A New Fluorescent Probe Based on N-(2-carboxymethyl)benzoaza-15-crown-5 for Sensitive and Selective Determination of Cu2+

Copper is widely used and therefore it is a pollutant metal. It is important to develop probes that can selectively determine copper with high sensitivity. The benzoaza-15-crown-5 derivatives are used as fluorescence sensing systems and excellent spectroscopic properties are demonstrated. The “N”, “O” atoms of the heterocyclic unit act as binding sites for recognizing copper ions. A new, simple, sensitive fluorescence method for the determination of Cu2+ ions was developed and analytical characteristics of the proposed probe were estimated. The Cu2+ ions can significantly quench the fluorescence intensity of N-(2-carboxymethyl)benzoaza-15-crown-5 (Cr) in ethanol/H2O (4:6, v/v) solvent mix containing urotropine buffer (pH 7.5) at λex = 274 nm and λem = 308 nm. The probe has high photostability. Under optimal conditions, the quenching of fluorescence intensity depends on the concentration of Cu2+ ions in the range of 1.70 × 10-6 - 2.38 × 10-4 М, detection limit was 0.56 μМ. This method was applied for the determination of Cu2+ ions in drinking water. The quenching effect in the presence of copper (II) can be explained by the termination of intramolecular charge transfer from the chelate center to the aromatic part of the molecule due to chelation.