Multistimuli-Responsive Self-Healable and Moldable Nickel(II)-Based Gels for Reversible Gas Adsorption and Palladium Sequestration via Gel-to-Gel Transformation

Abstract

We report the in situ formation of Ni-based supramolecular organogel and organic−aqueous gels using amine appended triazole ligand, having varying morphology and rheological properties. These gels are self-healable and moldable or injectable respectively depending on the absence or presence of water in the gelation medium. Our studies reveal that the formation and rupture of hydrogen bonds assisted by the solvent movement is responsible for the self-healing nature of the gels. The porous structure of the gel has been observed from the migration of dye molecules on the self-healed gel. In addition, the gels show dual function of reversible adsorption of toxic gases and sequestration of heavy metal ions, especially palladium via gel-to-gel transformation. It is imperative to stress that such transformation is extremely rare for small molecule based metallogels. The dynamic nature of Ni−N triazole interactions has been utilized in achieving the reversible gas/vapor responsive behavior of the metallogels, which could be suitable in developing colorimetric probes for the detection of toxic gases and heavy metal ions. Such multifunctional gels are exceptional in contemporary literature and are expected to find utility in fabricating smart multistimuli-responsive gel-based materials in the future.

Self‐Foaming Metal‐Organic Gels Based on Phytic Acid and Their Mechanical, Moldable, and Load‐Bearing Properties.

“…Self‐sustainability is the ability of gels to stand by itself and withstand change or deformation when acted upon by external forces [8,11,32,59,60] . To study the self‐sustaining and load‐bearing property of the foaming gel, PA−Fe‐1 : 4 gel was cut into cylinders with a diameter of 2.0 cm and a height of 1.4 cm, and coins were placed on its top in succession (Figure 8).…”

“…Self-sustainability is the ability of gels to stand by itself and withstand change or deformation when acted upon by external forces. [8,11,32,59,60] To study the self-sustaining and load-bearing property of the foaming gel, PAÀ Fe-1 : 4 gel was cut into cylinders with a diameter of 2.0 cm and a height of 1.4 cm, and coins were placed on its top in succession (Figure 8). As mentioned above, the gas bubbles of PAÀ Fe-1 : 4 wet gel decreased when gel-sol transition occurred at room temperature for 2-3 times, and the resulting PAÀ Fe-1 : 4 gel with nearly no bubbles was chosen in the supporting force experiments.…”

“…Metal‐organic gels are a kind of supramolecular gels containing metal ions, metal‐organic moieties, and metal nanoparticles [7] . Incorporation of metal components may enrich or modify gel morphologies, [8] and contribute to improve the optical, [9] electrochemical [10] and mechanical properties [11,12] . A variety of metal‐organic gels have been developed for various applications, such as selective adsorption, [11] biosensors, [13,14] and electrocatalysis [15] .…”

“…[7] Incorporation of metal components may enrich or modify gel morphologies, [8] and contribute to improve the optical, [9] electrochemical [10] and mechanical properties. [11,12] A variety of metal-organic gels have been developed for various applications, such as selective adsorption, [11] biosensors, [13,14] and electrocatalysis. [15] Although the gels with various defined shapes or patterned structures are convenient for processing, delivery, and storage in large-scale industrial production, [16][17][18] few metal-organic gels with self-supporting and moldable properties have been reported, [11,12,16,19,20] and metal-organic gels with controllable shape, structure, and mechanical properties remains to be exploited.…”

Switchable Supramolecular Configurations of Al3+/LysTPY Coordination Polymers in a Hydrogel Network Controlled by Ultrasound and Heat

“…Additionally, the hydrogel was highly robust and could sustain weights as high as 100 g (Figure 5h−i) without any release of the immobilized solvent. Such excellent load-bearing abilities of low-molecular-weight supramolecular hydrogels have been reported rarely in the present literature studies, 45,46 which are originated from the abundant crosslinking moieties of ions and multiple bonding sites of ligands. The stoichiometric-controlled self-healing ability of the Al 3+ / LysTPY hydrogel was further studied.…”