Light-Induced Selective Control of Excitonic States in Supramolecular Nanotubes.

Selective control of excitonic states in supramolecular assemblies remains a fundamental challenge, owing to spectral congestion and the close relation between electronic structure and molecular organization. Here, we demonstrate that controlled optical illumination can be used to selectively reconfigure excitonic functionality in double-walled supramolecular nanotubes. By combining two-dimensional electronic spectroscopy, cryogenic transmission electron microscopy, and polarization-resolved single-nanotube microscopy, we show that light exposure selectively suppresses the outer-wall excitonic response through an oxygen-mediated photooxidative degradation of the chromophores. Structural analysis reveals that the resulting disorder is largely confined to the outer wall, while the cylindrical scaffold and excitonic order of the inner wall are preserved. Measurements on individual nanotubes immobilized in a solid-state matrix further demonstrate that the polarization anisotropy of the inner-wall exciton remains unchanged, indicating that its excitonic symmetry and delocalized character are maintained. Together, these findings establish light as an additive-free and noncontact control parameter for modifying excitonic landscapes in complex supramolecular architectures.