Cyclometalated Platinum(II) Complexes as Highly Sensitive Luminescent Switch-On Probes for Practical Application in Protein Staining and Cell Imaging

A method to prepare highly luminescent cyclometalated platinum(II) complexes as switch-on probes for application in protein staining and cell imaging, was reported. The finished products showed several properties like MLCT emission in the visible spectral region, solubility and stability in aqueous staining solutions at room temperature, and binding to proteins through non-covalent interaction. The UV-visible absorption and NMR spectroscopy used for the study revealed that platinum(II) complexes remained stable in aqueous solution for 72 hours at room temperature. The cyclometalated platinum(II) complexes acted as protein-binding probes that can be used for the staining of protein mixtures in 1D and 2D SDS-PAGE without interfering with peptide-mass fingerprinting analysis and for live cell imaging. The MLCT emission of platinum(II) complexes were sensitive to auxiliary ligands.