The synthesis, structures, optical properties, and electronic structures of the tetraphenyltetrathiaporphyrin dication (S(4)TPP(2+), 6) and tetrakis(pentafluorophenyl)tetrathiaisophlorin (S(4)F(20)TPP, 7) are reported. S(4)TPP(2+) (6) and S(4)F(20)TPP (7) were synthesized by acid-catalyzed condensation of the corresponding hydroxylmethylthiophene, followed by oxidation. The electronic structures of S(4)TPP(2+) (6) and S(4)F(20)TPP (7) were analyzed by using UV/Vis-absorption spectroscopy and by magnetic circular dichroism (MCD) spectroscopy and the bands were assigned by using time-dependent density functional theory (TD-DFT) and ZINDO/s calculations. A red-shift of the Q bands of S(4)TPP(2+) (6) is observed relative to the spectra of tetraphenylporphyrins because a destabilization of the HOMO leads to a narrower HOMO-LUMO band-gap. Michl's perimeter model was used to assign the absorption bands and MCD spectra of S(4)F(20)TPP (7). Current-density maps and nucleus-independent chemical-shift (NICS) calculations of S(4)TPP(2+) (6) and of a model compound predict marked modification to the diamagnetic ring current, whilst nonaromatic character is predicted for S(4)F(20)TPP (7).
A hybrid catalyst consisting of polymer-coated Ru nanoparticles (Ru-PVP, PVP: poly(N-vinyl-2-pyrrolidone)) embedded in a porous metal-organic framework of ZIF-8 (Ru-PVP@ZIF-8) was synthesized by the crystallization of ZIF-8 in a methanol solution of Ru-PVP. The structural properties of Ru-PVP@ZIF-8 were examined by N2 gas adsorption, infrared spectra, and X-ray powder diffraction measurements. We successfully identified the most appropriate pretreatment conditions for surface activation of the Ru nanoparticles in the catalyst. The pretreated Ru-PVP@ZIF-8 was applied for a CO oxidation reaction with H2 gas feeds. Ru-PVP@ZIF-8 was found to exhibit higher catalytic activities and higher CO2 selectivity than those observed on a carbon-supported Ru-PVP (Ru-PVP/C), implying that the pores of the ZIF-8 provide a more suitable environment for the reaction with O2 and CO gases.
Benzo[1,2,3,4,5]tetrathiaselenepin is an unstable cyclic polychalcogenide. Isopropyl and/or methoxy groups at the neighboring of polychalcogen ring sterically stabilized the unstable ring. Replacing of aromatic unit from benzene to naphthalene also gave thermodynamic stability to the ring. Synthesis, characterization, and stability of some novel polychalcogenides are reported.
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