Self-assembled metallogels formed from N,N′,N′′-tris(4-pyridyl)trimesic amide in aqueous solution induced by Fe(iii)/Fe(ii) ions

Abstract

In this work, we report self-assembled metallogels formed from a ligand of trimesic amide, N,N',N''-tris(4-pyridyl)trimesic amide (TPTA), induced by Fe(III)/Fe(II) ions. TPTA is difficult to dissolve in water even in the presence of some metal ions such as Cu(2+), Co(2+), Ni(2+), K(+), Na(+) and Mg(2+) under heating, and it exhibits no gelation ability. Interestingly, upon heating TPTA can be dissolved easily in aqueous solution containing Fe(3+)/Fe(2+), and subsequently self-assembled into metallogels after cooling. The metallogels could also be formed in aqueous solutions of mixed metal ions containing Fe(3+)/Fe(2+), indicating that the other metal ions do not affect the formation of Fe(III)-TPTA and Fe(II)-TPTA metallogels. The high selectivity of metallogel formation to Fe(3+)/Fe(2+) may be used for application in the test of Fe(3+)/Fe(2+). The metallogels obtained are characterized by scanning electron microscopy, Fourier transform infrared spectra, nuclear magnetic resonance spectra, rheological measurements and scanning tunneling microscopy. The results indicate that TPTA can self-assemble into fibrous aggregates in Fe(3+)/Fe(2+) aqueous solution through the metal-ligand interactions and intermolecular hydrogen bonding. This kind of metallogel also possesses good mechanical properties and thermoreversibility.

Multi‐Responsive Supramolecular Hydrogels Derived from Gemini Surfactants for Visual Recognition of Isomerization

“…However, it levels off when the concentration is increased to a certain value. Similar results are obtained by DSC experiments (Figure d) and also observed in our previous work . We also tried to observe rheological and DSC behaviors of the TM 8 hydrogel with α ‐CD.…”

Organometallic Hydrogels

“…This formation is highly selective and can be used for Fe 3+ /Fe 2+ detection. In addition, fibers of the resulting metallogel become entangled to form a close‐knit porous network through the metal–ligand interactions and intermolecular hydrogen bonding, endowing the whole system with good mechanical properties and thermoreversibility . Luminescent hydrogels can be readily obtained from iminodiacetic acid, pyridine moiety ligands and chelate via lanthandine ions, especially europium (red emission) and terbium (green emission) trivalent ions, induced supramolecule assembly .…”

Self-healing, luminescent metallogelation driven by synergistic metallophilic and fluorine–fluorine interactions

“…[23][24][25][26][27] Metallogels contain metal components and organic components with appropriate binding sites. Low molecular weight organic ligands, biopolymers and synthetic polymers having functional groups such as carboxylic acid, amines, thiols and alkynes have been used as coordination sites for a diverse range of mono-, di-, and trivalent metal ions (Ag + , Fe 2+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Pd 2+ , Pt 2+ , Fe 3+ , and Au 3+ ), metal clusters or nanoparticles, [28][29][30][31] wherein a combination of metal chelation and other non-covalent interactions such as H-bonding, van der Waals interaction, electrostatic interaction, p-stacking and metallophilic interactions has been explored to achieve hierarchical self-assembly. [32][33][34] Metallogels involving low molecular weight organic ligands result in discrete coordination complexes or coordination polymerization upon complexation.…”