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ET(33) dye as a tool for polarity determinations: Application to porous hybrid silica thin-films

Paper ID Volume ID Publish Year Pages File Format Full-Text
27099 44001 2010 6 PDF Available
Title
ET(33) dye as a tool for polarity determinations: Application to porous hybrid silica thin-films
Abstract

ET(33) (2,6-dichloro-4-(2,4,6-triphenyl-N-pyridino)-phenolate) was proven to be an effective tool to determine the polarity of the pore environment in sol–gel matrices prepared using acid catalysis. The probe molecules have been trapped during the formation of the organically modified silica matrices, occupying both, the inner porosity and the outer porosity of the matrix.The effect of the chemical modification of the silica film on the polarity of the pore environment was studied as a function of the organic modifying groups and their relative amount in the silica matrix. The usage of the ET(33) polarity probe allowed the identification of different pore environments (sites) within a matrix, attending to the relative amount of functional groups in the pores. A progressive decrease of the polarity of the samples prepared was observed as the amount of the organic modifying groups was increased. Hybrid matrices could be prepared via sol–gel processing, having polarities between 40 and 60 kcal mol−1 in the Reichardt's ET(30) scale, which can be controlled by the amount and nature of the organic modifying groups. A particular case was observed in samples modified with pentafluorophenyl groups (–C6F5), which showed very high pore polarities, close to that of unmodified matrices, in which pore environments rich in OH groups and rich in –C6F5 groups could not be distinguished, due to their similar polarity.The ET(33) polarity dye was found to provide a four times higher sensitivity than the known probe Nile Red for the determination of the polarity of the pore environment, as reflected by the much larger shift of the absorption peak of the dye due to changes in polarity. Due to its stability in acidic media, the ET(33) is suitable to be used in hybrid matrices prepared using acid catalysis, as are most of those prepared by the sol–gel method.

Keywords
Polarity; Sol–gel; Hybrid; Thin film; ET(33)
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ET(33) dye as a tool for polarity determinations: Application to porous hybrid silica thin-films
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 210, Issue 1, 5 February 2010, Pages 17–22
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us