Reversible, photoresponsive, dynamic wide-range emission color from polymer-matrixed naphthalene diimide single-luminogen

Smart materials with dynamic luminescence-color are potentially useful for sensors, displays and data storage devices. Herein a new photoresponsive luminescent material with a dynamic wide-range emission color was successfully developed through individually dispersing naphthalene diimide (NDI) possessing aliphatic carboxylic acid substitution on the diimide nitrogen atoms (NDI-COOH) into polymer matrix. Experiments and mechanism studies demonstrated that it was the photo-generated stable NDI radical anions that led to the unique photoresponsive dynamic emission color. Notably, a new mechanism involving twice energy transfer between NDI and NDI radical anions for photo-enhanced room-temperature phosphorescence (RTP) luminescence was presented. The present dynamic reversible emission approach, not only outlines a principle for the design of photo-induced radical anions with tunable luminescence, but also expands the scope of encryption and decryption of confidential information.