A novel aggregation-induced enhanced emission aromatic molecule: 2-aminophenylboronic acid dimer

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Aggregation-induced enhanced emission (AIEE) is crucial for optoelectronics, biomedical probes, and chemical sensors.
• Most reported AIEE molecules possess complex structures with multiple aromatic rings or polycyclic skeletons.
• Aggregation-caused quenching (ACQ) is a common phenomenon in fluorescent molecules.

Purpose of the Study:

• To investigate the solid-state emissive properties of 2-aminophenylboronic acid (2-APBA).
• To identify and characterize novel AIEE molecules with simple structures.
• To elucidate the mechanism behind the AIEE behavior of 2-APBA and explore its potential applications.

Main Methods:

• Synthesis and characterization of 2-aminophenylboronic acid (2-APBA).
• Solid-state fluorescence spectroscopy to study emission properties.
• Crystallographic analysis to determine molecular structure and packing.
• Investigation of dynamic covalent bonds (B-N and B-O) for reversible transformations.

Main Results:

• 2-aminophenylboronic acid (2-APBA) exhibits strong fluorescence in the solid state, acting as a novel AIEE molecule.
• 2-APBA exists in a dimeric form in the solid state, and this dimer is the active AIEE species.
• The AIEE mechanism involves ordered aggregation of dimeric units via intermolecular interactions, avoiding π-π stacking.
• Reversible transformation between the fluorescent dimer and non-fluorescent monomer was achieved through dynamic covalent B-N and B-O bonds.

Conclusions:

• 2-aminophenylboronic acid (2-APBA) is a simple yet effective AIEE molecule, challenging the notion that complex structures are required.
• The unique AIEE mechanism in 2-APBA, driven by intermolecular interactions and dynamic covalent bonds, offers new design principles for AIEE materials.
• The reversible nature of 2-APBA aggregation holds significant promise for applications in molecular recognition, sensing, and controlled drug release.