Rapid and simultaneous detection of Cr (III) and Fe (III) ions by a new naked eye and fluorescent probe and its application in real samples

We describe a new naked eye and fluorescent chemosensor which exhibited greater selectivity and specificity toward Cr3+ and Fe3+ ions over other tested metal ions. The newly synthesized compound, RBCB displayed a visual color change and fluorescence enhancement with Cr3+ and Fe3+ ions. Structural characterization of the title compound was carried out by FTIR, NMR and mass spectral analysis. Interaction of RBCB to Fe3+ and Cr3+ leads to spirolactum ring opening of rhodamine which inturn evokes a 56 and 25-fold fluorescence enhancement. For RBCB, the limit of detection even lower than the permissible [Cr3+] or [Fe3+] in drinking water as per WHO standard. The low RSD % and high recoveries demonstrate that RBCB can serve as a potential sensor for the accurate detection of Cr3+ and Fe3+ in real samples. DFT, FTIR and Mass spectral studies reveal that RBCB binds to Cr3+ and Fe3+ in a 1:1 pattern evidenced by Job's plot analysis. Furthermore, the sensor is insensitive to pH 6-10 therefore can be applied for environmental and biological samples. Moreover, titration experiments against sodium-EDTA revealed that the test compound can be used as reversible probe for Cr3+ and Fe3+ ions. (C) 2017 Elsevier B.V. All rights reserved.