A Colorimetric and Ratiometric Fluorescent Probes Based on Intramolecular Charge Transfer

A new colorimetric and ratiometric fluorescent anion receptor based on 4-methyl-1-hydroxybenzo-phenone p-nitrophenylhydrazone 1,was designed and synthesized.In the compound 1,the phenolic hydroxyl moiety and the hydrazone moiety are anion binding sites and the nitrobenzene moiety is a signaling group.Upon addition of AcO-,H2PO4-,F-,the color of receptor 1 in DMSO solutions changed from yellow to purple,while no obvious color changes were observed on addition of the other anions tested.Accordingly,the sensor 1 could sense visually AcO-,H2PO4-,F-without resorting to any spectroscopic instrumentation.The binding properties of the receptor 1 with anions such as AcO-,H2PO4-,F-,Cl-,Br-,I-were investigated by UV-Vis and Fluorescent titrations.The 1H NMR titrations further looked into the nature of host-guest interactions.