Oxygen charge-transfer complexes with

Onodera, K., Furusawa, C.-I., Kojima, M., Tsuchiya, M., Aihara, S., Akaba, R., Sakuragi, H. and Tokumaru, K. (1985). Mechanistic considerations on photoreaction of organic compounds via excitation of contact charge transfer complexes with oxygen. 

Takeya, H., Kuriyama, Y. and Kojima, M. (1998). Photooxygenation of stilbenes in zeolite by excitation of their contact charge transfer complexes with oxygen. Tetrahedron Lett. 39, 5967-5970... 

Charge-transfer complexes with oxygen, which absorb in the UV wavelength range Unwanted oligomeric substances... 

Phthalic thioanhydride forms charge-transfer complexes with A.A-diethylaniline and various aromatic hydrocarbons (e.g., a 1 1 complex with naphthalene).131 When oxygen and sulfur are members... 

The radical anion of molecular oxygen (O ) has been prepared and trapped in a range of alcohols, water and benzene but not in aliphatic hydrocarbons (Bennett et al., 1968a). In contrast to COg the e.s.r. spectrum shows that 0 interacts strongly with its immediate environment. This interaction which alters the separation of the upper molecular orbitals of the anion is strongly dependent on the nature of the matrix. Previously, the Oj" radical ion has been stabilized only in ionic materials such as the alkali halides thus it is of particular interest to find that this anion can be trapped successfully in a non-polar matrix (benzene). There is some evidence (Evans, 1961), from optical spectroscopic studies that molecular oxygen can form a weak charge transfer complex with the 77-electron system in benzene and it seems probable that O2 is stabilized in benzene by the formation of a similar complex. 

Kojima and co-workers also examined the photo-oxidation of stilbenes in zeolite Y [150]. The presence of O2 in the stilbene-NaY sample led to a red-shifting of the tail end of the diffuse reflectance spectrum and was assigned to the charge-transfer complex with O2. Upon excitation at 313/366 nm, both cis- and /ra .v-stilbene undergo photo-oxygenation to form benzaldehyde. Phenanthrene, the expected product from the ]2 -f 4] cycloaddition reaction of excited m-stilbene, was also formed. The details of the mechanism leading to benzaldehyde and phenanthrene... 

Molecular oxygen forms charge transfer complexes with the compounds in question, giving rise to strong absorptions at longer wavelengths than do the oxygen-free compounds. The photochemistry of these CT-complexes is also a subject of this review. 

According to Nishida ° the [27t-l-27r] cycloadditions proceed via dipolar intermediates, whereas the [2n + 2(7] cycloadditions start with a single-electron-transfer process. In [27i-l-27t] additions a deeply colored charge-transfer complex is initially formed and the reaction is favored by polar solvents (as is usually the case with [2jt-l-2jt] additions of TCNE to electron-rich alkenes). Vinylcyclopropanes with a very low ionization potential afford the [2 t-f 2(t] product they do not form a charge-transfer complex with TCNE and the reactions have to be performed under oxygen-free conditions (Table 5). 

Lu et al. have reported that the fluorescence intensities of Eu3+ and Tb3+ are markedly enhanced when they are bound on to a poly(acrylamide-acrylic acid copolymer). Dhake et al. have observed interesting differential effects of pressure on the fluorescence of a polymer and the corresponding monomer. Sterically hindered piperidines have for long been of interest as efficient photostabilisers of polymers. Gugumus has now reported that these stabilisers form charge-transfer complexes with molecular oxygen, thereby preventing the formation of such complexes with the polymer. 

The oxidation of polyacetylene is more rapid than expected, due to its forming a charge-transfer complex with oxygen. The initial exposure to oxygen or air causes many orders of magnitude increase in the... 

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