Dual-channel fluorescent sensor for rapid Cu²⁺ and Fe³⁺ detection: Enhanced sensitivity and selectivity with...

The AR-2 sensor, derived from a triazole-substituted acridinedione, exhibits distinct responses to Cu²⁺ and Fe³⁺ ions. It shows fluorescence enhancement in the presence of Cu²⁺ ions and a reduction in fluorescence with Fe³⁺ ions. This sensor is distinguished by its high sensitivity, selectivity, rapid response time, reversibility, and broad operating pH range, with shallow detection limits for both ions. Structural and photophysical analyses of AR-2 were conducted using density functional theory (DFT) and various spectroscopic techniques. The binding modes and recognition mechanisms for Cu²⁺ and Fe³⁺ ions were elucidated through multiple experimental approaches. Additionally, AR-2 demonstrated efficacy in the rapid, visual detection of these ions via paper test strips and swab tests. It successfully identified Cu²⁺ and Fe³⁺ ions in real water and food samples, achieving notable recovery rates. The AR-2 sensor also excelled in fluorescence imaging, effectively visualizing iron and copper pools in seed sprouts.