- The aluminium(III) complex of hypocrellin B as a PDT photosensitizer
-
The complex of hypocrellin B (HB) with aluminium was synthesized to improve the water solubility and red absorption of the parent pigment. The complexation of HB with Al3+ resulted in the formation of a complex with 1 : 1 Al(III) : HB stoichiometry (Al3+-HB) measured by molar ratio and continuous variation methods, respectively. The structure of this complex has been characterized by UV-Vis, IR, 1H NMR and elemental analysis data. Compared with HB, the complex possesses excellent solubility in water; in addition, the absorption wavelength of Al3+-HB shifts bathochromically into the phototherapeutic window (600-900 nm). The generation of active oxygen species, including the superoxide radical anion (O2·-) and singlet oxygen (1O2) by Al3+-HB photosensitization was observed. The efficiency of O2· generation by Al3+-HB was twice as much as that of HB. Under our experimental conditions, the rate of O2·-generation by Al3+-HB was about 2.3 μM min-1 measured by the cytochrome c reduction method using 578 nm light. The quantum yield of singlet oxygen (1O2) was 0.23 in DMSO determined by the 9,10-DPA (diphenylanthracene) photobleaching experiments. These results suggest that the new complex possesses an enhanced type I process but a decreased type II process as compared with hypocrellin B.
- Ma,Zhao,Jiang
-
-
Read Online
- A Leaf-Inspired Luminescent Solar Concentrator for Energy-Efficient Continuous-Flow Photochemistry
-
The use of solar light to promote chemical reactions holds significant potential with regard to sustainable energy solutions. While the number of visible light-induced transformations has increased significantly, the use of abundant solar light has been e
- Cambié, Dario,Zhao, Fang,Hessel, Volker,Debije, Michael G.,No?l, Timothy
-
-
Read Online
- Ring-opening metathesis polymer sphere-supported seco-porphyrazines: Efficient and recyclable photooxygenation catalysts
-
Crossover Linstead macrocyclization of norbornenyl-tagged diaminomaleonitrile with dipropylmaleonitrile gave the corresponding magnesium diaminohexapropylporphyrazine, which was subsequently converted into its zinc seco-derivative. Polymerization gave the corresponding ROMPgel and ROMPsphere (ROMP = ring-opening metathesis polymer) reagents, the latter of which proved efficient as an immobilized catalyst for the sensitized production of singlet oxygen for the purification-minimized parallel synthesis of endoperoxides and ene adducts.
- Fuchter, Matthew J.,Hoffman, Brian M.,Barrett, Anthony G. M.
-
-
Read Online
- Photocatalytic Properties of a Palladium Metallosquare with Encapsulated Fullerenes via Singlet Oxygen Generation
-
Singlet oxygen has recently attracted a great deal of attention due to its strong oxidizing properties, which makes it useful in organic synthesis and biological studies. However, the photosensitizers that are required for singlet oxygen generation remain
- Martínez-Agramunt, Víctor,Peris, Eduardo
-
-
Read Online
- "Dark" Singlet Oxygenation of Hydrophobic Substrates in Environmentally Friendly Microemulsions
-
The molybdate-catalyzed "dark" singlet oxygenation of hydrophobic compounds with hydrogen peroxide proceeds efficiently with low catalyst loadings (10-3 mol%) in chlorine-free w/o microemulsions. These micro-heterogeneous systems are composed of sodium dodecyl sulfate (SDS)/n-buta-nol/water/organic phase, the latter being either a "green" solvent such as ethyl acetate or a liquid substrate, such as α-terpinene or β-citronellol. Very high reactor yields with improved product/SDS ratio can be obtained for the "dark" singlet oxygenation of such liquid substrates.
- Nardello, Veronique,Herve, Melanie,Alsters, Paul L.,Aubry, Jean-Marie
-
-
Read Online
- An unusual photosensitizer: Dyad of eosin-tris(2,2′-bipyridine)Ru(II)
-
(Matrix presented) A dyad of eosin and tris(2,2′-bipyridine)Ru(II) was prepared, and its photophysical properties were investigated. The photosensitization of eosin is greatly enhanced by introduction of tris(2,2′-bipyridine)Ru(II), which is verified via
- Jing, Bingwen,Zhang, Manhua,Shen, Tao
-
-
Read Online
- 9,10-diphenyl-9,10-epidioxyanthracene and 9,10-dihydro-10,10-dimethoxy-9-phenylanthracen-9-ol
-
9,10-Diphenyl-9,10-epidioxyanthracene, C26H18O2, (I), was accidentally used in a photooxygenation reaction that produced 9,10-dihydro-10,10-dimethoxy-9-phenylanthracen-9-ol, C22H20O3, (II).
- Usman, Anwar,Fun, Hoong-Kun,Li, Yun,Xu, Jian-Hua
-
-
Read Online
- The contribution of reactive oxygen species to the photobleaching of organic fluorophores
-
Photoexcitation of fluorophores commonly used for biological imaging applications generates reactive oxygen species (ROS) which can cause bleaching of the fluorophore and damage to the biological system under investigation. In this study, we show that sin
- Zheng, Qinsi,Jockusch, Steffen,Zhou, Zhou,Blanchard, Scott C.
-
-
Read Online
- Synthesis of a water-soluble cyclodextrin modified hypocrellin and ESR study of its photodynamic therapy properties
-
A water-soluble cyclodextrin modified hypocrellin B (HBCD) was designed and synthesized. HBCD retained the phototherapeutic properties and exhibited much stronger photoinduced damage to calf thymus DNA (CT DNA) than hypocrellin B and mercaptoacetic acid substituted hypocrellin B (MAHB). The mechanism of electron transfer from CT DNA to the triplet state of HBCD was confirmed by steady-state electron spin resonance (ESR) and a time-resolved ESR study.
- Ou, Zhi-Ze,Chen, Jing-Rong,Wang, Xue-Song,Zhang, Bao-Wen,Cao, Yi
-
-
Read Online
- Hydrotrioxydes organometalliques generateurs d'oxygene singulet
-
Germanium and silicon hydrotrioxides R3MOOOH produced by low temperature ozonation of the corresponding germanes and silanes, have been characterized by NMR spectroscopy and by the generation of nascent oxygen.The effect of solvents on the stability of the hydrotrioxides has also been studied.The kinetics of the decomposition in CD3COCD3 have been monitored by NMR.The stabilities are similar (ΔG* ca. 17 kcal/mol at -50 deg C), but the mechanisms of their respective decompositions are probably different (ΔH* 13.3 kcal mol-1 and ΔS* -17 cal mol-1 deg-1 for Et3GeOOOH and ΔH* 17.2 kcal/mol ΔS* +1.6 cal mol-1 deg-1 for Et3SiOOOH.
- Koenig, M.,Barrau, J.,Hamida, N. Ben
-
-
Read Online
- Improving singlet oxygen resistance during photochemical water oxidation by cobalt porphyrin catalysts
-
Enabling the production of solar fuels on a global scale through artificial photosynthesis requires the development of water oxidation catalysts with significantly improved stability. The stability of photosystems is often reduced owing to attack by singl
- Nakazono, Takashi,Parent, Alexander R.,Sakai, Ken
-
-
Read Online
- Visible-Light-Induced Oxazoline Formations fromN-Vinyl Amides Catalyzed by an Ion-Pair Charge-Transfer Complex
-
Visible-light photoredox catalysis plays an important role in various reactions which are inaccessible under typical thermal conditions. Distinctly different from common visible-light photoredox catalysis which often involves transition-metal complexes, conjugated organic dyes, or electron donor-acceptor complexes, herein, the use of ion-pair charge-transfer (IPCT) complex-induced visible-light photoredox catalytic reactions are described, wherein the cyclization-methoxylation ofN-vinyl amides in methanol was achieved under irradiation with blue LEDs. The reaction employs a heteroarenium iodide as the photocatalyst and can be extended to cyclization-alkoxylation, ?acyloxylation, and ?hydroxylation. This protocol provides an eco-friendly synthetic route to a wide range of oxazoline derivatives. Mechanistic investigations with UV-visible spectroscopy and control experiments confirm the existence of the IPCT absorption band in the visible region for the heteroarenium iodide, which is responsible for the observed reactivity.
- Sun, Rui,Yang, Xiao,Ge, Yicen,Song, Jintong,Zheng, Xueli,Yuan, Maolin,Li, Ruixiang,Chen, Hua,Fu, Haiyan
-
p. 11762 - 11773
(2021/09/28)
-
- Potassium Poly(Heptazine Imide): Transition Metal-Free Solid-State Triplet Sensitizer in Cascade Energy Transfer and [3+2]-cycloadditions
-
Polymeric carbon nitride materials have been used in numerous light-to-energy conversion applications ranging from photocatalysis to optoelectronics. For a new application and modelling, we first refined the crystal structure of potassium poly(heptazine imide) (K-PHI)—a benchmark carbon nitride material in photocatalysis—by means of X-ray powder diffraction and transmission electron microscopy. Using the crystal structure of K-PHI, periodic DFT calculations were performed to calculate the density-of-states (DOS) and localize intra band states (IBS). IBS were found to be responsible for the enhanced K-PHI absorption in the near IR region, to serve as electron traps, and to be useful in energy transfer reactions. Once excited with visible light, carbon nitrides, in addition to the direct recombination, can also undergo singlet–triplet intersystem crossing. We utilized the K-PHI centered triplet excited states to trigger a cascade of energy transfer reactions and, in turn, to sensitize, for example, singlet oxygen (1O2) as a starting point to synthesis up to 25 different N-rich heterocycles.
- Antonietti, Markus,Guldi, Dirk M.,Hussain, Tanveer,Karton, Amir,Markushyna, Yevheniia,Mazzanti, Stefano,Oschatz, Martin,Sánchez Vadillo, José Manuel,Savateev, Aleksandr,Strauss, Volker,Tarakina, Nadezda V.,Tyutyunnik, Alexander P.,Walczak, Ralf,ten Brummelhuis, Katharina
-
supporting information
p. 15061 - 15068
(2020/06/17)
-
- Extremely Photostable Electron-Deficient Phthalocyanines that Generate High Levels of Singlet Oxygen
-
A robust lead-mediated synthetic procedure for the generation of phthalocyanines substituted with electron-withdrawing groups has been developed. The free-base phthalocyanine and various metal complexes were prepared without discernible degradation of the
- Furuyama, Taniyuki,Miyaji, Yusuke,Maeda, Kazuya,Maeda, Hajime,Segi, Masahito
-
supporting information
p. 1678 - 1682
(2019/01/04)
-
- Visible-light-driven selective alkenyl C-P bond cleavage of allenylphosphine oxides
-
An efficient method for highly selective alkenyl C-P bond cleavage, enabled by organic dyes and visible-light irradiation, was developed. This novel protocol involves a highly regioselective radical pathway initiated by singlet oxygen, affording diverse a
- Wei, Kai,Luo, Kai,Liu, Fang,Wu, Lei,Wu, Li-Zhu
-
supporting information
p. 1994 - 1998
(2019/03/29)
-
- A Continuous Stirred-Tank Reactor (CSTR) Cascade for Handling Solid-Containing Photochemical Reactions
-
Visible-light photoredox reactions have been demonstrated to be powerful synthetic tools to access pharmaceutically relevant compounds. However, many photoredox reactions involve insoluble starting materials or products that complicate the use of continuo
- Pomberger, Alexander,Mo, Yiming,Nandiwale, Kakasaheb Y.,Schultz, Victor L.,Duvadie, Rohit,Robinson, Richard I.,Altinoglu, Erhan I.,Jensen, Klavs F.
-
supporting information
p. 2699 - 2706
(2019/11/28)
-
- Energy-Efficient Solar Photochemistry with Luminescent Solar Concentrator Based Photomicroreactors
-
The sun is the most sustainable light source available on our planet, therefore the direct use of sunlight for photochemistry is extremely appealing. Demonstrated here, for the first time, is that a diverse set of photon-driven transformations can be efficiently powered by solar irradiation with the use of solvent-resistant and cheap luminescent solar concentrator based photomicroreactors. Blue, green, and red reactors can accommodate both homogeneous and multiphase reaction conditions, including photochemical oxidations, photocatalytic trifluoromethylation chemistry, and metallaphotoredox transformations, thus spanning applications over the entire visible-light spectrum. To further illustrate the efficacy of these novel solar reactors, medicinally relevant molecules, such as ascaridole and an intermediate of artemisinin, were prepared as well.
- Cambié, Dario,Dobbelaar, Jeroen,Riente, Paola,Vanderspikken, Jochen,Shen, Chong,Seeberger, Peter H.,Gilmore, Kerry,Debije, Michael G.,No?l, Timothy
-
supporting information
p. 14374 - 14378
(2019/08/30)
-
- Material-Efficient Microfluidic Platform for Exploratory Studies of Visible-Light Photoredox Catalysis
-
We present an automated microfluidic platform for in-flow studies of visible-light photoredox catalysis in liquid or gas–liquid reactions at the 15 μL scale. An oscillatory flow strategy enables a flexible residence time while preserving the mixing and heat transfer advantages of flow systems. The adjustable photon flux made possible with the platform is characterized using actinometry. Case studies of oxidative hydroxylation of phenylboronic acids and dimerization of thiophenol demonstrate the capabilities and advantages of the system. Reaction conditions identified through droplet screening translate directly to continuous synthesis with minor platform modifications.
- Coley, Connor W.,Abolhasani, Milad,Lin, Hongkun,Jensen, Klavs F.
-
supporting information
p. 9847 - 9850
(2017/08/08)
-
- Effects of N-Oxidation on Heteroaromatic Macrocycles: Synthesis, Electronic Structures, Spectral Properties, and Reactivities of Tetraazaporphyrin meso-N-Oxides
-
Heteroaromatic N-oxides such as pyridine and quinoline N-oxides are well studied in organic chemistry, and N-oxide formation has long been utilized for tuning the reactivities of heteroaromatics. However, the scope of aromatic N-oxidation is still restric
- Toriumi, Naoyuki,Yanagi, Shunsuke,Muranaka, Atsuya,Hashizume, Daisuke,Uchiyama, Masanobu
-
supporting information
p. 8309 - 8314
(2017/06/23)
-
- Singlet oxygen generation from poly[4-diacetoxyiodo]styrene and hydrogen peroxide
-
Treatment of hydrogen peroxide with a polymer-supported hypervalent iodine compound, poly[4-diacetoxyiodo] styrene (PDAIS), generates singlet molecular oxygen (1O2). Singlet oxygen generation was proved by trapping with typical organic compounds such as conjugated dienes, aromatic dienes, and electron-rich alkene. When compared to monomer analogue, the use of PDAIS in peroxidation of substrates gave slightly better yields (45%–96%). Regeneration and reuse of PDAIS showed similar activity. The mechanism underlying generation of singlet oxygen and reaction scope was examined.
- ?atir, Mustafa
-
p. 467 - 475
(2017/09/15)
-
- Design of porphyrin-based conjugated microporous polymers with enhanced singlet oxygen productivity
-
Novel non-toxic materials with antimicrobial surfaces are needed for medicinal applications. Potential alternatives for bacterial inactivation include materials that produce singlet oxygen, O2(1Δg), a short-lived, highly o
- Hynek, Jan,Rathousky, Ji?í,Demel, Jan,Lang, Kamil
-
p. 44279 - 44287
(2016/06/09)
-
- Antibacterial photoactivity and photosensitized oxidation of phenols with meso -tetra-(4-benzoate, 9-phenanthryl)-porphyrin and its metal complexes (Zn and Cu)
-
We performed the synthesis and characterization of meso-tetra-(4-benzoate- 9-phenanthryl)-porphyrin and its Zn and Cu complexes. Synthesis of meso-tetra-(4-benzoate-9-phenanthryl)-porphyrin was carried out by dry gaseous HCl, meso-tetra-(4-carboxyphenyl)-porphyrin, and 9-phenantrol in tetrahydrofuran. The preparation of metal complexes was carried out using the method of the acetates. All porphyrins were characterized by FT-IR, NMR ( 1H and 13C), MS, UV-visible, and fluorescence spectroscopy. Their photophysical properties: photostability, fluorescence quantum yields, energy transfer, and generation of singlet oxygen were determined and compared with the meso-tetraphenylporphyrin. Photochemical studies on their effectiveness as photosensitizers were performed through photo-oxidation of alcohols, phenol, and 2-naphthol. Higher efficiency of degradation was obtained with photostable TB9FPCu. The antibacterial photoactivity assay was tested against Escherichia coli and its viability was measured by chemiluminescence. The highest inactivation levels were obtained by ester TB9FP and Zn complex. The properties of the photosensitizer and its efficiency vary as a result of modifying its structure. The results obtained show that the efficiency of a photosensitizer depends on multiple factors. Thus, we can say that the copper complex is efficient in degradation of alcohol, while the metal-free porphyrin is better for antibacterial applications. 2014
- Oviedo, Olycen,Zoltan, Tamara,Vargas, Franklin,Inojosa, Marcel,Vivas, Julio C.
-
p. 1715 - 1730
(2014/07/08)
-
- Double alkylene-strapped diphenylanthracene as a photostable and intense solid-state blue-emitting material
-
We report the synthesis and photochemical and photophysical properties of double alkylene-strapped 9,10-diphenylanthracene derivatives 3a-c (a: C6 strap, b: C7 strap, c: C8 strap) in which the reactive central aromatic ring of the anthracene moiety is pro
- Fujiwara, Yutaka,Ozawa, Ryota,Onuma, Daiki,Suzuki, Kengo,Yoza, Kenji,Kobayashi, Kenji
-
p. 2206 - 2212
(2013/04/24)
-
- Identification of ros produced by photodynamic activity of chlorophyll/cyclodextrin inclusion complexes
-
Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The 1O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10-diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen ( 1O2) luminescence decay at 1270 nm. Moreover, 2,7-dichlorofluorescin and ferricytochrome c (Cyt Fe3+) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe3+ of the ferricytochrome to Fe2+, respectively. For the first time, photodynamic activity in vitro of natural Chlorophyll a (Chl a) has been investigated evidencing which types of ROS are formed. Chl a has been solubilized in aqueous solution by means of various cyclodextrins forming inclusion complexes. The ROS production has been carried out in the system using specific molecules, called primary acceptors, which react selectively with the reactive species.
- Cellamare, Barbara M.,Fini, Paola,Agostiano, Angela,Sortino, Salvatore,Cosma, Pinalysa
-
p. 432 - 441
(2013/07/19)
-
- Microphotochemistry using 5-mm light-emitting diodes: Energy-efficient photooxidations
-
Commercial, inexpensive 5-mm milliwatt light-emitting diodes are effective sources for batch microphotochemical oxidations. Using limited quantities of singlet oxygen, these oxidations are atom economical and therefore useful for labeling experiments with rare isotopes. Georg Thieme Verlag Stuttgart · New York.
- Carney, John M.,Hammer, Reagan J.,Hulce, Martin,Lomas, Chad M.,Miyashiro, Dayna
-
experimental part
p. 2560 - 2566
(2012/09/07)
-
- High-efficiency microphotooxidation using milliwatt LED sources
-
Inexpensive milliwatt light emitting diode (LED) sources allow energy- and atom-efficient microphotochemical reactions. Thus, sources constructed from three 120 mW 5 mm diameter 627 nm LED's enable μmol-mmol scale methylene blue-sensitized singlet oxygen photooxidations of various arenes and cyclopentadienones using a 3-5 M excess of oxygen in 82-98% yields.
- Carney, John M.,Hammer, Reagan J.,Hulce, Martin,Lomas, Chad M.,Miyashiro, Dayna
-
supporting information; experimental part
p. 352 - 355
(2011/02/28)
-
- Cholesterol hydroperoxides generate singlet molecular oxygen [O 2(1Δg)]: Near-IR emission, 18O-labeled hydroperoxides, and mass spectrometry
-
In mammalian membranes, cholesterol is concentrated in lipid rafts. The generation of cholesterol hydroperoxides (ChOOHs) and their decomposition products induces various types of cell damage. The decomposition of some organic hydroperoxides into peroxyl
- Uemi, Miriam,Ronsein, Graziella E.,Prado, Fernanda M.,Motta, Flavia D.,Miyamoto, Sayuri,Medeiros, Marisa H. G.,Di Mascio, Paolo
-
experimental part
p. 887 - 895
(2012/04/11)
-
- A new peroxide fragmentation: Efficient chemical generation of 1O2 in organic media
-
Monoactivated derivatives of 1,1-dihydroperoxides undergo an unprecedented base-promoted fragmentation to efficiently generate singlet oxygen ( 1O2) in anhydrous organic solvents.
- Ghorai, Prasanta,Dussault, Patrick H.
-
supporting information; experimental part
p. 4572 - 4575
(2009/12/27)
-
- Remote substituent effects on the photooxygenation of 9,10- diarylanthracenes: Strong evidence for polar intermediates
-
Two different reaction pathways in the photooxygenation of 9,10-diarylanthracenes are identified, with strong evidence for polar (forward, singlet oxygen addition) and radical (backward, thermolysis) intermediates. The Royal Society of Chemistry.
- Fudickar, Werner,Linker, Torsten
-
p. 1771 - 1773
(2008/12/22)
-
- Elucidation of the Electron Transfer Reduction Mechanism of Anthracene Endoperoxides
-
The homogeneous and heterogeneous reductions of the endoperoxides 9,10-diphenyl-9,10-epidioxyanthracene (DPA-O2) and 9,10-dimethyl-9,10-epidioxyanthracene (DMA-O2) were investigated, and they were found to undergo a dissociative elec
- Donkers, Robert L.,Workentin, Mark S.
-
p. 1688 - 1698
(2007/10/03)
-
- Calcium peroxide diperoxohydrate as a storable chemical generator of singlet oxygen for organic synthesis
-
Calcium peroxide diperoxohydrate (CaO2·2H2O2) is an environmentally friendly generator of singlet oxygen (1O2, 1Δg) that can be used in organic synthesis as an alternative to the regular photochemical method. This compound produces 1O2 in various solvents and can be easily recovered by filtration for further regeneration. Both monitoring of 1O2 luminescence at 1270 nm and specific trapping have shown that CaO2·2H2O2 can be stored for several days at -80 °C and that the yield of 1O2 is equal to 25%. Oxidation of typical organic substrates in methanol or THF through [4 + 2] or [2 + 2] cycloaddition and ene reaction have been carried out on a preparative scale with total conversion and selectivity.
- Pierlot, Christel,Nardello, Veronique,Schrive, Jordane,Mabille, Caroline,Barbillat, Jacques,Sombret, Bernard,Aubry, Jean-Marie
-
p. 2418 - 2423
(2007/10/03)
-
- A seco-porphyrazine: Superb sensitizer for singlet oxygen generation and endoperoxide synthesis
-
seco-Porphyrazine 2 was found to effectively catalyze the [4+2] cycloaddition of singlet oxygen to a range of 1,3-dienes under mild conditions.
- Trabanco, Andrés A.,Montalban, Antonio Garrido,Rumbles, Garry,Barrett, Anthony G. M.,Hoffman, Brian M.
-
p. 1010 - 1012
(2007/10/03)
-
- Preparative oxidation of organic compounds in microemulsions with singlet oxygen generated chemically by the sodium molybdate/hydrogen peroxide system
-
A reverse (water in oil) microemulsion has been designed to oxidize hydrophobic organic substrates with singlet oxygen (1O2, 1Δ(g)) generated from the disproportionation of hydrogen peroxide catalyzed by molybdate ions. The microemulsion was prepared by mixing methylene chloride, sodium dodecylsulfate, n-butanol, and aqueous molybdate. Flash photolysis studies have shown that in such media singlet oxygen exhibits a similar kinetic behavior that under homogeneous conditions (τ(Δ) ? 42 μs). Various typical organic substrates have been oxidized on the preparative scale with this chemically generated singlet oxygen, and the expected oxidation products have been isolated in high yields.
- Aubry, Jean-Marie,Bouttemy, Sabine
-
p. 5286 - 5294
(2007/10/03)
-
- Ozonides de phosphite source d'oxygene singulet: rendement, mecanisme
-
The ozonides of several phosphites in solution in dichloromethane have been reacted with some scavengers of singlet oxygen (1O2) like rubrene (2), tetraphenylcyclopentadienone (4), and 9,10-diphenylanthracene (6).These ozonides react on the sca
- Caminade, Anne Marie,Khatib, Fayez El,Koenig, Max,Aubry, Jean Marie
-
p. 3203 - 3209
(2007/10/02)
-
- OZONIDES DU PHOSPHORE STABILITE ET STEREOCHIMIE
-
A phosphorus ozonides series was obtained by reaction of ozone on various phosphites (1a-13a).The oxidative addition of ozone leads to trioxophosphetane ring formation branched on pentacoordinated (1b-9b) or hexacoordinated (10b-13b) phosphorus.The stability and stereochemistry of these compounds were studied.
- Khatib, F. el,Caminade, A. M.,Koenig, M.
-
-
- Phosphides and Arsenides as Metal-Halogen Exchange Reagents. Part 2. Reactions with Aromatic Dihalides
-
1,2-Dihalogenobenzenes react with two molar equivalents of lithium diphenylphosphide in the presence of furan to give, after oxidation, triphenylphosphine oxide (major) and the corresponding 2-halogenophenyldiphenylphosphine oxide.No trace of furan-dehydrobenzene adduct was observed in these reactions; however, 1- and 2-naphthyldiphenylphosphine oxides (9:4) were detected.These compounds were the major products from the reaction of the furan-dehydrobenzene adduct with diphenylphosphide, although the ratio of 1- to 2-isomers was quite different (1:9) in this case.Reaction of lithium diphenylphosphide with 3,4-dichloronitrobenzene gave tetrachloroazobenzene (40percent) as the only isolated product and attempts to replace 1,2-dihalogenobenzenes with 2-halogenobenzenediazonium salts gave much lower yields of products.Although dehydrobenzene is thought to be involved in many of these reactions, alternative mechanisms also operate, depending on the halides used.The reaction of lithium diphenylarsenide with 1,2-dihalogenobenzenes gave triphenylarsine as the major product and it seems likely that similar mechanisms to those involved in reactions of diphenylphosphide are operating.Surprisingly, dehydrobenzene-furan adduct reacted with diphenylarsenide to give naphthalene in high yield.
- Gillespie, Donal G.,Walker, Brian J.,Stevens, David,McAuliffe, Charles A.
-
p. 1697 - 1703
(2007/10/02)
-
- PHOTO-OXYGENATIONS DE COMPOSES AROMATIQUES SENSIBILISEES PAR DES ACCEPTEURS D'ELECTRON
-
Photo-oxygenation of aromatic compounds sensitized by electron acceptors, like 9-10 dicyanoanthracene (DCA) is shown to proceed by two distinct mechanism each one beginning by an electron-transfer step : in the first way superoxide ion is involve
- Santamaria, Jean
-
p. 4511 - 4514
(2007/10/02)
-
- Mechanism of Thermolysis of Endoperoxides of Aromatic Compounds. Activation Parameters, Magnetic Field, and Magnetic Isotope Effecs
-
A mechanistic investigation has been made of the thermolysis of several endoperoxides of anthracenes and naphthalenes which produce molecular oxygen and the parent aromatic species quantitatively.Qualitative thermochemical measurements in the solid state indicate that in all cases studied, the reactions were endothermic.This situation appears to be valid in solution also.Clean first-order kinetics were observed for these thermolyses.Activation parameters were derived from the temparature dependence of the first-order rate constants.The primary yields of singlet oxygen (1O2) from the several endoperoxides were determined, and a correlation was discovered between the A factors (ΔS values) for thermolysis and the yield of 1O2.It was found that high A factors (positive ΔS values) correlated with relatively low yields of 1O2 and that low A factors (slightly negative or near zero ΔS values) correlated with nearly quantitative yields of 1O2.These two results are interpreted in terms of a diradical mechanism which leads to low yield of 1O2 and a concerted mechanism which leads to quantitative yields of 1O2.This interpretation is consistent with the observation of a magnetic field effect on the yield of 1O2 from endoperoxides whose thermolyses proceed with positive ΔS values and the absence of a magnetic field effect on the yield of 1Oi endoperoxides whose thermolyses proceed with near zero ΔS values.Further support for the occurrence of a diradical mechanism is available from the demonstration of a special 17O isotope effect on the thermolysis of an endoperoxide which is postulated to undergo thermolysis principally via a diradical intermediate.The thermolysis of endoperoxides which decompose mainly by a diradical mechanism yields triplet molecular oxygen that is selectively enriched in 17O.
- Turro, Nicholas J.,Chow, Ming-Fea,Rigaudy, Jean
-
p. 7218 - 7224
(2007/10/02)
-
- TRANSFORMATIONS PHOTOCHIMIQUES d'ENDOPEROXYDES DERIVES d'HYDROCARBURES AROMATIQUES POLYCYCLIQUES-I; CAS DU PHOTOOXYDE DE DIPHENYL-9,10 ANTHRACENE; OBTENTION ET PROPRIETES DU DIEPOXYDE ISOMERE
-
When irradiated at long wavelengths (λ>=435 nm), the 9,10-endoperoxide of 9,10-diphenylanthracene 1a isomerizes to the 4a,10:9,9a-diepoxide 4a, which can be isolated at low temperature.On warming at 20-25 deg C, 4a gives only the benzocyclobutenic diether 6a by electrocycling ring opening and cyclisation, whereas under irradiation it undergoes, degradation to 10-hydroxy-10-phenyl-9-anthrone 7a and isomerizations to the bicyclic acetal 8a and to the benzofurobenzofuran 9a.These transformations of 4a explain previous results obtained when irradiating 1a under various conditions; their mechanisms are discussed.
- Rigaudi, J.,Scribe, P.,Breliere, C.
-
p. 2585 - 2593
(2007/10/02)
-