Reversible Redox Switching of Concurrent Luminescence and Visual Color Change Based on Lanthanide Metallogel

Abstract

The development of reversible redox supramolecular gels capable of concurrent luminescence switch and visible color change with the facile redox process has always been an intriguing challenge. A redox-responsive supramolecular lanthanide metallogel with strong luminescence and yellow color is obtained via coordination interaction between 3,5-dinitrosalicylic acid (DNSA) and europium (Eu3+). Upon the addition of TiO2 to the prepared gel (DNSA/Eu3+ gel), the oxidation process of the gel (DNSA/Eu3+/TiO2 gel) can be easily achieved by UV irradiation. The DNSA/Eu3+/TiO2 gel exhibits a concurrent reversible “on–off” luminescence and color change in response to redox stimuli. The DNSA/Eu3+/TiO2 gel shows a concurrent quench of luminescence and a color change from yellow to red when the gel was stimulated by the reductant. Upon UV irradiation, the luminescence and color of the reduced DNSA/Eu3+/TiO2 gel restored to its initial state due to the strong oxidation ability of hydroxyl radicals derived from photocatalytic oxidation of TiO2. The results of UV–vis and mass spectroscopy indicated that the reversible redox responsiveness of DNSA/Eu3+/TiO2 gel depends on the reversible oxidation–reduction reactions of DNSA. Moreover, DNSA/Eu3+/TiO2 gel remains stable because the morphology of the gel had no change during the redox process. Exemplarily, the application of DNSA/Eu3+/TiO2 gels to achieve luminescent patterning was investigated. The results demonstrated that the prepared metallogel has potential applications in the fields of writable materials, anticounterfeiting, sensors, and others.

A V(iii)-induced metallogel with solvent stimuli-responsive properties: structural proof-of-concept with MD simulations

“…On the other hand, it is worth mentioning that p-p stacking and p-cation interactions is recognized as stable and strong as hydrogen bonds and salt bridges. [35][36][37][38][39] In all MG1 to MG3 simulated systems, small aggregates of gelator molecules were preferentially organized in a parallel fashion, around the solvated V III ions and the calculated centroid-centroid distances between adjacent gelator molecules were in better agreement with previous reports in the MG3 simulation (Table 2). 72,73 We studied the RDF of V III cations concerning the BTC and Ade molecules, conrming the gelator molecules aggregation around the V III cations (Fig.…”

“…[31][32][33][34] To bring out the potency of these so materials in denitive manners for specic applications, tuning of multiple non-covalent interactions such as hydrogen bonding, p-p stacking, electrostatic effects, and van der Waals forces, can be helpful. [35][36][37][38][39] In recent years metallogels have drawn attention, due to their broad range of applications. 36,[40][41][42] In comparison with organogels, in metallogels, the introduction of metal ions into the gelator molecules triggers some of the most fascinating "smart" material features.…”

“…[35][36][37][38][39] In recent years metallogels have drawn attention, due to their broad range of applications. 36,[40][41][42] In comparison with organogels, in metallogels, the introduction of metal ions into the gelator molecules triggers some of the most fascinating "smart" material features. 43,44 Less-studied metallogels not only merge incorporated metal characteristics (including conductive, catalytic, redox, or optical features) but also introduce additional subtle non-covalent interactions into the resulted molecular assemblies.…”

Stimuli responsive dynamic transformations in supramolecular gels

“…22). 276 The gel exhibited the characteristic red fluorescence of Eu 3+ . The yellow colour of the gel turned to red on addition of NaBH 4 due to reduction of DNSA to 3-amino-5nitrosalicylic acid.…”

Tough, Transparent, and Anti-Freezing Nanocomposite Organohydrogels with Photochromic Properties

“…Another common type of photochromic material is metal oxides. These metal oxides, such as tungsten oxide (WO 3 ), − molybdenum trioxide, , titanium dioxide (TiO 2 ), , and vanadium pentoxide, are often composed of transition metal oxides and aggregate into nanoparticles. A wide range of optical applications such as photo-printing and high-level encryption with the help of smartphones can be obtained through nanoparticles-based photochromic materials .…”