Selective and Sensitive Two New Macroacyclic Schiff base Fluorescent Turn-Off Receptors for Fe3+, DFT Calculation and Their Antibacterial Activity

Two new Macroacyclic Schiff base chemosensors (L-1 and L-2) were synthesized by the one pot condensation reaction of 2-[3-(2-formyl phenoxy)propoxy]benzaldehyde and aminophenol in a 1:2 molar ratio and were characterized by IR, NMR spectroscopy. Both Schiff bases displayed high selectivity and sensitivity towards Fe3+ over other metal ions in H2O-DMF solution (Ag+,Cu2+, Ni2+, Zn2+, Mg+2, Mn+2, Pb+2, Co+2, Hg+2, Cr+3, Na+, Ba+2 and Cd2+) due to their structure including oxygen donor atoms. The test results showed fluorescence quenching of the fluorophores when Fe3+ was bound to the recognition units. From test results, a high selectivity for Fe3+ were discovered in this type of sensors, especially, the probe based on 2-aminophenol exhibited more significant quenching in fluorescence intensity compared with 4-aminophenol-based due to its rigidity structure. In addition, the structure of ligands and their antibacterial properties was investigated.