کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1231037 | 1495200 | 2016 | 6 صفحه PDF | دانلود رایگان |
• Six fluorescein-nitroxide radical hybrid-compounds were synthesized.
• Fluorescence of the compounds before and after addition of AsA was measured.
• Bonding of the radical to the fluorescein hydroxyl reduced the fluorescence intensity.
• The fluorescence after radical reduction increased by a maximum of 3.21-fold.
Six fluorescein-nitroxide radical hybrid-compounds (2ab, 3ab, 4, and 5) were synthesized by the condensation of 5- or 6-carboxy-fluorescein and 4-amino-TEMPO (2ab), 5- or 6-aminofluorescein and 4-carboxy-TEMPO (3ab), and fluorescein and 4-carboxy-TEMPO (4), or by reaction of the 3-hydroxyl group of fluorescein with DPROXYL-3-ylmethyl methanesulfonate (5). Fluorescence intensities (around 520 nm) after reduction of the radical increased to 1.43-, 1.38-, and 1.61-folds for 2a, 2b and 3b respectively; 3a alone exhibited a decrease in intensity on reduction. Since 4 was readily solvolyzed in PBS or even methanol to afford fluorescein and 4-carboxy-TEMPO, its fluorescence change could not be measured. Hybrid compound 5 containing an ether-linkage between the fluorescein phenol and 3-hydroxymethyl-DPROXYL hydroxyl centers, was stable and on reduction, showed a maximum increase (3.21-fold) in relative fluorescence intensity in PBS (pH 5.0), despite its remarkably low absolute fluorescence intensity.
Figure optionsDownload as PowerPoint slide
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 169, 5 December 2016, Pages 66–71