Charge transfer photooxidation

Mn(acac)3 in the above mechanism undergoes an intramolecular photooxidation-reduction reaction arising from the ligand to metal charge transfer process (LMCT). 

Blatter, F. and Frei, H. (1993). Very strong stabilization of alkene-02 charge transfer states in zeolite NaY red-light-induced photooxidation of 2,3-dimethyl-2-butene. J. Am. Chem. Soc. 115, 7501-7502... 

The 02 ion appears to play an important role in a number of photooxidation reactions (see Section VI,C) for example, the photo-oxidation of alkenes over TiOz. However, it seems likely that OJ is not, in many cases, active in the oxidation step but further conversion occurs to give a mononuclear species, not detected directly, which then oxidizes the adsorbed hydrocarbons. Photo-oxidation of lattice oxygen in the M=0 systems (e.g., V2Os supported on PVG) gives rise to an excited charge transfer state such as V4 + -0 . This excited state can react as O- either by addition to a reactant molecule or by an abstraction reaction (see Section V of Ref. /). In the presence of oxygen, 03 is formed which then reacts further with organic molecules. 

Beside charge transfer excitation, the independently excited molecule could conduct an electron transfer reaction. Photooxidation of Leuco Ethyl Crystal Violet (tris (p-N, N-diethylaminophenyl) methane) in the presence of carbon tetrachloride is thought to proceed by electron transfer from excited LECV to CC14 (74). Complex formation in the ground state is hardly observed. 

Charge Transfer Interactions in the Photooxidation of Phenothi-azine". In "Excited States Biol. Mol." Birks, J. B., Ed. Proc. Int. Conf., 1974 Wiley Chichester, 1976 p. 116. 

Photooxidation of the central atom Os(II) in hexacoordinated porphyrin complexes is supposed to start with the ejection of an electron from an charge-transfer to solvent excited state, CTTS, of the complexes. A complicated set of elimination, addition and redox steps involving radicals terminates in the formation of the complexes OsIV(Por)Cl2. Solvent molecules (CC14, CHC13, CH2C12) served as a source of chlorine atoms [92, 192]. 

For Fe2+ in octahedral coordination, we do not expect photooxidation of organic molecules via 02"- Fe2+ charge transfer. However, the possibility of photoreduction of organics via transitions from the Fe(3d) orbitals to the Fe(4s) orbitals or Fe(4s) conduction band should be considered. The lowest energy Fe(3d)- Fe(4s) transition is calculated to be 58600 cm"1. Although... 

From spectroscopic and biochemical studies it has become clear that DNA-mediated CT is extremely sensitive to the re-stacking of the intervening DNA bases and to disruption and perturbation of the DNA structure or conformation. This indicates that sensing of DNA damage could be accomplished, at least in part, on the basis of CT chemistry. In considering these possibilities, it is important to discover whether DNA-mediated CT does occur within the cell. Charge transfer in HeLa cell nuclei has recently been probed by use of a rhodium photooxidant [15]. 

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