Photooxidation of nickel(II) azamacrocyclic complexes to trivalent nickel complexes on excitation in the charge-transfer-to-solvent band

Prakash, Halan; Natarajan, P.

doi:10.1016/j.jphotochem.2004.04.016

Cited by 8 publications

(1 citation statement)

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“…There have been a few reports of CTTS absorption and/or photoionization for cationic species. ,,,− That there are not more such reports may be partly due to competing absorptions involving some of the many electronic states that are characteristic of such complexes because these may obscure the CTTS absorptions. In analogy to the iodide photoionization, the photoionization co-products of cations (S m + ) would be expected to involve a succession of geminate {S ( m +1)+ ,e – } IP ion pair species analogous to the {I • ,e – } IP radical pairs, oxidized substrate, and free electron species.…”

Section: Introductionmentioning

confidence: 99%

Chemical Scavenging Yields for Short-Lived Products from the Visible Light Photoionization of the Tris(bipyridine)ruthenium(II) Triplet Metal-to-Ligand Charge-Transfer Excited State

Alnaed

Endicott

2018

J. Phys. Chem. A

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The rate of visible light photoionization of the tris(bipyridine)ruthenium(II) triplet metal-to-ligand charge-transfer excited state (3MLCT) is very strongly dependent on the acid concentration in aqueous solution, and the pattern of this dependence is similar to that reported for the photoionization of iodide. With 405 nm visible irradiation of 3MLCT, less than 15% of the photoionized products appear as free solvated electrons in bulk solution, while more than 75% of the photoproducts appear to be solvent-separated, (oxidized substrate)–electron ion pairs that efficiently recombine with the photo-oxidized complex in the absence of an electron scavenger. The quantum yield of free solvated electrons generated by these 405 nm irradiations is approximately 0.004, but the net quantum yield of scavengeable electrons is estimated to be about 0.04. A visible-region photoionization threshold energy for the 3MLCT is consistent with thermodynamic expectations, and similar behavior is expected for many redox-active complexes.

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