Cylindrical solitons in shallow water of variable depth

Summary The propagation and the interaction of cylindrical solitons in shallow vater of variable depth are studied. Starting from the cylindrically symmetric version of the equations describing long waves in a beach, a Korteweg-de Vries equation type ψ_τ+6ψψ_ξ+ψ_ξξξ=−Γ(τ)ψ is derived. Since no exact analytical solution has been found to date for this equation, some remarkable cases in which the equation takes up a tractable form are analysed. Finally the interaction between cylindrical imploding and expanding waves is considered and the phase shifts caused by the head-on collision are given. This work was supported by CNR-GNFM.     

Straightforward access to enantioenriched pyrazyl alcohols using chiral organomagnesiates

The clean iodine-metal exchange of iodopyrazine and subsequent enantioselective addition of the intermediate pyrazyl magnesiate to aldehydes using ((R,R)-TADDOLate)Bu₂MgLi₂ is reported. New chiral pyrazylalcohols were obtained in enantiomeric excesses of up to 90%.     

Separation of diadenosine polyphosphates by capillary electrophoresis

The influence of buffer composition and pH on the electrophoretic behavior of diadenosine polyphosphates with a phosphate chain ranging from two to five phosphate groups has been examined. The electrophoretic mobility in carbonate buffer increases according to the number of phosphates, whereas in borate buffer the mobility changes in an irregular way as a function of pH. This finding can be rationalized by a well-known interaction of borate with ribose rings, which modifies the charge and the hydrodynamic radius of each diadenosine polyphosphate in a different way. Our study shows that the best separation of diadenosine polyphosphates can be achieved at the highest pH values of the range examined both in borate and carbonate buffers.     

Electronic Properties of Mono‐Substituted Tetraferrocenyl Porphyrins in Solution and on a Gold Surface: Assessment of the Influencing Factors for Photoelectrochemical Applications

Two unsymmetric meso‐tetraferrocenyl‐containing porphyrins of general formula Fc₃(FcCOR)Por (Fc=ferrocenyl, R=CH₃ or (CH₂)₅Br, Por=porphyrin) were prepared and characterized by a variety of spectroscopic methods, whereas their redox properties were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) approaches. The mixed‐valence [Fc₃(FcCOR)Por]ⁿ⁺ (n=1,3) were investigated using spectroelectrochemical as well as chemical oxidation methods and corroborated with density functional theory (DFT) calculations. Inter‐valence charge‐transfer (IVCT) transitions in [Fc₃(FcCOR)Por]⁺ were analyzed, and the resulting data matched closely previously reported complexes and were assigned as Robin–Day class II mixed‐valence compounds. Self‐assembled monolayers (SAMs) of a thioacetyl derivative (Fc₃(FcCO(CH₂)₅SCOCH₃)Por) were also prepared and characterized. Photoelectrochemical properties of SAMs in different electrolyte systems were investigated by electrochemical techniques and photocurrent generation experiments, showing that the choice of electrolyte is critical for efficiency of redox‐active SAMs.