Diporphyrinyl derivatives of 1,10-phenanthroline and 2,2′-bipyridyl

The title derivatives were synthesized containing two meso-tri-p-tolylpheneleneporphyrin units attached via amide bridges to 4, 7- and 4,4′ positions of the respective heteroaromatic spacers.     

Influence of Proton Chemical-Shift Anisotropy on Magic-Angle Spinning Spectra of Hydrate Crystals

It is shown that the proton chemical-shift anisotropy of hydrate crystals affect dipolar powder pattern at 7.0 T. This may be clearly observed via an asymmetric envelope of dipolar spinning sidebands in magic-angle spinning proton spectra.     

Chiral invariant Gross-Neveu model: Classical versus quantum

We present a unification of different and independently investigated aspects of the chiral invariant Gross-Neveu model. Special emphasis is placed on the relevance of classical (c-number, non Grassmann) spinor solutions of the G-N field equations for the construction, and thus understanding of the respective quantized Fermi model. To get an insight into the “quantum meaning of classical field theory” if specialized to the G-N case, we perform the path integral quantization procedure which first leads to the Fermi oscillator problem, and then, after appropriate generalizations, to the quantum Fermi G-N model. Path integrals are carried out with respect to c-number spinor paths only, and in fact no reference is necessary to the Grassmann algebra methods, which are conventionally used to integrate out fermions.     

The application of 13C and 1H NMR spectroscopy to the investigation of the dinitrogen fixation process in the system (η-C5H5)2TiCl2-Mg

The N₂ reduction reaction in the system (η-C₅H₅)₂TiCl₂-Mg in tetrahydrofuran was examined. The ¹³C and ¹H NMR results as well as the chemical properties of the products formed revealed that the reaction yielded a mixture of compounds in which the titanium atom was bonded both to the μ-(η⁵: η⁵-fulvalene) ligand and to the cyclopentadienyl ligands. In this system dinitrogen undergoes reduction to N^3?, which then forms M₃N bridges (M = Ti, Mg). The nitride nitrogen may readily be oxidized to imide nitride N^?1, which may react further, e.g. with carbon monoxide to produce isocyanates, or, with excess oxidizing agent N₂. THF in this system undergoes polymerisation. In addition, a ?OC₄H₉ alkoxy group is formed which makes the substitution of the cyclopentadienyl group bonded to the titanium atoms possible.     

Complexes of Schiff base of gossypol with n-butylamine and some monovalent or bivalent cations studied by ESI MS, NMR, FT-IR as well as PM5 semiempirical methods

A Schiff base of gossypol with n-butylamine [GSBN] was shown to be capable of complexation of 2H⁺, Li⁺, Ca²⁺ and Ba²⁺ cations. This process of complex formation was studied by ESI mass spectrometry, ¹H and ¹³C NMR and FT-IR spectroscopy as well as by PM5 semiempirical method. It was found that gossypol Schiff base can form a 1:2 complex with H⁺ and 1:1 complexes with Li⁺, Ca²⁺ and Ba²⁺ cations. In all complexes the Schiff base of gossypol with metal cations exists in enamine-enamine tautomer, whereas in the 1:2 complex with H⁺ the imine-imine tautomer was found. The metal cations are coordinated through oxygen atoms of the O₁H(O₁,H) hydroxyl groups and a lone pair of an N-atom. The structures of these complexes were calculated by PM5 semiempirical method and discussed.     

Fillable contact structures on torus bundles over circles

We will construct an example of a strongly symplectically fillable contact structure on a torus bundle over the circle with parabolic monodromy.

     

Monoexcited singlet states and conformation of some acylpyridines

Substituent effects on the UV-spectra of formyl-, acetyl- and benzoylpyridines are investigated. The UV-bands are discussed by comparison with the calculated energies and oscillator strengths of all planar and twisted 2-acyl-, 3-acyl- and 4-acyl derivatives using the SCF CI-1 method. The structure of each ¹π^* ← ¹π transition is determined from the contributions of the individual MO transitions and their LCAO characteristics. The conformation of acylpyridines is discussed.