Phosphole-containing π-systems have emerged as building blocks with enormous potential as electronic materials because of the tunability of the phosphorus center. Among these, asymmetric P-bridged trans-stilbenes are still rare, and here an elegant and efficient synthesis toward such fluorescent molecular frameworks is described. Fine-tuning of the photophysical properties is attempted by enforcing the planarization of the phosphorus tripod and thus increasing the interaction between the phosphorus lone pair and the π-system. The electronic structure of the π-conjugated frameworks is analyzed with NMR, UV-vis and fluorescence spectroscopy, and time-dependent density functional theory (TD-DFT) calculations.

Novel bis(azidophenyl)phosphole sulfide building block 8 has been developed to give access to a plethora of phosphole‐containing π‐conjugated systems in a simple synthetic step. This was explored for the reaction of the two azido moieties with phenyl‐, pyridyl‐ and thienylacetylenes, to give bis(aryltriazolyl)‐extended π‐systems, having either the phosphole sulfide (9) or the phosphole (10) group as central ring. These conjugated frameworks exhibit intriguing photophysical and electrochemical properties that vary with the nature of the aromatic end‐group. The λ3‐phospholes 10 display blue fluorescence (λem = 460–469 nm) with high quantum yield (ΦF = 0.134–0.309). The radical anion of pyridyl‐substituted phosphole sulfide 9b was observed with UV/Vis spectroscopy. TDDFT calculations on the extended π‐systems showed some variation in the shape of the HOMOs, which was found to have an effect on the extent of charge transfer, depending on the aromatic end‐group. Some fine‐tuning of the emission maxima was observed, albeit subtle, showing a decrease in conjugation in the order thienyl < phenyl < pyridyl. These results show that variations in the distal ends of such π‐systems have a subtle but significant effect on photophysical properties.

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