Studies On Fluorescent Probes Of Metal Ions Based On Rhodamine6G Schiff Bases Derivatives

Metal ions play important roles in environment and physiological process oforganisms. Elevated concentrations of ions in environment may pollute the soil andsurface water, which may hamper the growth of plants and the self-purificationcapability of the sea or rivers. If the concentration of metal ions in human bodyunbalanced, causing a wide range of diseases. Therefore, the metal ions detection hasvery important significance. Fluorescence analysis method is simple, high sensitivity,good selectivity, and speediness, and widely used to detect metal ions in recent years.Rhodamine derivatives have unique characteristic of structure and excellentspectroscopic properties, become ideal chromophore to construct “turn-on”fluorescent probes. Obvious detectable change in the color (from colourless to pink)and fluorescence (turn on) is observed due to the conversion of spirolactam ring formto the acyclic xanthene form of the rhodamine derivative after binging with targetspecies.On the basis of summarizing predecessors’ work, in this paper we make use ofthe ring-opening mechanism to design and synthesis two rhodamine6G-based schiffbase fluorescent probes L1and L2for the detection of metal ions, many analysismethods are used to confirm their structure. L1showed high selectivity and sensitivitytowards Cu2+over a wide range of tested metal ions, exhibiting an almost200-foldfluorescence increase after adding Cu2+to the solution. The1:1binding ratio betweenchemosensor L1and Cu2+was1:1. Other common ions almost have little interferencefor the recognition of Cu2+. The detection limit was estimated to be9.12×107M.Fluorescent probe L2was water-soluble, and exhibited remarkable preference towardAl3+in aqueous medium with good sensitivity, the detection of L2for Al3+wastransient and reversible. EDTA can remove Al3+from the coordination sites of thecomplex to release the cyclic utilization. We have also investigated the binding ratio,binding constant, limit detection, reversibility and pH influence of L2. Therecognition behaviors were investigated by both experimental and theoretical studies.More importantly, confocal laser scanning microscopy results showed that L2was cell membrane permeable and could be used for detecting Al3+in living cells.