The Effect of Sterics and Pre-Twisted Molecular Geometry on the Photophysical Properties of Nitrophenyl-Substituted Polycyclic 1,2-BN Heteroarenes
Disciplines
Materials Chemistry | Organic Chemistry
Abstract (300 words maximum)
Replacing one of the sp2 C=C bonds of a polycyclic aromatic hydrocarbon with a boron-nitrogen bond results in flat-structured heterocycles known as aromatic azaborines (AAs). AAs are well-known for their distinct optoelectronic properties, which include photochemical stability, high molar absorption coefficient, and high fluorescent quantum yields, as well as large Stokes shifts and tunable absorption/emission spectra, making them ideal candidates for a wide range of applications. Adding a -NO2 group to AA scaffolds, specifically pyrrolidinone-fused-1,2-azaborines (PFAs), to redshift their absorbance and emission and create electron-deficient n-type organic conjugates, causes significant emission quenching due to aggregate formation induced by strong intermolecular π-π stacking at high concentrations. This emission quenching phenomenon is referred to as aggregation-caused quenching (ACQ) emission. 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 by incorporating a pre-twisted molecular geometry by including bulky substiturnts such as methyl group will result in -NO2-phenyl substituted PFAs with aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), solvatochromic and thermochromic properties. These findings will help to improve future AIE-active PFAs and better understand how molecular geometry affects these compounds' optoelectronic capabilities.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Carl Saint-Louis
The Effect of Sterics and Pre-Twisted Molecular Geometry on the Photophysical Properties of Nitrophenyl-Substituted Polycyclic 1,2-BN Heteroarenes
Replacing one of the sp2 C=C bonds of a polycyclic aromatic hydrocarbon with a boron-nitrogen bond results in flat-structured heterocycles known as aromatic azaborines (AAs). AAs are well-known for their distinct optoelectronic properties, which include photochemical stability, high molar absorption coefficient, and high fluorescent quantum yields, as well as large Stokes shifts and tunable absorption/emission spectra, making them ideal candidates for a wide range of applications. Adding a -NO2 group to AA scaffolds, specifically pyrrolidinone-fused-1,2-azaborines (PFAs), to redshift their absorbance and emission and create electron-deficient n-type organic conjugates, causes significant emission quenching due to aggregate formation induced by strong intermolecular π-π stacking at high concentrations. This emission quenching phenomenon is referred to as aggregation-caused quenching (ACQ) emission. 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 by incorporating a pre-twisted molecular geometry by including bulky substiturnts such as methyl group will result in -NO2-phenyl substituted PFAs with aggregation-induced emission (AIE), aggregation-induced emission enhancement (AIEE), solvatochromic and thermochromic properties. These findings will help to improve future AIE-active PFAs and better understand how molecular geometry affects these compounds' optoelectronic capabilities.