0000000000160687
AUTHOR
Koichiro Tanaka
showing 5 related works from this author
Wavelength selective light-induced magnetic effects in the binuclear spin crossover compound{[Fe(bt)(NCS)2]2(bpym)}
2007
Using Fourier transform infrared spectroscopy, x-ray diffraction, and magnetic susceptibility measurements under light irradiation, the selective light-induced excited spin state trapping (LIESST) and the reversible-LIESST effect have been evidenced and studied in depth in the binuclear spin crossover compound {[Fe(bt)(NCS)2]2bpym}. In this system, each magnetic site can switch from low spin (LS) to high spin (HS), so that three states exist, namely, the LS-LS, HS-LS, and HS-HS. All these techniques shine a new light on the high phototunability of this system. In addition to the direct photoswitching from the LS-LS to the HS-LS or to the HS-HS state, here we show that photoinduced switching…
Selective Photoswitching of the Binuclear Spin Crossover Compound{[Fe(bt)(NCS)2]2(bpm)}into Two Distinct Macroscopic Phases
2005
The low-spin (LS-LS, $S=0$) diamagnetic form of the binuclear spin crossover complex ${[\mathrm{Fe}(\mathrm{bt})(\mathrm{NCS}{)}_{2}{]}_{2}(\mathrm{bpm})}$ was selectively photoconverted into two distinct macroscopic phases at different excitation wavelengths (1342 or 647.1 nm). These long-lived metastable phases have been identified, respectively, as the symmetry-broken paramagnetic form (HS-LS, $\mathrm{S}=2$) and the antiferromagnetically coupled (HS-HS, $S=0$) high-spin form of the compound. The selectivity may be explained by the strong coupling of the primary excited states to the paramagnetic state.
Bidirectional photo-switching of the spin state of iron(II) ions in a triazol based spin crossover complex within the thermal hysteresis loop
2009
Abstract We have investigated the effect of short laser pulses (532 nm, 4 ns, −2 ) on the spin state of iron(II) ions in the spin crossover compound {[Fe II (Htrz) 2 (trz)](BF 4 )} within the hysteresis region of the high-spin (HS) to low-spin (LS) first-order thermal phase transition. Using Raman spectroscopy we have evidenced quasi-complete HS → LS as well as LS → HS photo-conversions, which can be induced by a single laser shot in the descending (351 K) and ascending (378 K) branches of the hysteresis loop, respectively. No effect has been observed, however, close to the center of the hysteresis loop even for repeated exposures.
Spin crossover and photomagnetism in dinuclear iron(II) compounds
2007
Abstract In this paper, we review recent work reported in the field of molecular spin crossover phenomena in dinuclear compounds. Following a comprehensive overview on the synthesis and properties of new iron(II) dinuclear compounds presenting the spin crossover phenomenon, we focus this review on recent efforts made in studying and understanding the photo-physical properties of the {[Fe(L)(NCX)2]2bpym} (L = bt or bpym, X = S or Se) family of compounds. Finally, literature on the different theoretical approaches treating the static and dynamic properties of dinuclear complexes presenting two-step thermal spin transition is briefly summarized.
Light induced excited spin state trapping in the binuclear spin crossover compound [Fe(bpym)(NCS)2]2(bpym) exhibiting a high-spin ground state
2008
Abstract A photo-magnetic effect is evidenced using near-infrared light in the binuclear complex [Fe(bpym)(NCS) 2 ] 2 (bpym). This compound has a 5 T 2g – 5 T 2g ground state and exhibits no thermal spin crossover – in contrast to the analogous [Fe(bpym)(NCSe) 2 ] 2 (bpym). The estimated photo-conversion ratio is ca. 30%. By means of magnetic susceptibility measurements as well as Raman and infrared absorption spectroscopies, the nature of the photo-induced phase was established as the 5 T 2g – 1 A 1g state, which means that only one iron center is converted to low-spin. The photo-induced state was completely converted back to the ground state either by visible light excitation or by heatin…