Dual-emissive fluorescent probe based on phenolphthalein appended diaminomaleonitrile for Al3+ and the colorimetric recognition of Cu2+

A novel dual emissive fluorescent probe was designed and synthesized by linking phenolphthalein and diaminomaleonitrile units. The present probe (PDM) can be used not only for fluorogenic detection of Al3+ by way of the excited enol-keto forms but also colorimetric detection of Cu2+. PDM probe showed a selective fluorescence enhancement with dual channel emissions for Al3+ in a mixture of EtOH/H2O (9/1). 1H NMR and DFT methods were also carried out to support the complexation between PDM and Al3+ ion. In addition, PDM presented highly selective colorimetric response for Cu2+ over other metal ions. The reversibility of PDM-Al3+ and PDM-Cu2+ complexes was successively established with the addition of TBAF and EDTA, respectively. The detection limits were determined to be 92.0 nM for Al3+ and 2.81 μM for Cu2+. The obtained results revealed that the designed PDM probe could be suitable for monitoring Al3+ under UV lamp and Cu2+ in water samples with the naked eye, which was rapid, convenient, low-cost and environmental friendly.