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

Abstract

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.

Keywords: DFT; Pd2+; UV-Vis; fluorescent probe.