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 the optical properties of conjugated polymers primarily focus on modifications of the polymer backbone, including donor–acceptor engineering and adjusting the 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 (Δλ_max = 47 nm for PCT-8 and PBT-7), optical band gaps (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.