Renatus Sinkeldam - A multisensing emissive pyrimidine.

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      Publication Details (including relevant citation   information):

      R. W. Sinkeldam, P. Marcus, D.   Uchenik, Y. Tor, ChemPhysChem,    2011, 12,   2260-5.


      Fluorescent nucleoside analogs, commonly used to explore nucleic   acid dynamics, recognition and damage, frequently respond to a   single environmental parameter. Herein we address the development   of chromophores that can simultaneously probe more than one   environmental factor while having each associated with a unique   spectroscopic signature. We demonstrate that an isomorphic   emissive pyridine-modified 2-deoxy-uridine 1,   containing multiple sensory elements, responds to changes in   acidity, viscosity, and polarity. Protonation of the pyridine   moiety (pKa 4.4) leads to enhanced emission   (λem=388 nm) and red-shifted absorption   spectra (λabs=319 nm), suggesting the   formation of an intramolecular hydrogen bond with the neighboring   pyrimidine carbonyl. This “locked” conformation can also be   mimicked by increasing solvent viscosity, resulting in a stark   enhancement of emission quantum yield. Finally, increasing   solvent polarity substantially impacts the chromophore’s Stokes   shift [from 5.8×103 cm−1 at   ET(30)=36.4 kcal mol−1 to 9.3   ×103 cm−1 at   ET(30)=63.1 kcal mol−1]. The   opposite effect is seen for the impact of solvent polarity of the   protonated form. The characteristic photophysical signature   induced by each parameter facilitates the exploration of these   environmental factors both individually and simultaneously.

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