Ring‐opening metathesis polymerization‐Derived Organoborane Polymers as Strong Lewis Acids and Luminescent Materials

Decoration of polymers with Lewis acidic borane moieties is attractive as it enables the development of functional materials for use as powerful supported catalysts, chemical sensors, and building blocks of novel supramolecular materials. The dynamic nature of Lewis acid‐base interactions is of central importance in these application fields. However, methods to access well‐defined polymeric Lewis acids with tunable Lewis acid characteristics remain very limited. In this article, a flexible route to a family of norbornene‐functionalized triarylboranes is reported, which can be polymerized under mild conditions using ring‐opening metathesis polymerization to yield borane Lewis acid‐functionalized homo‐ and copolymers. By varying the aryl substituents about the boron center, steric and electronic tuning of the Lewis acid moieties is achieved. The latter allows for the rational design of polymers with tunable Lewis acid strength, approaching that of the widely utilized molecular Lewis acid B(C 6 F 5 ) 3 , enhanced air‐stability, and desirable luminescent characteristics. The complexation behavior, stability, and photophysical properties of the new monomers and borane polymers are investigated in depth.