Polyazaacenes – On the Way to Stable, Fluorescent and Redox‐Active Derivatives

Abstract

A new synthetic method for the preparation of polyazaacenes is described starting from two different nucleophilic building blocks. Disubstituted oxalic amidines 1 can be cyclized under mild conditions with 2,3-dichloro-5,6-dicyanopyrazine (3) to yield 5,6-dihydropyrazino[2,3-b]pyrazines 4a-c. By employing higher temperatures and 2 equiv. of 3, octaazanaphthacene 6 can be isolated. Similarly, pyrazino [2,3-b]pyrazines 2 and bielectrophile 3 yielded novel dodecaazahexacenes 8 in addition to semicyclized derivative 9. When tetraazafulva-

Diaquabis(propane-1,3-diamine)nickel(II) bis(propane-1,3-diamine)disulfatonickelate(II)

“…1. Ni atoms in complex cations and anions display a slightly distorted octahedral coordination, being linked to four N atoms of two 1,3-propane-diamine ligands and two O atoms of two water molecules of complex cation or two sulfo-groups of complex anion.Three types of hydrogen-bond interactions between O atoms of the sulfogroups and H atoms of the water molecules aswell as NH 2 groups of the 1,3-diaminopropane ligand are presented ofFig 2.The bond distances and angles in the title molecule agree well with the corresponding bond distances and angles reported in closely related compounds(Clegg et al, (1992);Nowicka et al, (2002);Kim & Lee, (2002);Fritsky et al, (2004);Stockner et al, (2007)). …”

“…For the structures of related complexes, see: Clegg et al (1992); Kim & Lee (2002); Fritsky et al (2004); Nowicka et al (2002); Stockner et al (2007); Duesler & Raymond (1978); Jurnak & Raymond (1974); Solans et al (1982).…”

Phenanthroline‐Fused Pyrazinacenes: One‐Pot Synthesis, Tautomerization and a RuII(2,2′‐bpy)2 Derivative

“…These properties include their more usually cited molecular electronic applications as n‐ or p‐type semiconductors . Pyrazinacenes are a specific type of heteroacene containing linearly‐fused 1,4‐pyrazine units exemplified in work by Stöckner and co‐workers who prepared pyrazinacenes containing up to six linearly‐fused pyrazine groups . Other examples containing different multiplicities have also been prepared often incorporated in CH‐acene derivatives .…”

Stable and Easily Accessible Functional Dyes: Dihydrotetraazaanthracenes as Versatile Precursors for Higher Acenes

“…The substitution at the amino group causes a “frozen” dihydro form and, consequently, prevents oxidation by air. There are examples that such dihydro derivatives show much higher stabilities18 and intense fluorescence7c, 10a compared with the fully aromatic species. The simple introduction of substituents enabled us to synthesise a multitude of different dihydroazaanthracenes.…”