0000000000160690
AUTHOR
N. Ould Moussa
Wavelength selective light-induced magnetic effects in the binuclear spin crossover compound{[Fe(bt)(NCS)2]2(bpym)}
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
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.
Light induced excited spin state trapping in the binuclear spin crossover compound [Fe(bpym)(NCS)2]2(bpym) exhibiting a high-spin ground state
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…