Detection of phosphates in water utilizing a Eu-mediated relay mechanism

• Published in: New journal of chemistry Vol. 46; no. 4; pp. 1839 - 1844
• Main Authors: Farshbaf, Sepideh, Dey, Kaustav, Mochida, Wakana, Kanakubo, Masashi, Nishiyabu, Ryuhei, Kubo, Yuji, Anzenbacher, Pavel
• Format: Journal Article
• Language: English
• Published: 28.01.2022
• DOI: 10.1039/d1nj04578d
• ISSN: 1144-0546

Three carboxamidequinoline ligands were synthesized and their complexes with Eu 3+ were used for recognition and detection of organic/inorganic phosphates in water. The signal transduction process is based on an "On-Off-On" switch in the fluorescence signal utilizing changes in the intramolecular charge transfer (ICT). The fluorescence emission of ligands is quenched upon exposure to the Eu 3+ (Off signal). Following the addition of the phosphate analytes the ligand-Eu 3+ complex disassembles, which results in the regeneration of the original emission of the ligand (On signal). In general, the Eu 3+ complexes show higher affinity towards adenosine 5′-triphosphate (ATP) and lower affinity to other phosphates, namely adenosine 5′-diphosphate (ADP), adenosine 5′-monophosphate (AMP), pyrophosphate (H 2 P 2 O 7 2− , PPi), and dihydrogenphosphate (H 2 PO 4 − , Pi). Fluorescent carboxyamidoquinolines form ensembles with Eu 3+ that can be successfully leveraged in sensing of phosphates showing off-on fluorescence signaling.