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1.
Serenella Medici Marcella Gagliardo ScottB. Williams PrestonA. Chase Serafino Gladiali Martin Lutz AnthonyL. Spek GerardP.M. vanKlink Gerard vanKoten 《Helvetica chimica acta》2005,88(3):694-705
Achiral P‐donor pincer‐aryl ruthenium complexes ([RuCl(PCP)(PPh3)]) 4c , d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3‐phenylenebis(methylene)]bis[diisopropylphosphine] ( 2c ) or [1,3‐phenylenebis(methylene)]bis[diphenylphosphine] ( 2d ) and the N‐donor pincer‐aryl complex [RuCl{2,6‐(Me2NCH2)2C6H3}(PPh3)], ( 3 ; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P‐donor pincer‐aryl ruthenium complexes [RuCl(P*CP*)(PPh3)] 4a , b by reacting P‐stereogenic pincer‐arenes (S,S)‐[1,3‐phenylenebis(methylene)]bis[(alkyl)(phenyl)phosphines] 2a , b (alkyl=iPr or tBu, P*CHP*) and the complex [RuCl{2,6‐(Me2NCH2)2C6H3}(PPh3)], ( 3 ; Scheme 3). The crystal structures of achiral [RuCl(equation/tex2gif-sup-3.gifPCP)(PPh3)] 4c and of chiral (S,S)‐[RuCl(equation/tex2gif-sup-6.gifPCP)(PPh3)] 4a were determined by X‐ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh3)] complexes and chiral [RuCl(P*CP*)(PPh3)] complexes were tested as catalyst in the H‐transfer reduction of acetophenone with propan‐2‐ol. With the chiral complexes, a modest enantioselectivity was obtained. 相似文献
2.
Stopping criteria for inner iterations in inexact potential reduction methods: a computational study
S. Cafieri M. D’Apuzzo V. De Simone D. di Serafino 《Computational Optimization and Applications》2007,36(2-3):165-193
We focus on the use of adaptive stopping criteria in iterative methods for KKT systems that arise in Potential Reduction methods
for quadratic programming. The aim of these criteria is to relate the accuracy in the solution of the KKT system to the quality
of the current iterate, to get computational efficiency. We analyze a stopping criterion deriving from the convergence theory
of inexact Potential Reduction methods and investigate the possibility of relaxing it in order to reduce as much as possible
the overall computational cost. We also devise computational strategies to face a possible slowdown of convergence when an
insufficient accuracy is required. 相似文献
3.
B. Bonelli M. C. Bruzzoniti E. Garrone E. Mentasti B. Onida C. Sarzanini V. Serafino E. Tarasco 《Chromatographia》2002,56(1):S189-S191
Summary Mesoporous silica-based materials have been synthesized and studied for applications in the environmental field. Haloacetic
acids have been chosen as test compounds since they are byproducts of disinfection processes of water for human consumption.
For this purpose mesoporous materials have been synthesized in acid, basic or neutral conditions. The effect of composition
and synthesis conditions of mesoporous materials on their retention properties have been studied. The retention mechanism
has also been elucidated in term of electrostatic interactions and as a function of the residual surfactant content in the
materials.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
4.
Gärtner F Cozzula D Losse S Boddien A Anilkumar G Junge H Schulz T Marquet N Spannenberg A Gladiali S Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(25):6998-7006
The synthesis of novel, monocationic iridium(III) photosensitisers (Ir-PSs) with the general formula [Ir(III)(C^N)(2)(N^N)](+) (C^N: cyclometallating phenylpyridine ligand, N^N: neutral bidentate ligand) is described. The structures obtained were examined by cyclic voltammetry, UV/Vis and photoluminescence spectroscopy and X-ray analysis. All iridium complexes were tested for their ability as photosensitisers to promote homogeneously catalysed hydrogen generation from water. In the presence of [HNEt(3)][HFe(3)(CO)(11)] as a water-reduction catalyst (WRC) and triethylamine as a sacrificial reductant (SR), seven of the new iridium complexes showed activity. [Ir(6-iPr-bpy)(ppy)(2)]PF(6) (bpy: 2,2'-bipyridine, ppy: 2-phenylpyridine) turned out to be the most efficient photosensitiser. This complex was also tested in combination with other WRCs based on rhodium, platinum, cobalt and manganese. In all cases, significant hydrogen evolution took place. Maximum turnover numbers of 4550 for this Ir-PS and 2770 for the Fe WRC generated in situ from [HNEt(3)][HFe(3)(CO)(11)] and tris[3,5-bis(trifluoromethyl)phenyl]phosphine was obtained. These are the highest overall efficiencies for any Ir/Fe water-reduction system reported to date. The incident photon to hydrogen yield reaches 16.4% with the best system. 相似文献
5.
Alberico E Baumann W de Vries JG Drexler HJ Gladiali S Heller D Henderickx HJ Lefort L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(45):12683-12695
The mechanism of the asymmetric hydrogenation of methyl (Z)-2-acetamidocinnamate (mac) catalysed by [Rh(MonoPhos)(2)(nbd)]SbF(6) (MonoPhos: 3,5-dioxa-4-phosphacyclohepta[2,1-a:3,4-a']dinaphthalen-4-yl)dimethylamine) was elucidated by using (1)H, (31)P and (103)Rh NMR spectroscopy and ESI-MS. The use of nbd allows one to obtain in pure form the rhodium complex that contains two units of the ligand. In contrast to the analogous complexes that contain cis,cis-1,5-cyclooctadiene (cod), this complex shows well-resolved NMR spectroscopic signals. Hydrogenation of these catalyst precursors at 1 bar total pressure gave rise to the formation of a bimetallic complex of general formula [Rh(MonoPhos)(2)](2)(SbF(6))(2); no solvate complexes were detected. In the dimeric complex both rhodium atoms are ligated to two MonoPhos ligands but, in addition, each rhodium atom also binds to one of the binaphthyl rings of a ligand that is bound to the other rhodium metal. Upon addition of mac, a mixture of diastereomeric complexes [Rh(MonoPhos)(2)(mac)]SbF(6) is formed in which the substrate is bound in a chelate fashion to the metal. Upon hydrogenation, these adducts are converted into a new complex [Rh(MonoPhos)(2){mac(H)(2)}]SbF(6) in which the methyl phenylalaninate mac(H)(2) is bound through its aromatic ring to rhodium. Addition of mac to this complex leads to displacement of the product by the substrate. No hydride intermediates could be detected and no evidence was found for the involvement at any stage of the process of complexes with only one coordinated MonoPhos. The collected data suggest that the asymmetric hydrogenation follows a Halpern-like mechanism in which the less abundant substrate-catalyst adduct is preferentially hydrogenated to phenylalanine methyl ester. 相似文献
6.
Francesca Gladiali Massimo Grossi Filomena Pacella P. N. Srikanth 《Calculus of Variations and Partial Differential Equations》2011,40(3-4):295-317
In this paper we consider the problem $$\left\{ \begin{array}{ll} -\Delta u=u^p+\lambda u & \quad\hbox{ in }A,\\ u > 0&\quad \hbox{ in }A,\\ u=0 &\quad \hbox{ on }\partial A, \end{array}\right. $$ where A is an annulus of ${\mathbb{R}^N,N\ge2}$ and p?>?1. We prove bifurcation of nonradial solutions from the radial solution in correspondence of a sequence of exponents {p k } and for expanding annuli. 相似文献
7.
8.
Daniela di Serafino Susana Gomez Leopoldo Milano Filippo Riccio Gerardo Toraldo 《Journal of Global Optimization》2010,48(1):41-55
The detection of gravitational waves is a long-awaited event in modern physics and, to achieve this challenging goal, detectors
with high sensitivity are being used or are under development. In order to extract gravitational signals emitted by coalescing
binary systems of compact objects (neutron stars and/or black holes), from noisy data obtained by interferometric detectors,
the matched filter technique is generally used. Its computational kernel is a box-constrained global optimization problem
with many local solutions and a highly nonlinear and expensive objective function, whose derivatives are not available. To
tackle this problem, we designed a real-coded genetic algorithm that exploits characteristic features of the problem itself;
special attention was devoted to the choice of the initial population and of the recombination operator. Computational experiments
showed that our algorithm is able to compute a reasonably accurate solution of the optimization problem, requiring a much
smaller number of function evaluations than the grid search, which is generally used to solve this problem. Furthermore, the
genetic algorithm largely outperforms other global optimization algorithms on significant instances of the problem. 相似文献
9.
Casa G Castrillo A Galzerano G Wehr R Merlone A Di Serafino D Laporta P Gianfrani L 《Physical review letters》2008,100(20):200801
We report on a new optical implementation of primary gas thermometry based on laser-absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) nu1+2nu2(0)+nu3 transition in CO2 gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of approximately 1.6 x 10(-4). 相似文献
10.