Thixotropic Hydrogel Derived from a Product of an Organic Solid-State Synthesis: Properties and Densities of Metal-Organic Nanoparticles.

Metallogels form from Cu(II) ions and tetratopic ligand rctt-1,2-bis(3-pyridyl)-3,4-bis(4-pyridyl)cyclobutane. The tetrapyridyl cyclobutane was synthesized in the org. solid state. The gel forms with a variety of counteranions and gels water. The hydrogel is thixotropic and is composed of nanoscale metal-org. particles (NMOPs), a high surface area of which likely accounts for the gelation of the polar aq. medium. A shear stress profile of the thixotropic hydrogel gave a yield value of 8.33 Pa. A novel combination of at. force microscopy (AFM) and scanning transmission x-ray microscopy (STXM) is used to assess the densities of individual NMOPs. A d. of 1.37 g/cm3 was detd. A single-crystal x-ray diffraction study demonstrates the ability of the unsym. cyclobutane 3,4'-tpcb to self-assemble with Cu(II) ions in [Cu2(hfac)4(3,4'-tpcb)]∞ (hfac is hexafluoroacetylacetonate) to form a solvated 1-dimensional coordination polymer. [on SciFinder(R)]