A simple internal charge transfer probe offering dual optical detection of Co (II) via color and fluorescence modulations

A newly designed internal charge transfer chemosensor, DIPZON exhibits Co2+ selective optical responses, which include 112 nm red shift in absorption and a dramatic 37-fold enhancement in the fluorescence output in the buffer CH3OH/H2O (1:1 v/v) system. By contrast, the optical responses were not as sensitive with several other biologically relevant metal ions examined with the binding interactions following the sequence Co2+ > Cu2+ > Zn2+ > Cd2+ >> Ba2+ ≈ Ca2+ ≈ Mg2+ ≈ K+ ≈ Na+ ≈ Li+.