Drastic lattice softening in mixed triazole ligand iron( ii ) spin crossover nanoparticles

Mario Piedrahita-Bello (1) , Karl Ridier (1) , Mirko Mikolasek (2) , Gábor Molnár (1) , William Nicolazzi (1) , Lionel Salmon (1) , Azzedine Bousseksou (1)

1 LCC - Laboratoire de chimie de coordination
2 ESRF - European Synchrotron Radiation Facility

A series of spin-crossover (SCO) coordination nanoparticles (ca. 60 nm) with the general formulae [Fe(Htrz)1+y−x(trz)2−y(NH2trz)x](BF4)y·nH2O (x = 0, 0.1, 0.2 and 0.3) were synthesized in concentrated solutions without using any surfactant or polymer. The nanoparticle powders were investigated by transmission electron microscopy, powder X-ray diffraction, magnetometry, calorimetry, Raman/IR spectroscopies, elemental analysis and 57Fe Mössbauer spectrometry. Remarkably, the latter revealed a large decrease of the lattice stiffness when incorporating a small amount of amino-triazole ligand, reflected by the drop of the Debye temperature from 285 K (x = 0) to 205 K (x = 0.3). This collapse of the lattice cohesion was attributed to a reorganization of the supramolecular interactions between the Fe-triazole chains. This effect on the SCO properties is also discussed.

Domaines: Chimie de coordination

Mario Piedrahita-Bello, Karl Ridier, Mirko Mikolasek, Gábor Molnár, William Nicolazzi, et al.. Drastic lattice softening in mixed triazole ligand iron( ii ) spin crossover nanoparticles. Chemical Communications, 2019, 55 (33), pp.4769-4772. ⟨10.1039/C9CC01619H⟩. ⟨hal-02335045⟩