Relativistic all-electron two-component self-consistent density functional calculations including one-electron scalar and spin-orbit effects

We have implemented a Gaussian basis-set two-component self-consistent field method based on the fourth-order nuclear-only Douglas-Kroll-Hess approximation. Two-electron spin-orbit effects are included using Boettger's screened-nuclear spin-orbit approximation. In our two-component approach, the spin-orbit interaction is taken into account in a variational fashion employing a generalized Kohm-Sham scheme which allows one to work with hybrid density functionals. For open-shell systems we adopt the noncollinear spin-density approximation. Results are presented for equilibrium bond lengths, harmonic vibrational frequencies, and bond dissociation energies with local spin-density, generalized gradient approximation, and hybrid functionals in a set of benchmark molecules.     

Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Gas-phase enzymatic esterification on immobilized lipases in MCM-41 molecular sieves

Several lipolytic enzymes were immobilized in the pores of MCM-41 and Al-MCM-41 molecular sieves and used as catalysts in the gas-phase esterification of acetic acid with ethanol. The entrapment of enzymes depended on the molecular sieve and the type of enzyme used. The order of enzymatic activity for enzymes entrapped in the pores of MCM-41 and Al-MCM-41 in the esterification reaction was OF (Rhizopus niveus lipases)<FAP-15 (Rhizopus oryzae lipases)<LEX (Mucor javanicus lipases)<PS (Pseudomonas cepacia lipases)<AK (Pseudomonas fluorescens lipases). Experiments carried out between 298 and 318 K showed no effect of temperature on catalyst yield, suggesting that the enzymes were appropriately immobilized in the pores of the molecular sieves, thus avoiding possible processes such as denaturing or autolysis.     

Atomic and electronic structure of microclusters

The atomic and electronic structure of alkali metal, noble metal and Si_N (N=6,10) clusters examined theoretically are reviewed. On metal clusters, validity of the spherical jellium model is discussed by examining stabilization by multiplets formation and crystalline fields. In connection with the fragmentation of metal clusters, the shell correction of a largely deformed metal clusters is discussed by referring to Strutinsky's theory of nuclear fission. On the Si₆ and Si₁₀ clusters a large reconstruction theoretically found is discussed in terms of the interaction among dangling bonds. Finally, recent work on dynamical properties of clusters are briefly reviewed.     

Addition of activated olefins to cyclic N-acyliminium ions in ionic liquids

Organoindate(III) ionic liquid (BMI·InCl₄) was successfully employed in the nucleophilic addition of allyltrimethylsilane, silyl enol ethers and ketene silyl acetals to in situ generated cyclic N-acyliminium ions at room temperature without the need of an external Lewis acid. The corresponding α-substituted heterocycles were obtained in good yields and the recovered ionic liquid phase could be reused at least three times.     

Practical digest for evaluating the uncertainty of analytical assays from validation data according to the LGC/VAM protocol

The estimation of the measurement uncertainty of analytical assays based on the LGC/VAM protocol from validation data is fully revisited and discussed in the light of the study of precision, trueness and robustness.     

Tuning energy landscapes and metal–metal interactions in supramolecular polymers regulated by coordination geometry

Herein, we exploit coordination geometry as a new tool to regulate the non-covalent interactions, photophysical properties and energy landscape of supramolecular polymers. To this end, we have designed two self-assembled Pt(ii) complexes 1 and 2 that feature an identical aromatic surface, but differ in the coordination and molecular geometry (linear vs. V-shaped) as a result of judicious ligand choice (monodentate pyridine vs. bidentate bipyridine). Even though both complexes form cooperative supramolecular polymers in methylcyclohexane, their supramolecular and photophysical behaviour differ significantly: while the high preorganization of the bipyridine-based complex 1 enables an H-type 1D stacking with short Pt⋯Pt contacts via a two-step consecutive process, the existence of increased steric effects for the pyridyl-based derivative 2 hinders the formation of metal–metal contacts and induces a single aggregation process into large bundles of fibers. Ultimately, this fine control of Pt⋯Pt distances leads to tuneable luminescence—red for 1vs. blue for 2, which highlights the relevance of coordination geometry for the development of functional supramolecular materials.

In this article, we exploit coordination geometry as a new tool to control the energy landscape and photophysical properties (red vs. blue luminescence) of supramolecular polymers.     

Isolation of 1,2,3,4-tetrahydrobenzo[f]quinolin-2-ones on the reaction of 2-arylidenenaphthylamines with 4-hydroxycoumarin. IV

The reaction of 2-arylidenenaphtylamines with 4-hydroxycoumarin results in Hoffman-Martius type rearrangement yielding 2H-benzo[f][1]benzopyrano[4,3-b]quinolin-2-ones I and the compounds II. This work describes the structure elucidation of the compounds II. The structure was confirmed using ir, nmr and X-ray spectroscopy.     

E- and Z-vinyloxyboranes (alkenyl borinates): stereoselective formation and aldol condensation

Vinyloxyboranes, intermediates of Hooz' reaction, are almost exclusively $\text{E}$-isomers which can be isomerized to the $\text{Z}$-isomers. Both isomers undergo stereoselective aldol condensations.