Search

This article focuses on electrochemical tuning of the magnetic phase transition. The ability of certain molecules and molecule-based materials to change the nature of their electronic ground state under the presence of an external perturbation is well-known. This leads to functional materials in which a physical property (absorption of light, magnetic moment, electrical conductivity, can be tuned through the application of an external stimulus. abundant in the literature on spin crossover compounds. Less common is the observation of this behavior in magnetically ordered molecule-based materials.

The thermal spin-crossover behaviour, photoexcitation and subsequent relaxation, as well as the pressure-induced spin-crossover behaviour at 298 K are discussed for the non-porous two-dimensional Hofmann-like coordination polymer [Fe(3-Clpy)2Pd(CN)4] ( 1). The title compound undergoes a two-step, cooperative thermal-induced SCO with critical temperatures Tc1↓ = 159.6 K and Tc1↑ = 164.5 K for the first step and Tc2↓ = 141.4 K and Tc2↑ = 148.4 K for the second step. Irradiation of the low-spin state with green light (514 nm) at 10 K induced the photoexcitation of around 60 % of the iron(II) centres to the high-spin state (LIESST effect). The subsequent cooperative relaxation processes were recorded at several temperatures and analysed. The effect of cooperativity on the photoexcitation was investigated by the LITH (light-induced thermal hysteresis) procedure. At 300 K, the coordination polymer 1 underwent a cooperative spin-crossover transition at around 0.6 GPa. The thermodynamic analysis of the pressure-induced SCO transition afforded the enthalpy and cooperativity parameters Δ HHL( p) = 22.01 kJ mol-1 and Γ( p) = 7.47 kJ mol-1, consistent with previous results. [ABSTRACT FROM AUTHOR]