Sharp Turns and Fluorescent Repeats: Modular Construction and Shape‐Dependent Electronic Properties of π‐Conjugated Chain Molecules

In search of the design rules for structural ordering of open‐chain molecules, we have built a series of zig‐zag shaped π‐conjugated structures with ring‐fused heteroaromatics as sharp turns and tolane‐based linear fragments as light‐emitting units. Using only a finite number of common building blocks, an efficient “double‐elongation” strategy was implemented to construct a series of π‐conjugated oligomers with precise length control (55–89 % yields). Our approach takes advantage of the modular nature of the bis(triazolo)benzene synthesis and the masked reactivity of the nitro group. A combination of photophysical and DFT computational studies revealed that the bis(triazolo)benzene–tolane repeat units behave as electronically decoupled light‐absorbing/emitting units (λmax,em = 408–422 nm; ΦF = 20–25 % in THF). Such context‐independent photophysical properties promise their potential applications in chemical sensing and switching. Electronically conjugated yet photophysically disjointed: A new chain elongation strategy was devised to construct zigzag‐shaped oligomers, in which sharp turn motifs and fluorescent fragments are placed in alternating patterns. Despite sharing a rigid π‐conjugated backbone, each repeat unit maintains its inherent energy window to display context‐independent light‐absorbing and emitting properties.