STUDY AND APPLICATION OF A NOVEL PROBE USING TWISTED INTRAMOLECULAR CHARGE-TRANSFER FLUORESCENCE

This paper reports the investigation of the twisted intramolecular cha rge transfer (TICT) of 4-(diethylamino)benzoic acid (DEABA) in aqueous beta-cyclodextrin (beta-CD) and methylated beta-cyclodextrin (beta-MC D) solution by studying the typical TICT dual fluorescence and makes a comparison between the TICT behavior of DEABA and 4-(dimethylamino)be nzoic acid (DMABA). In pure water, DEABA and DMABA emit only locally e xcited (LE) fluorescence, and the TICT fluorescence band is developed with the addition of beta-Cd or beta-MCD. Both LE and TICT fluorescenc e bands are continuously enhanced upon an increase of beta-CD or beta- MCD concentration. The microenvironmental change of beta-CD caused by methylation can be indicated with DEABA. The ratio of TICT to LE fluor escence intensities resulting from excitation at 280 nm decreased mark edly with increasing the size of the alcohol molecules or the concentr ation of methanol, ethanol, propanol and butanol. The ratio is unaffec ted by the intensity of the source which affects absolute intensities and can be used to quantify alcohol concentrations. This possibility h as been tested for the determination of single alcohol in synthetic wa ter samples.