No abstract

The Cu(II) ion is a toxic metal ion contributing to water pollution and poses a challenging problem for the industrial sector encompassing semiconductor chips, microelectronics, dialysis water and pharmaceutical applications. 1,2 The accumulation of Cu(II) ions in the environment has highlighted the necessity for an efficient system to monitor Cu(II) ions and their entry into the food chain. This is an important consideration because Cu(II) ions are believed to induce risky neurodegenerative diseases such as myeloneuropathy, anaemia, Parkinson's disease, Wilson's disease and Alzheimer's disease. [3][4][5] The safety limit of Cu(II) in drinking water has been set as less than 1.3 ppm (<16 μM) by the US Environmental Protection Agency. 6 Consequently, there is a need to develop highly selective and sensitive devices for the naked-eye detection of trace amounts of Cu(II) ions. Recently, the monitoring of ions by colour signal changebased sensors has attracted attention because of their simplicity, rapidity, high selectivity and sensitivity. 7,8 The methods employed for the selective detection of the Cu(II) ion involved an ultraviolet-visible (UV-vis) spectrophotometer or a colorimeter based on the coloured complexes, in which Cu(II) was bonded with in each chromogenic receptor. Numerous effective chemosensing methods have been reported, utilising rhodamine B, 9 naphthalimide, 10 coumarin