[A new probe for Ca2+ based on the rhodamine B amide armed homotrioxacalix[3] arene-Sb3+ complex]

A new fluorescence probe based on the rhodamine B amide-armed homotrioxacalix[3]arene (1) has been synthesized, and its Ca(2+)-selective chromogenic properties were investigated in acetonitrile Tris-HCl buffer (pH 7) solution by UV-Vis and fluorescence spectroscopies. Upon the addition of Sb3+ ion, the spirocyclic ring of 1 was opened and a significant fluorescence enhancement and colorimetric change was observed. However, addition of Ca2+ ion to the solution of 1-Sb3+ complex leads to a strong fluorescence quenching of the original 1-Sb3+ complex. The phenomenon exhibited a pronounced Ca2+ selective fluoroionophoric behavior over other coexistent metal ions and provided the ratiometric determination as well as naked-eye detection of Ca2+ ions.