Internally 1,3-phenylene- and 2,5-thienylene-bridged decaphyrins 2 and 3 have been synthesized. While 2 shows modest aromatic character derived from the global 46π-conjugated circuit, 3 displays larger aromatic character owing to the contribution of an (annuleno)annulene-type network consisting of two twisted Möbius aromatic thiahexaphyrin segments in addition to the global 46π-network. Upon protonation, these decaphyrins underwent large structural changes to acquire strong aromaticity. Protonated 3 has been revealed to take on a planar structure composed of fused two triangular thiahexaphyrin segments.
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