A meso–meso β‐β β‐β Triply Linked Subporphyrin Dimer

A meso–meso β‐β β‐β triply linked subporphyrin dimer 6 was synthesized by stepwise reductive elimination of β‐to‐β doubly Pt^II‐bridged subporphyrin dimer 9 . Dimer 6 was characterized by spectroscopic and electrochemical measurements, theoretical calculations, and picosecond time‐resolved transient absorption spectroscopy. X‐ray diffraction analysis reveals that 6 has a bowl‐shaped structure with a positive Gaussian curvature. Despite the curved structure, 6 exhibits a remarkably red‐shifted absorption band at 942 nm and a small electrochemical HOMO–LUMO gap (1.35 eV), indicating an effectively conjugated π‐electronic network.     

Concentration Dependence of Mössbauer Parameters of SnCl−3 and SnBr−3 Complex Ions

Mössbauer parameters of frozen salt solutions could be correlated with apparent degree of dissociation, γ. KSnCl₃ and KSnBr₃ were dissolved in 0.5 M H₂SO₄, whereas NH₄ SnCl₃ was dissolved in 0.5 M HClO₄. Mössbauer studies were made at different concentrations.     

Mössbauer Spectroscopic Studies of Supported α-Fe2O3 and Fe Catalysts I: Particle Size Determination and Support Effect

The chemical state of particles of 5wt% Fe in α-Fe₂O₃ and the subsequently reduced iron particles supported on different particle size (50–200 mesh) of silica (SiO₂), alumina (Al₂O₃), magnesium oxide (MgO) and carbon (C) was examined by Mössbauer spectroscopy at various stages of calcination and reduction. The particle size of the α-Fe₂O₃ supported on different mesh sizes (50, 100, 140, 200 mesh) of SiO₂ has been determined. The strength of metal-support interaction with respect to the kind of support was found to be MgO>SiO₂>Al₂O₃>C.     

Mössbauer Spectroscopic Studies of Supported α-Fe2O3 and Fe Catalysts II: The Effect of the Second Metal Addition

The effect of the addition of a second metals such as Zn and Ni on the calcinaton and reduction of alumina, magnesia and silicasupported iron catalysis with total iron loading of 5wt% is investigated by Mössbauer spectroscopy. It is shown that the reducibility of supported α-Fe₂O₃ is gradually increased by adding the second metal. The values of the magnetic hyperfine field obtained from Mössbauer spectra for the Zn or Ni-added α-Fe₂O₃ or Fe catalysts decreased with increasing second metal loading.