A multi responsive phosphonic acid based fluorescent sensor for sensing Fe3+, benzaldehyde and antibiotics

Abstract

Herein, we report a multi responsive and selective fluorescent chemo sensor with anthracene as a fluorophore and phosphonic acid group as receptor (anthracene-9,10-diylbis(methylene)) diphosphonic acid (ANDP) for detecting Fe3+, benzaldehyde and few antibiotics. The sensor was characterised by single crystal X-ray diffraction and 1H NMR. ANDP could selectively and sensitively detect Fe3+ and benzaldehyde in DMSO-water with the detection limits of 5.09 µM and 39.8 µM respectively. 1H NMR, FT-IR and Fluorescence life time measurements suggests the interaction of Fe3+ with the sensor and the oxygen of phosphonic acid group is responsible for the interaction in both the sensing of iron ion and benzaldehyde. Mainly nitro group based antibiotics (NFZ, MDZ, FZD) and TCL sensitively quenched the fluorescence of the sensor with the detection limit of 2.07 µM, 1.25 µM, 1.19 µM and 0.66 µM. The quenching mechanism was further discussed and it was found that the photo induced electron transfer (PET) was responsible for the quenching of fluorescence intensity of ANDP. The HOMO and LUMO energies were estimated by DFT calculations.