Blue Emission of a Soluble Poly(p‐phenylene) with a Cross‐Conjugated Bisimidazole‐Based Chromophore

Abstract

A novel poly(p‐phenylene) (6) has been synthesized by a cruciform combination of a polyphenylene backbone with 2,2′‐(p‐phenylene)‐bis(4,5‐diphenylimidazole) (5) as an additional, orthogonal chromophore. Polymer 6 showed in solution and in the solid state, a blue‐green emission, which is obviously arising from the second bisimidazole‐based chromophore. UV‐Vis spectroscopy, and cyclic voltammetry revealed that the optical and electronic properties of 6 were fully determined by the incorporated 2,2′‐(1,4‐phenylene)bisimidazole structure. The bisimidazole unit led to high solubility and, despite the steric demand of the substituents, at the same time to the blue‐green emission of the poly(p‐phenylene) (6). In addition, the oxidation of 6 with potassium ferricyanide yielded a low bandgap polymer with a quinoid‐type structure and a bandgap of 1.6 eV.magnified image

Polyphenylene‐Based Materials: Control of the Electronic Function by Molecular and Supramolecular Complexity

“…[21][22][23] Linear polyphenylenes are generally considered as rod-like materials, and unsubstituted derivatives represent nonsoluble polymers with limited processability. However, their processability is dramatically improved by introducing solubilizing groups onto the main chain [24] leading to a torsion of the polymer backbone. In addition, methine bridges, as in polyfluorenes [25,26] , block the rotation between the monomer units, thus leading to improved solubilities.…”

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

“…A similar synthetic strategy is used for the construction of diimidazole-type push–pull systems bearing two imidazole rings, which serve as donor and acceptor moieties [ 16 – 19 ]. A sequential construction of the chromophore backbone by modern cross-coupling reactions represents another synthetic approach used for the synthesis of superior diimidazole chromophores [ 20 ].…”

Bismuth(III)--SiO$_{2}$ catalyzed synthesis of polysubstituted imidazoles with the participation of azaaryl derivatives of aniline in four-component reactions

“…Tetrasubstituted imidazole scaffold is an essential part of numerous bioactive compounds, 1−6 conjugated and fluorescent materials, 7,8 and metal-coordinating ligands. 9,10 Condensation of 1,2-diketones, aryl aldehydes, primary amines, and ammonium acetate is one of the most common synthetic tools for the preparation of 1,2,4,5-tetrasubstituted imidazoles.…”