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The self-consistent-charges density-functional tight-binding (SCC-DFTB) method is used to investigate the behavior of ammonium cyanate in the solid state under high pressure. The results have shown that the transformation of ammonium cyanate into urea is strongly exothermic.

The complete determination of an early-generation dendrimeric material was carried out directly from powder X-ray diffraction data using the direct space genetic algorithm technique for structure solution followed by Rietveld refinement. The success of this new technique paves the way for the future application of this approach to enable complete structure determination of other dendritic materials that cannot be prepared as single crystal samples suitable for single crystal X-ray diffraction studies.

Confocal Raman microspectrometry is used to study the C-Br stretching band for the gauche end-group conformation of the 1,8-dibromooctane guest molecules, allowing an assessment of possible changes in the conformational properties of the guest molecules as a consequence of the exchange process. The wider implications are discussed in relation to fundamental aspects of the molecular transport process in the crystalline solid.

Solid-State (super 13)C NMR and (super 2)H NMR techniques are used to investigate structural and dynamic properties of hydrogen-bonded complexes or sheets, inclusion compound and pure crystalline phase of urea. Ribbons of urea molecules alternating with ribbons of alpha,omega-dicyanoalkane molecules are present within each sheet.

Dynamic properties of the hydroxyl groups in a selectively deuterated sample of triphenylsilanol (Ph3SiOD) are studied using variable-temperature solid-state (super 2)H NMR spectroscopy. The crystal structure of triphenylsilanol contains eight crystallographically independent molecules, which are arranged in two tetrameric building units.

Research was conducted to examine the structural characterization of the hydrogen-bonding arrangement in triphenylmethanol via single-crystal neutron diffraction, single-crystal X-ray diffraction and high-resolution solid-state 13C NMR spectroscopy. An accurate determination of the positions of the hydrogen atoms in the hydrogen-bonding arrangement was obtained by the single-crystal neutron diffraction experiments while the single-crystal X-ray diffraction experiments have extended previous studies across a wider temperature range. The high-resolution solid-state 13C NMR experiments have provided insights into local structural aspects of the hydrogen-bonded tetramers.

Ion association affects conductivity of aqueous electrolyte solutions. The electrolyte behaves as an ideal solution if ions are far enough apart to keep Coulombic interactions negligible. The interactions between ions increase as the average distance between the ions decreases and the solution is less and less ideal. Molar conductivity is related to the conductivity and the stoichiometric concentration. Students with little practical experience can do a simple conductance equipment experiment with magnesium sulfate. They can compare results with those the Fuoss-Onsager and Onsager equations would make predictable.

The energy obstacles for a 'chair-chair' ring inversion mechanism, that was shown by temperature-dependent variations in high-resolution solid state C NMR spectra of thiourea inclusion compounds to take place in monosubstituted cyclohexane guest molecules within the thiourea tunnel, were identified. The NMR spectra recorded in slow exchange settings directly established the comparative populations of the axial and equational conformers of the guest molecules. The equational conformer is found primarily in guest molecules with X = CH3, NH2 and OH, while the axial conformer is found primarily in those with X = Cl, Br and I.

A study was done on a double tert-butyl group rotation using a combination of solid state 13C CP/MAS NMR techniques. Results of internal molecular motion obtained by this method were consistent with line shape analysis findings. Large anisotropic displacement parameters observed for the tert-butyl carbons in cis-4-tert-butyl-1-(tert-butylsulfonyl)cyclohexane was found to arise from the rotation of tert-butyl groups.

A study is conducted to demonstrate that the structure of ammonium cyanate, the NH(sub 4)(super +) cations form N-H...N hydrogen bonds to four cyanate N atoms at laternate corners of a distorted cube. To understand the nature of the transformation of ammonium cynate into urea, knowledge of the crystal structure of ammonium cynate is necessary.

The article presents a newly developed technique, which employs the cross-polarization magic angle spinning (CPMAS) NMR spectroscopy for in situ solid-state analysis of crystallization from solution. The approach is shown to be extremely helpful in studying the evolution and properties of the solid-state structures that are produced during crystallization.

The nature of glycine-glycine interactions in aqueous solution is studied by using molecular dynamics simulations at four different concentrations. The different aspects of the clustering of glycine molecules are examined as a function of both temperature and concentration and the aspects of the lifetimes of glycine-glycine hydrogen bonding are examined by means of hydrogen-bond correlation functions.

The article discusses a newly developed technique, called the residue-based charge flipping (RBCF), which is used to carry out the structure solution from X-ray diffraction data. Results concluded RBCF algorithm to be extremely effective, as it do not require the specification of a positive threshold electron density value.

A newly developed method is used for in situ solid-state NMR studies of adsorption processes, in order to map the structural evolution of water adsorbed in nanoporous voids within a widely used siliceous host material known as MCM-41. The studies have described the kinetics of the adsorption process, including the discovery that the adsorption has occurred in two well-defined regimes corresponding to an initial regime of rapid adsorption and a subsequent regime of slower adsorption.

Confocal Raman microspectrometry is used for probing the kinetic aspects of the guest exchange process in a urea inclusion compound. The transport of the new pentadecane guest molecules along the tunnel has displayed a linear dependence on time, with the rate of the process in the region of 70-100 nm [s.sup.-1].