A ratiometric fluorescent probe for ferric ion based on a 2,2′-bithiazole derivative and its biological applications

Abstract A new bithiazole-based ratiometric fluorescent chemosensor 4,4′-n-butyl-5,5′-(pyridin-4-yl)-2,2′-bithiazol (L) is prepared and its metal ion sensing properties have been investigated. It exhibits high sensitivity and selectivity toward Fe 3+ among a series of metal ions in EtOH: H 2 O (9:1, v/v). The probe displays a quick response for Fe 3+ over a broad pH range, and the presence of Fe 2+ can also be detected by adding an oxidant like Na 2 O 2 or H 2 O 2 . The association constant of resultant [FeL 2 ] cation is calculated to be 2.76 × 10 3  M −2 , and the detection limit for Fe 3+ is found to be 0.6 μM. The living cell and zebrafish imaging experiments demonstrate its value on the practical applications for biological systems.