This study develops a new type of C3-symmetric triphenylene triimide (TTI) bearing different oligo(ethylene glycol) side chains via imide linkages. By exploiting the unique TTI molecule as a building block, supramolecular polymerization is explored based on π–π stacking and hydrophilic/hydrophobic interactions in various solvents and the rates of heating/cooling process. The molecular chirality of the TTI unimer induces a preferential helicity formation in fibrous structures, while the achiral side chain allows the formation of linear nanofibers. The stacking type of supramolecular polymerization is highly dependent on the point chirality of the side chains, as indicated by the spectroscopic analyses, including ultraviolet–visible (UV/vis) and circular dichroism (CD) spectroscopy with atomic force microscopy (AFM), transmission electron microscopy (TEM), and wide-angle X-ray scattering (WAXS). Interestingly, the supramolecular polymerization does not occur in its monomeric state due to the generation of radical anions from the imide groups upon UV irradiation. In contrast, the fibrous structure in the assembled state is maintained, owing to the intermolecular interaction. This study provides a new direction in the phototriggered control of the supramolecular chiral assembly.

Circularly polarized light (CPL) is an inherently chiral entity and is considered one of the possible deterministic signals that led to the evolution of homochirality. While accumulating examples indicate that chirality beyond the molecular level can be induced by CPL, not much is yet known about circumstances where the spin angular momentum of light competes with existing molecular chiral information during the chirality induction and amplification processes. Here we present a light-triggered supramolecular polymerization system where chiral information can both be transmitted and nonlinearly amplified in a “sergeants-and-soldiers” manner. While matching handedness with CPL resulted in further amplification, we determined that opposite handedness could override molecular information at the supramolecular level when the enantiomeric excess was low. The presence of a critical chiral bias suggests a bifurcation point in the homochirality evolution under random external chiral perturbation. Our results also highlight opportunities for the orthogonal control of supramolecular chirality decoupled from molecular chirality preexisting in the system.

Introduction of asymmetry into a supramolecular system via external chiral stimuli can contribute to the understanding of the intriguing homochirality found in nature. Circularly polarized light (CPL) is regarded as a chiral physical force with right- or left-handedness. It can induce and modulate supramolecular chirality due to preferential interaction with one enantiomer. Herein, this review focuses on the photon-to-matter chirality transfer mechanisms at the supramolecular level. Thus, asymmetric photochemical reactions are reviewed, and the creation of a chiral bias upon CPL irradiation is discussed. Furthermore, the possible mechanisms for the amplification and propagation of the bias into the supramolecular level are outlined based on the nature of the photochromic building block. Representative examples, including azobenzene derivatives, polydiacetylene, bicyclic ketone, polyfluorenes, Cn-symmetric molecules, and inorganic nanomaterials, are presented.

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. Here we report a system where the entire process of induction, control and locking of supramolecular chirality can be manipulated by light. Combination of triphenylamine and diacetylene moieties in the molecular structure allows 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 ultraviolet light, respectively. By using visible circularly polarized light, the supramolecular chirality of the resulting aggregates is selectively and reversibly controlled by its rotational direction, and the desired supramolecular chirality can be arrested by irradiation with ultraviolet circularly polarized light. This methodology opens a route to ward the formation of supramolecular chiral conducting nanostructures from the self-assembly of achiral molecules.