Engineering Stimuli-Responsive Multifunctional Fluorescent Materials
Disciplines
Materials Chemistry | Organic Chemistry
Abstract (300 words maximum)
Replacing one of the C=C bonds of a polycyclic aromatic hydrocarbon with a BN 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 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 recently demonstrated that inserting a twisted molecular geometry into the scaffold of -NO2 substituted PFAs relieves the π-π stacking interaction and results in aggregation-induced emission (AIE) at high concentrations, alleviating the ACQ issue. Even though the ACQ problem is resolved, the twisted -NO2 substituted PFA has limitations, such as low solubility in major solvents, which results in the loss of important optical properties. To overcome these limitations, we incorporated a benzoxadiazole derivative as an electron-deficient heterocycle to expand the π-system of the PFA while maintaining the twisted molecular geometry. The inclusion of the benzoxadiazole derivative resulted in increase solubility and the restoration of important optical properties creating stimuli-responsive multifunctional fluorescent materials. These findings will aid in the development of future electron-deficient chromophores with high solubility, as well as the improvement of optical properties for stimuli-responsive multifunctional fluorescent materials.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Carl Saint-Louis
Engineering Stimuli-Responsive Multifunctional Fluorescent Materials
Replacing one of the C=C bonds of a polycyclic aromatic hydrocarbon with a BN 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 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 recently demonstrated that inserting a twisted molecular geometry into the scaffold of -NO2 substituted PFAs relieves the π-π stacking interaction and results in aggregation-induced emission (AIE) at high concentrations, alleviating the ACQ issue. Even though the ACQ problem is resolved, the twisted -NO2 substituted PFA has limitations, such as low solubility in major solvents, which results in the loss of important optical properties. To overcome these limitations, we incorporated a benzoxadiazole derivative as an electron-deficient heterocycle to expand the π-system of the PFA while maintaining the twisted molecular geometry. The inclusion of the benzoxadiazole derivative resulted in increase solubility and the restoration of important optical properties creating stimuli-responsive multifunctional fluorescent materials. These findings will aid in the development of future electron-deficient chromophores with high solubility, as well as the improvement of optical properties for stimuli-responsive multifunctional fluorescent materials.