The single emission at 400nm originated from mostly excited-state intermolecular hydrogen bonding has been observed for 0.05mM p-N,N-dimethyaminosalicylic acid (DMAS) in aqueous solutions (pH=1.7). Upon addition of β-CD, however, the 400nm emission band is diminished, accompanied by a broadening of the bandwidth along with an appearance of a new band at 350nm. According to the band analysis, the broad emission was found to be composed of two emission bands arising from the excited-state intramolecular proton transfer (ESIPT) and the excited-state intramolecular charge transfer (ICT), respectively. Being consistent with these steady-state spectroscopic results, the picosecond time-resolved fluorescence study unraveled three decay components corresponding to two different proton transfer processes and the excited ICT state with ca. 5.6ns, 160ps and 1.5ns, respectively. It is noteworthy that the relative amplitude of 1.5ns component attributable to the ICT state is enhanced in parallel with an increase of 160ps ESIPT component. These results are interpreted in terms of the proton transfer coupled-charge transfer processes.
|Number of pages||9|
|Journal||Journal of Photochemistry and Photobiology A: Chemistry|
|Publication status||Published - 2001 Jan 15|
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Physics and Astronomy(all)