Self-quenching and Cross-quenching Reactions of Excited Platinum(II) Diimine Complexes
Titel:
Self-quenching and Cross-quenching Reactions of Excited Platinum(II) Diimine Complexes
Auteur:
Fleeman, Wendi L. Connick, William B.
Verschenen in:
Comments on inorganic chemistry
Paginering:
Jaargang 23 (2002) nr. 3 pagina's 205-230
Jaar:
2002-05
Inhoud:
Neutral platinum(II) diimine complexes undergo self-quenching in fluid solution, characterized by a linear increase in the emission decay rate with concentration. The corresponding quenching rates (∼10 9 -10 10 M -1 s -1 ) are nearly diffusion limited. The accumulated evidence suggests that an excited platinum complex, M*, reacts with a ground-state complex, M, to form an excimer, M 2 *, which rapidly relaxes to give two ground-state complexes. The reaction mechanism and the nature of the excimer are discussed in context of the electronic structures, spectroscopy, and quenching kinetics of these complexes. Steady-state cross-quenching experiments suggest that an excited platinum complex also can react rapidly (∼10 9 -10 10 M -1 s -1 ) with a different ground-state platinum diimine complex (Q), presumably to form an exciplex, MQ*. In contrast, aromatic molecules and platinum(II) complexes lacking a diimine ligand are relatively ineffective quenchers. These results suggest that both the diimine ligand and platinum center are important for quenching.
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