Michela Brunelli

Temperature- and Pressure-induced Proton Transfer in the 1:1 Adduct Formed between Squaric Acid and 4,4 '-Bipyridine

We have applied a combination of spectroscopic and diffraction methods to study the adduct formed between squaric acid and bypridine, which has been postulated to exhibit proton transfer associated with a single-crystal to single-crystal phase transition at ca. 450 K. A combination of X-ray single-crystal and very-high flux powder neutron diffraction data confirmed that a proton does transfer from the acid to the base in the high-temperature form. Powder X-ray diffraction measurements demonstrated that the transition was reversible but that a significant kinetic energy barrier must be overcome to revert to the original structure. Computational modeling is consistent with these results. Modeling also revealed that, while the proton transfer event would be strongly discouraged in the gas phase, it occurs in the solid state due to the increase in charge state of the molecular ions and their arrangement inside the lattice. The color change is attributed to a narrowing of the squaric acid to bipyridine charge-transfer energy gap. Finally, evidence for the possible existence of two further phases at high pressure is also presented.

Crystal structure and phase transitions across the metal-superconductor boundary in the SmFeAsO 1 − x F x ( 0 ≤ x ≤ 0.20 ) family

The fluorine-doped rare-earth iron oxyarsenides

Mechanistic Insights into a Gas–Solid Reaction in Molecular Crystals: The Role of Hydrogen Bonding

{\text{REFeAsO}}_{1\ensuremath{-}x}{\text{F}}_{x}

Negative thermal expansion of ReO3 in the extended temperature range

(

Methane Adsorption in a Supramolecular Organic Zeolite

\text{RE}=\text{rare}

Zipping and Unzipping of a Paddlewheel Metal–Organic Framework to Enable Two‐Step Synthetic and Structural Transformation

earth) have recently emerged as a new family of high-temperature superconductors with transition temperatures

Rare Earth doped ceria: a combined X-ray and neutron pair distribution function study

({T}_{c})

A glass capillary cell for in situ powder X-ray diffraction of condensed volatile compounds. Solid HCFC-123a and HCFC-124.

as high as 55 K. Here we use high-resolution synchrotron x-ray diffraction to study the structural properties of

Influence of the Nd 4ƒ states on the magnetic behavior and the electric field gradient of the oxypnictides superconductors NdFeAsO1-xFx

{\text{SmFeAsO}}_{1\ensuremath{-}x}{\text{F}}_{x}