Amphiprotism-Coupled Near-Infrared Emission in Extended Pyrazinacenes Containing Seven Linearly Fused Pyrazine Units

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Development of novel organic chromophores for advanced applications.
• Exploration of nitrogen-rich heterocyclic compounds for unique electronic properties.
• Need for materials emitting within the near-infrared biological transparency window.

Purpose of the Study:

• Synthesize and characterize peripherally substituted tetradecaazaheptacene (N₁₄Hp) compounds.
• Investigate their photophysical properties, including emission in the near-infrared region.
• Assess the potential of these pyrazinacene derivatives for various applications.

Main Methods:

• Organic synthesis of N₁₄Hp compounds.
• X-ray crystallography for structural elucidation.
• UV-Vis absorption and emission spectroscopy to determine photophysical properties.

Main Results:

• Successful synthesis of N₁₄Hp compounds with a planar acene-like chromophore.
• Electronic absorption and emission observed in the 650-900 nm near-infrared biological transparency window.
• High photoluminescence quantum yields (Φ_PL) up to ~0.61 at 686 nm and ~0.58 at 712 nm for the monodeprotonated state.

Conclusions:

• Peripherally substituted tetradecaazaheptacene (N₁₄Hp) compounds exhibit promising amphiprotism-coupled emission.
• The planar, nitrogen-rich chromophore demonstrates stability and utility.
• These pyrazinacenes are suitable for applications leveraging their near-infrared photophysical properties.