Evolution of supramolecular chirality from self-assembly of achiral compounds and control over its handedness is closely related to the evolution of life, and development of supramolecular materials with desired handedness has been a very challenging issue. We have demonstrated that the entire process of induction, control, and locking of supramolecular chirality can be manipulated by light. Combination of triphenylamine (TPA) and diacetylene (DA) moieties in the molecular structure allowed photoinduced self-assembly of the molecule into helical aggregates in a chlorinated solvent by visible light and covalent fixation of the aggregate via photopolymerization by UV. Simply by employing circularly polarized light (CPL) as a light source in the self-assembly process of a TPA-containing molecule, we show that self-assembled aggregates with supramolecular chirality can be generated, driven by the helical stacking of the TPA moieties. Our data suggests that the chiral bias generated by irradiation of the TPA moiety with CPL is amplified by the self-assembly process, which promotes enrichment of one enantiomer by the enantioselective helical stacking and forms aggregates with specific handedness. The handedness of the aggregates is exclusively dictated by the rotational direction of the CPL and can even be switched in a totally reversible fashion. Furthermore, by incorporating a diacetylene moiety that undergoes topochemical photopolymerization by UV (254 nm), we demonstrate that the desired handedness can be permanently locked by circularly polarized UV light (CPUL) irradiation, which knits the self-assembled structure with covalent bonds.

Light-induced self-assembly of achiral molecules containing triphenylamine for supramolecular chirality and chiral polymers

253rd National Meeting (2017)

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