Author
Hiroaki Shimizu
Bio: Hiroaki Shimizu is an academic researcher from Ehime University. The author has contributed to research in topics: Crown ether & Methylene. The author has an hindex of 2, co-authored 2 publications receiving 122 citations.
Papers
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TL;DR: In this article, the properties of Cu(II) complexes of saturated macrocyclic ligands with square-pyramidal array were examined by cyclic voltammetry, electron spin resonance, visible absoption and magnetic circular dichroism spectroscopy.
123 citations
TL;DR: In this article, a new 5-O-membered crown ether spin-labeled with a triphenylmethyl group was prepared and the intramolecular unpaired π-electron delocalization was investigated by ENDOR.
Abstract: A new 5-O-membered crown ether spin-labelled with a triphenylmethyl group was prepared. The intramolecular unpaired π-electron delocalization was investigated by ENDOR. The ENDOR of the crown methylene group adjacent to the aromatic ring revealed non-equivalence in the magnitude of the proton hyperfine splittings. Based on the temperature-dependent ENDOR line separation, the activation energy of the conformational change of the methylene protons was estimated. Upon metal chelation into the crown ring the dissociation of the dimer to the monomer radical was greatly affected, and an increase in the activation energy of the vibrating methylene protons was detected.
2 citations
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TL;DR: Structural and thermodynamic features of the binding interactions of DNA with bleomycin, its metal complexes, and adducts of metallobleomycins are reviewed, and the DNA cleavage reaction involving iron-bleomycin is examined.
128 citations
TL;DR: In this article, the development of the coordination chemistry of N-alkylated cyclam ligands from its inception in 1973 with the first report of tetramethylcyclam was examined.
100 citations
TL;DR: The known redox potentials of selected Cu 2+ /Cu + couples complexed with N-, S- and O-donor ligands are empirically correlated with various characteristics of the ligands as mentioned in this paper.
83 citations
TL;DR: In this paper, the electrochemical and spectral properties of three copper(II) complexes were investigated by cyclic voltammetry, electronic and ESR spectra, and the results from spectroscopic and redox studies were consistent with the crystallographic results and perfectly related to each other.
Abstract: The electrochemical and spectral behaviors of three copper(II) complexes [CuL1] 1, [CuL2] 2 and [CuL3] 3, where L1, L2 and L3 are the dianions of macrocyclic oxamido Schiff bases, have been investigated by cyclic voltammetry, electronic and ESR spectra. These macrocyclic complexes, which incorporate both oxamido and imine groups, can undergo quasi-reversible reduction (CuII → CuI) and oxidation (CuII → CuIII). The crystal structures of 1 and 2 have been determined by single-crystal X-ray analysis. The difference in ring size leads to significant differences in molecular and crystal structure, electronic and ESR spectra and redox behavior. In the [14]N4 macrocyclic complex, 2, the CuN4 chromophore assumes a nearly square-planar co-ordination geometry, but the geometry in the [15]N4 macrocyclic complex, 1, is distorted towards tetrahedral. The results from spectroscopic and redox studies are consistent with the crystallographic results and perfectly related to each other. The main factors that determine the relative stability of CuI and CuIII in these complexes are the size, geometry and flexibility of the co-ordination cavity.
81 citations
70 citations