The detection of multiple analytes by using visual colorimetric and fluorometric multimodal chemosensor based on the azo dye

In recent decades, researchers have conducted in-depth studies of the design and synthesis of colorimetric/fluorometric probes and the application of such probes to biological and practical samples. The multifunctional colorimetric and fluorescent azo benzene-based probe (4′-hydroxyl-2,4-diaminoazobenzene, MP ) was designed to detect Al 3+ , Fe 3+ , Cu 2+ and F¯. Based on the distinct redshift of the absorption band and a significant color change (yellow → purple), MP was utilized for both naked-eyed and quantitative detection of Al 3+ and Fe 3+ after formation of the 1:1 complex. Test paper coated with MP and used in conjunction with a cell phone was used for colorimetric detection of Al 3+ and Fe 3+ ions (20 μM–2.0 mM) in water samples through naked-eye and digital image colorimetry. The " MP -Fe 3+ " coordination shift that occurs in the presence of the competitive ligand F¯ was used in the colorimetric measurement of F¯ in toothpaste. In the presence of Cu 2+ ion, the non-emissive MP has transformed into fluorescent benzotriazole product PMP (Φ = 0.53) through the bimolecular rate-limiting step, and the second-order rate constant k is calculated as 31 ± 2 M −1 s −1 . MP exhibits a "turn-on" fluorescence response in the presence of Cu 2+ that is greater than its response in the presence of competitive species such as Fe 3+ , Al 3+ , Co 2+ , Fe 2+ , Zn 2+ , Cd 2+ , Mg 2+ , Mn 2+ , Ni 2+ and Ag + . MP was shown to have low toxicity to living HeLa cells and to present good imaging characteristics for tracking of Cu 2+ in vivo.