A single carbazole based chemosensor for multiple targets: sensing of Fe3+ and arginine by fluorimetry and its applications

Abstract A simple carbazole derived Schiff base fluorescent chemosensor (C1) has been synthesized and characterized successfully to recognize sequentially Fe3+ ion and an amino acid, arginine (Arg). The chemosensor (C1) shows specific response “on-off-on” towards Fe3+ and Arg among different competing cations and amino acids. Interestingly, the fluorescence emission got turned-off for C1-Fe3+ complex and turned-on for the detection of arginine. The binding ability of sensor C1 with Fe3+ and arginine was advocated using fluorometric titrations, Job’s plot, B-H plot and density functional theory studies (DFT). The significant color changes of sensor C1 from aqua blue to transparent blue to aqua blue were monitored under UV-lamp of 365 nm during the sensing process, which additionally supported the complex formation. The sensor C1 accomplishes the lowest detection limit of 12.22×10-9 M and binding constant of 2.09×104 M-1 for Fe3+ detection. This efficient fluorescent candidate was utilized for the detection of Fe3+ in applications such as molecular logic gate, smart-phone based on-site detection, live cell bio-imaging and real sample analysis.