Synthesis and multifunctional sensing ability of axially chiral tetranuclear europium clusters

Abstract

The synthesis of chiral lanthanide metal clusters has always attracted the interest of researchers. Herein, a pair of chlorine anion-induced axially chiral tetranuclear europium clusters, namely, [Eu₄Cl₂(R-BNP)₈(EtOH)₈(H₂O)₄]Cl₂·7H₂O (R-4) and [Eu₄Cl₂(S-BNP)₈(EtOH)₈(H₂O)₄]Cl₂·7H₂O (S-4), are synthesized under solvothermal conditions. In the structure, a unique tetranuclear europium cluster is encapsulated by eight chiral binaphthol phosphate ligands. The chirality between enantiomers is confirmed by single-crystal X-ray diffraction and circular dichroism. Furthermore, since R-4 and S-4 can fluoresce red at room temperature, they can be used for the detection of Fe³⁺ ions and nitro explosives. In addition, cycling tests of the sensing have shown that R-4 and S-4 can be used as excellent fluorescent sensors.