Pre-Twisted Molecular Geometry's Effect on the Optical Properties of Nitrophenyl Substituted Polycyclic 1,2-BN-Heteroarenes
Disciplines
Chemistry | Materials Chemistry | Organic Chemistry
Abstract (300 words maximum)
Incorporating a three-coordinate boron center into the structure of polycyclic aromatic hydrocarbons by replacing one of the C=C bonds with a B-N bond creates a more planar scaffold. These flat-structured heterocycles partially substituted with a boron-nitrogen bond known as aromatic azaborines, are highly regarded for their unique optoelectronic properties such as photochemical stability, high molar absorption coefficient, and high fluorescent quantum yields, as well as large Stokes shifts and tunable absorption/emission spectra, making them excellent candidates for a variety of applications such organic light-emitting diodes (OLEDs). Adding a -NO2 group as a strong electron-accepting group to the scaffold of aromatic azaborines, particularly pyrrolinone-fused-1,2-azaborines (PFAs), in an effort to redshift their absorbance and emission and create electron-deficient n-type organic conjugates, results in significant emission quenching due to intersystem crossing. Another issue with -NO2-substituted PFAs is that they aggregate at high concentrations due to strong intermolecular π-π stacking interactions. In turn, aggregate formation causes emission quenching, also known as Aggregation-Caused Quenching (ACQ). This practical limitation poses significant challenges for -NO2-substituted PFAs’ use in many applications. We hypothesized that increasing the steric interactions through the PFA scaffold and creating a larger twist in the molecular geometry by including bulkier moieties such as methyl group will result in -NO2-phenyl substituted PFAs with aggregation-induced emission (AIE), solvatochromism and thermochromism properties. These findings will aid in the development of more improved future AIE-active PFAs, as well as the understanding of how molecular geometry influences these compounds' optoelectronic properties.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Carl J. Saint-Louis
Pre-Twisted Molecular Geometry's Effect on the Optical Properties of Nitrophenyl Substituted Polycyclic 1,2-BN-Heteroarenes
Incorporating a three-coordinate boron center into the structure of polycyclic aromatic hydrocarbons by replacing one of the C=C bonds with a B-N bond creates a more planar scaffold. These flat-structured heterocycles partially substituted with a boron-nitrogen bond known as aromatic azaborines, are highly regarded for their unique optoelectronic properties such as photochemical stability, high molar absorption coefficient, and high fluorescent quantum yields, as well as large Stokes shifts and tunable absorption/emission spectra, making them excellent candidates for a variety of applications such organic light-emitting diodes (OLEDs). Adding a -NO2 group as a strong electron-accepting group to the scaffold of aromatic azaborines, particularly pyrrolinone-fused-1,2-azaborines (PFAs), in an effort to redshift their absorbance and emission and create electron-deficient n-type organic conjugates, results in significant emission quenching due to intersystem crossing. Another issue with -NO2-substituted PFAs is that they aggregate at high concentrations due to strong intermolecular π-π stacking interactions. In turn, aggregate formation causes emission quenching, also known as Aggregation-Caused Quenching (ACQ). This practical limitation poses significant challenges for -NO2-substituted PFAs’ use in many applications. We hypothesized that increasing the steric interactions through the PFA scaffold and creating a larger twist in the molecular geometry by including bulkier moieties such as methyl group will result in -NO2-phenyl substituted PFAs with aggregation-induced emission (AIE), solvatochromism and thermochromism properties. These findings will aid in the development of more improved future AIE-active PFAs, as well as the understanding of how molecular geometry influences these compounds' optoelectronic properties.