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• Spin-crossover nanoparticles of [Fe(pyrazine){Au(CN) 2 } 2 ] complex are obtained. • Synthesis was performed in solutions with Triton X-100 in presence of C 5 /C 6 alcohols. • The size of nanoparticles lies in a range of 38‒54 nm depending on the alcohol used. • The nanomaterials maintain hysteretic spin crossover above room temperature. Spin-crossover nanoparticles represent a very versatile class of switchable nanomaterials. Here we describe the synthesis and characterization of Fe(II) coordination complex nanoparticles displaying above room temperature bistability. Synthesis of the [Fe(pz){Au(CN) 2 } 2 ] (pz – pyrazine) nanoparticles was performed in solutions using Triton X-100 surfactant in presence of C 5 /C 6 alcohols. The size of nanoparticles lies in a range of 38‒54 nm depending on the alcohol used with crystallites of 13-16 nm. The obtained nanomaterials maintain hysteretic cooperative spin crossover above room temperature as found in optical and spectroscopic experiments, but the spin transition temperatures are shifted towards room temperature in comparison with a bulk sample. [Display omitted] [ABSTRACT FROM AUTHOR]

Here we describe the elaboration and investigation of composites prepared from the spin-crossover (SCO) complex [Fe(pyrazine){Au(CN) 2 } 2 ] and poly(vinylidene fluoride) matrix, with different contents of the active phase (10–35 wt%). Optical measurements demonstrated that all composites preserve temperature induced hysteretic spin transitions. Tensile mechanical analysis showed a non-linear change of the Young's modulus upon increase of the complex content. Thermomechanical analysis upon a constant strain demonstrated pronouncable alterations of the applied stress in the SCO region. Composites with smaller loads require less stress to attain a given strain in the high-spin state, however for those with high loads the behaviour is more sophisticated. The modelling of stress vs. temperature behaviour revealed that this may be interpreted through a miscellaneous interplay of expansion of both the polymer and the complex, the contribution of both components to the elastic properties of composites, and the effects of SCO on these properties. [Display omitted] • Insertion of a spin-crossover complex into PVDF leads to switchable composites. • Reinforcement of the films with low loads of the complex is observed. • Thermomechanical behaviour of composites reveals mechanical effects of SCO. • Basic tensile properties of SCO composites are emerged. [ABSTRACT FROM AUTHOR]