Structural investigation of Fe(III)-salen complexes as “turn-on” fluorogenic probes for selective detection of pyrophosphate ions

In this work, we revisited the disassembly approach (also known as Zelder's approach) recently proposed for sensing pyrophosphate (PPi) in water and based on decomposition of metal-salen complexes. A systematic study devoted to structural optimization novel class PPi-responsive fluorogenic probes was conducted. Screening eight different vicinal diamines ( i.e. , bridge salen ligand) combined with use 8-formyl-7-hydroxycoumarin salicylaldehyde derivative) fluorescent reporter, has led a set fully characterized coumarin-salen Fe(III) series analytical validations helped us identify that complexes derived from ethylenediamine racemic 1,2-propylenediamine backbones exhibit best selective PPi-sensing performances (the limits detection were estimated 3.15 × 10 −6 M 2.81 respectively). The implementation both fluorescence time-course measurements RP-HPLC-fluorescence analyses enabled gain further insights into activation mechanism disassembly-based probes. This therefore demonstrates is valuable strategy achieve activity-based anions. • various diamine bridges synthesized. Coumarin-salen used detect through approach. ethylene- offered performances. complex showed good selectivity limit 10-6 M. Disassembly deciphered by NMR analyses.