Synthesis of a NIR-Absorbing Bis(1,1,4,4-tetracyanobuta-1,3-diene) Derivative via the [2 + 2] Cycloaddition–Retroelectrocyclization Click Reaction of 1,1,2,2-Tetracyanoethene and Alkynylated Dibenzochrysene

We report a study on the [2 + 2] cycloaddition between 1,1,2,2-tetracyanoethene (TCNE) and a 2,9-bis(alkynylated)dibenzo[b,def]chrysene derivative functionalized with diphenylamine electron-donating groups. The resulting bis(1,1,4,4-tetracyanobuta-1,3-diene) (TCBD) derivative exhibits a noticeably reduced optical band gap of 1.43 eV and displays broad absorption extending into the near-infrared (NIR) region, up to 900 nm. Protonation and both electrochemical and chemical oxidation of the diphenylamine units induce NIR absorption bands, highlighting the molecule's potential for optoelectronic applications.