Synthesis and Properties of Cross‐Shaped Donor–Acceptor Dyes: Tunable Emission From Visible to Near‐Infrared in Solution and Solid‐State

This article reports the synthesis and characterization of cross‐conjugated donor–acceptor dyes based on a N , N , N ’, N ’‐tetraphenyl‐1,4‐phenylenediamine core, substituted at the 2,5‐positions with various electron‐withdrawing groups (carbonyl, imines, nitriles, or electron‐poor heterocycles). Electrochemical studies reveal electronic communication between para ‐substituted donor groups and, in some cases, between acceptor groups. Photophysical studies show tunable absorption and emission properties based on the strength of the electron‐withdrawing groups, a trend that is rationalized through computational analysis. Notably, some compounds exhibit long emission lifetimes in solution, whereas all dyes emit in the solid state, with emission extending into the near‐infrared (up to > 1000 nm).