Solution and solid-state fluorescence emission from cyanostyrene molecules with multiple nitrogen atoms

Area of Science:

• Materials Science
• Organic Chemistry
• Photophysics

Background:

• Polynitrogen compounds exhibit unique fluorescence properties.
• Designing molecules with distinct solution and solid-state emission is challenging.
• Structure-property relationships are crucial for optimizing luminescence.

Purpose of the Study:

• To propose a design strategy for dual-state fluorescence emission using polynitrogen atoms.
• To synthesize and characterize D-A type cyanopyridine ethylene molecules.
• To investigate the factors influencing luminescence in solution and solid states.

Main Methods:

• Utilizing benzimidazole as an electron donor and pyridine as an electron acceptor.
• Constructing D-A type cyanopyridine ethylene molecules.
• Performing theoretical calculations to analyze molecular conformation and electronic states.
• Evaluating fluorescence quantum yields in both dilute solution and solid states.

Main Results:

• Compound 1 exhibits energy-close isomers in dilute solutions with planar conformations, enhancing radiation efficiency (up to 42.7% quantum yield).
• A distorted cyanobenzene structure in the solid state minimizes π-π stacking.
• Hydrogen bonding limits molecular vibration and rotation, leading to strong solid-state emission (up to 27.4% quantum yield).

Conclusions:

• The proposed design strategy successfully yields molecules with dual-state luminescence.
• Optimized molecular design can enhance fluorescence efficiency in both solution and solid states.
• These dual-state luminescence systems show potential for information encryption and temperature sensing applications.