Tunable Luminescence of Nonaromatic Borate Esters

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Nonconventional luminophores typically feature electron-rich heteroatoms.
• Emerging luminophores with electron-deficient atoms, such as boron, are gaining attention.
• Boron-containing substances offer unique electronic properties for photoluminescence applications.

Purpose of the Study:

• To investigate the photoluminescent properties of bis(pinacolato)diboron (BE1) and bis(2,4-dimethylpentane-2,4-glycolato)diboron (BE2).
• To explore the aggregation-induced emission (AIE) characteristics of these boron compounds.
• To understand the mechanism behind their photoluminescence and its tunability.

Main Methods:

• Synthesis and characterization of bis(pinacolato)diboron (BE1) and bis(2,4-dimethylpentane-2,4-glycolato)diboron (BE2).
• Photoluminescence spectroscopy in dilute solutions and aggregate states.
• Investigation of external stimuli (excitation wavelength, compression, oxygen) on photophysical properties.

Main Results:

• BE1 and BE2 are nonemissive in dilute solutions but exhibit strong photoluminescence in aggregate states.
• The compounds display aggregation-induced emission (AIE) characteristics.
• Photoluminescence is tunable by excitation wavelength, compression, and oxygen presence, consistent with the clustering-triggered emission (CTE) mechanism.

Conclusions:

• Bis(pinacolato)diboron and its analogue demonstrate significant aggregation-induced emission.
• The observed photoluminescence is controllable via external factors, suggesting potential for sensor applications.
• The clustering-triggered emission mechanism provides a framework for understanding their photophysical behavior.