Spectroscopic Properties and Conformational Analysis of Methyl Ester of Sinapic Acid in Various Environments.

A methyl ester of sinapic acid (MESA) has recently attracted attention due to its antioxidant action. This article presents results of a study on the spectral and physicochemical properties of MESA, using quantum chemistry (QC), steady-state (absorption and fluorescence), and time-resolved fluorescence techniques (TCSPC). The pK of the phenol group in the ground state was determined (8.

Fluorescence emission properties of 8-aza analogues of caffeine, theophylline, and related N-alkyl xanthines.

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.