Novel meso-substitution reactions of metalloporphyrins

Smith, Kevin M.; Barnett, Graham H.; Evans, Brian; Martynenko, Zoya

doi:10.1021/ja00514a015

Cited by 96 publications

(42 citation statements)

References 7 publications

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“…[21] Nitration of the zinc-complex of 3 H with AgNO 2 and I 2 in CHCl 3 [22] gave only the mononitrated porphyrin 15 (42 % yield), which was converted to 6 FH under acidic conditions (Scheme 3). A dinitrated porphyrin was not formed under these condition, but it has been found that the combination of NaNO 2 and (4-BrC 6 H 4 ) 3 NSnCl 5 [23] converts 15 into dinitrated porphyrin 16 (12 %), which was hydrolyzed to 8 FH (Scheme 3). TFAcatalyzed condensation of pyrrole with 14 gave pentafluoro- phenyl-substituted dipyrrylmethane 17 (85 %), [24] which was then treated with 4-methoxycarbonyl-benzaldehyde and 14 to give porphyrin 18 in 16 % yield (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Energy-Gap Dependence of Photoinduced Charge Separation and Subsequent Charge Recombination in 1,4-Phenylene-Bridged Zinc-Free-Base Hybrid Porphyrins

et al. 2000

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A series of 1,4-phenylene-bridged ZP-HP hybrid porphyrins (ZP = zinc porphyrin, HP = free-base porphyrin) 1-8 ZH have been prepared in which an electron-donating ZP moiety is kept constant and electron-accepting HP moieties are varied by introducing electron-accepting substituents, so that the energy gap for charge separation, ZP-1HP*--> ZP(+)-HP-, covers a range of about 0.9 eV in DMF. Here selective excitation at the HP moiety was employed to avoid complication in the determination of electron transfer rates derived from energy transfer, 1ZP*-HP --> ZP-1HP*. Definitive evidence for the electron transfer has been obtained in three solvents (benzene, THF, and DMF) through picosecond-femtosecond transient absorption studies, which have allowed the determination of the rates of the photoinduced charge separation, ZP-1HP* --> ZP(+)-HP-, and subsequent thermal charge recombination ZP(+)-HP- --> ZP-HP. Dyad 1ZH in THF exhibits a biphasic fluorescence decay that indicates thermal repopulation of the ZP-1HP* from ZP(+)-HP-; this has been also supported by the transient absorption spectra. On this ground, the energy levels of the ZP(+)-HP- ion pairs have been estimated. Similar biphasic fluorescence decay has been observed for 5 ZH in benzene; this allows furhter estimation of the energy level of the ZP(+)-HP- ion pairs. The free-energy-gap dependence (energy-gap law) has been probed from the normal to the upper limit region for the rate of the charge separation alone, and only the inverted region for the rate of the charge recombination. It was not possible to reproduce both energy-gap dependencies of the charge separation and the charge recombination assuming common parameter values for the reorganization energy and electronic interaction responsible for the electron transfer with the classical Marcus equation. Although both energy-gap dependencies can be approximately reproduced by means of the simplified semiclassical equation, which takes into consideration the effect of the high-frequency vibrations replaced by one mode of averaged frequency, many features, which include the effects of solvent polarity, electron-tunneling matrix element, and so forth on the energy-gap law, are considerably different from those of the previous studied porphyrin-quinone systems with weaker inter-chromophore electronic interactions.

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Section: Resultsmentioning

confidence: 99%

Energy-Gap Dependence of Photoinduced Charge Separation and Subsequent Charge Recombination in 1,4-Phenylene-Bridged Zinc-Free-Base Hybrid Porphyrins

et al. 2000

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“…[11,12] Treatment of Zn(II)-octaethylporphyrin with tris(p-bromophenyl)ammoniumylhexachloroantimonate generates the π cation radical of the porphyrin which was reacted with triphenylphosphine. A demetallation reaction gave the meso-triphenylphosphonium octaethylporphyrin chloride 1, but the UV-visible absorption spectroscopy indicated that there was a significant resonance contribution from the porphyrin cation.…”

Section: Reactions Using Susbtitution Of Porphyrinic Macrocyclesmentioning

confidence: 99%

Survey of Synthetic Routes towards Phosphorus Substituted Porphyrins

Bessmertnykh‐Lemeune¹,

Stern²,

Gorbunova³

et al. 2014

MHC

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“…In the presence of nitric acid in sulfuric acid, porphyrin (1) is exclusively nitrated at the meso positions to form, predominantly, the meso-5-nitro (103) and 5,10-dinitro derivatives (104), instead of the meso-5,15-dinitro derivatives [92]. The meso-mononitro derivative of 2 is formed by using nitric acid in acetic acid (105), whereas meso-di (106, 107), and tri-(108) derivatives are formed by using nitric acid in sulfuric acid at 0 C. The meso-di-substituted products (both 106 and 107) are formed roughly in 1: 1 ratio (Figure 26.17). The meso-tetra-substituted product (109) is not formed under this methodology [93].…”

Section: Halogenationmentioning

confidence: 99%

“…The p-cation radicals of the metalloporphyrins, particularly 2, are usually formed by various oxidizing agents such as iodine, thallium(III) nitrate, tris(p-bromophenyl)ammonium hexachloroanitimonate (TBAH) and N-chlorobenzotriazole, which are stable in methanolic solution but do react with various nucleophiles such as cyanide, thiocyanate, chloride, imidazole, acetate, azide, pyridine and triphenylphosphine to produce the corresponding meso-substituted macrocycles [105]. For example, the Mg(II), Zn(II) and Co(II) complexes of 2 react with N 2 O 4 in CH 2 Cl 2 to produce the corresponding meso-nitro derivatives in good yield [106].…”

Section: Reactions Of P-cation Radicalsmentioning

confidence: 99%