Symmetric and Asymmetric Metal Complexes

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Chemistry: Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (31 August 2019) | Viewed by 7736

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Department of Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Tokyo 162-8601, Japan
Interests: inorganic coordination chemistry; physical inorganic chemistry (magnetism and spectroscopic properties); structural chemistry (X-ray crystallography) ; bioinorganic chemistry; nano-materials for environmental applications (biofuel cell or DSSC)
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Special Issue Information

Dear Colleagues,

Symmetric and asymmetric metal complexes may be important in many aspects of coordination chemistry, not only structure and properties but also synthesis and (bio)organic reactions. Metal complexes usually have symmetric coordination geometry around their central metals, such as octahedral, tetrahedral, or square planar, and so on. Historically, stereochemistry and symmetry (and asymmetry by chirality) have helped A. Werner to establish these compounds and a research field within chemistry. In addition to molecular structures, their crystal structures, including supramolecular structures; spectroscopic properties, including electronic states; and theoretical treatment, such as ligand field theory, molecular orbitals, and symmetry (in DFT), are important concepts of metal complexes. This Special Issue of Symmetry, “Symmetric and Asymmetric Metal Complexes”, features articles on such papers related to metal complexes or coordination chemistry in general.

Prof. Dr. Takashiro Akitsu
Guest Editor

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Keywords

  • Metal complex
  • chirality
  • spectroscopy
  • crystallography
  • molecular orbital

Published Papers (2 papers)

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Research

19 pages, 4703 KiB  
Article
Orientation of Chiral Schiff Base Metal Complexes Involving Azo-Groups for Induced CD on Gold Nanoparticles by Polarized UV Light Irradiation
by Nobumitsu Sunaga, Tomoyuki Haraguchi and Takashiro Akitsu
Symmetry 2019, 11(9), 1094; https://doi.org/10.3390/sym11091094 - 2 Sep 2019
Cited by 13 | Viewed by 3294
Abstract
In this study, we report the synthesis, characterization, and chiroptical properties of azo-group-containing chiral salen type Schiff base Ni(II), Cu(II), and Zn(II) complexes absorbed on gold nanoparticles (AuNPs) of 10 nm diameters. Induced circular dichroism (CD) around the plasmon region from the chiral [...] Read more.
In this study, we report the synthesis, characterization, and chiroptical properties of azo-group-containing chiral salen type Schiff base Ni(II), Cu(II), and Zn(II) complexes absorbed on gold nanoparticles (AuNPs) of 10 nm diameters. Induced circular dichroism (CD) around the plasmon region from the chiral species weakly adsorbed on the surface of AuNP were observed when there were appropriate dipole–dipole interactions at the initial states. Spectral changes were also observed by not only cis-trans photoisomerization of azo-groups but also changes of orientation due to Weigert effect of azo-dyes after linearly polarized UV light irradiation. Spatial features were discussed based on dipole-dipole interactions mainly within an exciton framework. Full article
(This article belongs to the Special Issue Symmetric and Asymmetric Metal Complexes)
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10 pages, 3756 KiB  
Article
Chiral Recognition of Azo-Schiff Base Ligands, Their Cu(II) Complexes, and Their Docking to Laccase as Mediators
by Fuki Kunitake, Jong-Yeon Kim, Shiomi Yagi, Shu Yamzaki, Tomoyuki Haraguchi and Takashiro Akitsu
Symmetry 2019, 11(5), 666; https://doi.org/10.3390/sym11050666 - 14 May 2019
Cited by 15 | Viewed by 2804
Abstract
Chiral crystals were discovered due to spontaneous resolution when enantiomers of 4-phenyldiazenyl-2-[(R or S)-(1-phenylethyl)-iminomethyl]phenol and its racemic mixture were prepared. Using two ligands per molecule, optically active R,R and S,S enantiomers and meso R,S diastereomer [...] Read more.
Chiral crystals were discovered due to spontaneous resolution when enantiomers of 4-phenyldiazenyl-2-[(R or S)-(1-phenylethyl)-iminomethyl]phenol and its racemic mixture were prepared. Using two ligands per molecule, optically active R,R and S,S enantiomers and meso R,S diastereomer of Cu(II) complexes were prepared. Strong chiral recognition was expected for them. Laccase has attracted attention as a catalyst that reduces oxygen to water in a cathode of biofuel cells, which can be effectively mediated by metal complexes. Furthermore, azobenzene can align perpendicularly to the polarization direction of irradiating linearly polarized ultraviolet light (Weigert effect) as well as to the conventional cis-trans photoisomerization accompanying the shift of redox potential. Thus, we also studied the photo-induced control of cis-trans forms and the alignment of these Cu(II) complexes as a mediator to fit laccase appropriately. We discuss photo-induced control on not only electronically but also sterically-favored redox conditions. The meso(R,S)-form of the Cu(II) complex in cis-form was found to be the best at increasing the current of cyclic voltammetry (CV) among the three R,R and S,S enantiomers and the R,S diastereomer of the Cu(II) complexes. Full article
(This article belongs to the Special Issue Symmetric and Asymmetric Metal Complexes)
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