94846-72-7Relevant articles and documents
Modifying the Product Distribution of a Reaction within the Controlled Microenvironment of a Colloidosome
Mann,Ellis,Twyman
, p. 4031 - 4037 (2016/07/06)
A water-soluble colloidosome composed of PGMA-PS latex was used as a microcapsule to host a catalyzed oxidation reaction within its dodecane core. When compared to a control reaction a significant colloidosome effect was observed. Specifically, a 233% increase in the relative yield of all products was observed for the colloidosome reaction. Furthermore, when the product distributions were calculated it was evident that a switch in selectivity had taken place. These studies showed there is a significant reduction in the relative yield of the epoxide product compared to the remaining oxidation products. Additional control experiments confirmed that rate enhancements were not simply a result of concentration and that reactions were not occurring in the outer latex phase. As a consequence of these control experiments, we suggest that the colloidosome enhancement and shift in product distribution, comes about from differences in electronic environment at or close to the interface between the internal oil phase and the outer colloidal particles. This environment is able to stabilize any specific intermediates and or transition states leading to enhanced reactions for these products and higher relative yields.
UV-Vis, Fluorescence and EPR Studies of Porphyrins in Bilayers of Dioctadecyldimethylammonium Surfactants
Esch, J.H. van,Feiters, M.C.,Peters, A.M.,Nolte, R.J.M.
, p. 5541 - 5551 (2007/10/02)
The incorporation characteristics of three simple tetraarylporphyrins into bilayers of dioctadecyldimethylammonium surfactants was studied by UV-vis, fluorescence, and EPR spectroscopy.The porphyrins used are tetraphenylporphyrin (TPP), tetrakis(4-(hexadecyloxy)phenyl)porphyrin (THPP), and tris(4-(hexadecyloxy)phenyl)(4-methylpiridinium)porphyrin tosylate (TrHPyP).At low porphyrin to surfactant molar ratios (5 x 1E-4) the porphyrins show a strong fluorescence.Increasing this ratio to 5 x 1E-3 causes a change in the UV-vis spectra and a decrease of the fluorescence intensity.Time-resolved fluorescence measurements indicated that the latter is due to the formation of non-fluorescent porphyrin aggregates.The spectral characteristics of the porphyrin aggregates are discussed in terms of the formation of different types of aggregates.The location of the porphyrins within the bilayers was investigated by fluorescence quenching experiments using iodide, 9(10)-bromooctadecanoic acid, and 16-bromohexadecanoic acid.These experiments suggest that THPP is located in the middle of the bilayer and TrHPyP near the aqueous interface.For the parent compound TPP no well-defined position was found.EPR spectroscopy on cast films of dioctadecyldimethylammonium surfactants with the copper derivatives of the porphyrins incorporated (porphyrin-to-surfactant ratio = 5 x 1E-3) revealed a clear anisotropic distribution of the latter molecules in the cast bilayers.The angles between the porphyrin normals and the bilayer normal were determined by comparison of experiment with simulated spectra.In the case of THPP and TrHPyP these angles agree very well with an arrangement in which the long porphyrin axis lies parallel to the bilayer surface.The arrangement of TPP aggregates could not be established.
