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(E)-4-[(4-nitrophenyl)diazenyl]phenyl anthracene-9-carboxylate

Proposed for publication in Acta Crystallographica E.

Rodriguez, Marko A.; Zifer, Thomas Z.; Vance, Andrew L.; Wong, Bryan M.; Leonard, Francois L.

In the title compound, C{sub 27}H{sub 17}N{sub 3}O{sub 4}, the azo group displays a trans conformation and the dihedral angles between the central benzene ring and the pendant anthracene and nitrobenzene rings are 82.94 (7) and 7.30 (9){sup o}, respectively. In the crystal structure, weak C-H...O hydrogen bonds, likely associated with a dipole moment present on the molecule, help to consolidate the packing.

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TYPE Journal Article YEAR 2008
OSTI

Cupric siliconiobate. Synthesis and solid-state studies of a pseudosandwich-type heteropolyanion

Inorganic Chemistry

Anderson, Travis M.; Alam, Todd M.; Rodriguez, Marko A.; Bixler, Joel N.; Xu, Wenqian; Parise, John B.; Nyman, M.

The Na+ and [Cu(en)2(H2O) 2]2+ (en = ethylenediamine) salt of a pseudosandwich-type heteropolyniobate forms upon prolonged heating of Cu(NO3)2 and hydrated Na14[(SiOH)2Si2Nb 16O54] in a mixed water-en solution. The structure [a = 14.992(2) Å, b = 25.426(4) Å, c = 30.046(4) Å, orthorhombic, Pnn2, R1 = 6.04%, based on 25869 unique reflections] consists of two [Na(SiOH)2Si2Nb16O54]13- units linked by six sodium cations, and this sandwich is charge-balanced by five [Cu(en)2(H2O)2]2+ complexes, seven protons, and three additional sodium atoms (all per a sandwich-type cluster). Diffuse-reflectance UV-vis indicates that there is a λmax at 383 nm for the CuII d-d transition and the 29Si MAS NMR spectrum has two peaks at -78.2 ppm (151 Hz) and -75.5 ppm (257 Hz) for the two pairs of symmetry-equivalent internal [SiO4]4- and external [SiO3(OH)]3- tetrahedra, respectively. Unlike tungsten-based sandwich-type complexes, the [Na(SiOH)2Si 2Nb16O54]13- units are linked exclusively by Na+ instead of one or more d-electron metals. © 2008 American Chemical Society.

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TYPE Journal Article YEAR 2008
ScopusOSTIDOI

A beryllium dome specimen holder for XRD analysis of air sensitive materials

Powder Diffraction

Rodriguez, Marko A.; Boyle, Timothy J.; Yang, Pin Y.; Harris, Damon L.

A specially designed specimen holder employing a beryllium dome has been fabricated for collection of X-ray diffraction (XRD) data from highly reactive materials. The specimen holder has a robust O-ring type seal (< 10-9 Torr) and no observed intensity artifacts in the 1° to 150° 2θ range. The design also minimizes specimen displacement errors and allows for analysis of both powders and bulk specimens (i.e., pellets). The simple design makes for straightforward assembly of the holder within the confines of a glove box. XRD analysis of hygroscopic LaBr3 powders collected with this holder are suitable for Rietveld structure refinement, yielding unit cell lattice parameters of a=7.9703(6) Å and c=4.5122(6) Å cell volume= 248.44(6) Å3; Rp =7.70%. © 2008 International Centre for Diffraction Data.

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TYPE Conference YEAR 2008
ScopusOSTIDOI

In situ X-ray diffraction analysis of (CFx)n batteries: signal extraction by multivariate analysis

Journal of Applied Crystallography

Rodriguez, Marko A.; Nagasubramanian, Ganesan N.; Keenan, Michael R.

In this study, (CFx)n cathode reaction during discharge has been investigated using in situ X-ray diffraction (XRD). Mathematical treatment of the in situ XRD data set was performed using multivariate curve resolution with alternating least squares (MCR–ALS), a technique of multivariate analysis. MCR–ALS analysis successfully separated the relatively weak XRD signal intensity due to the chemical reaction from the other inert cell component signals. The resulting dynamic reaction component revealed the loss of (CFx)n cathode signal together with the simultaneous appearance of LiF by-product intensity. Careful examination of the XRD data set revealed an additional dynamic component which may be associated with the formation of an intermediate compound during the discharge process.

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TYPE Journal Article YEAR 2007
OSTIDOI
Results 76–100 of 118
Results 76–100 of 118