Does cooperativity influence the lifetime of the photo-induced HS state?

Abstract

We have first recalled the T(LIESST) procedure which consists to determine the temperature above which the photo-magnetic effect is erased. In addition we have selected to series of iron(II) spin crossover complexes, the [Fe(PM-L) 2(NCS)2] and [Fe(bpp)2]X2· nH2O families, to analyse the influence of the cooperativity on the stability of the photo-induced HS state. Some of these complexes exhibit gradual thermal spin crossover behaviours while some others undergo an abrupt thermal transition, with and without hysteresis. Interestingly, whatever the cooperativity effect on the thermal spin crossover transition, the lifetime of the metastable state of all these derivates remains governed by the T(LIESST) = T0 - 0.31 T1/2 relation. Finally, we have investigated the magnetic and the photomagnetic properties of a [Fe(bpp)2]-Nafion film. Once more the role of the cooperativity on the stability of the photoinduced HS state appears minor. Conversely, the influence of the nature and the geometry of the inner coordination sphere appears preponderant. © 2005 IOP Publishing Ltd.