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Influence of pH on dendritic structure of strongly fluorescent persulfate-treated poly(amidoamine) dendrimer

Paper ID Volume ID Publish Year Pages File Format Full-Text
27332 44016 2011 8 PDF Available
Title
Influence of pH on dendritic structure of strongly fluorescent persulfate-treated poly(amidoamine) dendrimer
Abstract

The influence of pH on the dendritic structure of strongly fluorescent ammonium persulfate (APS)-treated poly(amidoamine) (PAMAM) dendrimers was examined. The APS-treated PAMAM dendrimers were prepared by aging of 0.2 mM aqueous solutions of a hydroxyl groups-terminated, generation-five PAMAM (G5OH) dendrimer together with 200 μl of 0.1 M APS solutions. The G5OH dendrimer showed an absorbance at 280 nm, which was red-shifted to 360 nm after APS treatment. The APS-treated G5OH dendrimer solutions emitted much stronger fluorescence than the pristine G5OH dendrimer solutions when irradiated at 360 nm. The pH of the G5OH dendrimer solution is 7.6 while that of the APS-treated G5OH dendrimer solution is 5.2. The pore surface of both pristine and fluorescent G5OH dendrimers was altered more significantly under acidic than basic conditions. The tertiary amine groups of the pore surface of the fluorescent G5OH dendrimers were protonated by APS treatment as well as under the acidic condition; therefore, the pore surface of the G5OH dendrimer was filled with tertiary ammonium cations, which were, however, further deprotonated under basic conditions. The sulfur anions (VI and II) were generated during the hydrolysis of APS, which were interacted with the G5OH dendrimers under both acidic and basic conditions.

Graphical abstractAmmoniumpersulfate (APS)-treated, hydroxyl groups-terminated generation-five poly(amidoamine) (G5OH) dendrimer solutions emitted much stronger fluorescence than the pristine G5OH dendrimer solutions when irradiated at 360 nm. The pH of the pristine G5OH dendrimer solution is 7.6, while that of the APS-treated G5OH dendrimer solution is 5.2. The pore surface of both pristine and fluorescent G5OH dendrimers was altered more significantly under acidic than basic conditions. The tertiary amine groups of the pore surface of the fluorescent G5OH dendrimers were protonated by APS treatment as well as under the acidic condition. Thus, the pore surface of the APS-treated G5OH dendrimer was filled with tertiary ammonium cations, which were, however, further deprotonated under basic conditions.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The aging of poly(amidoamine) (PAMAM) dendrimer in the presence of a persulfate solution emitted much stronger fluorescence than the pristine dendrimer. ► The persulfate-treated PAMAM dendrimer showed a larger red shift in wavelength. ► The pore surface of persulfate-treated PAMAM dendrimer contains tertiary ammonium cations. ► Pristine PAMAM dendrimer were solely filled with tertiary amine groups on the pore surface. ► The pore surface of both pristine and fluorescent PAMAM dendrimers was altered more significantly under acidic than basic conditions.

Keywords
Poly(amidoamine) dendrimer; Ammonium persulfate treatment; Fluorescence; Dendritic structure; FT-IR spectroscopy; X-ray photoelectron spectroscopy
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Influence of pH on dendritic structure of strongly fluorescent persulfate-treated poly(amidoamine) dendrimer
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 224, Issue 1, 15 November 2011, Pages 102–109
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Price was $35.95
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Price after discount Only $4.95
100% Money Back Guarantee
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