A photochromic diethylamino methanone Schiff base with its application in color-shift-based binary data recording and information encryption-decryption

In this study, a diethylamino methanone Schiff base (HBAPE) was reported. Its synthesis, quantum chemical calculations, photophysical behaviors containing aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) were systematically studied. More importantly, HBAPE exhibits photochromism in response to UV light via reversible tautomerism, where a remarkable color change in both absorption and emission was observed. Thermal treatment or visible-light exposure would activate the reverse reaction to restore the compound to its pristine state. The color change in the photochromic process is well quantified by RGB and CIE L*a*b* color space, and the latter exhibits high compatibility and accuracy owing to the utilization of the derived color shift (ΔE*Lab). Based on ΔE*Lab analysis, the limits of detection (DL) are calculated to be as low as 6.2 μW/cm2 (by manual color picking) and 2.6 μW/cm2 (by chromatic meter measurement), suggesting high sensitivity towards UV radiation. We further develop a prototype of data-recording film that can write and erase binary data by UV and heating/visible-light, respectively. The data recording film shows high signal contrast by utilizing ΔE*Lab as the output, achieving nice rewritability. A strategy for data encryption-decryption was developed. With an inert compound as the background covering, the information can be concealed via heating or visible-light, and revealed by UV radiation, providing a reliable strategy for information safety.