Ricerc@Sapienza

Ettringite, reported with ideal formula Ca6Al2(SO4)3(OH)12·26H2O, is recognized as a secondary-alteration mineral and as an important crystalline constituent of Portland cements, playing different roles at different time scales. It contains more than 40 wt% of H2O. The crystal structure and crystal chemistry of ettringite were investigated by electron microprobe analysis in wavelength-dispersive mode, infrared spectroscopy, and single-crystal neutron diffraction at 20 K.

Seven 5-and 6-halogenated derivatives of uracil or 1-methyluracil (halogen = Cl, Br, I) were
studied by single crystal X-ray diffraction. In contrast with pure 5-halouracils, where the presence
of N-H…O and C-H…O hydrogen bonds prevents the formation of other intermolecular interactions,
the general ability of pyrimidine nucleobases to provide electron donating groups to halogen
bonding was confirmed in three crystals and cocrystals containing uracil with the halogen atom at

The effects that an increase of environmental pH has on the triple helix of scleroglucan (Sclg)
and on the Sclg/borax hydrogel are reported. Rheological experiments show that the hydrogel is less
sensitive to pH increase than Sclg alone, while at pH = 14 a dramatic viscosity decrease takes place for
both systems. This effect is evidenced also by the reduced water uptake and anisotropic elongation
detected, at pH = 14, by the swelling behaviour of tablets prepared with the Sclg/borax system.

High resolution, total neutron and X-ray scattering data have been used in synergy with Molecular Dynamics simulations to access atomistic scale insight into the structure of anisole and 2,3,5-trimethylanisole, two aromatic compounds bearing an electron-donating methoxy group. A detailed description is provided for the main interactions occurring in these systems, including π-π stacking and weak hydrogen bonding correlations: C–H⋯O and C–H⋯π.

A combined IRMPD and DFT study of the isomeric forms of protonated pyridoxine, pyridoxamine and pyridoxal has allowed to establish the spectroscopic and some peculiar structural features of these basic components of the vitamin B6 group in the gas phase, with the aim to offer a standpoint free from the environmental effects, which could help in understanding their behavior in the condensed phase typical of biological systems. The imine-enamine and the neutral-zwitterion tautomerism have been considered.