Electron affinity and redox potential of tetrafluoro-p-benzoquinone: A theoretical study

The electron affinity of tetrafluoro-p-benzoquinone (2.69 eV) and the mono- (2.10 eV), 2,3-di- (2.29 eV), 2,5-di- (2.28 eV), 2,6-di- (2.31 eV) and tri- (2.48 eV) fluoro derivatives of p-benzoquinone have been calculated via standard ab initio molecular orbital theory at the G3(MP2)-RAD level of theory. Comparison of calculated electron affinities with the available experimental values shows excellent agreement between theory and experiment. The reduction potential of tetrafluoro-p-benzoquinone in acetonitrile vs. SCE (−0.03 V) has been calculated at the same level of theory and employing a continuum model of solvation (CPCM), and is also in excellent agreement with the experimental value (−0.04 V vs. SCE).     

Excess Molar Volumes, Excess Molar Enthalpies and Excess Isentropic Compressibilities of 1-Methyl Pyrrolidin-2-one with Water and Propanols

Excess molar volumes V ^E, excess molar enthalpies H ^E, and speeds of sound u for 1-methyl pyrrolidin-2-one (1) + water or propan-1-ol or propan-2-ol (2) binary mixtures have been measured over the entire composition range (at 308.15 K) using a dilatometer, calorimeter and interferometer. Speeds of sound data, u, of (1 + 2) binary mixtures have been utilized to determine excess isentropic compressibilities, $ \kappa_{S}^{\text{E}} $ . The observed V ^E, H ^E and $ \kappa_{S}^{\text{E}} $ data have been analyzed in terms of (1) Graph theory (which involves the topology of the constituents of mixture), and (2) the Prigogine–Flory–Patterson theory. Analysis of V ^E data in terms of Graph theory suggests that 1-methyl pyrrolidin-2-one, water, propan-1-ol, and propan-2-ol exist as associated molecular entities. IR studies lend additional support to the proposed molecular entities in (1 + 2) mixtures. It has been observed that V ^E, H ^E and $ \kappa_{S}^{\text{E}} $ values predicted by Graph theory compare well with their corresponding experimental values.     

Topological analysis of eigenvectors of the adjacency matrices in graph theory: The concept of internal connectivity

The topological properties of eigenvectors of adjacency matrices of a graph have been analyzed. Model systems studied are n-vertex-m-edge (n-V-m-E) graphs where n = 2–4, m = 1–6. The topological information contained in these eigenvectors is described using vertex-signed and edge-signed graphs. Relative ordering of net signs of edge-signed graphs is similar to that of eigenvalues of the adjacency matrix. This simple analysis has also been applied to naphthalene, anthracene and pyrene. It provides a sound basis for the application of graph theory to molecular orbital theory.     

Synthesis,crystal structures and photoluminescence of 7-(N,N′-diethylamino)-3-phenylcoumarin derivatives

Two new coumarin derivatives, 7-(N,N′-diethylamino)-3-(4-hydroxyphenyl)-coumarin and 7-(N,N′-diethylamino)-3-(4-bromophenyl)-coumarin, were synthesized successfully. Their structures were verified by single crystal X-ray crystallography. The UV–vis absorption and fluorescence of the compounds were discussed. The compounds exhibit strong blue emission under ultraviolet light excitation. The molecular structures, the lowest energy transitions and the UV–vis spectra of 7-(N,N′-diethylamino)-3-(4-hydroxyphenyl)-coumarin and 7-(N,N′-diethylamino)-3-(4-bromophenyl)-coumarin have been studied with density functional theory (DFT) and time-dependent density functional theory (TD-DFT) at B3LYP/6-31G(d) level.     

Theoretical study of the potential energy surface for CH3 and CH4 losses from ethyltoluenes

The decomposition of o-, m-, and p-ethyltoluene has been studied by density functional theory. It was found that monomolecular homolytic methyl loss from ethyl moiety seems to be the most favorable mechanism than other proceeding through ethyl, ring-methyl and hydrogen loss. Two possible channels of methane elimination from o-ethyltoluene were studied at B3LYP/6-311++G(df,p) level of theory.     

Studies with inorganic precipitative membranes: XI. Membrane potential response,characterization and evaluation of effective fixed charge density

Membrane potentials arising across parchment supported nickel and cobalt phosphate membranes when they separete 1:1 electrolyte solutions of concentration c₁ and c₂ such that c₁=10 c₂, have been measured. The membranes in contactwith dilute solutions have been found to carry a negative charge whereas the charge reversal was observed when the membrane was separating concentrated solutions. The membrane potential data have been used according to the procedure prescribed by Teorell-Meyer-Sievers theory (the TMS theory) to derive the value of effective fixed charge density of membranes. The electrical double layer at the membrane-solution interface has been suggested to control the over all rate of diffusion.     

Structures and binding energies of the (dibenzoylmethanato)boron difluoride complexes with aromatic hydrocarbons in the ground and excited states. Density functional theory calculations

Structures of the (dibenzoylmethanato)boron difluoride molecule (DBMBF2) and its complexes with a series of aromatic hydrocarbons (benzene; toluene; o-, m-, and p-xylenes, naphthalene; anthracene; and pyrene) in the ground and the first singlet excited states have been calculated. The calculations have been performed by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) for the ground and excited states, respectively, with the empirical dispersion correction. It has been shown that the complexes in the ground and excited states have similar stacking structures and are characterized by short contacts between the F atom of DBMBF2 and H atoms of the hydrocarbon molecule, which decrease on transition from the ground to the excited state. The calculated binding energies in the complexes in the excited state are two to three times higher than those in the ground state. The charge transfer in the ground state of the complexes is insignificant and directed from DBMBF2 to the ligand, while in the excited state it is 0.6–0.8 e and directed from the ligand to DBMBF2.     

Microviscosity effects on the vibrational relaxation rates in molecular liquids

The isotropic Raman band of the CO stretching mode of the N,N-dimethylformamide (DMF) molecule has been studied as a function of solvents' hydrodynamic properties. The effect of solvent viscosity on linewidth (Γ_iso) has been studied in detail, particularly using the theory of microviscosity. Modifications have been made in the ƒ(ϱ, η, n) parameter which relates the vibrational relaxation rate with viscosity, density and dispersion energy on the basis of microviscosity.     

The elastic strain energy of crystallographic shear planes in reduced tungsten trioxide

The elastic strain energy in reduced tungsten trioxide, which contains crystallographic shear (CS) planes, has been calculated using Fourier transform theory. This allows the effects of non nearest-neighborCS planes to be evaluated, and also enables one to assess the relaxation energy of ions in theCS planes as well as the strain energy of the matrix between theCS planes. The results are presented for{10m} (2 ? m ? 7) and {001}CS plane types. They are compared with experimental data and also with the results of previous calculations using classical elasticity theory.     

Studies on the temperature dependence of isotope effects arising in low-temperature acetaldehyde photolysis

The temperature dependence of hydrogen isotope effects arising in the photolysis of mixtures of acetaldehyde-h₄ and -d₄ has been studied experimentally. The temperature maximum of these effects (ξ = 40 at T 27 K) has been found. Good agreement of theory and experiment has been obtained in the approximation of strong exciton-phonon coupling.     

Limitations,mechanism and understanding of the origins of stereocontrol in (S)-dimethylsulfonium-(p-tolylsulfinyl)methylide-mediated epoxidation reactions

The reaction of the (S)-dimethylsulfonium-(p-tolylsulfinyl)methylide with aldehydes gave α,β-epoxy sulfoxides with high enantioselectivity and diastereoselectivity dependent on the aldehyde. The mechanism of the ‘model’ reactions [ylide substituted with Me S(O) or Ph S(O) with MeCHO or PhCHO] has been studied in detail using density functional theory.     

Electrochemical synthesis of 2-arylimino-4,5-di(2-furyl)-1,3-dioxoles and (E)-1,2-di(2-furyl)vinylene bis(N-arylchloroformimidates). HF and B3LYP computational study of the topomerization mechanism of aryliminodioxoles

Cathodic reductions of 2,2′-furils in the presence of N-arylcarbonimidoyl dichlorides lead to 2-arylimino-4,5-di(2-furyl)-1,3-dioxoles in high yields, along with minor amounts of (E)-1,2-di(2-furyl)vinylene bis(N-arylchloroformimidates). HF and B3LYP density functional theory methods have been applied to the determination of molecular geometries and to study the topomerization mechanism of aryliminodioxoles. The molecular structure of (E)-1,2-di(2-furyl)vinylene bis[N-(2-chloro-4-methylphenyl)chloroformimidate] has been determined by X-ray crystallography and compared with the calculated structure.     

Optical constants of monoclinic anisotropic crystals: Orthoclase

The optical constants of the monoclinic crystal orthoclase [ideal composition 4(KAlSi₃O₈)] have been derived in the i.r. region of the spectrum by the use of dispersion theory. Values for the E||b orientation and for the a—c plane have been used, together with a theory of the emittance of particulate materials, to simulate the spectrum of orthoclase powder.     

Novel Triazole Thiole ligand and some of its metal chelates: Synthesis,structure charactertization,thermal behavior in comparison withcomputational caculations andbiological activities

Structural and molecular properties of HL, 4-amino-5-(2,2-dichloro-1-methylcyclopropyl)-4H-1,2,4-triazole-3-thiol toward the transition metal ions namely Fe(III), Co(II) and Ni(II) had been studied using elemental analyses, magnetic, electronic, FT- IR, ¹H-NMR and Thermal analyses (TGA and DTA). The interpretation of thermal decomposition stages had been evaluated. The computations had been done by software of Gaussian 09W package. The geometries of triazole-thiole ligand and its metal chelates were fully optimized using density functional theory B3LYP method. (DFT)/GENECP level by implementing Def2TZVP basis set was used for Fe, Co and Ni-atoms; and basis set 6-311++G (d, p) was used for remainder atoms. There are no symmetry constrains had been applied during geometry optimization. The mixed basis set was selected due to its flexibility. HOMO and LUMO energy values for chelates, chemical hardness and electronegativity had been calculated. NBO calculations had been done at the same level using (NBO 3.1) program involved in the software of Gaussian 09W for measurement qualitatively the intra-molecular delocalization in systems under investigation. The first 15, 85, 65 and 65 low-lying excited states for ligand and Fe, Co and Ni chelates respectively had been calculated within the vertical linear-response. TD-DFT approximation at the same level of theory was used to calculate the electronic absorption spectra of the studied compounds. Their structures are confirmed by successful correlation between experimental and theoretical calculations. The ligand and its metal chelates had been examined against two bacteria such as Gram-positive (Staphylococcus aureus ATTC 12600), GraM–Negative (Escherichia coli ATTC 11775) and two fungus (Aspergillus flavus and Candida albicans) and molecular docking using Auto Dock tools were utilized.     

Theoretical study of tricarbonyliron complexes of para-quinodimethane and related conjugated hydrocarbons

The tricarbonyliron complexes of para-quinodimethane and related conjugated hydrocarbons have been studied by semi-empirical methods. The observed geometrical structure for bis(tricarbonyliron)-para-quinodimethane is rationalized in terms of simple Hückel theory.     

Magnetic circular dichroism spectra and electronic spectra of 4,5-benzotropone and thiopheno[c]tropone

Magnetic circular dichroism (MCD) and absorption spectra of 4,5-benzotropone and thiopheno[c]tropone have been measured. The n→π* forbidden transitions of both compounds are assigned by using the theory of Seamans et al. [J. Am. chem. Soc. 94, 6464 (1972)].     

DFT and experimental study on the IR spectra and structure of 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) and its oxyanion

The structure of o-vanillin molecule and its oxyanion have been studied by density functional theory (DFT), employing the B3LYP functional and 6-311++G** basis set. All conformational isomers of o-vanillin and of its anion have been located and their relative energies have been determined. The IR spectral changes, caused by the conversion of the molecule into the corresponding oxyanion have been studied. In a general agreement between theory and experiment, the conversion causes a frequency decrease of the carbonyl stretching band ν(CO) and essential intensity increases of the aromatic skeletal bands as well as methyl stretching band ν(CH₃). According to the NBO electric charge analysis, the oxyanionic center bears 60% of the whole anionic net charge.     

Deformation homogene et plastique du poly(ethylene-terephthalate) amorphe

The drawing behaviour of amorphous poly(ethylene-terephthalate) has been undertaken at temperature (i) T = 80° (homogeneous deformation); (ii) T = 20° (plastic deformation); (iii) and two stage drawing: homogeneous drawn at T = 80° followed by cold drawing at T = 20°.The results (birefringence, draw ratio-shrinkage force) are discussed in term of the gaussian theory of rubber elasticity and the Mooney-Rivlin equation.     

Fries rearrangement of dibenzofuran-2-yl ethanoate under photochemical and Lewis-acid-catalysed conditions

The Fries rearrangement of dibenzofuran-2-yl ethanoate as a route to o-hydroxyacetyldibenzofurans has been investigated, both under thermal Lewis-acid catalysed and non-catalysed photochemical conditions. The reactions were examined theoretically at semi-empirical (PM3 and ZINDO/S) and density functional theory (DFT) levels. The correct selection of reaction conditions provides viable preparative routes to ortho-acylated hydroxydibenzofurans.