Modification of Electron Acceptors with Fused Alicyclic Rings through Inverse Electron-Demand Diels-Alder Reactions to Tune the Optical Properties of Conjugated Polymers

Abstract

Traditional strategies for manipulating optical properties of conjugated polymers primarily focus on modifications to the polymer backbone, including donor-acceptor engineering and adjustments to conjugation length. Here, we report a novel approach to modulate the electronic structure of conjugated polymers by incorporating alicyclic rings through inverse electron-demand Diels-Alder reactions. Two conjugated polymers, PCT-8 and PBT-7, were synthesized using monomers with an eight-membered and a bridged six-membered aliphatic ring, respectively. These structural modifications lead to noticeable changes in UV-visible absorption (Δλmax = 47 nm for PCT-8 and PBT-7), optical band gap (2.38 eV and 2.19 eV, PCT-8 and PBT-7, respectively), polymer packing, and intermolecular interactions, while maintaining the integrity of the polymer backbone. Besides, both polymers demonstrate electrochromic properties. This strategy offers a versatile, minimally invasive method for tuning the optical properties of conjugated polymers, paving the way for the design of multifunctional materials for optoelectronic applications.