Unveiling electron transfer in a supramolecular aggregate for adaptive and autonomous photochromic response.

Interactive and responsive materials are dynamic molecular systems that are capable of modulating their behavior and adapting to environment autonomously. Photochromic materials are among the fascinating class of dynamic responsive systems and widely used in molecular switches and optoelectronic devices. However, the phototriggered color changing largely relies on the conformation transformation of the photochromic motif, which significantly limited their usage in organic liquid solutions. Herein, we demonstrate a photochromic organic supramolecular system by using electron-rich N,N-dimethylacetamide (DMA) and electron-deficient naphthalenediimide (NDI) as a donor and acceptor, respectively. In the binary system, the photo-induced electron transfer through lone pair···π interactions pathway leads to dynamic photochromic response not only in the solution but also in the crystalline aggregated state. Furthermore, by incorporating the supramolecules in the polymer matrix, the transparent polymeric film also exhibits rapid photochromic response, which makes it a promisingly interactive and adaptive photochromic material.