The introduction of alkynyl groups into the 2,3-positions of developing NIR chromophores. The electron absorption properties of differentially N,NЈ-disubstituted dialkynyl the 1,4-diazabuta-1,3-diene (DAD) backbone succeeds along two complementary synthetic routes either by condensing DADs gave no indication for a push-pull effect across the DAD skeleton and suggest the ynimine moiety as the active triisopropylsilyl-terminated dialkynyl-1,2-diones with primary aromatic amines or by a palladium-mediated chromophore of dialkynyl DADs. The electrochemical properties of the title compounds were determined by cyclo-alkynylation of bis(imidoyl chlorides). X-ray crystallographic analyses of two dialkynyl DAD derivatives reveals their and steady state voltammetry and show that introducing alkynyl groups leads to more easily reducible DAD systems. planar (E-s-trans-E) conformations in the solid state. However, the central CC bond of both DAD backbones Again, the perception of dialkynyl DADs as covalently linked, but electronically decoupled ynimine units is investigated has a length of 1.491(2) A ˚, and is therefore too long to indicate efficient delocalization across the DAD core.
corroborated by the redox potential of a differentially N,NЈdisubstituted dialkynyl DAD. Similar conclusions were The UV/Vis spectra of dialkynyl DADs demonstrate that their absorptions in comparison to those of non-alkynyl DADs are drawn from semiempirical MO (PM3) calculations of dialkynyl DADs. bathochromically shifted by more than 40 nm, thereby demonstrating the suitability of the title compounds for chromophores, [5] has led us to consider expanding this units to assemble several metal binding sites within one mo-