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Photosensitizers cationic

Positively charged photosensitizers, particularly cationic metallophthalocy-anines, have been proved to be most efficient in photodynamic inactivation of both Gram-negative and -positive bacteria. The reason is believed to lie in the electrostatic interaction of cationic photosensitizer with negatively charged sites at the outer surface of the bacterial cell wall, which facilitates the photosensitizer molecule binding to bacterial cells. [Pg.337]

Michelsen et al. reported a new class of cationic photosensitizers 466 for PDT. These unsymmetrical substituted benzonaphthoporphyrazines are synthesized to have one to eight positive charges. The Q-band transition exhibits a red shift from 680 to 760 nm dependent upon the number of annealed naphthalene rings. The singlet-oxygen yields of these compounds are normally higher compared with zinc phthalocyanine. [Pg.210]

Lee, Smith, and Hatton observed that the viscosity and gelation of mixtures of hydrophobically modified poly(acrylic acid) and a cationic photosensitive surfactant can be controlled reversibly by switching irradiation of the sample between UV and visible. [Pg.266]

The chemical pathways leading to acid generation for both direct irradiation and photosensitization (both electron transfer and triplet mechanisms) are complex and at present not fully characterized. Radicals, cations, and radical cations aH have been proposed as reactive intermediates, with the latter two species beHeved to be sources of the photogenerated acid (Fig. 20) (53). In the case of electron-transfer photosensitization, aromatic radical cations (generated from the photosensitizer) are beHeved to be a proton source as weU (54). [Pg.124]

Photooxidafions are also iudustriaHy significant. A widely used treatment for removal of thiols from petroleum distillates is air iu the presence of sulfonated phthalocyanines (cobalt or vanadium complexes). Studies of this photoreaction (53) with the analogous ziuc phthalocyanine show a facile photooxidation of thiols, and the rate is enhanced further by cationic surfactants. For the perfume iudustry, rose oxide is produced iu low toimage quantifies by singlet oxygen oxidation of citroneUol (54). Rose bengal is the photosensitizer. [Pg.435]

In general, physico-mechanical properties of polymers depend on the molecular weight. However, the physico-mechanical properties of PSs decreased in the presence of cationic catalysis, but increased in the case of the binding of functional groups to the aromatic ring in spite of the destruction of PS. Therefore, new properties such as adhesion and photosensitive capability increase... [Pg.270]

Photo-induced Diels Alder reaction occurs either by direct photo activation of a diene or dienophile or by irradiation of a photosensitizer (Rose Bengal, Methylene Blue, hematoporphyrin, tetraphenylporphyrin) that interacts with diene or dienophile. These processes produce an electronically excited reagent (energy transfer) or a radical cation (electron transfer) or a radical (hydrogen abstraction) that is subsequently trapped by the other reagent. [Pg.163]

Corma, A., Fornes, V., Garcia, H., Miranda, M.A., Primo, J. and Sabater, M.-J. (1994). Photoinduced electron transfer within zeolite cavities eiv-Stilbcnc isomerization photosensitized by 2,4,6-triphenylpyrylium cation imprisoned inside zeolite Y. J. Am. Chem. Soc. 116, 2276-2280... [Pg.263]

Amphiphilic compounds and other chemicals used are shown in Figs. 5 [3,4] and 6 [36] together with their abbreviations. The synthetic procedures for A-S-D triad, A-S dyad, and H light harvesting antenna molecules in Fig. 5 were described previously [3,37,38]. A cationic cyanine dye with two long alkyl chains (CD) in Fig. 5 was purchased from Japanese Research Institute for Photosensitizing Dyes,... [Pg.196]

Menadione (79) has been shown by Krishna et al. to act as a photosensitizer for thymine degradation. Spin-trapping experiments with several nucleosides showed that the photosensitizations occurred by electron transfer from the substrate to the excited triplet state of menadione to form the cation radical of the substrate and the anion radical of menadione, both of which were detected... [Pg.72]

The development of new classes of cationic photoinitiators has played a critical role in the production of highly sensitive, acid-catalyzed deep-uv photoresists. Sulfonium salts have been widely used in this respect (4). These materials are relatively easy to prepare and structural modifications can be used to produce desired wavelength sensitivity. Triphenylsulfonium salts are particularly well suited for deep-uv application and in addition can be photosensitized for longer wavelength. These salts are quite stable thermally and certain ones such as the hexafluoroantimonate salt are soluble in casting solvents and thus easily incorporated within resist materials. [Pg.28]

Tegos GP, Demidova TN, Arcila-Lopez D, Lee H, Wharton T, Gali H, Flamblin MR (2005) Cationic fullerenes are effective and selective antimicrobial photosensitizers. Chem. Biol. 12 1127-1135. [Pg.21]

Merchat M, Bertolini G, Giacomini P, Villanueva A, Jori G (1996) Meso-substituted cationic porphyrins as efficient photosensitizers of gram-positive and gram-negative bacteria. J Photochem Photobiol B 32 153-157. [Pg.104]


See other pages where Photosensitizers cationic is mentioned: [Pg.804]    [Pg.297]    [Pg.37]    [Pg.158]    [Pg.209]    [Pg.185]    [Pg.138]    [Pg.2812]    [Pg.804]    [Pg.297]    [Pg.37]    [Pg.158]    [Pg.209]    [Pg.185]    [Pg.138]    [Pg.2812]    [Pg.439]    [Pg.241]    [Pg.252]    [Pg.1070]    [Pg.193]    [Pg.1070]    [Pg.20]    [Pg.129]    [Pg.11]    [Pg.973]    [Pg.984]    [Pg.75]    [Pg.239]    [Pg.248]    [Pg.38]    [Pg.64]    [Pg.96]    [Pg.142]    [Pg.615]    [Pg.645]    [Pg.107]    [Pg.656]    [Pg.428]    [Pg.95]    [Pg.101]    [Pg.107]    [Pg.74]    [Pg.35]    [Pg.316]   
See also in sourсe #XX -- [ Pg.209 , Pg.220 ]




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