1417534-85-0Relevant academic research and scientific papers
Modified 6-aza uridines: Highly emissive pH-sensitive fluorescent nucleosides
Sinkeldam, Renatus W.,Hopkins, Patrycja A.,Tor, Yitzhak
, p. 3350 - 3356 (2012)
Optimized facile syntheses and highly desirable spectroscopic properties of two isomorphic fluorescent pyrimidines, comprising a 1,2,4-triazine motif conjugated to a thiophene (1 a) or a furan (1 b), are described. Although structurally related to their 5-modified uridine counterparts, these modified 6-aza-uridines reveal dramatically improved fluorescence properties and a remarkable sensitivity to polarity and pH changes. The thiophene derivative 1 a has an absorption maximum around 335 nm, which upon excitation yields visible emission with a polarity-sensitive maximum and fluorescence quantum yield ranging from 415 nm (Φ=0.8) to 455 nm (Φ=0.2) in dioxane and water, respectively. Nucleoside 1 a also displays susceptibility to acidity. Correlating emission intensity and solution pH yields a pKa value of 6.7-6.9, reasonably close to physiological pH values. The results illustrate that highly sought-after fluorescence features (brightness and responsiveness) are not necessarily the trait of large fluorophores alone, but can be observed with probes that meet stringent isomorphic design criteria.
