OsO 4 -Mediated Dihydroxylation of meso -Tetraphenylporphyrin N -Oxide and Transformation of the Resulting Diolchlorin N -Oxide Regioisomers (original) (raw)
Related papers
The Journal of Organic Chemistry, 2009
The methyltrioxorhenium (MTO)/pyrazole-mediated H 2 O 2 oxidation of octaethylporphyrin and a number of meso-tetraarylporphyrins offers simple and good yielding access to the corresponding N-oxides, only few of which were prepared before. The crystal structure of a free base tetraarylporphyrin N-oxide demonstrates the degree to which the oxygenated pyrrole moiety is slanted with respect to the rest of the otherwise nearly planar macrocycle. The method is also suitable to the preparation of hitherto unknown chlorin N-oxides. Oxidation of meso-tetraphenyldithiaporphyrin and meso-tetraphenyldithiachlorin furnishes the corresponding novel S-oxides. The optical properties of the novel chromophores are described and rationalized.
Journal of Porphyrins and Phthalocyanines, 2009
We have synthesized a series of tetrakis(arylvinylene)phthalocyanines from the corresponding phthalonitriles. According to 1 H and 19 F NMR data, the cis-or trans-conformations of the starting materials retain du ring condensation, thus phthalocyanines formed are in all-cis or all-trans form. The cis-trans photoisomerization occurs easily for phthalonitriles, while phthalocyanines retain their conformations under UV beam.
Chlorin-Type Photosensitizers Photochemically Derived from Vinyl Porphyrins¶
Photochemistry and Photobiology, 2001
The reaction of singlet oxygen with four vinyl-substituted dicarboxylic porphyrins, vinyldeuteroporphyrin (VD), ethylvinyldeuteroporphyrin (EVD), hydroxyethylvinyldeuteroporphyrin (HVD) and protoporphyrin (PP) in organic solutions is investigated. The main products, the ''hydroxyaldehyde'' chlorin-type derivatives, are formed with a concentration-dependent photochemical quantum yield that reaches a maximum of 7.4 ؎ 1.6 ؋ 10 Ϫ3 . However, owing to the high turnover of singlet-oxygen production, these chlorin-type compounds are easily prepared photochemically with a chemical yield of 70% and little side product formation. In chemical ionization mass spectrometry, these compounds display an unusual fragmentation with a loss of 16 mass units. This is attributed to the loss of the oxygen bound to the saturated carbon of the modified pyrrole unit. All these compounds sensitize the formation of singlet oxygen with a yield around 0.8. They interact with singlet oxygen with rate constants of 5 ؋ 10 6 -9 ؋ 10 6 M Ϫ1 s Ϫ1 , lower than those measured for vinyl porphyrins. These data are likely to help in the characterization of photoproducts of vinyl porphyrins relevant to photodynamic therapy (PP, HVD). As exemplified with VD and EVD, they also point out the reaction of singlet oxygen as an efficient route to chlorin-type photosensitizers.
Chemistry at the porphyrin periphery
1999
The objective of this work was to synthesize novel aromatic compounds based on tetraphenylporphyrins. These compounds are potential photosensitizers for use in photodynamic therapy. Several approaches were employed towards this goal. Numerous tetraphenylporphyrins possessing a variety of substituents were synthesized, characterized and used as starting materials to prepare the analogous diol chlorins via the patented osmium tetroxide oxidation. Compounds possessing hydroxy, methoxy, alkyl and halogen substituents were prepared. Studies involving the syntheses of these variously substituted mesotetraphenyl-v/c-2,3-dihydroxy-2,3-chlorins and analysis of their in vitro biological test results are presented and discussed. A number of these compounds appear very promising, particularly diphenyl-2,3-dihydroxy-2,3-chlorin (125) which had an LD50 value of 0.0024 uJVI 450 times as potent as the commercially available standard Photofrin. Attempts to improve the oxidation reaction via the reve...
Journal of Fluorescence, 2020
New porphyrin analogues have been designed and synthesized using pyrrole, various aldehydes and propionic acid. The formation of desired compounds was analyzed by utilizing the spectral analysis such as IR, NMR and Mass spectroscopy. The studies on absorption and fluorescence emission of synthesized porphyrins were used to evaluate photophysical characteristics such as molar excitation coefficient and Stokes shift. The estimated values of fluorescence lifetime and fluorescence quantum yield of synthesized porphyrins were found to be variable due to the presence of change in the electron donating and withdrawing characters. The efficiency of generation of singlet oxygen by each synthesized porphyrin as photosensitizer was measured in terms of singlet oxygen quantum yield through photooxidation of 9,10-dimethylantharacene. The obtained singlet oxygen quantum yield values were found to be higher in case of porphyrins those have more electron withdrawing characters rather than donating characters as compared to reference 5,10,15,20-tetraphenylporphyrin (H 2 TPP). The singlet oxygen quantum yield values of synthesized porphyrins varied from 0.52 to 0.66. Pleasingly, some of synthesized porphyrins are found to be photostable and competent to discover as PDT agents as compared to reference H 2 TPP.
Organometallics, 2012
Metal−carbon bonds are known to form during the metal-catalyzed transformations of various organic compounds such as phenylhydrazines by the heme-containing proteins cytochrome P450, hemoglobin, and myoglobin. The preparation and characterization of synthetic organometallic porphyrins of the group 8 metals are thus of interest, and their properties help enlighten the general discussion of metalloporphyrin−carbon bond chemistry. We have prepared a representative set of (por)Ru(NO)R compounds (por = T(p-OMe)PP, T(p-CF 3)PP; R = Me, Et) containing Ru−alkyl bonds trans to NO. We have determined the X-ray crystal structure of (T(p-OMe)PP)Ru(NO)Et, which represents the first crystal structure reported for any organometallic nitrosyl porphyrin with an alkyl ligand trans to NO; the structure reveals a significantly bent RuNO moiety at 153°in this {RuNO} 6 compound. We have characterized the redox behavior of the (T(p-OMe)PP)Ru(NO)-containing compounds by cyclic voltammetry and infrared spectroelectrochemistry, and we have determined that the first oxidations are porphyrin-centered.
Preparation and Photophysical Studies of Porphyrin-C~O Dyads
1994
Porphyrin-Ca dyads in which the two chromophores are linked by a bicyclic bridge have been synthesized using the Diels-Alder reaction. The porphyin singlet lifetimes of both the zinc (Pz,-C,) and free base (P-C,) dyads, determined by time-resolved fluorescence measurements, are 1 7 ps in toluene. This substantial quenching is due to singlet-singlet energy transfer to C,. The lifetime of Pzn-'Cm is-5 ps in toluene, whereas the singlet lifetime of an appropriate C a model compound is 1.2 ns. This quenching is attributed to electron transfer to yield Pa' +-C,'-. In toluene, P-k a is unquenched; the lack of electron transfer is due to unfavorable thermodynamics. In this solvent, a transient state with an absorption maximum at 700 nm and a lifetime of-10 ps was detected using transient absorption methods. This state was quenched by oxygen, and is assigned to the C a triplet. In the more polar benzonitrile, P-' C, under oes photoinduced electron transfer to give P' +-Cm'-. The electron transfer rate constant is-2 x 10 s 11-? * To whom correspondence should be addressed.
Photochemistry and Photobiology, 1998
The tetraruthenated porphyrin, p-[meso-5,10,15,20-tetra(pyridy1)porphyrinl tetrakis[bis-(bipyridine)chloride ruthenium(II)] (TRP) is a supramolecular cationic species. The aim of the present investigation was to evaluate the photodynamic properties of TRP and Zn-TRP to damage DNA with emphasis on the mechanistic aspects. The ability for tetraruthenated porphyrin derivatives to induce photosensitization reactions has been determined using 2'-deoxyguanosine as a DNA model compound. The main photooxidation products of the targeted nucleoside were identified and classified according to their mechanisms of formation, involving either a radical pathway (type I) or a singlet oxygen-mediated mechanism (type 11). Quantification of the different oxidation products provides a means to evaluate the relative contribution of type I and type I1 pathways associated with the oxidative photosensitization of 2'-deoxyguanosine by tetraruthenated porphyrin derivatives. Results indicate that '02 plays a major role in the mechanism of photooxidation mediated by these porphyrin derivatives. In addition an increase of the photosensitizing effect in the presence of zinc is observed. For each sensitizer, the ratio between type I1 and type I photoproducts has been calculated and compared to that of other known dyes such as methylene blue and riboflavin.
New A3B porphyrins as potential candidates for theranostic. Synthesis and photochemical behaviour
Dyes and Pigments, 2019
The study reports a series of results obtained by synthesis, spectral and morphological analysis of new tetrapyrrolic structures: 5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (P1.2), Zn(II)-5-(4-hydroxy-3methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Zn(II)1.2) and Cu(II)-5-(4-hydroxy-3-methoxyphenyl)-10,15,20-tris-(4-carboxymethylphenyl) porphyrin (Cu(II)1.2), as potential candidates for theranostics. Porphyrins were obtained by microwave synthesis under solvent-free conditions and characterized by elemental analysis, FT-IR, UV-Vis and NMR spectroscopies. The absorption properties of the synthetized compounds were studied in different solvents (ethanol, polyethylene glycol 200, dimethylsulfoxide, dichloromethane, chloroform). The spectral profile of the new porphyrins was completed by studying the fluorescence emission and singlet oxygen formation quantum yields. P1.2 and Zn(II)1.2 exhibit fluorescence while for Cu(II)1.2 the fluorescence emission is negligible. P1.2 and Zn(II)1.2 exhibited photodynamic therapy (PDT) acceptable values of singlet oxygen generation. In the case of Cu(II)1.2 this parameter is reduced ca. 5 times. For powdered samples of P1.2 adsorbed onto powdered PEG a detailed study was performed correlating the fluorescence emission intensity with sample absorption to determine the concentration range where aggregation does not occur. Fluorescence emission quantum yields and lifetimes were determined for all samples under study to determine the useful range of concentrations for PDT use. Atomic force microscope (AFM) studies were also made, which exhibit the aggregate species formation for high loadings of the porphyrin P1.2 adsorbed onto specific surfaces.