An efficient long fluorescence lifetime polymer-based sensor based on europium complex as chromophore for the specific detection of F−, CH3COO−, and H2PO4−

Abstract

A novel long fluorescence lifetime europium-complexed copolymer (Eu-polymer) has been designed and synthesized via the classic free radical copolymerization reaction as an efficient fluorescent sensor for F⁻, CH₃COO⁻, and H₂PO₄⁻. The anions-sensitivity of Eu-polymer was evaluated using a series of anions in DMSO solution. On binding to F⁻, CH₃COO⁻, or H₂PO₄⁻, fluorescence quenching of Eu-polymer was demonstrated by an approximately 95% reduction in the fluorescence intensity, while no obvious fluorescence change could be observed in the presence of other anions. Compared with its small molecular counterpart, Eu-polymer exhibits higher sensitivity and selectivity. Most importantly, the Eu-polymer sensor can efficiently recognize and sense F⁻ even in the presence of competitive anions, such as CH₃COO⁻ and H₂PO₄⁻, which demonstrates the ability of Eu-polymer to function as a selective fluorescence sensor for F⁻. The fluorescence quenching can be attributed to the strong hydrogen bonding interaction (and deprotonation interaction at high concentration for F⁻) between anions and the imidazole group of Eu-polymer. Due to the long fluorescence lifetime of this Eu-polymer, it can efficiently eliminate the effects of auto-fluorescence and light scattering from surrounding biological environments, so this sensor will be very significant for application in biological and environmental fields.