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 properties, its use in polymer chemistry has only been realized quite recently. Herein, we present a comprehensive study of oligo- and poly(arylene iminoborane)s comprising a backbone of phenylene or thiophene 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. Our modular synthetic approach allowed us to prepare four polymers and 12 monodisperse oligomers with modulated electronic properties. Alternating electron-releasing diaminoarylene and electron-accepting diborylarylene building blocks gave rise to a pronounced donor-acceptor character. Effective pi-conjugation over the arylene iminoborane backbone is evidenced by systematic bathochromic shifts of the low-energy UV-vis absorption maximum with increasing chain length, which is furthermore supported by crystallographic and computational investigations. Furthermore, 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 backbone. Polymers, copolymers, and oligomers from combinations of backbone-BN-doped poly(p-phenylene vinylene) (PPV) and poly(thiophene vinylene) (PTV) with tailored properties have been prepared by a modular approach. The pi-conjugated donor-acceptor-type backbone structure gives rise to efficient solid-state emission and aggregation-induced emission (AIE) behavior.+image

Automated summary

This study focuses on oligo- and poly(arylene iminoborane)s with a backbone of phenylene or thiophene moieties linked via B=N units. The researchers successfully prepared various polymers and oligomers with tailored electronic properties using a modular synthetic approach. The compounds exhibited effective pi-conjugation, solid-state emission, and aggregation-induced emission behavior.