Dual Lewis Acid- and Base-Responsive Terpyridine-Based Hydrogel: Programmable and Spatiotemporal Regulation of Fluorescence for Chemical-Based Information Security

A huge amount of data inundated in our daily life; there is an ever-increasing need to develop a new strategy of information encryption-decryption-erasing. Herein, a polymeric DCTpy/PAM hydrogel has been fabricated to store information via controllable Eu3+/Zn2+ ionoprinting for hierarchical and multidimensional information decryption. Eu3+ and Zn2+ have a competition and dynamic interaction toward DCTpy under NH3 stimuli in the polymeric DCTpy/PAM hydrogel network. The Eu(III)/Zn(II)@DCTpy/PAM hydrogel exhibits light red fluorescence of Eu3+ due to the antenna effect. Upon the addition of NH3, dissociation of the Eu3+-DCTpy complex takes place, and the Zn(II)/DCTpy/NH3 complex is formed with both ICT (intramolecular charge-transfer) and PET (photo-induced electron-transfer) process characteristics that exhibits yellow emission color. Subsequently, HCl can quench the fluorescence of the resulting hydrogel. By integrating transparency, adhesiveness, and programmable stimuli responsiveness of the hydrogel blocks in to one system, complex, multistage, and time-controlled information storage-encryption-decryption-erasing in sequence with multidimensions is illustrated via the molecule diffusion method. This work provides a novel and representative strategy in fabricating information encryption-decryption-erasing materials with high capacity and complexity by a simple terpyridine-based hydrogel.