The article deals with the synthesis of hybrid coordination polymer nanosheets of nanometric thickness, formed by metal cations and organic ligands, using supercritical CO2 as solvent.
These materials are often obtained as large micrometre-sized polycrystalline powders. However, since the development of graphene, the interest in the preparation of two-dimensional (2D) nanostructured materials has grown steadily due to their potential technological applications: in many cases, 2D nanostructures exhibit superior properties compared to their 3D counterparts. Preparation of 2D nanostructures is a challenge in the case of materials whose structure is not layered, and thus has no natural tendency to form flakes or nanosheets.
Herein, coordination polymers with formula [M(deox)2(bpy)]∞ (M = Cu, Co, Mn, Ni or Zn) precipitated as nanosheets arranged in different morphologies as a function of the medium are successfully synthesized. Poorly soluble [M(deox)2(H2O)x] precursor requires supercritical CO2 and ethanol as co-solvent. Highly soluble [M(deox)2(tbpy)2(H2O)x] produces the target coordination polymer in pure supercritical CO2. All samples are obtained with laminar morphology with nanometric thickness. The samples prepared using supercritical CO2 shows the formation of 15-60 nm thick flakes arranged in a desert rose–type conformation.
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