Synthesis, Physical Properties, and Anion Recognition of Two Novel Larger Azaacenes: Benzannelated Hexazaheptacene and Benzannelated N , N ′‐Dihydrohexazaheptacene

Two novel larger azaacenes with six or ten N atoms in their backbones, benzannelated 9,11,13,22,24,26‐hexazatetrabenzo[a,c,l,n]heptacene ( HATBH , 1 ) and benzannelated 9,26‐dihydro‐9,11,13,22,24,26‐hexaza‐tetrapyrido[3,2‐a: 2′,3′‐c: 3′′,2′′‐l: 2′′′,3′′′‐n]heptacene ( DHATPH, 2 ), have been successfully synthesized in two steps. The theoretical band gaps estimated through DFT calculations for HATBH ( 1 ) and DHATPH ( 2 ) are 1.949 eV and 2.278 eV, which are close to the experimentally obtained optical band gaps (2.14 eV and 2.39 eV). Interestingly, HATBH ( 1 ) can act as efficient anion sensor for F − and H 2 PO 4 − , while DHATPH ( 2 ) selectively responds to F − among the ten different anions used (F − , Cl − , Br − , I − , PF 6 − , HSO 4 − , NO 3 − , BF 4 − , AcO − , and H 2 PO 4 − ). Our synthetic strategy could offer a promising and easy way to obtain even larger azaacenes.