Enantioselective Crystal Growth Induced by Mesoscopic Helical Platforms

We report enantioselective crystallization of tetraphenylethylene (TPE) directed by chiral silica nanohelices (SNHs), yielding crystalline assemblies with distinct morphologies and chiroptical signatures that are modulated by both template handedness and evaporation kinetics. When TPE solutions are deposited onto SNH-functionalized substrates and allowed to crystallize through slow solvent evaporation at 4°C, small orthorhombic crystals (2-5 μm) form with strong induced electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) whose sign is correlated to the underlying SNH handedness. In contrast, rapid evaporation at room temperature leads to dendritic crystalline assemblies with strong ECD but weaker CPL with reduced correlation to the template handedness. Fluorescence microscopy confirms that emission originates exclusively from crystalline domains, consistent with restriction of intramolecular rotation upon crystal packing. The results show that right-handed (P-) and left-handed (M-)SNH preferentially promote the formation of distinct TPE enantiomeric crystals, providing a robust platform for template-directed chirality-controlled crystallization.