| Budget Amount *help |
¥4,010,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Research Abstract |
Photomagnetic properties of a series of binuclear diiron(II) complexes belonging to the [{Fe(NCS)(py-X)}_2(bpypz)_2] family with bpypz = 3,5-bis (pyridine-2-yl)pyazolate and X = 4-Mepy (1), py (3), 3-Mepy (4), 3-Cipy (5) and 3-Brpy (6) have been investigated. The reflectivity T(LIESST) temperatures as well as the kinetic decays. All these complexes display a complete thermal spin transition centred between 100-150 K, and undergo the light-induced excited spin state trapping (LIESST) effect at low temperatures. The T(LIESST) relaxation temperature of the photoinduced high-spin state for each compound has been determined. For all of them the T(LIESST) curves at low temperature have been found close to antiferromagnetic response of the [{Fe (NCS)(3,5-Me_2py)}_2(bpypz)_2] (7) complex characterized by two iron(II) metal ions in HS electronic configuration, giving some evidences of a quantitative LS-LS → HS-HS photoconversion process. Depending on the nature of the cooperativity, kinetics have been treated with stretched exponential, simply exponential or sigmoidal model. Interestingly this series of dinuclear complexes follow a previously proposed linear relation between T(LIESST) and their thermal spin-transition temperatures T_<v2>: T(LIESST) = T_0-0.3 T1_<v2> To for these compounds is equal to 100 K. Based on that and by using the empirical linear relation found between the thermal spin transition and the Hammett constant, the HS-HS properties of complex 7 have been understood as a reflect of the physical impossibility that the T(LIESST) was higher than T_<v2>. The close vicinity of the thermal spin crossover phenomenon on 7 has been successively checked by applying hydrostatic pressure.
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