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Bin Du Adam Langlois Daniel Fortin Christine Stern Pierre D. Harvey 《Journal of Cluster Science》2012,23(3):737-751
The title cluster is luminescent at 77?K and exhibits an unsaturated site for binding anions when the counter ion is PF6 ?. A series of five non-luminescent metalloporphyrins exhibiting carboxylate anchoring groups were synthesized and characterized. These are the sodium salts of the 5-carboxyphenyl-tri-10,15,20-tolyl-, trans-di-5,10-carboxyphenyl-di-15,20-tolyl-, and tetra-5,10,15,20-carboxyphenyl(metallo)porphyrin (metallo?=?chloroiron(III), nickel(II)) anions. Evidence for supramolecular assemblies between the carboxylates and the cluster is provided by 31P NMR and UV?Cvis spectroscopy. The binding constant, K1n, extracted from the UV?Cvis data via Benesi-Hildebrand, Scott and Scatchard plots are approximately 21,000?±?5,000?M?1 for the nickel(II) species, in agreement with the previously reported zinc(II) ones (K11?=?20,000?±?2,000?M?1), but those for the chloroiron(III) are measured to be lower (12,500?±?3,500?M?1). This association is accompanied by a complete quenching of the luminescence of the cluster which can only be due to an efficient energy transfer to the d?Cd states of the chloroiron(III) and nickel(II) species but an electron transfer from the nickel(II)-containing chromophore to the cluster is also possible. This work demonstrates the profound effect that supramolecular interactions may have on the photophysical properties despite the long donor?Cacceptor separation. 相似文献
295.
MaxwellD. Cummings Jimmy Lindberg Tse‐I Lin Herman deKock Oliver Lenz Elisabet Lilja Sara Fellnder Vera Baraznenok Susanne Nystrm Magnus Nilsson Lotta Vrang Michael Edlund sa Rosenquist Bertil Samuelsson Pierre Raboisson Kenneth Simmen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2010,122(9):1552-1552
296.
The nonlinear bulk compressibility of entangled multiwalled carbon nanotubes is studied. The analogy with textile fibre assemblies is explored by means of the well established van Wyk model. In view of the small diameter of the nanotubes, the possible effect of adhesive van der Waals interactions at tube-tube contacts is analysed. It is found, however, that the contribution of adhesive contacts to the bulk stress should be negligible. Compression experiments are performed on multi-walled carbon nanotubes and show that van Wyk's model is able to describe the response, although the values of the dimensionless parameter k of van Wyk's model were lower than expected. There is indeed no indication that van der Waals interactions play any significant role. 相似文献
297.
Noe Oña Antonio Romero Carmen Assiego Claudia Bello Pierre Vogel M. Soledad Pino-González 《Tetrahedron: Asymmetry》2010,21(17):2092-2099
An approach to the synthesis of polyhydroxyazepane derivatives from sugar-based epoxyamides or epoxyalcohols, in which the total regioselective epoxide opening by nitrogen nucleophiles is the key step, is described. Thus, novel polyhydroxyazepane carboxamides and aminomethyl polyhydroxyazepanes, with potential pharmacological interest, are synthesized from diacetone d-mannose. Configurational assignments of the obtained products were determined. 相似文献
298.
Clément Barrière Virginie Latour Pierre Fau Anne-Marie Caminade Cédric-Olivier Turrin 《Tetrahedron letters》2012,53(15):1908-1911
We present a simple strategy to obtain non-symmetrical polyethylene glycols equipped with telechelic phosphorus-containing dendrimeric moieties having adhesive phosphonate surface functions. The dendronized PEG tails were characterized by means of multi-nucleus NMR. The grafting abilities of model symmetrical PEG compounds equipped with telechelic amino-bis(methylene-dimethylphosphonates) and amino-bis(methylenephosphonic acids) were rapidly screened on plasma treated silicon wafers and activated silica. 相似文献
299.
Insertion Reactions of Neutral Phosphidozirconocene Complexes as a Convenient Entry into Frustrated Lewis Pair Territory 下载免费PDF全文
Dr. Adrien T. Normand Dr. Gerald Kehr Prof. Pierre Le Gendre Prof. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):4285-4293
Neutral phosphidozirconocene complexes [Cp2Zr(PR2)Me] (Cp=cyclopentadienyl; 1a : R=cyclohexyl (Cy); 1b : R=mesityl (Mes); 1c : R=tBu) undergo insertion into the Zr?P bond by non‐enolisable carbonyl building blocks (O=CR′R′′), such as benzophenone, aldehydes, paraformaldehyde or CO2, to give [Cp2Zr(OCR′R′′PR2)Me] ( 3 – 7 ). Depending on the steric bulk around P, complexes 3 – 7 react with B(C6F5)3 to give O‐bridged cationic zirconocene dimers that display typical frustrated Lewis pair (FLP)/ambiphilic ligand behaviour. Thus, the reaction of {[Cp2Zr(μ‐OCHPhPCy2)][MeB(C6F5)3]}2 ( 10a ) with chalcone results in 1,4 addition of the Zr+/P FLP, whereas the reaction of {[Cp2Zr(μ‐OCHFcPCy2)][MeB(C6F5)3]}2 ( 11a ; Fc=(C5H4)CpFe) with [Pd(η3‐C3H5)Cl]2 yields the unique Zr?Fe?Pd trimetallic complex 13a , which has been characterised by XRD analysis. 相似文献
300.
Although the synthetic potential of the intramolecular variant of the Diels-Alder reaction has now been fully recognized3, little attention has so far been paid to this type of addition using the furan nucleus as the diene partner4–8. The presence of an oxygenated cyclohexene system in several complex natural products (e.g. gibberellic acid, morphine), the diverse possibilities of the substituted 7-oxabicyclo |2.2.1|-2-heptene system for further transformation9, the expected enhanced reactivity and stereoselectivity of the intramolecular cycloaddition and the availability of a wide variety of commercial furan derivatives make the sequence a → b → c particularly attractive in total synthesis. 相似文献