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Incorporating heteroatoms can effectively modulate the molecular optoelectronic properties. However, the fundamental understanding of BN doping effects in BN‐embedded polycyclic aromatic hydrocarbons (PAHs) is underexplored, lacking rational guidelines to modulate the electronic structures through BN units for advanced materials. Herein, a concise synthesis of novel B2N2‐perylenes with BN doped at the bay area is achieved to systematically explore the doping effect of BN position on the photophysical properties of PAHs. The shift of BN position in B2N2‐perylenes alters the π electron conjugation, aromaticity and molecular rigidness significantly, achieving substantially higher electron transition abilities than those with BN doped in the nodal plane. It is further clarified that BN position dominates the photophysical properties over BN orientation. The revealed guideline here may apply generally to novel BN‐PAHs, and aid the advancement of BN‐PAHs with highly‐emissive performance. [ABSTRACT FROM AUTHOR]

Replacement of CC unit with its isoelectronic BN unit in aromatics provides a new class of molecules with appealing properties, which have attracted great attention recently. In this Concept, we focus on BN-substituted polycyclic aromatics with fused structures, and review their synthesis, photophysical, and redox properties, as well as their applications in organic electronics. We also present challenging synthetic targets, large BN- substituted polycyclic aromatics, such as regioregular BN heterosuperbenzenes, which can be viewed as BN-doped nanographenes. Finally, we propose an atomically precise bottom-up synthesis of structurally well-defined BN-doped graphenes. [ABSTRACT FROM AUTHOR]

Two functional main-chain linear polyrotaxanes, one a covalent polymeric chain that threads through many macrocycles ( P1) and the other a poly[ n]rotaxane chain that is composed of many repeating rotaxane units ( P2), were synthesized by employing strong crown-ether/ammonium-based ( DB24C8/ DBA) host-guest interactions and click chemistry. Energy transfer between the wheel and axle units in both polyrotaxanes was used to provide insight into the conformational information of their resulting polyrotaxanes. Steady-state and time-resolved spectroscopy were performed to understand the conformation differences between polymers P1 and P2 in solution. Additional investigations by using dynamic/static light scattering and atomic force microscopy illustrated that polymer P1 was unbending and had a rigid rod-like structure, whilst polymer P2 was curved and flexible. This flexible topology facilitated the self-assembly of polymer P2 into relatively large ball-shaped particles. In addition, the energy transfer between the wheel and axle units was controlled by the addition of specific anions or base. The anion-induced energy enhancement was attributed to a change in electrostatic interactions between the polymer chains. The base-driven molecular shuttle broke the DB24C8/ DBA host-guest interactions. These results confirm that both intra- and intermolecular electrostatic interactions are crucial for modulating conformational topology, which determines the assembly of polyrotaxanes in solution. [ABSTRACT FROM AUTHOR]