Metal films deposited over two-dimensional colloidal crystals (MFoCC) constitute a low-cost periodic structure with interesting photonic and plasmonic properties. It has previously been shown that this structure exhibits a behaviour similar to the well-known Extraordinary Optical Transmission (EOT) of metallic hole arrays in planar films. Here, we explore the transmission characteristics of AgFoCC by systematic comparison with that of the bare CC. Furthermore with additional reflectivity measurements we evaluate the AgFoCC overall plasmonic response, which, notably, exhibits a strong plasmon absorption band at wavelengths larger than those of the transmitted maximum. By corroborating these results with finite-difference time-domain electromagnetic simulations, we identify a hybrid metal-dielectric propagative mode in the transmission mechanism. On the contrary a strongly localized mode is responsible for the maximum light absorption by this structure. These results shed new light on the current understanding of this highly promising plasmonic structure, being useful for the design of surface-enhanced Raman scattering and enhanced fluorescence substrates.

We report results of a systematic Raman, SERS, and DFT study on four beta blocking molecules: Atenolol, Metoprolol, Propranolol, and, for the first time reported in the literature, Bisoprolol. The choice of these molecules was motivated by the structural similarities between Atenolol, Bisoprolol, and Metoprolol on one hand and by their differences relative to Propranolol. The density functional theory (DFT) approach, using the B3LYP method at the 6-311+G(d,p) level of theory, has been employed for geometry optimization and vibration bands assignments. The obtained results highlight the major role played by the central aromatic ring whose vibrations dominate the Raman spectra in all compounds. While the phenyl group vibrations dominate the Raman spectrum in the case of Atenolol, Bisoprolol, and Metoprolol, the spectrum of Propranolol presents high intensity vibrations of the naphthyl group. SERS performed on gold and silver colloids, at various pH conditions, revealed a higher sensitivity for Propranolol detection. The pH dependence of the spectrum indicates that the studied beta blockers attach themselves to the metal nanoparticles in a protonated form. The molecular adsorption geometry on metal nanoparticles surface has been evaluated by using the experimental SER spectra and the quantum chemical calculations.

Due to the presence of the carbonyl and imide groups in the structure of 5,5-diphenylhydantoin (DPH), the possibility for this compound to be involved in hydrogen bonding intermolecular interactions is obvious. Even though such interactions are presumably responsible for the mechanism of action of this drug, however, to the best of our knowledge, the self-hydrogen bonding interactions between the DPH monomers have not been addressed till now. Furthermore, studies reporting on the spectroscopic characteristics of this molecule are scarcely reported in the literature.Here we report on the possible dimers of DPH, investigated by quantum chemical calculations at B3LYP/6-31+G(2d,2p) level of theory. Twelve unique DPH dimers were structurally optimized in gas-phase, as well as in ethanol and DMSO and then were used to compute the population-averaged UV-Vis and NMR spectra using Boltzmann statistics. UV-Vis and NMR techniques were employed to assess experimentally the spectroscopical response of this compound. DFT calculations are also used to investigate the structural transformations between the solid and liquid phase, as well as for describing the electronic transitions and for the assignment of NMR spectra of DPH.

In this paper we report our experimental and theoretical studies on the effect of Gd impurity on the physical properties of the Heusler half-metallic ferromagnet Co 2 MnSi. The analysis of the band structures of the doped alloy shows that the half-metallic properties are completely conserved if Gd substitutes Mn atoms. This effect is not determined by the spin-orbit interaction, but through the coupling between the R(4f ) spin with the Mn(3d) itinerant electron spins. We evaluate the strength of such a coupling by calculating, in an ab initio fashion, the total energy of Co 16 GdMn 7 Si 8 compound for a parallel and antiparallel f -d coupling. The obtained magnetic moments of Co or Mn sites are in good agreement with the experimental ones.

The conformational changes of imatinib (IMT) are crucial for understanding the ligand-receptor interaction and its mechanism of action [Agofonov et al. (2014) Nature Struct Mol Biol 21:848-853]. Therefore, here we investigated the free energy conformational landscape of the free IMT base, aiming to describe the three-dimensional structures and energetic stability of its conformers. Forty-five unique conformers, within an energy window of 4.8 kcal mol −1 were identified by a conformational search in gas-phase, at the B3LYP/6-31G(d) theoretical level. Among these, the 20 most stable, as well as 4 conformers resulting from optimization of experimental structures found in the two known polymorphs of IMT and in the cAbl complex were further refined using the 6-31+G(d,p) basis set and the polarizable continuum solvation model. The most stable conformers in gas-phase and water exhibit a V-shaped structure. The major difference between the most stable free conformers and the bioactive conformers consists in the relative orientation of the pyrimidine-pyridine groups responsible for hydrogen bonding interactions in the ATP-binding pocket.The ratio of mole fractions corresponding to the two known (α and β) polymorphic forms of IMT was estimated from the calculated thermochemical data, in quantitative agreement with the existing experimental data related to their solubility. The electronic absorption spectrum of this compound was investigated in water and explained based on the theoretical TD-DFT results, considering the Boltzmann populationaveraged computed data at CAM-B3LYP/6-31+G(d,p) level of theory for the nine most stable conformers.