Ionogels as Precursors to Prepare ZnS Nanoparticles for Colorimetric Sensing of Sulfide Ions

In this study, novel supramolecular ionogels with an ultrahigh efficient gelation and robust mechanical properties were prepared by mixing 4'-para-phenylcarboxyl-2,2':6',2"-terpyridine (PPCT) and zinc ions (Zn2+) in ethylammonium nitrate (EAN). The microstructure of the ionogels was determined to be three-dimensional (3D) networks of fibrous aggregates. X-ray diffraction and Fourier-transform infrared spectroscopy measurements demonstrated that ionogel formation involve the following steps: the terpyridine rings of PPCT form an assembled unit via π-π interaction, the unit further aggregates to form fibers using Zn2+ via the hydrogen bonding and Zn2+-coordination, and the fibers stretch and intertwine to form a cross-linked network to immobilize EAN by solvophobic interactions, electrostatic interactions, and van der Waals forces. Rheological results revealed that ionogels exhibited high mechanical strength with an elastic modulus and a yield stress of 50000 and 900 Pa, respectively. The ionogels of PPCT a...