Exchange reaction of perfluoroalkyl- and perfluorooxaalkylimidoylamidines

Conclusions It was found that exchange reaction takes place between N-(perfluorobutyrylimidoyl)perfluoropropyl-amidine and N-(perfluoro-2-methyl-3-oxahexylimidoyl)perfluoro-2-methyl-3-oxahexylamidine at temperatures where their thermal condensation to triazines still does not take place.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2784–2787, December, 1977.     

Structure of 1,4-dichloro-1,4-bis(perfluoroalkyl)-1,3-diazatetra-1, 3-dienes from their13C,19F,and15N NMR spectra

Previously unknown 1,4-dichloro-1,4-bis(perfluoroalkyl)-1,3-diazatetra-1,3-Dienes have been prepared and shown to be mixtures of isomers of Z and E configurations. The structures have been identified and a quantitative estimate made of the ratio of Z and E isomers using¹³C,¹⁹F, and¹⁵N NMR spectroscopy.     

Nanocomposite proton conductors containing mesoporous oxides as the promising fuel cell membranes

Composite proton-conducting electrolytes are synthesized based on H₄SiW₁₂O₄₀ · xH₂O, CsHSO₄, (CsH₂PO₄)_0.9(CsHSO₄)_0.1 and mesoporous matrices SBA-15 and MCM-41 and their transport and structural characteristics are studied. Composites based on silicotungstic acid demonstrate the conductivity from ～10^?3 to 10^?4 S/cm in the temperature range of 25–140°C at the increased partial pressure of water vapor. The conductivity of systems CsHSO₄-SBA-15 (at T = 140–200°C) and (CsH₂PO₄)_0.9(CsHSO₄)_0.1-SBA-15 (at T = 200–230°C) reaches 10^?2 S/cm and is independent of humidity. The electrolytes studied are promising as proton-exchange membranes of fuel cells operating at low and medium temperatures.     

TDDFT studies of electronic structure and first hyperpolarizability of terta-nuclear cubane-like transition metal clusters

The TDDFT method is first applied in a series of tetra-nuclear transition metal clusters studies for nonlinear optical properties. The results indicate that the charge transfer inside the metal core [MCu3X4] (M=W, Mo; X=S, O, Cl, Se, Br) makes contribution to the optical nonlinearity. It is possible to enhance the hyperpolarizability by substituting the ligands of the clusters.     

Mechanisms of molecular polarization of bithiophenesilane dendrimers in solutions

A number of consecutive generations of bithiophenesilane dendrimers and their precursors are studied by the methods of the equilibrium electro-optical Kerr effect, dielectric polarization, and absorption spectroscopy in dilute toluene solutions. It is shown that the molecules of hybrid dendrimers containing bithiophene fragments covalently linked via silicon atoms are not kinetically rigid and feature the small-scale mechanism of interaction with external electric fields. A tris(bithiophene)methylsilane fragment is found to be the subunit responsible for the electro-optical and optical spectral properties of the above hybrid dendrimers. It is revealed that the polarization of bithiophensilane dendrimers predominantly shows the deformation pattern.     

Mechanism of Polymerization of 1, 3-Dioxolane Initiated by (C2H5)3 O+SbCl6 and SbCl5

The kinetics of polymerization of 1, 3-dioxolane (DiOX) initiated by (C₂H₅)₃O⁺SbCl₆ and SbCl₅ has been studied and the elementary stages of the process have been considered. The polymerization of DiOX by (C₂H₅)₃O⁺SbCl₆-is shown to proceed at a steady rate to high conversion. A constant concentration of active centers in the system is maintained due to the equal rates of decomposition of active centers and disproportionation. The nonsteady-state character of DiOX polymerization initiated by SbCl₅is associated with a relatively lower stability of the counter-ion SbCl₅ OR^? compared with SbCl₆. The initiation of DiOX polymerization by (C₂H₅)₃O⁺SbCl₆ proceeds without hydride-transfer reactions, and the concentration of active centers in the system is determined not by processes taking place in the initiation stage, but by the existence of a definite kind of equilibrium with the participation of active centers.     

Theoretical Investigations of Nonlinear Optical Properties of Transition Metal Cluster Anions

In the framework of density functional theory （DFT）, the electronic excitations and nonlinear optical （NLO） properties of six binuclear transition metal cluster anions with the formula of [Ch2M-（μ-Ch）2-M＇CN]^2- （M = Mo, W; Ch = S, Se; M＇ = Cu, Ag） have been systemically investigated at both cases of gas phase and DMF solution. The obtained electronic absorption spectra reveal that the element replacements of metals M and ligands Ch have significant influence on the absorptions, especially on the low-lying ones. In addition, the transitions of μ-Ch→M are dominant for the low-lying excitations, whereas the transitions of M＇→M as well as Ch→M are mainly responsible for the higher excitations. The calculated molecular first and second hyperpolarizabilities present the remarkable element substitution and solvent effects. The analyses show that the transitions involving μ-Ch→M charge transfer make the critical contributions to the first hyperpolarizability t, and that the charge transfers from the moieties of MCh4 to M＇CN as well as those of μ-Ch→M and M＇→M are responsible for the second hyperpolarizability y. Moreover, the introduction of solvent leads to the results that the transitions within the moieties of MCh4 and M＇CN make larger contributions to the hyperpolarizability, especially to γ.     

PHOTOREACTIVITY OF 5-GERANOXYPSORALEN AND LACK OF PHOTOREACTION WITH DNA

5-Geranoxypsoralen, commonly called bergamottin, a major furocoumarin contained in bergamot oil, is reported in vitro as a highly photoreactive psoralen. In ethanol, it exhibits quite a high triplet state quantum yield (approximately 0.37). The triplet state is involved in subsequent photochemistry which depends on the initial concentration and on the presence of oxygen. In contrast to most psoralens, absorption and fluorescence data suggest that 5-geranoxypsoralen does not interact with DNA in the dark. No UVA-induced interstrand cross-links in DNA were shown.     

QCD PERTURBATION THEORY AND NUCLEI (1) THE ENERGY SHIFTS OF HADRENS AND HADRONS MASS DIFFERENCE MASS DIFFERENCE

QCD perturbation theory for confined quarks and gluons (inhadrons) is discussed.Based on the equivalent potential for the quark-gluon interaction derived, the energyshifts of hadrons and hadron mass difference in MIT bag (cavity) model and correcpond-ing approximation of the w. f. with Gassian form are calculated.