Reshaping Chiral Self-Assemblies Through Alkyne-Involved Click Chemistry

Highly efficient click reactions in the solid state or space-confined condition potentially induce in situ compositional and structural evolution, offering opportunities for smart materials and nanofabrication technologies. Herein, we report a strategy for reshaping self-assembled chiral nanomaterials mediated by a [2+2] cycloaddition reaction. Amino acids grafted with large π-conjugated systems are employed as the primary building blocks, into which the electron-deficient tetracyanoquinodimethane (TCNQ) and ethynylaniline (EDA) are orthogonally introduced. These components form ternary co-assemblies through charge-transfer interactions and hydrogen bonding, respectively. In the aggregated phase, TCNQ and EDA undergo an efficient, spontaneous [2+2] cycloaddition reaction to afford a nonplanar adduct. This reaction is accompanied by the formation of macroscopic helices with high phase purity. Owing to the high efficiency of this reaction, such chiral architectures can be generated in situ by post-addition of the third component into preassembled binary systems. This topochemical synthetic strategy compensates for the narcissistic assembly by directly using the as-synthesized adduct, and remarkably enhances chiral induction as well as near-infrared chiroptical properties. In contrast to widely reported template effects, this system exhibits a distinctive cooperative behavior, wherein the insoluble reaction products undergo preferential and directional organization within the aggregates rather than remaining at original formation sites.