A New Benzoxazole-Based Fluorescent Macrocyclic Chemosensor for Optical Detection of Zn2+ and Cd2+

Background: Benzoxazole-containing ligands find many applications both in medicinal chemistry, catalysis and fluorescence chemosensing. macrocycles could be therefore a good strategy to achieve stable selective fluorescent complexes with suitable metal ions. In this work, the synthesis, binding, photochemical properties of new ligand (L) are reported. L is cyclophane macrocycle containing 1,3-bis(benzo[d]oxazol-2-yl)phenyl (BBzB) fluorophore an aliphatic tetra-amine chain form macrocyclic skeleton. Methods: Spectrophotometric spectrofluorimetric measurements, 1H NMR analysis, DFT calculations were performed. Results: behaves as PET-mediated chemosensor, being emissive at 390 nm acidic pH non-emissive basic pH. The chemosensor able detect Zn2+ Cd2+ aqueous medium (acetonitrile–water, 4:1 v/v) neutral through CHEF effect upon ion coordination. Paramagnetic ions (Cu2+) heavy atoms (Pb2+, Hg2+) resulted quenching or very low emission. Conclusions: was revealed PET-regulated for medium, bind up two one cations, respectively. molecule showed shifted emission towards visible region compared similar systems, suggesting co-planar conformation aromatic fragment All these data supported by experimental measurements theoretical calculations.