The COMPASS force field: parameterization and validation for phosphazenes

Carbon dioxide capture from point sources like coal-fired power plants is considered to be a solution for stabilizing the CO(2) level in the atmosphere to avoid global warming. Methane is an important energy source that is often highly diluted by nitrogen in natural gas. For the separation of CO(2) and CH(4) from N(2) in flue gas and natural gas, respectively, sorbents with high and reversible gas uptake, high gas selectivity, good chemical and thermal stability, and low cost are desired. Here we report the synthesis and CO(2), CH(4), and N(2) adsorption properties of hierarchically porous electron-rich covalent organonitridic frameworks (PECONFs). These were prepared by simple condensation reactions between inexpensive, commercially available nitridic and electron-rich aromatic building units. The PECONF materials exhibit high and reversible CO(2) and CH(4) uptake and exceptional selectivities of these gases over N(2). The materials do not oxidize in air up to temperature of 400 °C.

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Porous covalent electron-rich organonitridic frameworks as highly selective sorbents for methane and carbon dioxide

Poly(organophosphazene)s and related compounds: Synthesis, properties and applications

A Porous Crystalline Molecular Solid Explored by Hyperpolarized Xenon

To establish force-field-based (molecular) modeling capability that will accurately predict condensed-phase thermophysical properties for materials containing aliphatic azide chains, potential parameters for atom types unique to such chains have been developed and added to the COMPASS force field. The development effort identified the need to define four new atom types: one for each of the three azide nitrogen atoms and one for the carbon atom bonded to the azide. Calculations performed with the expanded force field yield (gas-phase) molecular structures and vibrational frequencies for hydrazoic acid, azidomethane, and the anti and gauche forms of azidoethane in good agreement with values determined experimentally and/or through computational quantum mechanics. Liquid densities calculated via molecular dynamics (MD) simulations were also in good agreement with published values for 13 of 15 training set compounds, the exceptions being hydrazoic acid and azidomethane. Of the 13 compounds whose densities are well simulated, nine have experimentally determined heats of vaporization reported in the open literature, and in all of these cases, MD simulated values for this property are in reasonable agreement with the published values. Simulations with the force field also yielded reasonable density estimates for a series of 2-azidoethanamines that have been synthesized and tested for use as hydrazine-alternative fuels.

Development and validation of COMPASS force field parameters for molecules with aliphatic azide chains

Phosphorus-nitrogen compounds. 30. Synthesis of platinum derivatives of polymeric and cyclic phosphazenes

Phosphorus-nitrogen compounds. 26. Molecular motion and molecular separations in cyclophosphazene clathrates

Phosphorus-nitrogen compounds. 31. Crystal and molecular structure of a platinum-cyclophosphazene complex: cis-dichloro[octa(methylamino)cyclotetraphosphazene-N,N'']platinum(II)

Robert W. Allen

Papers

Phosphorus-nitrogen compounds. 30. Synthesis of platinum derivatives of polymeric and cyclic phosphazenes

Phosphorus-nitrogen compounds. 26. Molecular motion and molecular separations in cyclophosphazene clathrates

Phosphorus-nitrogen compounds. 31. Crystal and molecular structure of a platinum-cyclophosphazene complex: cis-dichloro[octa(methylamino)cyclotetraphosphazene-N,N'']platinum(II)

Conformational Analysis of Poly(dihalophosphazenes)

Conformational Analysis of Poly(alkoxy-and aryloxyphosphazenes)