Self-assembled metallogels formed from N,N',N''-tris(4-pyridyl)trimesic amide in aqueous solution induced by Fe(III)/Fe(II) ions

• Published in: Soft matter Vol. 12; no. 1; pp. 191 - 199
• Main Authors: Zhong, Jin-Lian, Jia, Xin-Jian, Liu, Hui-Jin, Luo, Xu-Zhong, Hong, San-Guo, Zhang, Ning, Huang, Jian-Bin
• Format: Journal Article
• Language: English
• Published: England 07.01.2016
• Subjects: Amides; Amides - chemistry; Aminopyridines - chemical synthesis; Aminopyridines - chemistry; Aqueous solutions; Benzamides - chemical synthesis; Benzamides - chemistry; Cooling; Formations; Gels - chemistry; Heating; Hydrogen Bonding; Iron - chemistry; Metal ions; Organometallic Compounds - chemistry; Scanning tunneling microscopy; Spectra; Stress, Mechanical; Tricarboxylic Acids - chemistry
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/c5sm01513h

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.