Ribbon‐Type Boron‐Doped Polycyclic Aromatic Hydrocarbons: Conformations, Dynamic Complexation and Electronic Properties

Abstract

Molecular ribbons (MRs), one-dimentional topological polycyclic aromatic hydrocarbons (PAHs), are of importance for synthetic chemistry and material sciences. Herein, we disclose an effective strategy to develop boron-doped MRs, i.e. photochemical cyclization on conjugated organoboranes for rapid π-extension. A series of ribbon-type boron-doped PAHs that own multiple cove edges were synthesized using Mallory photoreaction in solution. Two of them feature isomeric C 68 B 2 π-skeletons with 2.2 nm in length, thus representing a new kind of boron-doped MRs. The boron atoms endow them with sufficient Lewis acidity, and notably, the formed Lewis acid-base adducts based on borondoped MRs display the photo-induced dual-dissociation behavior in the excited state and thus photochromism property. Moreover, despite of the highly contorted topological conformations, their potential utility as organic semiconductor was demonstrated by fabrication of organic field-effect transistors.

Aggregation-Induced Emission of Contorted Polycondensed Aromatic Hydrocarbons Made by Edge Extension Using a Palladium-Catalyzed Cyclopentannulation Reaction

“…Contorted polycyclic aromatic hydrocarbons (PAHs) are conjugated compounds whose out-of-plane geometry is mostly caused by an intramolecular steric congestion. , PAHs bearing cyclopentadienide units, which can be considered as cross-sectional units of fullerenes, disclose prominent optoelectronic − properties and, consequently, are employed in organic field-effect transistors (OFETs), organic light emitting diodes (OLEDs), and organic photovoltaics (OPVs). , Thus, there is a growing interest in exploring versatile and efficient synthetic strategies to make new contorted PAH structures and explore their chemical and physical properties . Among others, palladium- and nickel-catalyzed cross-coupling reactions, notably, Heck, Negishi, Suzuki–Miyaura, and Sonogashira, , are widely utilized in the synthesis of PAHs. − In addition, cycloaddition reactions have traditionally been used in the synthesis of large PAHs, namely, Diels–Alder reaction, which proved to be a versatile synthetic approach to make large aromatic compounds .…”