Positional Effects of Electron-Deficient Heterocycles on the Emission and Aggregation Behavior of polycyclic-1,2-BN-heteroarenes
Disciplines
Materials Chemistry | Organic Chemistry | Physical Chemistry
Abstract (300 words maximum)
Incorporation of a boron–nitrogen (B–N) unit into polycyclic aromatic hydrocarbons generates azaborines, a versatile class of heteroarenes that combine strong absorption, high photochemical stability, and tunable emission. Among them, nitro-substituted polycyclic-1,2-BN-heteroarenes (PBNHs) have emerged as promising electron-deficient n-type frameworks for organic optoelectronic devices. However, the introduction of –NO₂ groups often promotes strong π–π stacking, which induces aggregation-caused quenching (ACQ) and severely compromises fluorescence efficiency. To overcome this limitation, we designed and synthesized a series of PBNHs incorporating electron-deficient heterocycles at distinct positions on the pyrrolidinone hemisphere. By systematically varying heterocycle placement and introducing sterically demanding substituents, we sought to distort molecular planarity, suppress intermolecular stacking, and induce aggregation-induced emission enhancement (AIEE). Comprehensive spectroscopic studies revealed that the positional orientation of electron-deficient heterocycles exerts a pronounced influence on photophysical behavior, modulating emission efficiency, spectral response, and aggregation tendencies. Several derivatives exhibited reduced ACQ, and in select cases, clear AIEE activity while preserving favorable absorption and stability. These findings demonstrate that positional control of electron-deficient heterocycles is a powerful strategy for tailoring the optical properties of BN-based chromophores. This design principle enables the development of next-generation electron-deficient AIE-active azaborine materials with significant potential in sensing, adaptive photonics, and optoelectronic applications.
Use of AI Disclaimer
no
Academic department under which the project should be listed
CSM – Chemistry and Biochemistry
Primary Investigator (PI) Name
Carl J. Saint-Louis
Positional Effects of Electron-Deficient Heterocycles on the Emission and Aggregation Behavior of polycyclic-1,2-BN-heteroarenes
Incorporation of a boron–nitrogen (B–N) unit into polycyclic aromatic hydrocarbons generates azaborines, a versatile class of heteroarenes that combine strong absorption, high photochemical stability, and tunable emission. Among them, nitro-substituted polycyclic-1,2-BN-heteroarenes (PBNHs) have emerged as promising electron-deficient n-type frameworks for organic optoelectronic devices. However, the introduction of –NO₂ groups often promotes strong π–π stacking, which induces aggregation-caused quenching (ACQ) and severely compromises fluorescence efficiency. To overcome this limitation, we designed and synthesized a series of PBNHs incorporating electron-deficient heterocycles at distinct positions on the pyrrolidinone hemisphere. By systematically varying heterocycle placement and introducing sterically demanding substituents, we sought to distort molecular planarity, suppress intermolecular stacking, and induce aggregation-induced emission enhancement (AIEE). Comprehensive spectroscopic studies revealed that the positional orientation of electron-deficient heterocycles exerts a pronounced influence on photophysical behavior, modulating emission efficiency, spectral response, and aggregation tendencies. Several derivatives exhibited reduced ACQ, and in select cases, clear AIEE activity while preserving favorable absorption and stability. These findings demonstrate that positional control of electron-deficient heterocycles is a powerful strategy for tailoring the optical properties of BN-based chromophores. This design principle enables the development of next-generation electron-deficient AIE-active azaborine materials with significant potential in sensing, adaptive photonics, and optoelectronic applications.