New aza[5]helicene derivative for selective Fe(III) fluorescence sensing in aqueous media and its application in water samples

Abstract A new iron(III) fluorescence sensor AH2 was developed based on aza[5]helicene core structure this was the first report of aza[5]helicene derivative as fluorescence dye in sensing application. AH2 was designed and synthesized by using sample conditions with only a two-step reaction, i.e., Cu(II)-catalyzed aerobic oxidation of hydrazide/hetero Diels-Alder reaction with diene followed by oxidation. This AH2 compound showed excellent selectivity toward Fe(III) over other metals including the well-known interference ions of Fe(II) and Cu(II). It had a large Stokes shift in aqueous buffer solution with physiological pH. The solvent effect study showed positive solvatochromism with increasing solvent polarity. Additionally, this sensor had potential to detect Fe(III) in real water samples including drinking water, pond water, canal water and river water.