Multiple stimulus modulated organic crystal polymorphs with tunable luminescence behavior

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Polymorphism allows substances to exist in multiple crystalline forms, influencing their properties.
• Organic crystal polymorphism is typically controlled by solvent or temperature variations.
• Understanding structure-property relationships in polymorphs is crucial for materials design.

Purpose of the Study:

• To synthesize and characterize a novel compound, p-An-Br, with multiple stimulus-modulated crystal polymorphs.
• To investigate the relationship between molecular structure, crystal framework, and luminescence properties.
• To develop a sensitive method for methanol detection using the polymorphic crystals.

Main Methods:

• Synthesis of p-An-Br incorporating carbazole and anthracene chromophores.
• Induction of distinct polymorphs (G, Y, R) with varying fluorescence (green, yellow, red).
• Stimuli-responsive switching between polymorphs via methanol uptake/release.
• In-depth structural analysis of molecular conformations and noncovalent interactions.

Main Results:

• p-An-Br exhibits three polymorphs (G, Y, R) with distinct green, yellow, and red fluorescence.
• Dynamic color switching achieved through reversible methanol adsorption/desorption.
• Molecular conformations and noncovalent interactions significantly impact luminescence behavior.
• Crystal R demonstrated highly sensitive and specific methanol detection (limit of 39.35 ppm).

Conclusions:

• A novel strategy for controlling crystal polymorphism and luminescence is presented.
• The study highlights the critical role of molecular structure and interactions in polymorph properties.
• p-An-Br offers an effective platform for sensitive methanol sensing applications.