title: Thixotropic hydrogel derived from a product of an organic solid-state synthesis: properties and densities of metal-organic nanoparticles.
abstract: Metallogels form from Cu(II) ions and tetratopic ligand rctt-1,2-bis(3-pyridyl)-3,4-bis(4-pyridyl)cyclobutane. The tetrapyridyl cyclobutane has been synthesized in the organic solid state. The gel forms with a variety of counteranions and gels water. The hydrogel is thixotropic and is composed of nanoscale metal-organic particles (NMOPs), a high surface area of which likely accounts for the gelation of the polar aqueous medium. A shear stress profile of the thixotropic hydrogel gave a yield value of 8.33 Pa. A novel combination of atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) is used to assess the densities of individual NMOPs. A density of 1.37 g/cm(3) has been determined. A single-crystal X-ray diffraction study demonstrates the ability of the unsymmetrical cyclobutane 3,4'-tpcb to self-assemble with Cu(II) ions in [Cu(2)(hfac)(4)(3,4'-tpcb)](∞) (where hfac is hexafluoroacetylacetonate) to form a solvated 1D coordination polymer.
authors.affiliation: Department of Chemistry, 305 Chemistry Building, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, United States.
authors.forename: Tamara D
authors.initials: TD
authors.lastname: Hamilton
authors.forename: Dejan-Krešimir
authors.initials: DK
authors.lastname: Bučar
authors.forename: Jonas
authors.initials: J
authors.lastname: Baltrusaitis
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Flanagan
authors.forename: Yingjian
authors.initials: Y
authors.lastname: Li
authors.forename: Suman
authors.initials: S
authors.lastname: Ghorai
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Tivanski
authors.forename: Leonard R
authors.initials: LR
authors.lastname: MacGillivray
mesh_terms: D003300:Copper / Q000737:chemistry*; D003503:Cyclobutanes / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D017348:Microscopy, Electron, Scanning Transmission; D009942:Organometallic Compounds / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D014961:X-Ray Diffraction
chemical_list: D003503:Cyclobutanes; D008024:Ligands; D009942:Organometallic Compounds; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D003300:Copper