A new ternary Eu(III) β‐diketonate complex with diimine ligand and its application as fluorescent probe for highly sensitive and selective ammonia sensor

Abstract

The rapid and accurate detection of ammonia is very important for manufacture and environmental monitoring, which needs to be developed urgently. Herein, a thin film‐based fluorescence sensor is fabricated by using a ternary europium (III) complex probe for ammonia. The new complex Eu(TPM)3(2‐PBO) (1) was designed and synthesized by utilizing a trifluoromethyl substituted β‐diketone ligand TPM and a diimine ligand 2‐PBO (TPM = 1,1,1‐trifluoro‐5,5‐dimethyl‐2,4‐hexanedione, 2‐PBO = 2‐(2′‐pyridyl)‐benzoxazole). This complex probe was synthetically characterized by elemental analysis, crystallographic and spectroscopic analysis, and photoluminescence (PL) study. The crystallographic analysis revealed complex 1 as a neutral complex structure with the Eu(III) center in a distorted square antiprism EuO6N2 coordination polyhedron. Based on this complex probe, a thin film fluorescence sensor with highly sensitive and selective response to ammonia was developed by polymethyl methacrylate (PMMA): complex composite and cellulose paper support. When the paper‐based sensor was exposed to ammonia, its PL emission showed a sensing behavior of rapid quenching. Surprisingly, this new method can achieve excellent limit of detection as low as 2.740 × 10−6 ppm.