A colorimetric and fluorescent probe for multiple transition metal ions (Cu2+, Zn2+ and Ni2+): Fast response and high selectivity

Abstract A multi-metal colorimetric and fluorescent sensor based on Schiff base bearing an “O-N-N”-coordination site was developed. This newly designed sensor is a highly sensitive and selective “turn-on” fluorescent chemosensor towards Zn 2+ which is less affected by physiologically relevant metal ions, especially Cd 2+ . The cell imaging experiment further confirmed that the sensor could be used for monitoring trace Zn 2+ in living cells. On the other hand, evident color changes can be observed from colorless to yellow, orange and purple upon the sensor selective binding with Cu 2+ , Zn 2+ and Ni 2+ , respectively. The corresponding color changes can be directly discriminated by “naked eye”. Significant response from spectral shift provided distinctly different profiles for each of the three metal ions. Overall, the sensor could simultaneously detect and differentiate three transition metal ions through fluorogenic (Zn 2+ ) and chromogenic (Cu 2+ , Zn 2+ and Ni 2+ ) methods in real time and the detection limit was as low as 10 −8  M in aqueous medium.