Stabilization of Fluorescent Copper Nanoclusters by Dialdehyde Cellulose and Its Use in Mercury Ions Sensing
In synthesis of metal nanoclusters (NCs), small molecules were widely used as capping ligands and reducing agents. However, metal NCs were usually sensitive to solvent, aerobic atmosphere and prone to oxidation, so their photonic property would be deteriorated. In this work, 4-Aminothiophenol (PATP) was used as ligand to prepare Cu NCs and its fluorescence, morphology, electronic sates, were characterized. The as-prepared Cu NCs can be dispersed into aqueous media and its fluorescence was sensitive to Hg2+. It was found that after mixing the Cu NCs with 2,3- dialdehyde cellulose (DAC) prepared from oxidation by NaIO4, the fluorescence stability of Cu NCs can be enhanced from overnight to 7 days. This might be due to the reaction of amine group of the PATP with the aldehyde group on DAC to form Schiff bases and then reduced to form more stable C-N bound via reducing by NaBH4. Therefore, Cu NCs was attached on a rigid skeleton and its stability was increased. Furthermore, the composite of Cu NCs mixed with DAC can be used to prepare colorimetric cards for rapid detection of Hg2+ with high sensitivity.