range, that is visited in a periodic way. The duration of thecorresponding cycles and the transient until it emerges is affected by the bite size. Ourresults show that the most efficient use of the resource, measured as the balance betweengathering and traveled distance, corresponds to foragers that take larger portions butwithout exhausting the resource. We also analyze the use of space determining the numberof attractors of the dynamics, and we observe that it depends on the bite size and therecovery time of the resource. 相似文献
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