Phenothiazine transfer

In contrast to phenols (Section 5,3.4), phenothiazine (39) is reported to be an excellent scavenger of both carbon-centered and oxygen-centered radicals by hydrogen atom transfer and is also used to stabilize monomers in storage.198... 

Yonemura, H., Noda, M., Hayashi, K, Tokudome, H., Moribe, S. andYamada, S. (2002) Photoinduced intramolecular electron transfer reactions in fiillerene-phenothiazine linked compounds effects of magnetic field and spacer chain length. Mol. Phys., 100, 1395-1403. 

The reduction of tetrazolium salts by NADH is greatly accelerated by electron transfer agents (ETAs) such as phenazine methosulfate (PMS 233) or its derivatives.451-454 Other classes of ETAs such as quinones.455,456 ferricinium,457 phenothiazine,458 the viologens,459 acridiniums,460 and phe-nazinium or quinoxalinium salts461 as well as the enzyme diaphorase462 have been used. 

Keywords Pulse radiolysis Pyrene Phenothiazine Radical cation Hole transfer rate... 

Two Organic Molecules Hole Transfer from Pyrene + to Phenothiazine in DNA. 131... 

R. Bezman and L. R. Faulkner discussed theoretical and practical aspects for measurements of the efficiencies of chemiluminescent electron transfer reactions 189>. They also performed absolute measurements of the chemiluminescence of the fluoranthene- 10-methyl-phenothiazine system 211h... 

The most commonplace substrates in energy-transfer analytical CL methods are aryl oxalates such as to(2,4,6-trichlorophenyl) oxalate (TCPO) and z s(2,4-dinitrophenyl) oxalate (DNPO), which are oxidized with hydrogen peroxide [7, 8], In this process, which is known as the peroxyoxalate-CL (PO-CL) reaction, the fluorophore analyte is a native or derivatized fluorescent organic substance such as a polynuclear aromatic hydrocarbon, dansylamino acid, carboxylic acid, phenothiazine, or catecholamines, for example. The mechanism of the reaction between aryl oxalates and hydrogen peroxide is believed to generate dioxetane-l,2-dione, which may itself decompose to yield an excited-state species. Its interaction with a suitable fluorophore results in energy transfer to the fluorophore, and the subsequent emission can be exploited to develop analytical CL-based determinations. 

The electron-transfer reactions between the /3-cyclodextrin (/3-CD) N-substituted phenothiazine derivatives and /3-CD.ATPO (4-acetoxy-2,2,6,6-tetramethyl-1-oxopiperidinium hexachloroantimonate) were found to be influenced by the conformations of the phenothiazine derivatives restricted by the /3-CD cavity. N-Phenylphenothiazine (PPT) and A-phenylethylphenothiazine (PEPT), included by /3-CD, can transfer an electron to the /S-CD.ATP complex. No electron transfer was observed between the /3-CD.A-benzylphenothiazine (/3-CD.BPT) complex under the same conditions. The conformation of the /3-CD.BPT complex is such that the oxidation centre was shielded by the /3-CD wall and the substituent. However, electron-transfer reactions between y-CD.BPT and /3-CD.ATP and nitric acid occurred. ... 

Mechanisms involving glycol bond fission have been proposed for the oxidation of vicinal diols, and hydride transfer for other diols in the oxidation of diols by bromine in acid solution.The kinetics of oxidation of some five-ring heterocyclic aldehydes by acidic bromate have been studied. The reaction of phenothiazin-5-ium 3-amino-7-dimethylamino-2-methyl chloride (toluidine blue) with acidic bromate has been studied. Kinetic studies revealed an initial induction period before the rapid consumption of substrate and this is accounted for by a mechanism in which bromide ion is converted into the active bromate and hyperbromous acid during induction and the substrate is converted into the demethylated sulfoxide. 

In complex (81), the electron-donating phenothiazine moiety is separated from the Ru(bpy)2 " unit by a triazole bridge that carries a formal negative charge. An investigation of this system shows that such anionic bridges can mediate electron transfer between chromophore and quencher. ... 

Aliphatic amines act as reducing agents for the photoreduction of phenazine or phenothiazine dyes. It was found that polyamine induces a much higher photopotential than monoamine 91). The value of the photopotential was strongly dependent upon the number of amino or imino groups in one molecule when an oligoamine was used (Fig. 25). The electron transfer from the amine to the excited dye was proposed to be facile due to a bifunctional interaction between the dye and the adjacent free and protonated N-groups of the polyamine (24). 

Skraup quinoline synthesis, 443 Smiles rearrangement, phenothiazine, 534 Spiroalkylation, 222, 280 Spirocyclization, conjugate addition, 386 Spiroimidazolone formation, 335 Spiropyrazolopiperidine, 375 Stannylation, alkyne, 15 Stereoselective dehydration, 198 Grignard addition, 198, 199 reduction, 129, 226 hydroxyketone, 400 iminoketone beta, 553 oxazaborohydride, 585 transfer chirality, 321 Stilbene formation, self alkylation, 525 Stobbe condensation, benzophenone, 103... 

Phenothiazine (PTZ) and ferrocene (Fc), both of which have a small reorganization energy associated to the electron transfer, are the first comediators that have been considered. Each has a potential that falls between 0.22 and 0.75 V versus SCE, respectively, the potential of the Co(DTB)33+/2+ and of the dye [Ru(H2DCB)-(dnbpy)(NCS)2]+/0. Because of the facile electron transfer, the photooxidized dye would be predominantly reduced by the comediator. Its oxidized form (PTZ+ and Fc +) can then be rapidly intercepted by Co(II), preventing the direct charge recombination between the oxidized comediator and the electrons in the 2. Nanosecond... 

Masse141 obtained good yields on N-alkylating 2-chlorophenothiazine, using a biphasic system and TEBA as catalyst. When unreactive halides were used, a by-product was formed due to benzylation by the catalyst TEBA. This observation has been confirmed and clarified in a study of the behavior and stability of bi- and triphase transfer catalysts.142 Under the same conditions unsubstituted phenothiazine is not alkylated,143 indicating an activating efTect of the chloro substituent. 

Other dyes which participate efficiently as electron transfer catalysts include the xanthenes (217,218), thianthrenes (219), phenothiazines (220), and anthraquinonesulfonates (221). 

Heterocyclic substrates in SET processes have been widely studied, including the reactions of diliydroiiicotiiiamide,116 pyridine, and quinoline117 and also phenoxazine and phenotiiiazines.118 Phenothiazine has also been shown by ESR analysis to undergo an electron-transfer reaction witii its radical cation with an appreciable 15N/14N isotope effect.119 The reaction of phenazine di-A -oxidc radical cations with hydrocarbons shows evidence of non-radical processes.120... 

Electron and Energy Transfer from Phenothiazine Triplets... 

Phenothiazine is readily oxidized when irradiated in solution with chlorinated hydrocarbones (8). The reaction has been shown to be an electron transfer generating the phenothiazine (PTH) radical cation (PTH+ ) and the halogen anion as shown in equation 1. hv. ... 

Triplets of N-methyl-phenothiazine ( MPT) are found to reduce almost quantitatively Cu2+ but to transfer their energy to Ni2+ and Co2+... 

Since triplet N-methyl-phenothiazine reduces NOj, the redox potential of JmPT must be <-l V and has been estimated to be -1.8 V (20). The electron transfer rate observed for reaction 22 in aqueous DTAC micellar systems is 3.5xl03 M- s- and, thus, under the experimental conditions reported, about a factor of 10 slower than reaction 18. 

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