Film materials based on non-covalent hybrids of two-dimensional graphene oxide nanosheets with the spin-crossover molecular complex salt [Et4N][FeIII(5Cl-thsa)2]

Abstract

We consider the preparation of film hybrid composite materials formed by a self-assembly process via the non-covalent interactions of surface functional groups and graphene domains of graphene oxide (GO) nanosheets with anionic spin-crossover complexes [Fe^III(5Cl-thsa)₂]⁻ (5Cl-thsa²⁻ is 5-chlorosalicylaldehyde thiosemicarbazone) and cations [Et₄N]⁺ of the intercalant salt [Et₄N][Fe^III(5Cl-thsa)₂] (1). The introduction of salt 1 into the interlayer space of the GO nanosheets was observed for the first time, followed by the subsequent formation of a layered GO-1 hybrid material film, while the reversible thermally induced spin transition was maintained. The GO-1 hybrid material films were characterized by scanning electron microscopy, energy dispersive analysis, IR and Raman spectroscopy, and powder X-ray diffraction; their magnetic properties were studied. Comparative studies of the magnetic properties of complex 1 and the GO-1 hybrid material film showed the influence of the GO nanosheet matrix on the nature and completeness of the spin transition of intercalant 1. The semi-transition temperature of the GO-1 hybrid material (T_½ = 228 K) is shifted by ∼20 K towards the high-temperature region compared to that of the starting salt 1 (T_½ = 208 K).