Laser photolysis investigation of induced quenching in photoreduction of benzophenone by alkylbenzenes and anisoles

Unusual photobehavior of benzophenone triplets in hexafluoroisopropanol. Inversion of the triplet character of benzophenone

“…This was interpreted as due to a decrease in the free energy of the ET and the free energy of activation, both as an effect of the specific H-bonding of the BP chromophore by protic solvents and additives. The results in non-protic solvents were compatible with unproductive quenching via a charge-transfer state, which is known to operate for anisole [30][31][32]. Importantly, AN and BP do not form a ground-state charge-transfer complex in either ACN or HFIP.…”

Efficient Photochemical Oxidation of Anisole in Protic Solvents: Electron Transfer driven by Specific Solvent–Solute Interactions

“…It is noted that the data obtained in the nonprotic solvent ACN are well in accord with the literature data. [13,14] A correlation with bulk solvent properties has been previously reported for a subset of the BP/ anisole quenching data in a number of non-protic solvents [15] covering an only two-fold increase in k q on changing the solvent from benzene (e = 2.3) to acetonitrile (e = 35.9). [13,15] As can be read from the data in Table 1, there certainly exists no unifying correlation with the permittivity of the solvent.…”

“…A number of workers [13][14][15] associated the decay rates with the extent of charge-transfer interactions between the BP triplet and the quencher with the former being the acceptor and the latter being the donor. Such a mechanism necessarily bears a dependence on the redox properties both of the acceptor and the donor and therefore can be studied by tuning the redox properties of one of the partners.…”

“…This conclusion had been drawn earlier by a number of workers. [13][14][15] Shizuka et al [14] termed the reaction "induced quenching". Notably, this quenching pathway appears to be efficient since no transient products of the BP triplet quenching by anisole have ever been observed, even in the polar solvent acetonitrile (ACN) or in ACN/water mixtures.…”

Thermally controlled photocatalytic coalescence of functionalized gold nanoparticles

“…In addition, AuNPs can act as an electron-storage and transfer medium, reducing metal ions on their surface (seeding-growth) 13,14,27 . The benzophenone (BP) triplet excited state, 3 BP, is of nπ* nature and efficiently abstracts hydrogen atoms from good hydrogen donors 15 . As a consequence, the irradiation of BP in THF leads to ketyl radicals (BPH) that can act as electron donors (E ox =-0.25 Vvs SCE) 16,17 .…”