Speciation of lead in environmental waters by preconcentration on a new fullerene derivative

A novel fullerene derivative including a chelating group attached to the fullerene core has been prepared by photoreaction of C60 and sodium diethyldithiocarbamate (NaDDC) in toluene-methanol medium. The optimization of the synthesis procedure was monitored by UV-visible spectroscopy using the spectrum of C60 fullerene as reference; the new material, a C60-NaDDC monoadduct, showed a shoulder at 430 nm and an increase in the absorption band comprised between 425 and 500 nm. The solid was obtained by photolysis reaction in approximately 24 h, requiring further purification by preparative chromatography. Characterization of the brown product was accomplished by XRD and solid-state 13C MAS NMR; chemical modification was confirmed through the appearance of peaks close to the fullerene core peak located at 146.9 ppm, which can be assigned to carbon atoms of C60 that are covalently bonded to the diethyldithiocarbamate group to form a pyrrolidine ring-fused fullerene monoadduct. Using lead species as a model assessed the ability of the new material for the preconcentration of metallic and organometallic compounds, providing detection limits of 4-15 ng/L. The most interesting conclusions of the results were high adsorption efficiency, selectivity, and stability of the C60-NaDDC derivative (the packed material can be used for at least six months).