کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1360075 | 981423 | 2009 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Fluorescence emission properties of 8-aza analogues of caffeine, theophylline, and related N-alkyl xanthines Fluorescence emission properties of 8-aza analogues of caffeine, theophylline, and related N-alkyl xanthines](/preview/png/1360075.png)
Fluorescence emission properties of 8-azacaffeine, 8-azatheophylline and other N-alkylated 8-azaxanthines (8-azaXan) have been examined. It is shown that N-methylated 8-azaxanthines, as well as 8-azatheophylline, are highly fluorescent in aqueous medium as the neutral, and, in some instances, also as the monoanionic, forms. 8-Azacaffeine exhibits moderate emission, but its isomer, 1,3,8-trimethyl-8-azaXan, is highly fluorescent. All three 8-azaxanthines monomethylated on the triazole ring, as well as 8-azaxanthosine, exhibit increased acidity in the excited state. Some fluorescent pyrazolo[4,3-d]pyrimidine-5,7-diones, xanthine congeners of pyrazolo[4,3-d]pyrimidines, are also reported. Many of these are good fluorescent probes in enzymatic, receptor binding, and nucleic acid systems, some examples of which are presented. In particular, 8-azaXan is an excellent fluorescent probe for purine nucleoside phosphorylases, as a fluorogenic substrate in the reverse, synthetic pathway.
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Journal: Bioorganic & Medicinal Chemistry - Volume 17, Issue 6, 15 March 2009, Pages 2585–2591