Oxygen-vacancy dipoles and dimers in CaF2 crystals have been studied ab initio at DFT level and with the shell model using pair potentials. The calculated dipole reorientation barrier is 0.64 eV and the activation energy for diffusion of the dipoles is 1.61 eV. Optical absorption of O2--VA dipole have been calculated with TD DFT and identified with experimental absorption bands, which appeared ...

The synthesis of a new tetrabromobacteriochlorin BCBr4 is reported having the 3,4-dibromo-1H-pyrrole-2-carbaldehyde (10) as the major precursor. The BCBr4 was successfully employed in Pd cross-coupling reactions with methyl acrylate, phenyl acetylene and 4-ethynylanisole. In all three cases, the desired tetra-coupled products were obtained in good to excellent yields, and present a significant ...

The anti-inflammatory drug predinisolone (1) was reduced to 20β-hydroxyprednisolone (2) by the marine endophytic fungus Penicilium lapidosum isolated from an alga. The structural elucidation of 2 was achieved by 1D- and 2D-NMR, MS, IR data. Although, 2 is a known compound previously obtained through microbial transformation, the data provided failed to prove the C20 stereochemistry. To solve th...

Density Functional (DFT) and Time-Dependent Theory (TD-DFT) quantum chemical calculations were performed in order to gain deeper insight into the electronic structures of alkenylruthenium-triarylamine conjugates in their various accessible oxidation states. These compounds were experimentally scrutinized in their neutral, monoand dicationic states by infrared, UV/Vis/near-infrared and electron ...

Vibrational wavenumber assignments and geometrical parameters of single layer graphene (SLG) were investigated using density functional theory (DFT) with the basis set of 6-31G (d,p). The scaled vibrational assignments are found to be in good agreement with experimental values. The excitation energy, oscillator strength and wavelength were calculated using time dependent density functional theo...

The first luminescent cyclometallated platinum(II) complex bearing phosphinine co-ligands is reported. The long-lived luminescence, which it displays at 77 K, is assigned to a phosphinine-localised triplet excited state on the basis of electrochemical data and TD-DFT calculations.

The nature and magnitude of the optical gaps of rocksalt alkaline earth (MgO, CaO, SrO, MgS, MgSe) and transition metal chalcogenide (CdO, PbS) nanoparticles are studied using time-dependent density functional theory (TD-DFT) calculations on (MX)32 nanoparticles. We demonstrate, just as we previously showed for MgO, that TD-DFT calculations on rocksalt nanoparticles require the use of hybrid ex...

The size at which nonplanar isomers of neutral, pristine gold nanoclusters become energetically favored over planar ones is still debated amongst theoreticians and experimentalists. Spectroscopy confirms planarity is preferred at sizes up to Au7, however, starting with Au8, the uncertainty remains for larger nanoclusters. Au8 computational studies have had different outcomes: the planar D4h "cl...