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Effect of NH2 rotation on the fluorescence of 2-aminopurine in solution

Paper ID Volume ID Publish Year Pages File Format Full-Text
26019 43930 2013 6 PDF Available
Title
Effect of NH2 rotation on the fluorescence of 2-aminopurine in solution
Abstract

Since the introduction of 2-aminopurine (2AP) in 1969 as a fluorescent analogue of adenine, its intense fluorescence in aqueous solution and the subsequent reduction of this intensity in DNA has been a powerful tool for studies of structural changes in DNA. Herein, we show that the unusual intense fluorescence of 2AP in water is attributed to the formation of a closed complex between one water molecule and 2AP in the excited state. This configuration restricts the rotation of the 2-NH2 group which subsequently lowers the nonradiative decay rate. We supported this finding by attaching heavy masses to the amino group, dimethyl (2-(N(Me)2)) and diethyl (2-(N(Et)2)). By examining the fluorescence behavior in dioxane (an apolar, aprotic solvent), the lighter NH2 group can rotate in the excited state more freely which enhances the nonradiative loss of fluorescence. On the other hand, this rotation slows down sharply in the two heavy-group derivatives, leading to a restoration of the fluorescence intensity and lifetime very close to that of 2AP in water. Depletion of fluorescence was observed in the 2AP derivatives in water and is attributed to the population of a twisted intramolecular charge transfer (TICT) state due to the strong electron donating power of the NR2 groups, an effect that is absent for the parent 2AP.

Graphical abstractThe unusual intense fluorescence of 2-aminopurine (2AP) in aqueous solution is attributed to the restricted rotation of the 2-NH2 group by forming a closed complex between one water molecule and 2AP, reducing the loss of fluorescence. This mechanism is proved by attaching heavy masses to the amino group which reduces the rotational effect.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
DNA base analogue; 2-Aminopurine; Fluorescence; Lifetime; Hydrogen bond; Internal rotation
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Effect of NH2 rotation on the fluorescence of 2-aminopurine in solution
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 261, 1 June 2013, Pages 1–6
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