Highly sensitive chemosensor for Cu(II) and Hg(II) based on the tripodal rhodamine receptor

A new flexible tripodal compound 1 linked with three rhodamine groups as fluorophores and recognition sites was synthesized and its sensing behavior toward metal ions was investigated by UV–vis and fluorescence spectroscopy methods. It exhibited excellent selectivity for Cu(II) over miscellaneous metal ions including Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Al(III), Mg(II), Ca(II), Sr(II), Na(I), and K(I). While the fluorescence of the 1-Cu(II) complex could be enhanced significantly upon the addition of Hg(II) compound 1 may therefore be applicable as an OFF-ON fluorescent chemosensor for Cu(II) and Hg(II).