The synthesis, characterization of three isomers of rhodamine derivative and their application in copper (II) ion recognition

Three isomers of rhodamine derivative, ortho-pyridylaldehyde rhodamine hydrazone (1), meta-pyridylaldehyde rhodamine hydrazone (2), and para-pyridylaldehyde rhodamine hydrazone (3) were synthesized and characterized. And their recognition abilities for Cu2+ were studied by UV–Vis spectra. The result showed that ortho-pyridylaldehyde rhodamine hydrazone (1) due to having a suitable space coordination structure is a best selective probe for Cu2+ over other metal ions in 10 mmol/L HEPES buffer, pH 7.0/CH3OH (v/v, 1:1), and that it is a quick colorimetric and lagged fluorometric dual-model probe for Cu2+. Because it is a fluorescence turn-on probe, cell experiments show probe can permeate through cell membranes and react to Cu2+ within living cells.