Change in mechanism during fluorescence quenching of substituted anthracenes by triphenylphosphine

Substituent effect on the photoinduced electron-transfer reaction of para-substituted triphenylphosphines sensitised by 9,10-dicyanoanthracene

“…It has also been reported that 1a quenches DCA fluorescence in benzene with a rate constant of 1.1 × 10 10 dm 3 mol Ϫ1 s Ϫ1 (ref. 4). The quenching rate constant in benzene is equal to the diffusion-controlled rate constant in benzene at room temperature (k diff = 1.1 × 10 10 dm 3 mol Ϫ1 s Ϫ1 ).…”

Coulomb interactions for mediator-enhanced sensitized triplet–triplet annihilation upconversion in solution

“…Briefly, after excitation of the sensitizer and the energy transfer sequence and subsequent TTA-UC with DPA as annihilator, the emitted light is absorbed by DCA and with the help from a naphthalene redox mediator, the triphenylphosphine substrate is oxidized. Triphenylphosphine (1.9 × 10 10 M −1 s −1 in 2 : 98 water/ acetonitrile, 123 2.7 × 10 10 M −1 s −1 in acetonitrile) 126 and naphthalene (1.5 × 10 10 M −1 s −1 in acetonitrile) 65,127 quench excited DCA with almost diffusion-limited rate constants, and it has been shown previously for light-driven catalysis with DCA that a higher cage escape with the mediator enables a faster overall product formation. 65,[128][129][130] Electron transfer from the radical anion of DCA (DCA •− ) to molecular oxygen closes the catalytic cycle and overall, the phosphine is oxidized to its phosphine oxide.…”

Electron transfer induced photofragmentation as a route to free radicals

“…Fluorescent anthracene singlets with excited state redox potentials between 1.57 and 2.57 volts (E* vs SCE) [21] were quenched by a series of substituted benzylic trialkylstannanes. Rate constants for quenching (kq = kq + kq Table I) correlated with E* for constant r -e p r 1/2 quencher and with the ionization potential of the organotin compounds for constant fluoror.…”