posted on 2024-03-13, 12:34authored byHonoka Watanabe, Munetaka Iwamura, Koichi Nozaki
[Pt(NCN)MeCN]+ (NCN =
1,3-di(2-pyridyl)benzene,
MeCN
= acetonitrile) forms oligomers, such as dimers and trimers, in solutions
due to metallophilic interactions. The emission and absorption spectra
in the visible region are considerably changed by the concentrations
of the solutions because the excitation energy of the oligomers is
dependent on the degree of oligomerization. In this study, excited-state
dynamics of [Pt(NCN)MeCN]+ in acetonitrile were investigated
by time-resolved emission spectroscopy in time regions from microseconds
to nanoseconds at various concentrations. The time-resolved emission
spectra recorded with 355 nm photoexcitation showed the decay of the
blue–green emission and the rise of the red emission in the
microsecond time region. Stern–Volmer analysis of the time-resolved
data at various concentrations and wavelengths provides two bimolecular
rate constants (4.1 × 109 and 8.2 × 108 M–1 s–1) for the formation processes
of the excited-state T1 dimer and T1 trimer,
respectively. Kinetic parameters, such as the intrinsic decay rate
constants of the T1 monomer, T1 dimer, and T1 trimer, and the association and dissociation rate constants
of the T1 dimer and T1 trimer were estimated
by fitting the time-resolved emission data at various concentrations.