Shape-responsive host-guest chemistry: metal-free tetracationic porphyrin nonplanarity promoted by clay mineral interactions assessed by theoretical simulations.

Distortions in the porphyrin core from planarity can trigger a unique structure-property relationship, imparting its basicity, chemical stability, redox potential, and excited-state energetics, among other properties. The colour change promoted by such distortion is signed by red shifts in its electronic absorption spectra. The adsorption of guest -substituted free-base porphyrin species onto inorganic hosts, such as clay minerals (layered aluminium or magnesium silicates), is known to further promote colour changes.

Pressure-Induced Phase Transformations of Quasi-2D SrHfO.

We present an abinitio study of the quasi-2D layered perovskite SrHfO compound, performed within the framework of the density functional theory and lattice dynamics analysis. At high temperatures, this compound takes a centrosymmetric structure (S.G.

Correlation of Interface Interdiffusion and Skyrmionic Phases.

Magnetic skyrmions are prime candidates for the next generation of spintronic devices. Skyrmions and other topological magnetic structures are known to be stabilized by the Dzyaloshinskii-Moriya interaction (DMI) that occurs when the inversion symmetry is broken in thin films. Here, we show by first-principles calculations and atomistic spin dynamics simulations that metastable skyrmionic states can also be found in nominally symmetric multilayered systems.

Folic acid and sodium folate salts: Thermal behavior and spectroscopic (IR, Raman, and solid-state C NMR) characterization.

Folic acid (FA; vitamin B9) and its associated sodium salts, strongly relevant for many scientific and technological applications - from nutrition to pharmacology and nanomedicine, suffer from a lack of characterization combining experimental and theoretical. In this work, a spectroscopic investigation of FA and its synthesized sodium salts in the form of dianion (NaHFol) or trianion (NaFol) was scrutinized in their solid state. The spectroscopic (infrared, Raman, and solid state C-nuclear magnetic resonance) data interpretation was supported by theoretical calculations using the Density Functional Theory (DFT).

Group Theory Analysis to Study Phase Transitions of Quasi-2D SrHfO.

We present an study performed in the framework of density functional theory, group-subgroup symmetry analysis and lattice dynamics, to probe the octahedral distortions, which occur during the structural phase transitions of the quasi-2D layered perovskite SrHfO compound. Such a system is characterized by a high-temperature centrosymmetric structure and a ground-state ferroelectric phase. We have probed potential candidate polymorphs that may form the → transition pathways, namely , , and .