“Turn‐on” Fluorescence Chemosensor Based Probing of Cu2+ with Excellent Sensitivity: Experimental Study, DFT Calculations and Application in Living Cells and Natural Waters

AbstractDeveloping selective, precise, and rapid determination methods for Cu2+ sensing is of great significance for biological systems, public health, and environmental protection. Hence, a new coumarin‐based fluorescent chemosensor 3‐((E)‐(((E)‐3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)hydrazono) methyl)‐7‐(diethylamino)‐2H‐chromen‐2‐one (HBAC) for Cu2+ sensing in MeOH:H2O (80 : 20, v:v, pH=7 PBS buffer) media has been constructed. HBAC responded to Cu2+ with high selectivity and exhibited a relatively low LOD of 7.0 nM and ∼22‐fold fluorescent enhancement at 461 nm with the addition of Cu2+ (0.0‐5.0 μM). The reaction mechanism of the HBAC‐Cu2+ system has been fully examined by MALDI‐TOF‐MS, FT‐IR, and time dependent‐density functional theory (TD‐DFT) calculations. The sensing mechanism was occurred due to the chelation enhanced fluorescence (CHEF) and inhibition of PET phenomena. Furthermore, the chemosensor HBAC for Cu2+ sensing in living systems and natural spring water samples has been successfully utilized, suggesting that the prepared HBAC is an appropriate chemosensor for examining Cu2+ in biological and environmental systems.