Gel Materials with Rubber‐Rubbing‐Chromic Luminescence: A Portable Tool for On‐Spot Composing Highly Encrypted Information

Abstract

Gels generally comprise different intermolecular noncovalent interactions for sustaining self‐assembled structures, which renders them sensitive to external stimuli, while simultaneously sacrificing their stimuli‐responsive selectivity. Supramolecular and polymeric gels are constructed here by the coassembly of a dipyridinil phenol as the crosslinker with the gelator counterparts. In these systems, an ordered multiple H‐bonded network facilitates a proton transferred tautomerization caused by the triboelectric effect of rubber rubbing, resulting in an unprecedented rubber‐rubbing‐chromic luminescence. This process is efficient and highly selective, as the friction with other materials fails to cause such a phenomenon. This results in a unique negative charge (−117 nC J−1, exactly provided by the triboelectric effect of the rubber material) inducing the topochemical tautomerization at the gel level. Moreover, the polymeric gels exhibit superior mechanical properties and can be processed into a chalk‐like portable tool for writing. The composed luminescent information is also sensitive to rubber rubbing, featuring considerable practicability in on‐spot information encryption and anticounterfeiting.

Water molecular bridge-induced selective dual polarization in crystals for stable multi-emitters

“…2b ). As the phenol groups of ortho -pyridinil generally show absorption in a relatively short wavelength region without photoluminescence, 8 these results indicated that DMF and DMSO played a prominent role in pushing the dynamic equilibrium towards deprotonation, and the formation of phenolate species was the root of the luminescent properties. It seems that highly polar solvents like DMF and DMSO could stabilize the transition state to promote deprotonation, owing to different solvent effects.…”

“…This originated from the existence of molecular dimers maintained by intermolecular H-bonding between the proton donor of one molecule and the acceptor of another in the solid state. 8 Such intermolecular H-bonds in the bulk generated relatively weak polarization to produce new electronic transitions (a charge-transfer state) from polarized species. However, the photoluminescence of these bulk states is still weak.…”

“…ortho -Pyridinil phenols, a class of D–A molecular structures with both a proton donor and acceptor, can readily form an intermolecular H-bond dimeric structure through the proton donor and acceptor. 8 Inspired by the selective bonding mode in these structures, we expect that a stable H-bond network can be constructed formed from ortho -pyridinil phenols together with polar chemicals (like water) in an ordered and alternating fashion, so as to create an oriented polarization effect induced by a perfect H-bond environment.…”

Supramolecular Polymers with Photoswitchable Multistate Fluorescence for Anti-Counterfeiting and Encryption

“…In recent years, stimuli-responsive fluorescent materials (SFMs), whose luminescence is sensitive to environmental stimuli, have a wide range of applications in the fields of biosensors, bioimaging, anti-counterfeiting, information encryption, etc. − SFMs with various stimuli, including light, temperature, pressure, ion, acid–base, and humidity, have been studied. − Compared with other types of SFMs, photoswitchable fluorescent systems with the phototrigger mechanism display the desired properties, including remote control, waste-free, noninvasive, high spatial, and temporal resolution. − …”

Multiple-stimuli-responsive multicolor luminescent self-healing hydrogel and application in information encryption and bioinspired camouflage

“…[20][21][22][23] These materials usually show a change in optical properties in response to an external stimulus (e.g., pH, solvent, temperature, ions, and light). [24][25][26][27] Great efforts have been devoted to designing and developing stimuli-responsive materials. Until now, several strategies have proved to be simple and effective, including the introduction of carbon dots into self-healing gels, 28,29 doping aggregation-induced emission (AIE) molecules into a polymer network through physical or chemical bonding, [30][31][32] and the formation of lanthanide complexes between polymer chains.…”