Poly(arylene iminoborane)s, Analogues of Poly(arylene vinylene) with a BN-Doped Backbone: A Comprehensive Study.

Despite the great success of the concept of doping organic compounds with BN units to access new materials with tailored prop-erties, its use in polymer chemistry has only been realized quite re-cently. Herein, we present a comprehensive study of oligo- and poly-(arylene iminoborane)s comprising a back-bone of phenylene or thio-phene moieties, as well as combinations thereof, linked via B=N units. The novel polymers can be regarded as BN analogues of poly-(p-phenylene vinylene) (PPV) or poly(thiophene vinylene) (PTV) or their copolymers, respectively. Our modular syn-thetic approach al-lowed us to prepare four polymers and twelve monodisperse oligo-mers with modulated electronic properties. Alter-nating electron-re-leasing di-aminoarylene and electron-accepting dibo-rylarylene building blocks give rise to a pronounced donor-acceptor character. Effective π-con-ju-ga-tion over the arylene iminoborane back-bone is evidenced by sys-tematic bathochromic shifts of the low-energy UV-vis absorp-tion max-imum with increasing chain length, which is furthermore sup-ported by crystallographic and compu-tational investigations. Further-more, all compounds investigated show emission of visible light in the solid state and aggregation-induced emission (AIE) behavior, due to the presence of partially flexible linear B=N linkages in the back-bone.