Novel Supramolecular Thixotropic Metallohydrogels Consisting of Rare Metal–Organic Nanoparticles: Synthesis, Characterization, and Mechanism of Aggregation

Abstract

Even without obvious sticky sites, novel supramolecular thixotropic metallohydrogels consisting of rare metal–organic nanoparticles (MNPs) have been readily accessible from simple structured pincer-type terpyridine Cu(II) complexes at the gelator concentration as low as 0.25 wt %. The obtained soft materials have been fully characterized by using a combination of experimental techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), X-ray diffraction (XRD), high-resolution mass spectrometry (HR-MS), and rheology measurements. Based on these studies, hypothesized molecular assembly mechanisms for distinctly different morphologies observed in different solvents were proposed. Besides general heating–cooling gel preparation procedures, surprisingly, the metallohydrogel was formed by simply stirring the mixture of pincer ligand and Cu salts in water directly, further indicating thixotropic property and self-h...