Chiral assembly of AIE-active achiral molecules: An odd effect in self-assembly

The induction of chirality in supramolecular structures through hierarchical self-assembly of achiral compounds, and the control of their handedness, are closely related to the evolution of life and the chiral amplification found in nature. Here we show that the combination of achiral tetraphenylethylene, an AIE-active luminophore bearing four alkyl chains with either an odd or even number of carbon atoms via an amide linkage in the molecular structure, allows the induction and control of supramolecular chirality into well-defined helical superstructures by controlling the solvent composition and polarity. In particular, right handed supramolecular structures were produced from an even number of carbon atoms in the alkyl chains, whereas an odd number led to the assembly of left-handed superstructures. The twisted superstructure was visualised by scanning electron microscopy, and circular dichroism was used to observe chirality within the assembly. These controlled assemblies of an AIE-active molecule are of potential practical value, such as templates for helical crystallisation, catalysis or chiral mechanochromic luminescent superstructure formation.