• alkyne homocoupling
• magnetic copper materials

A green microwave-assisted method was developed to obtain copper-based magnetic materials, with different loading of the metal (1-6 wt%). Magnetite and graphene were used as supports. SQUID magnetometer was used to investigate the superparamagnetic properties of the synthetized materials. Furthermore, the synthetized materials were characterized by many appropriate techniques, including Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), surface area (BET), Fourier Transform Infrared spectroscopy (FT-IR), Raman, X-ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA). The magnetic measurements showed a superparamagnetic behaviour of these systems, which can be easily magnetically separated.
The more in depth characterization of these copper-based materials has confirmed the uniform surface areas and nanoparticles size about 10 nm. Copper active sites resulted in a mixture of Cu(I) and Cu(II) oxides, which were intercalated or deposited on the different supports.
The synthetised magnetic materials were tested as catalysts for the alkyne-alkyne homocoupling reaction with air as the only oxidant agent. The reaction was studied in autoclave, at different reaction temperatures. On the basis of these preliminary investigations, copper magnetic materials showed promising catalytic activity and selectivity towards the desired product (1,4-diphenyl-1,3-dibutyne yields > 99 %). Promising results were obtained also in terms of separation/recovery/re-use of these magnetic catalysts.