Development of a Ratiometric Fluorescent Cu(II) Indicator Based on Poly(-isopropylacrylamide) Thermal Phase Transition and an Aminopyridyl Cu(II) Ligand.

An aqueous Cu and Zn indicator is reported based on copolymerizing aminopyridine ligands and the environment-sensitive dansyl fluorophore into the responsive polymer poly(N-isopropylacrylamide) (PNIPAm). The metal ion binding creates charge and solvation that triggers PNIPAm's thermal phase transition from hydrophobic globule to hydrophilic open coil. As a basis for sensing the metal-binding, the dansyl fluorescence emission spectra provide a signal at ca.