Enantioselective Crystal Growth Induced by Mesoscopic Helical Platforms.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• Chirality is crucial in molecular recognition and material properties.
• Developing methods for enantioselective crystallization is essential for producing chiral materials.
• Tetraphenylethylene (TPE) is a molecule known for its aggregation-induced emission properties.

Purpose of the Study:

• To investigate the enantioselective crystallization of TPE using chiral silica nanohelices (SNHs) as templates.
• To explore how template handedness and crystallization conditions influence TPE crystal morphology and chiroptical properties.
• To establish a robust platform for chirality-controlled crystallization.

Main Methods:

• Enantioselective crystallization of TPE on SNH-functionalized substrates.
• Controlled solvent evaporation (slow at 4°C, rapid at room temperature).
• Characterization using electronic circular dichroism (ECD), circularly polarized luminescence (CPL), and fluorescence microscopy.

Main Results:

• SNHs successfully directed enantioselective crystallization of TPE.
• Slow evaporation at 4°C produced small orthorhombic TPE crystals with strong ECD and CPL correlated to SNH handedness.
• Rapid evaporation at room temperature resulted in dendritic TPE assemblies with strong ECD but weaker, less correlated CPL.
• Fluorescence microscopy confirmed emission originates from crystalline domains, indicating restricted intramolecular rotation.

Conclusions:

• Chiral silica nanohelices provide a versatile platform for controlling TPE crystallization.
• Both template handedness and evaporation kinetics significantly modulate the morphology and chiroptical signatures of TPE crystals.
• This work demonstrates a promising approach for template-directed, chirality-controlled synthesis of crystalline materials.