A novel tricyclic heterocyclic fluorescent probe for Pd2+ in aqueous solution: Synthesis, properties and theoretical calculations

Abstract A novel tricyclic heterocyclic compound, 5,5’-(furan-2,5-diyl)bis (1,3,4- thiadiazol-2-amine) (3), was easily synthesized, which has an excellent fluorescence performance and could be a chemical sensor of Pd2+ at a very broad pH range. Fluorescence titration shows that the detection limit of Pd2+ is up to 1.07 × 10−9 M with a good accuracy. Density function theory (Guassian 09) indicates that the coordination of Pd2+ decreases the coplanarity and conjugation of compound 3, resulting in a fluorescence quenching. Generally, compound 3 could be practically applied in the convenient detection of Pd2+ with high sensitivity, excellent selectivity, good accuracy, and short response time. Compound 3 was characterized by NMR, MS, FT-IR, UV–Vis, 1H NMR, 13C NMR, and HRMS.