Diaminoterephthalate‐EDTA and ‐EGTA Conjugates – “Turn on” Fluorescence Sensors for Zinc Ions

Abstract

AbstractA highly effective “turn‐on” fluorescence sensor with high selectivity for Zn2+ ions is reported. Its constitution simply consists of two units of the fluorescence dye diaminoterephthalate (DAT) and the chelate ligand EDTA. In total, four products (DAT)2EDTA and (DAT)2EGTA were prepared by conjugation of DATs with chelate ligands EDTA and EGTA as sensors for metal ions in solution. The fluorescence of all four compounds is strongly quenched by coordination of Cu2+ and Ni2+ ions. For one EDTA‐derivative, the fluorescence quantum yield is increased by the factor of five with ten equivalents of ScCl3. For both EDTA derivatives, the fluorescence quantum yield increased by the factor of five with one equivalent Zn(OAc)2. Therefore, the (DAT)2EDTA structures constitute fluorescence sensors with a high selectivity for Zn2+ accompanied by a strong “turn‐on” effect with Zn2+ ions. Furthermore, the coordination geometry of (DAT)2EDTA with Zn2+ was elucidated by X‐ray single crystal structure analysis of the trinuclear complex [ZnCl2]{Zn(OH2)[(DAT)2EDTA – 2 H]}2 ⋅ 6.5 H2O.