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A systematic study of the synthesis and properties of 1‐aza‐, 4‐aza‐, and 1,4‐diaza[4]helicenes as well as the previously unknown S‐shaped double 1,4‐diaza[4]helicenes has been reported. The synthetic route to the aza‐ and diaza[4]helicenes involved an electrophile‐induced cyclization of 3(2)‐alkynyl‐2(3)‐(naphthalen‐1‐yl)azines (i.e., quinoxaline, pyrazine, pyridine), which were prepared in two steps from the commercially available ortho‐dihalo‐substituted azine. Trifluoroacetic acid (TFA) and ICl were used as electrophiles. The ICl‐promoted cyclization provided the 5‐iodo derivatives of the aza‐ and diaza[4]helicenes in yields of 47–71 %. The use of TFA as the electrophile afforded the helicenes along with isomeric products from an alternative cyclization and subsequent 1,2‐shift of the C–C bond (e.g., naphtho[2,1‐f]quinoxalines or naphtho[2,1‐a]phenazines, 87–89 % total yield, 1.5–1.8:1 ratio). The presence of an iodine substituent in the hetero[4]helicenes allowed for the introduction of an alkynyl group by using a Sonogashira reaction. The subsequent cycloizomerization upon treatment with TFA gave the S‐shaped double 1,4‐diaza[4]helicenes. The molecular structures and crystal packing of the synthesized hetero[4]helicenes relative to those of [4]carbohelicene have been discussed.

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A new family of arylene‐ethynylene oligomers consisting of two, three and four “proton sponge” fragments (1,8‐bis(dimethylamino)naphthalene or DMAN) alternating with C≡C bonds were synthesized using various 2‐ and 4‐ethynyl and 2‐ and 4‐iodo derivatives of DMAN as synthetic building blocks in the Sonogashira coupling. X‐ray structural, photophysical, chemical and electrochemical properties showed that the oligomers are promising candidates to construct materials with varied rigidity (tuned by protonation), electron conductivity (tuned by mode of linkage), and proton conductivity (equilibration of protonated and free DMAN subunits).

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