π‐Conjugated Indole Dyads with Strong Blue Emission Made Possible by Stille Cross‐Coupling and Double Fischer Indole Cyclisation

Abstract

Small fluorescent π‐conjugated indolyl‐based molecules 4–6, 23 are prepared through direct Fischer synthesis or/and Stille cross‐coupling method in appreciable yields. Our synthetic results have shown the benefits using Stille approach when Fischer double cyclisation method to access the bisindole dyads 4–6, 23 is not efficient. The synthetic routes to these materials have been designed to investigate the substrate requirements for the respective cyclisation and CC‐coupling reactions and to evaluate their wider synthetic applicability. Comparative analysis of the different substituents and the different π‐bridging units e. g. pyridine, thiophene and thiazole on the electronic and photophysical properties of the final compounds 4–6, 23 has been carried out. The structure−property relationship of the final bisindole dyads has been investigated via photophysical characterisation, and computational modelling. The obtained compounds absorb near‐UV and visible (blue) light, with the spectral range dependent on the nature of the π‐bridging units, and are capable of bright blue emission.

Synthesis, characterization, and electrogenerated chemiluminescence of deep blue emitting eumelanin‐inspired poly(indoylenearylene)s for polymer light emitting diodes

“…Although the indole group has been used in several blue emitting materials, to our knowledge there are no examples showing utilization of the indole moiety through its 4‐ and 7‐positions in the blue emitting copolymers. Our approach was to synthesize deep blue emitting copolymers by incorporating an Eumelanin inspired indole core through the 4‐ and 7‐positions with fluorene and carbazole units.…”

“…[26][27][28][29][30] To further determine the structure-property relationships of this biomolecule, we previously synthesized an eumelanininspired indole core similar to the building blocks found in natural eumelanin. 31 Although the indole group has been used in several blue emitting materials, [32][33][34][35][36] to our knowledge there are no examples showing utilization of the indole moiety through its 4and 7-positions in the blue emitting copolymers. Our approach was to synthesize deep blue emitting copolymers Additional Supporting Information may be found in the online version of this article.…”