Palladium(0)‐Catalyzed Synthesis of Cross‐Conjugated Polymers: Transformation into Linear‐Conjugated Polymers through the Diels–Alder Reaction

Abstract

Das Spiel mit der Konjugation: Die Titelreaktion eines propargylischen Bis(carbonats) mit Dibor‐Verbindungen führt zu neuen kreuzkonjugierten Polymeren 1 mit 2,3‐Butadienylen‐Einheiten, die durch eine Diels‐Alder‐Reaktion in die linear konjugierten Polymere 2 umgewandelt werden können. Die cis‐verknüpften Polymere 2 zeigen in ihren Fluoreszenzspektren deutlich stärkere Stokes‐Verschiebungen als die kreuzkonjugierten Vorstufen 1.

Palladium-Catalyzed Cross-Coupling Polymerization: A New Access to Cross-Conjugated Polymers with Modifiable Structure and Tunable Optical/Conductive Properties

“…10 However, in contrast to widely investigated conjugated polymers, 11,12 the synthetic methods for cross-conjugated polymers, where the π-electron delocalization cannot extend along their backbones in accord with the classical resonance theory, 13 have been less reported (Scheme 1). 10,14−18 Swager et al 10 and the Koizumi group 14 synthesized CCPs with vicinal vinylidenes via Ti-and Pd-catalyzed processes, respectively. The Tilley 15 group prepared polyphenylenevinylidenes via the Zr-mediated process.…”

“…Furthermore, the introduction of vinylidenes into the main chain could facilitate postprocessing with a variety of methods, leading to various functional materials. 10,14 Herein, we report the first synthesis of a new series of CCPs via the Pd-catalyzed cross-coupling polymerization of N-tosylhydrazones and aryl halides, which provides polymers with well-defined structures, good processability, and thermal stability at good to excellent yields. Additionally, investigations on three different aspects including postmodification as well as optical and conductive properties have been conducted to demonstrate the interesting/unique characteristics of these CCP materials.…”