Andrea M. Goforth

The first ‘two-over/two-under’(2O/2U) 2D weave structure assembled from Hg-containing 1D coordination polymer chains

Self-assembly of HgI2 with a semirigid ditopic ‘Z’ type ligand affords the zigzag chains that interweave into a clothlike 2D network in a ‘two-over/two-under’ (2O/2U) fashion.

Surfactant-free hybridization of transition metal oxide nanoparticles with conductive graphene for high-performance supercapacitor

In order to improve specific capacitance and limit electrical resistance, high-quality exfoliated graphene decorated with transition metal (Fe, Mn, Co) oxide nanoparticles (NPs) has been successfully synthesized without the use of surfactantvia a simple, general, environmentally-friendly chemical process. The specific capacitance of as-prepared graphene/Mn3O4 composite reach 239.6 F/g, when employed as the anode material in neutral NaCl electrolyte solutions (cf. 98.2 F/g for pristine graphene and 141.4 F/g for pure Mn3O4 NPs), which indicate the synergetic effects from both graphene and attached Mn3O4 NPs. Moreover, the high conductivity of graphene eliminates the need for conductive carbon black as fillers. The current density of graphene/Mn3O4 reached as high as 4.5 A g−1 which is much higher than that of graphene oxide (GO) or reduced GO-based composites. This significant enhancement of capacitance and current density was attributed to the surfactant-free approach to hybridize graphene with transition metal oxide NPs, the excellent conductivity of pristine graphene combined with its large surface area, as well as a uniform distribution of NPs on the clean surface of conductive graphene. Thus the low-toxicity, inexpensive graphene-based hybrids show promising utility as high current density electrode materials for supercapacitor applications.

Synthesis, X-ray Opacity, and Biological Compatibility of Ultra-High Payload Elemental Bismuth Nanoparticle X-ray Contrast Agents

Inorganic nanoscale X-ray contrast agents (XCAs) offer many potential advantages over currently used intravascular molecular contrast agents, including longer circulation and retention times, lower administration volumes, and greater potential for site directed imaging. Elemental bismuth nanoparticles (BiNPs) are particularly attractive candidate XCAs due to the low cost, the high atomic number and high density of bismuth, and the likelihood that BiNPs will oxidatively decompose to biocompatible bismuth(III) ions at controlled rates for renal excretion. Herein we describe the synthesis of ultrahigh payload BiNPs in 1,2-propanediol using a borane reducing agent and glucose as a biocompatible surface stabilizer. Both synthetic solvent (1,2-propanediol) and surfactant (glucose) are evident on the BiNP surfaces when analyzed by 1H NMR and FT-IR spectroscopies. These particles contain ∼6 million Bi atoms per NP and have large inorganic cores (74 nm by TEM) compared to their hydrodynamic size (86 nm by DLS). Thus, the dense BiNP core constitutes the majority (∼60%) of each particle’s volume, a necessary property to realize the full potential of nanoscale XCAs. Using quantitative computed tomography in phantom and in vitro imaging studies, we demonstrate that these BiNPs have greater X-ray opacity than clinical small molecule iodinated contrast agents at the same concentrations. We furthermore demonstrate a favorable biocompatibility profile for these BiNPs in vitro. Altogether, these studies indicate that these ultrahigh payload BiNPs, synthesized from known biocompatible components, have promising physical and cytotoxicological properties for use as XCAs.

[Co(phen3)]2[Cu11I15]: a mixed-metal iodocuprate containing the novel [Cu10I15]5− and [Cu12I15]3−clusters

A new mixed-metal compound, [Co(phen3)]2[Cu11I15] (phen = 1,10-phenanthroline), containing the two novel copper(I) iodide anionic clusters [Cu10I15]5− and [Cu12I15]3−, has been synthesized solvothermally and structurally characterized by single crystal X-ray diffraction. The synthesis and structures of the two clusters are presented and the extensive edge-to-face and offset face-to-face interactions between the [Co(phen3)]2+ cations are described.

Synthesis and crystal structure of the two-dimensional coordination polymer catena(bis(μ3-iodo)-(μ 2-pyrazine)-di-copper(I))

AbstractThe two-dimensional coordination polymer [Cu2i2(pyz)]n (where pyz = pyrazine) has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction analysis. [Cu2i2(pyz)]n crystallizes in the space group P

Mapping of Defects in Individual Silicon Nanocrystals Using Real- Space Spectroscopy

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Synthesis and crystal structure of catena-poly[Rh2(OAc)4(C27H15N3)]⋅2CH2CL2, a novel Rh(II) organic/inorganic coordination polymer

with a = 4.1759(4) Å, b = 7.1281(7) Å, c = 8.1279(8) Å, α = 109.607(2)○, β = 101.769(2)○, γ = 96.676(2)○, and Z = 1. The sheet-like polymer is characterized by infinite “stair step” [Cu2i2]n double chains connected in two dimensions through bridging pyrazine ligands. The coordination environment about each copper is approximately tetrahedral having three Cu–I bonds and a single Cu–N bond.

Aerobic method for the synthesis of nearly size-monodisperse bismuth nanoparticles from a redox non-innocent precursor

To improve the performance of graphene and to extend its potential applications, one of the most effective efforts is to hybridize graphene with one or more metal/metal oxide nanocrystals (NCs). In this paper, we demonstrate the complementary techniques of X-ray diffraction, high resolution electron microscopy (HREM), energy-dispersive X-ray spectroscopy (EDX), and energy-filtered transmission electron microscopy (EFTEM), which enables us to optimize the synthetic conditions, improve the quality of attached NCs, and tailor the performance of graphene-based hybrids for green energy related applications. Specifically, we explored the EFTEM technique to characterize two graphene-based composites. For the first sample of graphene/CoO(x), we present how the oxygen elemental map can identify that the oxidization of attached cobalt NCs most likely occurred during post treatments, rather than during the solvothermal reaction; for the second sample of graphene/(Mn, Co, Ni)O(x), we demonstrate how two-dimensional elemental mapping can differentiate the distribution of Mn, Co, and Ni on the surface of graphene. The results indicate that the EFTEM technique can supply very valuable and indispensable information, which contributes to comprehensive evaluation of structure and performance of graphene based hybrids.