Facile synthesis of anthracene-appended amino acids as highly selective and sensitive fluorescent Fe3+ ion sensors

We designed new fluorescent chemical sensors for Fe3+ ion detection, by conjugating amino acids as receptors into an anthracene fluorophore. The conjugates were synthesized in solid phase by Fmoc-chemistry. Fluorescence sensors containing Asp (1) and Glu (2) both had exclusive selectivity for Fe3+ in 100% aqueous solution and in a mixed organic-aqueous solvent system. Other metal ions did not interfere with the detection ability of the sensors for Fe3+. The sensors detect Fe3+ ions via a chelation-enhanced fluorescent quenching effect. The binding affinity, reversible monitoring, and pH sensitivity of the sensors were investigated. In addition, detection of fluoride ion among halide ions was done by a chemosensing ensemble method with 1-Fe3+ and 2-Fe3+ complexes.