Photoisomerization of a Capped Azobenzene in Solution Probed by Ultrafast Time-Resolved Electronic Absorption Spectroscopy
| Autor: | John N. Moore, Ronald E. Hester, T. Q. Ye, Laurence C. Abbott, Igor K. Lednev |
|---|---|
| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 102:9161-9166 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp982368c |
| Popis: | Ultrafast time-resolved electronic absorption spectroscopy has been used to study the photochemistry of trans-azobenzene and trans-1, a derivative in which azobenzene is capped by an azacrown ether, on UV excitation to the S2(ππ*) state. Excitation of trans-1 results in transient absorption which decays with a dominant component of lifetime ca. 2.6 ps and in bleaching of the ground-state UV absorption band which recovers on a similar time scale. In contrast, excitation of trans-azobenzene results in transient absorption which decays with a dominant component with a shorter lifetime of ca. 1 ps, and in bleaching which recovers on a much longer time scale of ca. 18 ps. The recovery of the ground-state UV absorption band is not complete in either case, and the ultrafast data indicate that the quantum yield of trans-to-cis photoisomerization of 1 is approximately twice that of azobenzene. These observations demonstrate that the restricted rotational freedom of the phenyl groups in trans-1 has a significant ef... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|