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

Abstract

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.

A Paper‐Like Hydrogel for Versatile Information Encryption and Decryption Via Chemical‐Induced Phase Separation

“…The underlying mechanism is either the adjustment of chemical color, which is determined by the chemical structure of the chromophore involved, or the adjustment of physical color, which depends on the microstructure or is related to the physical properties such as transmission, refraction, scattering, and interference/diffraction. [20] Although hydrogel-based information storage using chemical color is highly designable and can be achieved by means of a wide range of stimuli, such as light, [21] electricity, [22] heat, [23] pH, [24] and lanthanide ions or other chemicals, [12,[25][26][27][28] it generally demands a specific material design and synthesis by incorporating responsive species (e.g., chromophores) that usually react to a single stimulus, limiting the versatility. As for hydrogel information storage based on physical color, most studies use polymers that undergo thermally induced phase separation on heating (LCST) or cooling (with an upper critical solution temperature: UCST), including PNIPAM, [29] poly(2-isopropyl-2oxazoline), [21] poly(acrylamide-co-acrylonitrile) [30] and polyacrylamide (PAAm), [31] to realize optical transmittance change.…”

Tailoring photoluminescence and multifunctionalities of lanthanide coordination complexes employing ligand-controlled aggregation states

“…28,29 In addition, dynamic luminescence is propitious to enhance the security of anti-counterfeiting techniques due to the excitation wavelength/chemical species-dependent luminescence color changes. 30,31 Unquestionably, considering the sharp emission bands, the long luminescence lifetime of Ln 3+ , and the diversity of sensitizers, Ln 3+ -based complexes would be the most promising dynamic anti-counterfeiting materials. For example, Yan et al reported an excited light and chemical stimulus-responsive Eu 3+ -functionalized hydrogel film for dynamic anti-counterfeiting.…”

An Azomethine-H-Based Fluorogenic Sensor for Formic Acid

“…Fluorescence-based detection of FA and other analytes has gained notable momentum in recent years, providing opportunities for hand-held detection, replacing overly sophisticated electronic systems. − Although fluorescent and luminescent probes have been used for FA sensing, most of these measurements are performed in solution, which is nonideal for the detection of gaseous FA or for sensor integration at the point of detection. Alternatively, metal-oxide semiconductor-based sensors have been developed to detect FA under different conditions.…”