A tetraphenylethylene derivative with reversible luminous colours applied in data security

Abstract

Exploration of the relationship between molecular structure and properties of materials, particularly the multi-stimuli-responsive types, remain a challenge. Herein, we designed, synthesized and tested the photo-physical properties of a multi-stimuli-responsive TPE derivative (TPE-(C3Br)4). The TPE-(C3Br)4 exhibits piezochromic emitting deep-blue to green-blue light under external grinding. Interestingly, both non-ground and ground TPE-(C3Br)4 exhibits vapochromic and thermochromic properties. When exposed to CH2Cl2 vapor for 3 min and thereafter heated at 90 °C for 5 min or heat at 140 °C for 3 min and exposed to CH2Cl2 vapor for 2 s, TPE-(C3Br)4 reversibly glows between deep-blue and green-blue. The ground sample glows between green-blue and deep-blue under only one stimulus for a few min (e.g. heating or fuming alone). The multi-stimuli-responsive properties of TPE-(C3Br)4 are attributed to variation in intermolecular stacking and intramolecular twisting. The TPE-(C3Br)4 was used to develop a new encryption-decryption method. These findings demonstrate the utility of smart responsive TPE-(C3Br)4 material in developing data protection systems.