Long-range triplet excited-state equilibration occurs over a nanometric distance between platinum(II) 8-quinolinolate ((3)Ptq(2) = 1.87 eV) and platinum(II) tetraphenylporphyrin ((PtTPP)-Pt-3 = 1.89 eV). The equilibrium is mediated by a fluorene-thiophene-fluorene bridge ((FTF)-F-3 = 1.92 eV) and is characterized by a double-exponential decay (tau(1) = 39 +/- 4 ps; tau(2) = 351 +/- 15 ps) that suggests the participation of three separate excited states : (3)Ptq(2), (FTF)-F-3, and 3PtTPP, respectively. Numerical simulation of the dual equilibrium allowed for estimation of the individual rate constants for each of the reversible steps (k(ET) = 3.9 x 10(9)-4.1 x 10(10) s(-1)). As a result of rapid triplet-state equilibration, almost 50% of the excited-state energy is directed from the PtTPP chromophore toward Ptq2, in spite of a small endothermic barrier (0.03 eV).
Montes, Victor A.; Rodgers, Michael A. J.; and Anzenbacher, Pavel Jr., "Excited-state Equilibration Over 30 Angstrom In A Platinum(ii) Quinolinolate-bridge-platinum(ii) Porphyrin Complex" (2007). Chemistry Faculty Publications. 154.