Novel Rhodamine-based Fluorescent Probes For Cu²⁺and Al³⁺:Synthesis And Recognition Properties

Metal cations are very important contaminants due to their toxicity can result in non-reversible harm to human body and environment systems. For this reason, many studies on environmental monitoring have received widespread attention. Thus, a highly selective and sensitive fluorsecent chemosensor for the detection of metal cations is urgently needed. As important fluorescent materials, rhodamine dyes and their derivatives are widely used in the field of metal ions recognition due to their special structure and good photophysical properties. On the basis of the previous work, two fluorescent sensors based on rhodamine were designed and synthesized. The detection behaviors and mechanisms were studied by UV absorption spectra and fluorescence emission spectra.A new fluorescent sensor1for the detection of Cu2+was designed and synthesized. The structure of sensor1was identified by NMR, FT-IR and MS. The recognition properties of sensor1were investigated through absorption spectra and fluorescence spectra as well. It turned out that sensor1lead to absorption and fluorescent enhancement upon adding Cu2+and exhibited a high sensitivity for Cu2+with detection limit of1.58×10-8M.A noval dual chemosensor2for Cu2+and Al3+was developed. The structure of sensor2was identified by NMR, FT-IR and MS. The recognition properties of sensor2were investigated through absorption spectra and fluorescence spectra as well. It showed that complexing with Al3+triggers the formation of ring-open with noteless color change and brings about much larger fluorescence enhancement, while Cu2+induces strong absorbance enhancement with weak fluorescence appears. The sensor2exhibited high sensitivity for Cu2+and Al3+. The limits of detection of Cu2+and Al3+were estimated to be2.9×10-7M and8.3×10-9M, respectively..