Determination of excimer emission quantum yield of Pt(dpb)Cl (dpbH=1,3-di(2-pyridyl)benzene and its analogues in solution

We investigated solvent and substituent effects on excimer emission of Pt(dpb)Cl (dpbH = 1,3-di(2-pyridyl)benzene). The excimer emission quantum yield (phi(D)) were varied from 26% in CH3CN, 15% in (CH3)(2)CO, 8.5% in CH2Cl2, 6.0% in MeOH, 5.6% in EtOH, and 2.2% in 2-PrOH, and the excimer emission lifetimes (tau(D)similar to 1 mu s) in the non-alcoholic solvents were slightly longer than those in the alcoholic solvents. Excimer emissions in the non-alcoholic solvents were peaking at similar to 710 nm red-shifted from those in the alcoholic solvents (lambda(D)similar to 700 nm). The attachment of F to phenyl moiety in ligand contributed to the increase in phi(D): 20% for Pt(F(2)dpb)Cl (F(2)dpbH = 4,6-difluoro-1,3-di(2-pyridyl)benzene), 16% for Pt(Fdpb)Cl (FdpbH = 4-fluoro-1,3-di(2-pyridyl)benzene) in (CH3)(2)CO, whereas it caused the decrease in tau(D) and no-remarkable shift of lambda(D). Introduction of methyl groups to pyridyl moieties effectively contributed to the blue-shift of spectrum and the remarkable increase in phi(D); that is, phi(D) = 74% was evaluated for Pt(Fmdpb)Cl (FmdpbH = 4-fluoro-1,3-di(4-methyl-2-pyridyl)benzene) in CHCl3, which could be compared with the monomer emission quantum yield phi(M) = 71%. In addition, the trimer emission quantum yield was evaluated as phi(T) = 41% for the complex.