Synthesis and spectral properties of mixed binuclear complexes derived from the ion pentacyano(4,4′-bipyridine)ferrate(II)

New complex analogous to Prussian Blue were synthesized both in solid phase and in aqueous solution by mixing the sodium salt of pentacyano(4,4-bipyridine)-ferrate(II) with Cu(II) and Fe(III) salts. Infrared and visible spectral data of these compounds indicate formation of a polymeric structure involving a cyanide bridge that connects the two metallic centers. Preference of cyanide over 4,4-bipyridine bridging can be explained on the basis of its greater basicity when coordinated to a pentacyanoferrate(II) moiety.Members of the Carrera del Investigador Científico, Conicet, Argentina.     

Synthesis of backbone modified cyclic peptides bearing dipicolylamino sidearms

Three analogues of the Lissoclinum class of cyclic peptides, bearing dipicolylamino functionalised side chains, have been synthesised using a stepwise approach followed by macrocyclisation. Attempts to incorporate dipicolylamino functionalised side chains prior to peptide synthesis resulted in epimerisation, but this was overcome by functionalising the ornithine side chains with dipicolylamino groups after the macrocyclisation reaction.     

Existence of global weak solutions for a viscous 2D bilayer Shallow Water model

We consider a system composed by two immiscible fluids in two-dimensional space that can be modelized by a bilayer Shallow Water equations with extra friction terms and capillary effects. We give an existence theorem of global weak solutions in a periodic domain.     

Multibeam second-harmonic generation by spatiotemporal shaping of femtosecond pulses

We present a technique for efficient generation of the second-harmonic signal at several points of a nonlinear crystal simultaneously. Multispot operation is performed by using a diffractive optical element that splits the near-infrared light of a mode-locked Ti:sapphire laser into an arbitrary array of beams that are transformed into an array of foci at the nonlinear crystal. We show that, for pulse temporal durations under 100 fs, spatiotemporal shaping of the pulse is mandatory to overcome chromatic dispersion effects that spread both in space and time the foci showing a reduced peak intensity that prevents nonlinear phenomena. We experimentally demonstrate arbitrary irradiance patterns for the second-harmonic signal consisting of more than 100 spots with a multipass amplifier delivering 28 fs, 0.8 mJ pulses at 1 kHz repetition rate.