“…Since the MLCT emission strongly depends on the orbital combination of polypyridyl ligands, the emission properties could be readily modulated by the variation of ligand properties [9,12,17,31,32], which provides a useful approach for the development of polypyridyl-ruthenium(II) complex-based luminescent chemosensors [33e39]. In previous works, we identified that the MLCT excited state of ruthenium(II) complexes could be corrupted by the intramolecular photoinduced electron transfer (PET) process when an electron donor or acceptor was attached to polypyridyl ligands, and the elimination of PET by the analyte-triggered reaction could restore the MLCT state to switch on the luminescence of the complexes [40e42].…”