A simple indolo[2,3-a]carbazole based colorimetric chemosensor for simultaneous detection of Cu²⁺ and Fe³⁺ ions

A new indolo[2,3-a]carbazole based colorimetric chemosensor C1 was designed and synthesized. The optical properties of C1 were investigated by UV-vis spectroscopy, UV-vis titrations, and fluorescence spectroscopy. The HOMO and LUMO values of C1 were obtained using density functional theory (DFT) calculations. The results indicate that C1 has specific selectivity and high sensitivity for detection of Cu²⁺ and Fe³⁺ ions compared with metal ions (K⁺, Na⁺, Mg²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Hg²⁺, Ag⁺, Co²⁺, Cr²⁺, Ni²⁺, Mn²⁺, Ba²⁺). The presence of Cu²⁺ ions leads to visible color change from yellow to colorless in an aqueous-acetonitrile solution, especially. Moreover, the detection limit for the analysis of Cu²⁺ and Fe³⁺ ions is found to be as low as 2.93 × 10^-7 M and 4.10 × 10^-7 M, respectively. Therefore, C1 should have potential applications as a practical colorimetric chemosensor for simultaneous detection of Cu²⁺ and Fe³⁺ in the environment and biological systems.