Anions porphyrin and

Photoinduced Hydrogen Evolution with Water-soluble Viologen-linked Anionic Porphyrin and Hydrogenase... 

Anionic porphyrins and metalloporphyrins can be ion exchanged into layered double hydroxide (LDH) materials... 

Smaragdytins Emeralds of expanded porphyrin family 12ACR1801. Specific binding of anionic porphyrin and phthalocyanine to the G-quadruplex with a variety of in vitro and in vivo applications 12MOL 10586. 

Samsonova and Nikiforov, 1984), and porphyrin and phthalocyanine metal complexes (Becker et al., 1985a, 1986b Becker and Grossmann, 1990) were tested. That a series of relatively simple anions such as the oxalate monoanion, tetraphenyl bor-anate (Ph4B ), bromide, chloride, and even tetrafluoroborate can act as donors is, at least for the last mentioned anion, surprising, but Becker et al. (1985 b) were able to trap aryl radicals and in some cases also donor radicals (Cl, COO ) by spin trapping with nitrosodurene and phenyl-tert-butylnitrone. The photochemical effect is postulated to be due to ion pairs ArNJ X-. 

The electronic absorption spectra of the products of one-electron electrochemical reduction of the iron(III) phenyl porphyrin complexes have characteristics of both iron(II) porphyrin and iron(III) porphyrin radical anion species, and an electronic structure involving both re.sonance forms Fe"(Por)Ph] and tFe "(Por—)Ph has been propo.sed. Chemical reduction of Fe(TPP)R to the iron(II) anion Fe(TPP)R) (R = Et or /7-Pr) was achieved using Li BHEt3 or K(BH(i-Bu)3 as the reductant in benzene/THF solution at room temperature in the dark. The resonances of the -propyl group in the F NMR spectrum of Fe(TPP)(rt-Pr) appear in the upfield positions (—0.5 to —6.0 ppm) expected for a diamagnetic porphyrin complex. This contrasts with the paramagnetic, 5 = 2 spin state observed... 

Fig.1. Structures of porphyrin 1, chlorophyll 2, and phthalocyanine 3. In the presence of metal salts M"+X (M=metal, X=counter anion, n=oxidation state or number of counter anions), porphyrins produce chelate complexes. Some metal chelates of the porphyrins, such as ZnPor, form further coordination bonds with other ligands such as pyridines...

Fig. 11a,b. Binding affinities of IgG, IgM, and the antibody dendrimer (Gl) with the cationic porphyrin (TMPyP) (a) and those with the anionic porphyrin (TCPP) (b) estimated by ELISA... 

Fig. 12a,b. The sensorgrams for the binding of the antibody dendrimer (a) or IgG (b) to the anionic porphyrin immobilized onto the surface of the sensor chip. Phosphate borate buffer (0.1 M, pH 9.0) was used. TCPP was immobilized via hexamethylenediamine spacer onto the sensor chip and then a solution of IgG or the dendrimer was injected to the flow cell. After 60 s from the injection of the antibody solutions, flow ceU was filled with buffer... 

Other anionic nitrogen-containing ligands which have been examined in the search for new non-metallocene catalysts include macrocyclic porphyrins and tetraazaannulenes. However, activities with these catalysts are low. 

The electrochemistry of a range of Ni(n) porphyrins and chlorins has been investigated. All complexes are reduced by a similar one-electron mechanism which appears to involve the formation of anion radicals (Chang, Malinski, Ulman Kadish, 1984). 

EPR-IR. The neutral sandwich complexes of Lu and the one-electron oxidized sandwich complexes of Zr have a jr-radical anion that can be observed by EPR spectroscopy. The EPR spectra for compounds 21, 23, 25, 27 and Collman s mixed porphyrin-pz system (30) give a signal for an S = j system with a g value of 2.0037, which is typical for an organic n radical (35). Further evidence for the Jt-radical character in sandwich compounds of phthalocyanines, porphyrins, and porphyrazines may be obtained from infrared (IR) spectroscopy by the presence of diagnostic marker bands (81). These intense bands are found in the IR spectra of Lu(III) compounds (21) (1150 cm-1) (35), 23 (1140 cm-1) (78), and 25 (1261 cm4) (34) and are absent in the Zr(IV) and Ce(IV) compounds 27,29, and 31. 

The anion optical sensor can also be fabricated with metalloporphyr-ins. For example, polymeric membranes doped with indium porphyrins and a lipophilic dichlorofluorescein derivative were shown to be very selective to chloride and acetate anions. The response mechanism is based on extraction of anions into the bulk organic film by indium porphyrins and a simultaneous coextraction of hydrogen ions. This results in protonation of the pH chromophore, and hence a change in the optical absorbance of the polymeric film. 

E. Wang, C. Romero, D. Santiago and V. Syntilas, Optical anion sensing characteristics of indium-porphyrin and lipophilic dichlorofluorescein doped polymer films, Anal. Chim. Acta, 433 (2001) 89-95. 

FIGURE 3.30. Reaction of iron(0) and iron(I) pophyrins with n-, s-, and r-butyl bromides. The chart shows the various porphyrins and their symbolic designations. iron porphyrins, aromatic anion radical, lines best-fitting parabolas through the aromatic anion radicals data. Dashed lines outer-sphere curves obtained by use of the Morse curve model (Section 3.2.2). Adapted from Figure 4 in reference 47b, with permission from the American Chemical Society. 

The product is exclusively carbon monoxide, and good turnover numbers are found in preparative-scale electrolysis. Analysis of the reaction orders in CO2 and AH suggests the mechanism depicted in Scheme 4.6. After generation of the iron(O) complex, the first step in the catalytic reaction is the formation of an adduct with one molecule of CO2. Only one form of the resulting complex is shown in the scheme. Other forms may result from the attack of CO2 on the porphyrin, since all the electronic density is not necessarily concentrated on the iron atom [an iron(I) anion radical and an iron(II) di-anion mesomeric forms may mix to some extent with the form shown in the scheme, in which all the electronic density is located on iron]. Addition of a weak Bronsted acid stabilizes the iron(II) carbene-like structure of the adduct, which then produces the carbon monoxide complex after elimination of a water molecule. The formation of carbon monoxide, which is the only electrolysis product, also appears in the cyclic voltammogram. The anodic peak 2a, corresponding to the reoxidation of iron(II) into iron(III) is indeed shifted toward a more negative value, 2a, as it is when CO is added to the solution. 

The water-soluble Fe porphyrin, 3Na+ [Fe(III)(TPPS)] -12H20 [H2TPPS4- = tetra-anionic form of meso-tetrakis(7r-sulfonatophenyl)porphine], has recently been shown to be an effective catalyst for the electroreduction of nitrite to ammonia [419]. The Fe meso-tetrakis(A -methyl-4-pyridyl) porphyrin and/or the Fe meso-tetrakis (jr -sulfophenyl) porphyrin complex shows a catalytic activity for the reduction of dioxygen in aqueous solutions, leading to hydrogen peroxide [420]. 

Fig. 18 Rate constants for the reaction of electrochemically generated iron(o), iron(i) and Co(i) porphyrins ( ) and aromatic anion radicals (A) with aliphatic halides as a function of their standard potentials, (Adapted from Lexa et al., 1981, 1988.)...

Analysis of the transition state in terms of energy is certainly a key aspect of the S 2-ET problem. Entropy considerations may, however, bring about additional information, possibly helping us to conceive better the transition between the two mechanisms. It was observed in this connection that, whereas the entropy of activation of both the anthracene anion radical and of the ETIOPFe(O) porphyrin (pp. 99, 100) (which have about the same standard potential) is close to zero in their reaction with s- and t-butyl bromides a definitely negative value, ca. — 20 eu is obtained for the reaction of the porphyrin with n-butyl bromide (Lexa et al., 1988). The same was found for the reaction of two other iron porphyrins, TPPFe(o) and OEP-Fe(i). These activation entropies were estimated from (153), where Z is... 

Of key importance in the Lewis acid promoted living anionic polymerization of methacrylic esters with aluminum porphyrin is how to suppress the undesired reaction between the nucleophile (2j ) and the Lewis acid, leading to termination of polymerization (Fig. 11). As mentioned in previous sections, one of our approaches was to make use of sterically crowded Lewis acids such as methyla-luminum bis(ort/zo-substituted phenolates). This section focuses attention on the steric bulk of the nucleophile component (2 ), by using strategically designed aluminum porphyrins and some other methacrylates, for the purpose of understanding the scope and limitation of this method (Fig. 12). 

A few current examples are shown below and include unsymmetrically substituted derivatives 14227, the cationic derivative 15228, the neutral derivative 16226 and the classic anionic derivative 17229 230, (tetrabenzoporphyrinato)zinc(II) , an intermediate structure between that of porphyrins and phthalocyanines, and have also been investigated in this respect. However, its quantum yield for singlet oxygen generation (0.023) in liposomes is much lower than that of Photofrin (0.19)177. 

Fig. 67. Schematic representation of three types of anionic porphyrins in a cast multibilayer film of 34. The overall bilayer organization is assumed to be the same as that of Fig. 64. For clarity, counterions are not shown and the bilayer units are separated from each other. The spacer portion is also not shown in Stereogram . Type I porphyrins (Fig. 66) are inserted into the bilayer along the molecular axis of the spacer chain. Type II porphyrins are randomly placed on the bilayer surface. Type III porphyrins lie flat on the bilayer [445]...

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