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On the structure and excited electronic state lifetimes of cytidine self-assemblies with extended hydrogen-bonding networks

Paper ID Volume ID Publish Year Pages File Format Full-Text
27824 44044 2009 7 PDF Available
Title
On the structure and excited electronic state lifetimes of cytidine self-assemblies with extended hydrogen-bonding networks
Abstract

The nucleoside cytidine (C) assembles in extended hydrogen-bonded aggregates in neat apolar solvents like n-hexane, when carrying inert hydrophobic groups at the 2′,3′,5′-oxygen atoms of the ribose moiety. The ensuing structures, which constitute model systems for DNA super-structures such as triplexes or quadruplexes, were elucidated by FTIR spectroscopy and further characterized by UV spectroscopy. The lifetimes of the optically excited electronic states of the aggregates were investigated using femtosecond UV fluorescence up-conversion spectroscopy. Time profiles were measured after excitation at a number of pump wavelengths between 296 nm ≥ λpump ≥ 262 nm. The bi-exponential decay curves were characterized by time constants (with 2σ error limits) of τ1,C = 0.58(1) ps (88–95% fractional amplitudes) and τ2,C = 19.4(13) ps (12–5%) independent of the pump wavelength. The results indicate that the C multimers compared to the monomer do not gain photostability by coupled excited-state electron–proton transfer in the H-bonded networks, in contrast with recent findings for G·G and the G·C Watson–Crick dimer.

Keywords
Cytidine; DNA base pairs; Hydrogen bonding; Self-assembly; Fluorescence; Electronic relaxation; Radiationless transitions
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On the structure and excited electronic state lifetimes of cytidine self-assemblies with extended hydrogen-bonding networks
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 208, Issues 2–3, 15 December 2009, Pages 164–170
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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