(Aza)Acenes Share the C2 Bridge with (Anti)Aromatic Macrocycles: Local vs. Global Delocalization Paths.

A strong conjugation present in fused systems plays a crucial role in tuning of the properties that would be showing a dependence on the efficiency of π-electrons coupling. The π-cloud available in the final structure can be drastically influenced by a side- or a linear fusion of unsaturated and conjugated hydrocarbons. The linear welding of naphthalene/anthracene or quinoxaline/benzo[g]quinoxaline with triphyrin(2.1.1) gives structures where the competition between local and global delocalization is distinguished. The aromatic character observed in skeletons strongly depends on the oxidation state of the macrocyclic flanking and is either extended over the whole system or kept as a composition of local currents (diatropic and paratropic) of incorporated units. The hybrid systems show the properties derived from the π-conjugations that interlace one another but also show a significant independence of (aza)acene subunits reflected in the observed spectroscopic properties.