Zinc tetraphenylporphin

Beside xanthene dyes, methylene blue,127 porphyrins and por-phins,128-130 zinc-tetraphenylporphin,128 a-hydroxyanthraquinones in alkaline alcoholic or pyridine solutions,112,131 vitamin A, /9-carotene, hypericin, rubrene, 3,4-benzpyrene, 20-methylcholanthrene, chlorophyll, and many other compounds have been found to be sensitizers of photooxygenation reactions.70,132,133 Some groups of dyes, however, such as porphyrins and porphins containing transition metals (e.g., Co), azo dyes, cyanine dyes, and triphenylmethane dyes either did not show any or only very poor sensitizer capabilities in the photooxygenation of a-terpinene.128,134... 

Weak electron acceptors with low triplet energies18 should be used as sensitizers. Tetraphenylporphin (34.0 keal/mol). metalloporphyrins (e.g.. zinc tetraphenylporphin), and hematoporphyrin (37.2 keal/mol) are suitable. Rose bengal (39.2-42.2 keal/mol) can be cm-... 

The extinction coefficient of triplet benzophenone has been remeasured as 7220 320 dm moF cm at 530 nm and this has been used to measure the triplet yield for zinc tetraphenylporphine. The sensitization of naphthalene by benzophenone has been examined in different hydrocarbon or ethanol-ether glasses.Internal heavy-atom effects on the T, states of monochloro-... 

Zinc tetraphenylporphine has been found to sensitize the photoredox reaction between N-phenylglycine and p-benzoquinone in polar solvents. In MeCN and at wavelengths above 500 nm, the ketone is reduced to hydro-quinone, and following decarboxylation of the glycine to PhN=CH2 and hydrolysis, aniline is formed. In ethanol solution, photosensitized reduction... 

Competitive photooxygenatloa with srasltlzer 1. methylene blue 2, rtd>rene 3. zinc tetraphenylporphine 4. rose bengal. B Direct method employing laser pulse excitation of sensitizer 1. methylene blue ... 

C 4H3iFeN402f Aquohydroxyirondll) tetraphenylporphine, 29, 617 C44H32N402Zn, Zinc tetraphenylporphine dihydrate, 29, 617 C44H36lN4Ni 0.08 I, 1,4,5,8,9,12,13,16-Octamethyl-tetrabenzo-por-phinato-nickeKlI ) iodide (partially oxidized), 46B, 502... 

Drago, R.S., Kroeger, M.K. and Stahlbush, J.R. (1981) An E and C analysis of donor numbers and Soret band shifts in adducts of zinc tetraphenylporphine. Irwrg. Chem., 20, 306-308. 

Essentially the same idea had been advanced by Linschitz [5] as early as 1961 to explain the fact that tertiary hydroperoxides were relatively poor in comparison with secondary peroxides in eliciting chemiluminescence from metallo-porphyrins such as zinc tetraphenylporphin (ZnTPP). It was suggested that the peroxide was reduced by the transfer of an electron from the metallo-porphyrin forming an alkoxy-radical and the charge transfer complex ZnTPP The... 

The influence of zinc tetraphenylporphin on the emission spectrum is taken into account, as ZnTPP was used as sensitizer in the singlet oxygen reaction it causes a blue shift by internal absorption). 

S2 - Sq fluorescence and radiationless transitions from the state of porphyrins have been studied in order to reveal photodynaunics of porphyrins. The S2 state fluorescence of zinc(II)-tetraphenylporphin is caused even by the excitation to the state. Two-photon absorption and optical-optical double resonance studies show that a stepwise two-photon absorption through the state is a main process populating the S2 state. 

Tetraphenylporphin (H2TPP) was prepared from pyrrole and benzaldehyde (25). The tetraphenylchlorin contamination was oxidized by use of 2,3-dichloro-5,6-dicyano-p-benzoquinone (26). Octaethylporphin (H2-OEP)was prepared by the method of Paine et al.(27) from 3,4-diethyl-2-ethoxy-carbony1-5-methyl-pyrrole (28). Zinc(II)-tetraphenylporphin (ZnTPP) was prepared by refluxing H2TPP and zinc acetate in dimethyl-formamide (29). ZnTPP was dissolved at a concentration of 10 -10 ... 

Another example of compounds with the fixed mutual location of porphyrin and quinone are the porphyrin-quinone compounds with a rigid bridge. Charge photoseparation in P-L-Q molecules in which L is the trip-ticene bridge, P is tetraphenylporphin, TPP, or its zinc complex, and Q is benzoquinone, BQ, naphthoquinone, NQ, or anthraquinone, AQ, has been studied [55]. The distance between the centres of P and Q fragments in these... 

Rearrangement of 1,4-endoperoxides. Co l PP catalyzes the rearrangement of 1,4-endoperoxides to. syn-l, 2 3,4-diepoxides at - 78 Neither me.w-tetraphenylporphine nor zinc mexo-tetraphenylporphine catalyzes this rearrangement. N,N.N, N -Tetramethyl-ethylenediamine catalyzes the reaction, but only very slowly. The yields from the catalyzed reaction are much higher than those obtained by thermolysis. 

Miscellaneous Metal Ions.—Mention has been made already of a relatively slow formation reaction for the normally labile manganese(ii) ion. Incorporations of the labile bivalent metal ions zinc(ii), copper(ii), manganese(n), cobalt(ii), and nickel(n) into water-soluble porphyrin molecules such as tetrakis-(4-N-methyI-pyridyl)porphine, tetrasulphonated tetraphenylporphine, and uroporphine are also relatively slow reactions. However, by taking into account the porphyrin deformation which is necessary, an Id mechanism can be fitted to these reactions. The rates of formation and dissociation of nickel(ii), copper(n), cobalt(ii), and zinc(ii) complexes of the sterically hindered ligand 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetra-decane (Meicyclam) are also 10 —10 smaller than is normal for these metal ions. ... 

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