BN-Fused Polycyclic Heteroarenes Containing Thiopyran Moieties: Synthesis, Aromaticity, and Dual-Chromic Behavior

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Boron nitride (BN)-fused polycyclic heteroarenes are known for unique optoelectronic properties.
• The fusion of azaborine and thiopyran rings in heteroarenes is an underexplored area.
• This gap limits chemical diversity and optical tunability in BN-heteroarene materials.

Purpose of the Study:

• To synthesize novel BN-embedded thiopyran derivatives.
• To investigate their photophysical properties, aromaticity, and dual-chromic behaviors.
• To explore the potential of these compounds as smart materials.

Main Methods:

• Straightforward synthesis of BN-embedded thiopyran derivatives with varying conjugation lengths.
• Systematic investigation of photophysical properties using spectroscopic techniques.
• Analysis of aromaticity changes and ion/proton interactions via NMR spectroscopy and theoretical calculations.

Main Results:

• Successful synthesis of BN-fused thiopyran derivatives.
• Incorporation of the thiopyran ring resulted in a narrow optical band gap.
• Demonstrated dual-chromic behavior in response to fluoride ions and protons.
• Fluoride ions coordinated to azaborine rings; protons interacted with cyclopenta[b]thiopyran moieties.
• Fluorination decreased azaborine aromaticity; protonation enhanced thiopyran aromaticity.

Conclusions:

• This study presents the first construction of BN-fused thiopyran derivatives.
• These novel compounds exhibit tunable optical properties and dual-chromic responses.
• The developed materials show promise as candidates for advanced dual-chromic smart applications.