biostudies-literatureUnknown62(48)Knighton RCA series of photoluminescent Ru(II) polypyridine complexes have been synthesized in a manner that varies the extent of the cationic charge. Two ligand systems (L1 and L2), based upon 2,2'-bipyridine (bipy) mono- or difunctionalized at the 5- or 5,5'-positions using <i>N</i>-methylimidazolium groups, were utilized. The resulting Ru(II) species therefore carried +3, +4, +6, and +8 complex moieties based on a [Ru(bipy)₃]²⁺ core. Tetra-cationic [Ru(bipy)₂(<b>L2</b>)][PF₆]₄ was characterized using XRD, revealing H-bonding interactions between two of the counteranions and the cationic unit. The ground-state features of the complexes were found to closely resemble those of the parent unfunctionalized [Ru(bipy)₃]²⁺ complex. In contrast, the excited state properties produce a variation in emission maxima, including a bathochromic 44 nm shift of the ³MLCT band for the tetra-cationic complex; interestingly, further increases in overall charge to +6 and +8 produced a hypsochromic shift in the ³MLCT band. Supporting DFT calculations suggest that the trend in emission behavior may, in part, be due to the precise nature of the LUMO and its localization. The utility of a photoactive polycationic Ru(II) complex was then demonstrated through the sensitization of a polyanionic Yb(III) complex in free solution. The study shows that electrostatically driven ion pairing is sufficient to facilitate energy transfer between the ³MLCT donor state of the Ru(II) complex and the accepting ²F_5/2 excited state of Yb(III).Inorganic chemistry19446-19456https://www.ebi.ac.uk/biostudies/studies/S-EPMC10698718biostudies-literaturePolycationic Ru(II) Luminophores: Syntheses, Photophysics, and Application in Electrostatically Driven Sensitization of Lanthanide Luminescence.PMC10698718Pope SJAKnighton RCBeames JMfalsePolycationic Ru(II) Luminophores: Syntheses, Photophysics, and Application in Electrostatically Driven Sensitization of Lanthanide Luminescence.A series of photoluminescent Ru(II) polypyridine complexes have been synthesized in a manner that varies the extent of the cationic charge. Two ligand systems (L1 and L2), based upon 2,2'-bipyridine (bipy) mono- or difunctionalized at the 5- or 5,5'-positions using <i>N</i>-methylimidazolium groups, were utilized. The resulting Ru(II) species therefore carried +3, +4, +6, and +8 complex moieties based on a [Ru(bipy)₃]²⁺ core. Tetra-cationic [Ru(bipy)₂(<b>L2</b>)][PF₆]₄ was characterized using XRD, revealing H-bonding interactions between two of the counteranions and the cationic unit. The ground-state features of the complexes were found to closely resemble those of the parent unfunctionalized [Ru(bipy)₃]²⁺ complex. In contrast, the excited state properties produce a variation in emission maxima, including a bathochromic 44 nm shift of the ³MLCT band for the tetra-cationic complex; interestingly, further increases in overall charge to +6 and +8 produced a hypsochromic shift in the ³MLCT band. Supporting DFT calculations suggest that the trend in emission behavior may, in part, be due to the precise nature of the LUMO and its localization. The utility of a photoactive polycationic Ru(II) complex was then demonstrated through the sensitization of a polyanionic Yb(III) complex in free solution. The study shows that electrostatically driven ion pairing is sufficient to facilitate energy transfer between the ³MLCT donor state of the Ru(II) complex and the accepting ²F_5/2 excited state of Yb(III).2023-01-01T00:00:00Z2023 Dec2025-04-26T11:50:00.671Z2025-04-06T13:47:09.996ZS-EPMC106987183798405810.1021/acs.inorgchem.3c02352