Probing the interplay between factors determining reaction rates on silica gel using termolecular systems

Kirkpatrick, Iain; Worrall, David R.; Williams, Siân L.; Buck, Craig J.T.; Meseguer, Rafael G.

doi:10.1039/c2pp25171j

Cited by 2 publications

(5 citation statements)

References 59 publications

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“…The shuttling 71 or mobility of the sensitizer on the surface prior to departure was not scrutinized with our fluoropolymers. However, the small decrease in the adsorptive affinity of 13 for 10 than 7 is attributed to the higher number of surface O−H groups in 10 than 7 .…”

Section: Results and Discusionmentioning

confidence: 99%

“…The data point to fluorinated media and an increase in τ Δ due to inefficient radiationless deactivation of 1 O 2 by C–F bonds compared to O–H and C–H bonds. 73–75 Unlike polyfunctionalized compounds or proteins, 76,77 the reaction center for 7 and 10 is the ethene site. Other than the ethene site, the surfaces do not chemically react with 1 O 2 , as would be expected of Teflon-like materials that are known to resist oxidation.…”

Section: Results and Discusionmentioning

confidence: 99%

“…After the ethene is photooxidized and broken, there is a partition between surface release and adsorption channels. The shuttling 70 or mobility of the sensitizer on the surface prior to departure was not scrutinized with our fluoropolymers. However, the small decrease in the adsorptive affinity of 13 for 10 compared to that for 7 is attributed to the higher number of surface O−H groups in 10 relative to 7.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Photoactive Fluoropolymer Surfaces That Release Sensitizer Drug Molecules

et al. 2015

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We describe a physical-organic study of two fluoropolymers bearing a photoreleasable PEGylated photosensitizer which generates 1O2(1Δg) [chlorin e6 methoxy tri(ethylene glycol) triester]. The surfaces are Teflon/polyvinylalcohol (PVA) nanocomposite and fluorinated silica. The relative efficiency of these surfaces to photorelease the PEGylated sensitizer [shown previously to be phototoxic to ovarian cancer cells (Kimani, S. et al J. Org. Chem 2012, 77, 10638)] was slightly higher for the nanocomposite. In the presence of red light and O2, 1O2 is formed, which cleaves an ethene linkage to liberate the sensitizer in 68–92% yields. The fluoropolymers were designed to deal with multiple problems. Namely, their success relied not only high O2 solubility and drug repellency, but that the C−F bonds physically quench little 1O2 for its productive use away from the surface. The results obtained here indicate that Teflon-like surfaces have potential uses of delivering sensitizer and singlet oxygen for applications in tissue repair and photodynamic therapy (PDT).

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Section: Results and Discusionmentioning

confidence: 99%

Section: Results and Discusionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Photoactive Fluoropolymer Surfaces That Release Sensitizer Drug Molecules

et al. 2015

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“…This model is applicable in systems such as these where transient species are either spectrally separated from one another, decay on very different timescales, or where the quantum yields of potentially interfering species are negligible (vide infra). We have established [6] that the fitting parameters are not dependent on the analysing wavelength across the absorption band of the species of interest in these systems [6]. Additionally, we have also successfully applied this model in the analysis of data for termolecular systems [4,5], and hence, the data presented here can be directly compared with our previously published work.…”

Section: Nanosecond Diffuse Reflectance Laser Flash Photolysis Experimentioning

confidence: 94%

“…The kinetics of decay of radical ions on silica gel and titania-silica surface is not simple since the surface is heterogeneous in nature and rates rarely conform to simple exponential kinetics. We have used the model described by Albery et al [31] to characterise our data sets [2][3][4][5][6][13][14][15], employing a comprehensive exploration of the parameter space in order to obtain a global optimum value for the rate constants 1 3 Energy and electron transfer reactions on silica gel and titania-… [2,3]. Additionally, we have used Monte-Carlo simulations to model the molecular behaviour and have found good correlations with experiment [15].…”

Section: Introductionmentioning

confidence: 99%

Energy and electron transfer reactions on silica gel and titania–silica mixed oxide surfaces

et al. 2019

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The energy and electron transfer reactions of anthracene co-adsorbed with an electron donor on silica gel and titania-silica mixed oxides have been studied by a combination of steady-state reflectance, emission spectroscopy, and nanosecond diffuse reflectance laser flash photolysis. Bimolecular rate constants for energy and electron transfer between anthracene and azulene have been measured; kinetic analysis of the decay of the anthracene triplet state and radical cation show that the kinetic parameters depend on the titania content of the sample and the azulene loading. The rate of energy and electron transfer reactions increases as a function of azulene loading and decreases with increasing titania content in titania-silica mixed oxides. These findings indicate that the observed rate of reaction is determined by the rate of diffusion of anthracene on the titania-silica surfaces, whereas, in contrast, the observed rate of reaction on silica gel is predominantly governed by the rate of diffusion of azulene.

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Probing the interplay between factors determining reaction rates on silica gel using termolecular systems

Cited by 2 publications

References 59 publications

Photoactive Fluoropolymer Surfaces That Release Sensitizer Drug Molecules

Photoactive Fluoropolymer Surfaces That Release Sensitizer Drug Molecules

Energy and electron transfer reactions on silica gel and titania–silica mixed oxide surfaces

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