New polymeric photosensitizers (original) (raw)
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Dyes and Pigments, 1989
Four halogenated xanthene dyes, viz. 2,4,.5,7-tetrabromo-, 45di-iodo-, 2,4,5tri-iodo-, and2,4,5,7-tetraiodo-succinylfluorescein have been synthesized, and the tri-iodo and the tetraiodo derivatives have been bound through ester union to a soluble, linear copoly(styrene-p-vinylbenzyl chloride). The quantum yields of singlet oxygen generation offree andpolymer-bounddyes, relative to Rose Bengal, have been determined in dimethylformamide solution. In the case of thefree iodinated dyes, the quantum yield increases with the number of iodines, ranging from 0.30 to 0.44. The two polymeric tri-iodo and tetraiodo dyes present values of 0.33 and0.34 respectively, and their photostabilities are much higher than those of the corresponding free dyes.
Journal of Polymer Science Part A: Polymer Chemistry, 1993
Thionine (1) has been covalently bound to linear copoly (styrene-p-vinylbenzyl chloride) and to linear copoly (acrylic acid-2-ethylhexyl acrylate). The resulting polymeric dyes, purified by ultrafiltration, present quantum yields of singlet oxygen generation in dimethylformamide solution lower than their corresponding low-molecular-weight models thionine hydrochloride (l.HC1) and N (3)-acetylthionine (Ac-1) , the decrease being more pronounced in the case of the polystyrene-dye photosensitizer. High chromophore concentrations within the volume encompassed by each macromolecule in the solution can explain this fall in efficiency. The free dyes thionine hydrochloride and its hydrolysis products thionoline (2) and thionol (3) behave as good singlet oxygen generators, with quantum yields of 0.71, 0.62, and 0.63, respectively.
Physical Chemistry Chemical Physics, 2013
Synthesis of 3-(N-hydroxypropyl) carboxamido-9,14-dicyanobenzo[b]triphenylene (DBTP-CO-NH-(CH 2 ) 3 -OH, 3). 2 (185 mg, 1 eq) was dissolved at 35°C in 65 mL of freshly distilled THF. The system was let under stirring at room temperature for 1 hour. Then DCC (152 mg, 1.2 eq) and NHS (102 mg, 1.2 eq) were added. The basicity of the reaction mixture was assured by adding 100 µL of Et 3 N. The reaction mixture was let under stirring for 4 hours, until complete conversion took place. 3-amino-1propanol (1.2 mL, 2 eq) was added directly into the flask. The reaction, which was followed by thin layer chromatography, was let running for 24 hours. After evaporating the solvent, the product was dissolved in methylene chloride and washed successively with 5% NaHCO 3 solution, 5% citric acid solution and brine. The organic fraction was dried over MgSO 4 during the night and purified by preparative thin layer chromatography, yielding compound 3 as a yellow powder in 40% yield. mp 273 °C.
Polymer Degradation and Stability, 1999
The interaction between photochemically generated singlet molecular oxygen [O 2 ( 1 Á g )] and the relatively recently reported photostable compound, 1 H -hydroxy-2 H -acetonaphthone (1OH2AN) has been studied. The behavior of the isomer 2 H -hydroxy-l-acetonaphthone (2OH1AN) was also investigated for comparative purposes. The former belongs to the family of extremely photostable intramolecular hydrogen bonded systems, much used in polymer photoprotection. Our study analyses the properties of these compounds as generators, by direct photoirradiation, and quenchers of the known oxidative species O 2 ( 1 Á g ) upon indirect, dyesensitized photoirradiation. Time resolved phosphorescence detection of O 2 ( 1 Á g ) and polarographic and spectrophotometric measurements demonstrate that both 1OH2AN and 2OH1AN are excellent O 2 ( 1 Á g ) quenchers in alkaline media (ionized-phenolic form). Nevertheless the process of quenching has a mainly chemical component, producing photodegradation of both isomers with photooxidation quantum eciencies of 0.33 and 0.16 for 1OH and 2OH derivatives, respectively. These compounds are poor O 2 ( 1 Á g ) quenchers when the molecular (non-ionized) phenolic form predominates through an exclusive O 2 ( 1 Á g )-physical quenching process. The failure of O 2 ( 1 Á g ) generation upon direct photoirradiation of 1OH2AN constitutes a desirable condition for a polymer photoprotector against photooxidative damage. #
The Journal of Organic Chemistry, 2005
Singlet molecular oxygen (a 1 ∆ g ) has been produced and optically monitored in time-resolved experiments upon nonlinear two-photon excitation of photosensitizers that contain triple bonds as an integral part of the chromophore. Both experiments and ab initio computations indicate that the photophysical properties of alkyne-containing sensitizers are similar to those in the alkenecontaining analogues. Most importantly, however, in comparison to the analogue that contains double bonds, the sensitizer containing alkyne moieties is more stable against singlet-oxygenmediated photooxygenation reactions. This increased stability can be advantageous, particularly with respect to two-photon singlet oxygen imaging experiments in which data are collected over comparatively long time periods. Frederiksen, P. K.; Jørgensen, M.; Mikkelsen, K. V.; Ogilby, P. R. J. Phys. Chem. A 2001, 105, 11488-11495. (10) Frederiksen, P. K.; McIlroy, S. P.; Nielsen, C. B.; Nikolajsen, L.; Skovsen, E.; Jørgensen, M.; Mikkelsen, K. V.; Ogilby, P. R.
Photodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen quantum yield (φ ∆) is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media. The singlet oxygen quantum yield is a quantitative measurement of the efficiency in which photosensitizers are able to use energy, in the form of light, to convert oxygen in the ground state to the reactive species singlet oxygen, O 2 (1 ∆ g), useful in photodynamic therapy. Singlet oxygen quantum yields of photosensitizers differ when measured in different solvents. The majority of the existing φ ∆ values found in literature for various photosensitizers are documented with the sensitizers in organic solvents though values in aqueous media are more valuable for actual applications. Determination of accurate and precise φ ∆ values in aqueous solution is a much more difficult problem than in organic media. Problems in aqueous solution arise primarily from the physicochemical properties of O 2 (1 ∆ g) in water. Singlet oxygen has a iv much shorter lifetime in water than it does in organic solvents, causing challenges with respect to quantitative detection of O 2 (1 ∆ g). The ensuing pages are an attempt to explore the theory and document the procedures developed to provide the accurate measurement of O 2 (1 ∆ g) in aqueous media. Details of this experimental method and singlet oxygen quantum yield results of new compounds relative to established photosensitizers will be presented. v I dedicate this work to my beautiful and amazing wife Amy. None of this would have ever been possible without her understanding, patience, and encouragement. I thank God for this opportunity and experience, to include all that I have learned about myself and what is really important in life as a result of these last two years of determined work. vi ACKNOWLEDGMENTS This thesis would not have been possible without the help of a number of individuals. I would like to thank Dr. Kevin Belfield and his research group for all of the support that they provided throughout the last two years. Particularly, I would like to thank Katherine Schafer for all the times she went out of her way to help me. Lastly, I would like to thank my friends and family who helped me along the way. Thank you. vii
Dye-sensitized photochemical transformation of some pharmaceutical drugs by singlet molecular oxygen
2009
Photochemistry and Solar Energy Laboratory, Department of Chemistry, University College of Science, M. L. Sukhadia University, Udaipur-313 001, Rajasthan, India <em>E-mail </em>: ameta_sc@yahoo.com, ameta_ra@yahoo.com, anilchohadia@yahoo.co.in Govt. Meera Girls P. G. College (M. L. Sukhadia University), Udaipur-313 001, Rajasthan, India <em>Manuscript received 22 May 2008, accepted 12 January 2009</em> Dye-sensitized photo-oxygenation of thiopentone and phenytoin by singlet molecular oxygen has been carried out under various reaction conditions, including variation of solvents and sensitizers. The product has been isolated and characterized by elemental analysis, physical, chemical and spectral data. A suitable mechanism has been proposed for the formation of photo product. To confirm the participation of singlet oxygen in the reaction, singlet oxygen scavengers have been used in the photo-oxygenation reaction.