A ready‐to‐use fluorescence probe of Pd2+ in water: novel tricyclic heterocyclic base on 1,3,4‐oxadiazole

A ready‐to‐use hetero‐tricyclic compound, 5,5′‐(furan‐2,5‐diyl) bis (1,3,4‐ oxadiazol‐2‐amine) (5), was synthesized with a good yield; it has an suitable fluorescence characteristic and research founded that it can respond to trace Pd2+ in water at a normal pH range. A fluorescence titration revealed the detection limit for Pd2+ was as low as 3.97 × 10−9 M. Density‐functional theory calculation using Guassian09 implied that the breakage of conjugation and coplanarity of compound 5 led to fluorescence quenching. Compound 5 could be applied as a chemical probe to detect trace amounts of Pd2+ with good accuracy, fast response time, excellent selectivity, and high sensitivity. FT‐IR, NMR, and MS were used to characterize the chemical structure of compound 5. Heterocyclic compound 5 is a fluorescent probe with great potential for detecting trace Pd2+ in water.