Relaxation pathways of photoexcited diaminostilbenes. The meta-amino effect

Frederick D. Lewis*, Wilfried Weigel, Xiaobing Zuo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The spectroscopy and photochemistry of several 3-substituted trans-diaminostilbenes have been investigated and the results compared with those from previous studies of 4,4′-diaminostilbenes. The excited-state properties of 3,5-diaminostilbene and 3,3′-diaminostilbene are similar to those for the parent 3-aminostilbene. These amines display long, temperature-independent singlet lifetimes and large fluorescence quantum yields. The long singlet lifetimes are a consequence of large barriers for torsion about the central double bond on the singlet state surface and low fluorescence rate constants. Thus, these diaminostilbenes display the "meta-amino effect" previously identified for 3-aminostilbene and for some amine-donor-acceptor substituted stilbenes. The 4,4′-diaminostilbenes also have larger torsional barriers in nonpolar solvents but shorter singlet lifetimes as a consequence of larger fluorescence and intersystem crossing rate constants. The photophysical properties of 3,4′-dimethylaminostilbene are similar to those of 4,4′-aminostilbenes; however, it has a lower torsional barrier, similar to that of the parent 4-aminostilbene.

Original languageEnglish (US)
Pages (from-to)4691-4696
Number of pages6
JournalJournal of Physical Chemistry A
Issue number19
StatePublished - May 17 2001

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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