English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

A study has been made of the emission spectra at room temperature, in aqueous and alcoholic media, of 4-aminopyrazolo(3,4-d)pyrimidine (APP) and some of its methylated derivatives. The cationic forms APPH + , N 2 -methyl-APPH +  and N 7 -methyl-APPH +  exhibit intense fluorescence un­der these conditions, the first two exhibiting excitation spectra which differ from the absorption spectra, pointing to the existence of a tautomeric equilibrium in the ground state. From the shape of the excitation spectra, and comparisons with methylated analogues in fixed tautomeric forms, it follows that the emission of APPH +  originates exclusively from the species N(2)-H,N(7)-H + , the other forms being non-fluorescent. The proportion of the emitting species, calculated from the ex­citation wavelength dependence of the quantum yield, is in good agreement with data for the ground state.

Fluorescence Emission Properties of the Cation of 4-Aminopyrazole(3,4-d) pyrimidine, an Adenine Analogue: Evidence for Phototautomerism