Direct observation of adduct formation of alkyl and aromatic iodides with cl atoms using cavity ring-down spectroscopy

The reactions of Cl atoms with RI (R = n-C3H7, n-C4H9, cyclo-C6H11, C6H5, C6F5, and p-CH3C6H4) have been studied using cavity ring-down spectroscopy at a temperature range of 233-313 K and at 100 Torr total pressure of N2 diluent. Visible absorption spectra of the RI-Cl adducts were recorded at 440-520 nm at 263 K. The yields of the adducts were temperature-dependent. There was no discernible reaction of the adducts in the presence of 100 Torr of O2 at 263 K. Theoretical calculations were performed for C4H9I-Cl and C6H5I-Cl for quantitative explanation of the absorption spectra and the strength of the I-Cl bonds in the charge-transfer complexes. Evidence for the adduct formation following the reaction of Cl with C6H5Br was sought but not found at 440 and 520 nm.     

Energy transfer reaction of cationic porphyrin complexes on the clay surface: effect of sample preparation method

Photochemical energy transfer of non-aggregated cationic porphyrins on an anionic-type clay (Smecton SA) surface was investigated. The efficiency of energy transfer and excited-state quenching in the absence of energy transfer were evaluated at various loading levels of porphyrin on the clay surface and were found to be significantly affected by the loading level. As the latter increased, both energy transfer efficiency and excited-state quenching increased. Judging from the dependency of energy-transfer efficiency on the porphyrin loading level, a partially clustered structure, but without aggregation, of porphyrins on the clay surface is proposed.     

Arrangement of ad-atoms of various kinds on substrates: Part II. Iridium and rhodium

The number of iridium sites and that of rhodium sites occupied by a foreign atom was determined with the aid of the pulse technique. In the case of iridium the foreign atoms included are Cu, Ag, Cd, Hg, In, Tl, Pb, Se, Te, As and Bi. The approximate value is 1 for the first two, 2 for the next five and 2.5–2.7 for the others. In the case of rhodium substrate, the foreign atoms included are Cu, Ag, Cd, Hg, In, Tl, Ge, Pb, As, Sb, Se, Te, and Bi. The approximate value is 1 for the first two, 2 for the next six, 2.4–2.6 for the next four and 3.0 for the last one. Silver and copper ad-atoms are closely packed both on the iridium and rhodium surface, but the ad-atoms of the other elements are arranged on the surfaces leaving empty sites for geometrical reasons, even when the monolayer is apparently complete.     

Benzyne-induced ring opening reaction of thiiranes. Efficient synthesis of phenyl vinyl sulfides

A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing cis-(phenylthio)-stilbene from cis-2,3-diphenylthiirane and trans-(phenylthio)stilbene from trans-2,3-diphenylthiirane.     

Penning ionization electron spectroscopy of C6H6 by collision with He*(2 3 S) metastable atoms and classical trajectory calculations: optimization of ab initio model potentials

The potential energy surface of benzene (C(6)H(6)) with a He*(2(3)S) atom was obtained by comparison of experimental data in collision-energy-resolved two-dimensional Penning ionization electron spectroscopy with classical trajectory calculations. The ab initio model interaction potentials for C(6)H(6)+He*(2(3)S) were successfully optimized by the overlap expansion method; the model potentials were effectively modified by correction terms proportional to the overlap integrals between orbitals of the interacting system, C(6)H(6) and He*(2(3)S). Classical trajectory calculations with optimized potentials gave excellent agreement with the observed collision-energy dependence of partial ionization cross sections. Important contributions to corrections were found to be due to interactions between unoccupied molecular orbitals and the He*2s orbital. A C(6)H(6) molecule attracts a He*(2(3)S) atom widely at the region where pi electrons distribute, and the interaction of -80 meV (ca. -1.8 kcal/mol) just cover the carbon hexagon. The binding energy of a C(6)H(6) molecule and a He* atom was 107 meV at a distance of 2.40 A on the sixfold axis from the center of a C(6)H(6) molecule, which is similar to that of C(6)H(6)+Li and is much larger than those of the C(6)H(6)+[He,Ne,Ar] systems.     

Synthesis and Photocatalytic Property of Hectorite/(Pt,TiO2) and H4Nb6O17/(Pt,TiO2) Nanocomposites

Abstract

TiO₂ and Pt have been intercalated in hectorite and H₄Nb₆O₁₇. The height of TiO₂ and Pt pillars was less than 0.8 nm and the band gap energy of TiO₂ pillars was ca. 3.3 eV. Both hectorite/TiO₂ and H₄Nb₆O₁₇(Pt, TiO₂) were capable of hydrogen evolution following irradiation from a high pressure mercury are (λ > 290 nm) in the presence of methanol as a sacrificial hole acceptor and the hydrogen evolution was enhanced by co-incorporation of Pt, although hectorite and hectorite/Pt did not show photocatalytic activity. Incorporation of Pt or Pt and TiO₂ in the interlayer of H₄Nb₆O₁₇ has resulted in enhanced photo evolution of hydrogen, however, TiO₂ alone in the interlayer of H₄Nb₆O₁₇ showed adverse photocatalytic activity.     

Phase-Separation Phenomena of Copolymer Solutions and Fractionation of Copolymers by Chemical Composition

Precipitation temperature-total polymer concentration diagrams for toluene solutions of two styrene-acrylonitrile copolymers different in chemical composition and their mixtures were determined and then triangular phase diagrams of this system were constructed from these diagrams. It is speculated from the triangular phase diagrams and experimentally shown that the copolymer may be effectively fractionated by chemical composition in this system.