TY - JOUR
T1 - Synthesis, crystal structures and electronic properties of Schiff base nickel (II) complexes
T2 - Towards solvatochromism induced by a photochromic solute
AU - Akitsu, Takashiro
AU - Einaga, Yasuaki
N1 - Funding Information:
This work was supported by Grant-in-Aid for the 21st Century COE program ’KEIO Life Conjugate Chemistry’ from the Ministry of Education, Culture, Sports, Science and Technology, Japan. The authors thank Professor Yohru Yamada and Dr. Taketo Ikeno (Keio University) for the use of the DSC apparatus, Professor Hidenari Inoue (Keio University) for the use of the CD spectrometer, and Professor Katsuya Inoue (Institute for Molecular Scicence) for the use of the SQUID instrument.
PY - 2005/10/3
Y1 - 2005/10/3
N2 - Two new mononuclear nickel (II) complexes incorporating Schiff base ligands, bis(N-R-1-phenylethyl- or N-2-propyl-3,5-dichlorosalicydenaminato) nickel (II), have been synthesized and characterized. The former chiral brown paramagnetic complex adopts a compressed tetrahedral [NiN2O 2] coordination geometry of Λ(R,R) absolute configuration with the coordination bond angles of N-Ni-N = 116.3(2)°and O-Ni-O = 141.4(2)°. On the other hand, the latter green diamagnetic complex adopts a square planar trans-[NiN2O2] coordination geometry. It is revealed that flexible distortion of the [NiN2O2] coordination environment and the overall dipole moment of the complexes are affected by both electronic withdrawing Cl-substituents and steric factors of the ligands. A structural phase transition occurs by heating in the solid state for both complexes. Negative solvatochromism relating to d-d and π-π* transitions can be observed, depending on the polarity of the solvents in which these complexes are dissolved. Furthermore, we have attempted to design a supramolecular solvatochromism system induced by a photochromic solute, that is a CHCl3 solution of the chiral Ni(II) complex and polar 4-hydroxyazobenzene solute. After UV light irradiation, we have successfully observed slight spectral changes of the π-π* bands in absorption and CD spectra due to conformational change of the R-1-phenylethylamine moieties of the chiral ligands.
AB - Two new mononuclear nickel (II) complexes incorporating Schiff base ligands, bis(N-R-1-phenylethyl- or N-2-propyl-3,5-dichlorosalicydenaminato) nickel (II), have been synthesized and characterized. The former chiral brown paramagnetic complex adopts a compressed tetrahedral [NiN2O 2] coordination geometry of Λ(R,R) absolute configuration with the coordination bond angles of N-Ni-N = 116.3(2)°and O-Ni-O = 141.4(2)°. On the other hand, the latter green diamagnetic complex adopts a square planar trans-[NiN2O2] coordination geometry. It is revealed that flexible distortion of the [NiN2O2] coordination environment and the overall dipole moment of the complexes are affected by both electronic withdrawing Cl-substituents and steric factors of the ligands. A structural phase transition occurs by heating in the solid state for both complexes. Negative solvatochromism relating to d-d and π-π* transitions can be observed, depending on the polarity of the solvents in which these complexes are dissolved. Furthermore, we have attempted to design a supramolecular solvatochromism system induced by a photochromic solute, that is a CHCl3 solution of the chiral Ni(II) complex and polar 4-hydroxyazobenzene solute. After UV light irradiation, we have successfully observed slight spectral changes of the π-π* bands in absorption and CD spectra due to conformational change of the R-1-phenylethylamine moieties of the chiral ligands.
KW - Chirality
KW - Crystal structures
KW - Nickel (II) complexes
KW - Schiff base
KW - Solvatochromism
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U2 - 10.1016/j.poly.2005.06.019
DO - 10.1016/j.poly.2005.06.019
M3 - Article
AN - SCOPUS:24644442850
VL - 24
SP - 1869
EP - 1877
JO - Polyhedron
JF - Polyhedron
SN - 0277-5387
IS - 14
ER -