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The activation of N2, CO2 or H2O to energy-rich products relies on multi-electron transfer reactions, and consequently it seems desirable to understand the basics of light-driven accumulation of multiple redox equivalents. Most of the previously reported molecular acceptors merely allow the storage of up to two electrons. We report on a terphenyl compound including two disulfide bridges, which undergoes four-electron reduction in two separate electrochemical steps, aided by a combination of potential compression and inversion. Under visible-light irradiation using the organic super-electron donor tetrakis(dimethylamino)ethylene, a cascade of light-induced reaction steps is observed, leading to the cleavage of both disulfide bonds. Whereas one of them undergoes extrusion of sulfur to result in a thiophene, the other disulfide is converted to a dithiolate. These insights seem relevant to enhance the current fundamental understanding of photochemical energy storage.  相似文献   
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In the present work, the two‐dimensional (2D) polymer poly[[μ4‐2‐(4‐nitrobenzenesulfonamido)benzoato‐κ4O1:O1:O1′:N6]silver(I)] (AgL), [Ag(C13H9N2O6S)]n, was obtained from 2‐(4‐nitrobenzenesulfonamido)benzoic acid (HL), C13H10N2O6S. FT–IR, 1H and 13C{1H} NMR spectroscopic analyses were used to characterize both compounds. The crystal structures of HL and AgL were determined by single‐crystal X‐ray diffraction. In the structure of HL, O—H…O hydrogen bonds between neighbouring molecules result in the formation of dimers, while the silver(I) complex shows polymerization associated with the O atoms of three distinct deprotonated ligands (L?). Thus, the structure of the Ag complex can be considered as a coordination polymer consisting of a one‐dimensional linear chain, constructed by carboxylate bridging groups, running parallel to the b axis. Neighbouring polymeric chains are further bridged by Ag—C monohapto contacts, resulting in a 2D framework. Fingerprint analysis of the Hirshfeld surfaces show that O…H/H…O hydrogen bonds are responsible for the most significant contacts in the crystal packing of HL and AgL, followed by the H…H and O…C/C…O interactions. The Ag…Ag, Ag…O/O…Ag and Ag…C/C…Ag interactions in the Hirshfeld surface represent 12.1% of the total interactions in the crystal packing. Studies of the interactions of the compounds with human serum albumin (HSA) indicated that both HL and AgL interact with HSA.  相似文献   
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Résumé Ce travail porte sur l'étude de solutions diluées d'un polymère de l'acide acrylique dans l'eau (concentration en poids 0,1%). Ce fluide présente des effets de seuil. La mesure du champ de vitesse par vélocimétrie laser permet une détermination précise de l'indice rhéologique,n, étant un paramètre essentiel de la loi de comportement proposée: . Les autres constantes peuvent être déduites d'essais rhéologiques classiques, à fort taux de cisaillement. Il est possible de corriger le gradient de pression mesuréP/L, afin d'obtenir la valeur véritable de ce gradient, notéedp/dz. L'analyse de l'écoulement dans un élargissement brusque montre que le seuil a une forte influence sur les zones de recirculation.
This work deals with the study of very dilute solutions of polyacrylic acid in water (weight concentration about 0.1%). These fluids seem to exhibit a yield effect. The determination of the fully developed velocity field by laser velocimetry allows us an accurate determination of the rheological indexn which is an essential parameter for the proposed rheological relationship: . Other constants can be determined from classical rheological experiments (high shear strain). It is possible to correct the experimental pressure gradientP/L so as to get the real value, noted asdp/dz. An analysis of the flow in an abrupt expansion shows that the yield effect strongly influences the recirculation zones.

D, d m diamètre intérieur d'une conduite cylindrique - C % concentration en poids - s Pa seuil de contrainte - K consistance - gradient de vitesse axiale - gradient pariétal de vitesse axiale - Pa s viscosité pour - Pa contrainte de cisaillement - m/s vitesse débitante - n indice de structure - dp/dz Pa/m gradient longitudinal de pression - z m abscisse longitudinale - u m/s vitesse axiale - écart entre le gradient de pression effectif et le gradient mesuré en Pa - P Pa différence de pression mesurée - L m distance entre 2 prises de pression - A Pa constante intervenant dans l'expression de - B 10–3 Pa s constante intervenant dans l'expression de  相似文献   
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