Reaction of CF3 radicals with H2S

Hydrogen abstration from H₂S by CF₃ radicals, generated by the photolysis of both CF₃COCF₃ and CF₃I, has been studied in the temperature range 314–434 K. The rate constant, based on the value of 10^13.36 cm³/mol · s for the recombination of CF₃ radicals, is given by with CF₃COCF₃ as the radical source, and with CF₃I as the radical source, where k₂ is in cm³/mol · s and E is in J/mol. These results resolve a previously existing controversy concerning the values of the rate constants for this reaction. They show that CF₃ radicals are less reactive than CH₃ radicals in attacking H₂S, and this behavior indicates that polar effects play a significant role in the hydrogen transfer reactions of CF₃ radicals.     

Double direct templating of periodically nanostructured ZnS hollow microspheres

We introduce a "double direct templating" method for obtaining hollow microspheres with periodically nanostructured walls. Silica or polystyrene colloids are dispersed in a self-assembled hexagonal lyotropic liquid crystal containing precursors for ZnS. The semiconductor ZnS mineralizes on the surface of the colloid, expressing a pore morphology that is a copy of the structure of the liquid crystal. After etching of the sacrificial colloids, hollow capsules with templated and uniform mesoporous shells are obtained.     

Propagation factors of Hermite–Gaussian beams in turbulent atmosphere

Based on the extended Huygens–Fresnel integral and the second-order moments of the Wigner distribution function, an analytical formulae for the propagation factors (M²-factors) of coherent and partially coherent one-dimensional Hermite–Gaussian beams in a turbulent atmosphere are derived. Evolution properties of the M²-factor of the Hermite–Gaussian beam in a turbulent atmosphere are studied numerically in detail. Our results show that the M²-factor of the Hermite–Gaussian beam increases upon propagation in a turbulent atmosphere. The M²-factor of the Hermite–Gaussian beam with larger beam order (or lower coherence) increases slower that of the Hermite–Gaussian beam with smaller beam order (or higher coherence) in a turbulent atmosphere, which means that the Hermite–Gaussian beam with a larger beam order and lower coherence is less affected by a turbulent atmosphere. Our results will be useful in long-distance free-space optical communications.     

Molecular structure, spectroscopic properties and DFT calculations of 2-(methylthio)nicotinic acid

The analyses of possible conformations, molecular structures, vibrational and electronic properties of 2-(methylthio)nicotinic acid molecule, C₇H₇NO₂S, with the synonym 2-(methylsulfanyl)nicotinic acid have been first presented theoretically. At the same time, FT-IR and micro-Raman spectra of 2-(methylthio)nicotinic acid were recorded in the regions 400–4000 cm^?1 and 100–4000 cm^?1, respectively. In our calculations, the DFTB3LYP method with 6–311G(d, p) basis set was used to have the structural and spectroscopic data about the mentioned molecule in the ground state and the results obtained were compared with experimental values. Furthermore, gauge invariant atomic orbital (GIAO) ¹H and ¹³C NMR chemical shifts in different solvents, UV-vis TD-DFT calculations, the highest occupied molecular orbitals (HOMO-2, HOMO-1, HOMO), lowest unoccupied molecular orbital (LUMO), molecular electrostatic potantial (MEP) surface, atomic charges and thermodynamic properties of molecule have been theoretically verified and simulated at the mentioned level. The energetic behavior of title molecule in different solvent media was investigated by using DFT/B3LYP method with 6–311G(d, p) basis set in terms of integral equation formalism polarizable continuum model (IEFPCM). In addition, the calculated infrared intensities, Raman activities, reduce masses and force constants of the compound under study have been also reported.     

Kaluza–Klein reduction of a quadratic curvature model

Palatini variational principle is implemented on a five dimensional quadratic curvature gravity model, rendering two sets of equations, which can be interpreted as the field equations and the stress-energy tensor. Unification of gravity with electromagnetism and the scalar dilaton field is achieved through the Kaluza–Klein dimensional reduction mechanism. The reduced curvature invariant, field equations and the stress-energy tensor are obtained in the actual four dimensional spacetime. The structure of the interactions among the constituent fields is exhibited in detail. It is shown that the Lorentz force density naturally emerges from the reduced field equations and the equations of the standard Kaluza–Klein theory are demonstrated to be intrinsically contained in this model.     

Crystal structure,spectroscopic characterization,DFT computations and molecular docking study of a synthesized Zn(II) complex

The Zn(II) complex, dichloro[N-hydroxy-1,1-di(2-pyridinyl)methanimine]zinc(II), was synthesized from the reaction between ZnCl₂ and di-2-pyridylketone oxime. The structural and spectral characterizations were performed by using single crystal X-ray diffraction, FT-IR, Laser-Raman, NMR and UV–Vis spectroscopic techniques. To support experimental evidences, computational results were obtained with the DFT/B3LYP method using the 6-311++G(d,p)+LanL2DZ mixed basis set. Theoretical analyses of some structural and spectroscopic results of effects of intermolecular Cl···H interactions in the crystal packing of the Zn(II) complex were investigated with the mentioned computational level. The non-bonding interactions in the experimental crystal packing of the complex were examined by Hirshfeld surface analysis. The HOMO and LUMO analyses were used for investigation of electronic transitions obtained with UV–Vis spectroscopy. NBO analyses were used to investigate the hyperconjugation interactions between donor and acceptor groups, coordination environment, electronic configuration and electron numbers of the Zn(II) metal ion and the natural atomic charges of the complex. The nucleophilic and electrophilic reactive sites of the complex were studied by MEP surface analysis. The static polarizabilities (α) and static hyperpolarizabilities (β) were analyzed theoretically to characterize NLO profile of the complex. The interaction with A-DNA (PDB ID: 1ZF6) of the Zn(II) complex was investigated with a molecular docking study.     

Novel C2-symmetric macrocycles bearing diamide-diester groups: synthesis and enantiomeric recognition for primary alkyl ammonium salts

We synthesized a series of novel macrocycles with diamide-diester groups (S,S)-1, (S,S)-2, (S,S)-3, and (R,R)-1, derived from dimethyloxalate and amino alcohols by high dilution technique, and evaluated enantiomeric recognition properties of these macrocycles toward primary alkyl ammonium salts by 1H NMR titration. Taking into account the host employed, important differences were observed in the Ka values of (R)-Am and (S)-Am for (S,S)-1 and (R,R)-1 hosts, KS/KR = 5.55 and KR/KS = 3.65, Delta Delta Go = 0.43 and -0.32 kJ mol-1, respectively. There seems a general tendency for the host to include the guests with the same absolute configuration.