Fig. 1. (a) Representative curved π-systems. (b) The resonance structures of π-extended stable wave-shaped PHs 1 and 2 reported in this work (p-QDM and m-QDM units are highlighted in red color; the flanked indeno[1,2-b]fluorene (IF1) and indeno[2,1-b]fluorene (IF2) in 1 and 2 are highlighted in blue color). The substituents are omitted in the resonance structures for clarity and the benzene rings in cyan color denote Clar's aromatic sextet rings.
