Zinc tetraphenylporphyrin

Dye-Sensitized Photoisomerization. One technological appHcation of photoisomerization is in the synthesis of vitamin A. In a mixture of vitamin A acetate (all-trans stmcture) and the 11-cis isomer (23), sensitized photoisomerization of the 11-cis to the all-trans molecule occurs using zinc tetraphenylporphyrin, chlorophyU, hematoporphyrin, rose bengal, or erythrosin as sensitizers (73). Another photoisomerization is reported to be responsible for dye laser mode-locking (74). In this example, one metastable isomer of an oxadicarbocyanine dye was formed during flashlamp excitation, and it was the isomer that exhibited mode-locking characteristics. 

Becker et al. (1985 a) also investigated the photolytic dediazoniation of arenediazonium salts sensitized by zinc tetraphenylporphyrin (ZnTPP). Due to the very different lifetimes of singlet and triplet ZnTPP (1.8 ns and 1.4 ms, respectively) it is possible to differentiate between singlet and triplet electron transfer reactions using different diazonium salt concentrations. 

In spite of the potentialities of reversed micelles entrapping nonaqueous highly polar solvents [34], very few investigations on the solubilization in such systems are reported in the literature. An example is the study of the solubilization of zinc-tetraphenylporphyrin (ZnTPP) in ethylene glycol/AOT/hydrocarbon systems by steady-state and transient... 

Magnetic field effects on the photoelectrochemical reactions of photosensitive electrodes are very important for practical applications of the MFEs in controlling the photoelectronic functions of molecular devices. Previously, we have examined MFEs on the photoelectrochemical reactions of photosensitive electrodes modified with zinc-tetraphenylporphyrin-viologen linked compounds [27, 28] and semiconductor nanoparticles [29, 30[. However, MEEs on the photoelectrochemical reactions of photosensitive electrodes modified with nanoclusters have not yet been reported. 

The functionalization of zinc porphyrin complexes has been studied with respect to the variation in properties. The structure and photophysics of octafluorotetraphenylporphyrin zinc complexes were studied.762 Octabromoporphyrin zinc complexes have been synthesized and the effects on the 11 NMR and redox potential of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraarylporphyrin were observed.763 The chiral nonplanar porphyrin zinc 3,7,8,12,13,17,18-heptabromo-2-(2-methoxyphenyl)-5,10,15,20-tetraphenylporphyrin was synthesized and characterized.764 X-ray structures for cation radical zinc 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrin and the iodinated product that results from reaction with iodine and silver(I) have been reported.765 Molecular mechanics calculations, X-ray structures, and resonance Raman spectroscopy compared the distortion due to zinc and other metal incorporation into meso dialkyl-substituted porphyrins. Zinc disfavors ruffling over doming with the total amount of nonplanar distortion reduced relative to smaller metals.766 Resonance Raman spectroscopy has also been used to study the lowest-energy triplet state of zinc tetraphenylporphyrin.767... 

Kadish et al. (1989) have described the effect of axially bound anions on the electroreduction of tris(IV) porphyrins in THF. Cyclic voltammetric investigations of zinc tetraphenylporphyrin in dichloromethane in the presence of background electrolyte anions reveal significant perturbations of the met-alloporphyrin s first one-electron oxidation, ranging from 0.86 V for TBAPF6 to 0.50 V for TBAC1 (Seely et al., 1994). 

Walker, F.A. and Benson, M., Entropy, enthalpy, and side arm porphyrins. 1. Thermodynamics of axial ligand competition between 3-picoline and a series of 3-pyridyl ligands covalently attached to zinc tetraphenylporphyrin. J. Am. Chem. Soc., 1980, 102, 5530-5538. 

Metallooctaethylporphyrins Zinc tetra(benzo-15-crown-5)porphyrin See also Metallotetraphenylporphrins dimerization effects, 141,147 Zinc tetrabenzoporphyrin—See Metalloporphyrins Zinc tetraphenylporphyrin See also Metalloporphyrins See also... 

A number of workers have studied zinc tetraphenylporphyrin complexes, and an intensive study of the luminescence properties of [ZnTPP] has been reported.1180 [ZnTPP] is also used in the well-known synthetic leaf experiments.11806... 

NADH Nicotineamide adenine dinucleotide reduced form. EDTA Ethylenediamine tetraacetic acid. RSH Mercaptoethanol. ZnTPP Zinc tetraphenylporphyrin. ZnTMPyP Zinc tetrakis(4-methylpyridyl)porphyrin. ZnTPPS Zinc tetraphenylporphyrin tetrasulfomate. 

In a supramolecular approach to fullerene-porphyrin hybrids, the assembly of a rigidly connected dyad, in which a zinc tetraphenylporphyrin, Zn(TPP), is noncovalently linked to a C60 derivative via axial pyridine coordination to the metal, was reported [219-222]. Photo excitation of the dyad Zn-complex led to electron transfer with very long lifetimes of the charge-separated pairs, as revealed by optical spectroscopy and confirmed by time-resolved electron paramagnetic resonance spectroscopy. Accordingly, two different solvent-dependent pathways can be considered for the electron-transfer processes. Either the excitation of the porphyrin chromophore is followed by fast intramolecular electron transfer inside the complex, or alternatively the free porphyrin is excited undergoing intermolecular electron transfer when the acceptor molecules ap-... 

Absorption and emission spectra of zinc tetraphenylporphyrin derivatives soluble and insoluble in water showed an equilibrium between two spectroscopically different porphyrin species incorporated in reversed micelles o r hpn /v IH i hv I -n-hcxadccy lammonium chloride in benzene formed by varying the water content... 

Condensing racemic l,2-methano[70]fullerene-71-carboxylic acid obtained by hydrolysis of its tert-butyl ester (( )-260, Scheme 1.25),243 with an amino derivative of zinc tetraphenylporphyrin, Imahori, Yamazaki, Sakata, and coworkers synthesized a C7o-containing dyad.355,446 Comparison with the C60-analogue showed that photoinduced electron transfer from the singlet excited Zn-porphyrin to the fullerene is faster in the C70 derivative. 

Four years after their initial report, the first alternative synthesis of homoporphyrins was reported by Callot and coworkers [14], In this work it was found that the reaction of zinc tetraphenylporphyrin 20 with disubstituted diazoalkanes (Scheme 6) gives, after workup, the corresponding free-base homoporphyrins, namely 21-25. Treatment of these expanded porphyrins with Ni(II) gives the corresponding nickel complexes, namely 26-30. Reactions of 21 with other metals also gives the expected metal complexes 31-34 [15-17]. 

Zinc tetraphenylporphyrinate forms a weak complex with Of in non-aqueous solutions. The bonding in this complex appears to be essentially ionic . We have already mentioned crystal structure determinations of lanthanide and actinide compounds. There is every reason to suppose that these elements have a rich dioxygen complex chemistry and this is confirmed by two recent papers For reasons of space, however, we shall not discuss the dioxygen complex chemistry of these elements. 

Prisner et al. measured the time dependence of CIDBP spectra in the photooxidation of zinc tetraphenylporphyrin (ZnTPP, SxlO" M) with duroquinone (DQ, 5x10 M) in ethanol at -28 °C with FTBSR [17]. The observed spectra are shown in fig. 5-8. Here, the signals with sharp HFS are due to DQ and the underlying broad ones are due to ZnTPP . 

One of the first reported Ceo-based donor-acceptor systems is also the H2P-C60 and the analog ZnP-Cso dyad (20), in which H2P denotes the metal-free base tetraphenyl porphyrin and ZnP is the corresponding zinc tetraphenylporphyrin... 

Tetramethoxyethylene in ether at -70 °C treated with oxygen under irradiation in the presence of zinc tetraphenylporphyrin furnishes a 94% yield of 1,1,2,2-tetramethoxydioxetane [37], Chemically generated singlet oxygen converts substituted ketenes into a-peroxylactones (equation 67) 20],... 

The photoionization of zinc tetraphenylporphyrin and chlorophyll a in vesicles was also followed up by the ESR spectroscopy of rapidly frozen vesicles . It was found that the radical cation yield decreases in negatively charged vesicles and increases in positively charged vesicles. The cationic vesicles obviously favour electron escape from the photoproduced cation via the vesicle interface into bulk water negatively charged surfaces hinder the escape. 

H. Nakamura, S. Usui, Y. Matsuda, T. Matsuo, K. Maeda, and T. Azumi, Time-resolved electron spin resonance spectra of linked radical pairs on laser excitation of zinc tetraphenylporphyrin-viologen systems,./. Phys. Chem. 97, 534-536 (1993). 

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