Substituent effects on the triplet-triplet absorption spectra of coumarin and its derivatives

  • Henry B
  • Lawler E
  • 4


    Mendeley users who have this article in their library.
  • 9


    Citations of this article.


Preliminary work on the triplet-triplet (T-T) absorption of coumarin and two of its 4-hydroxy substituted derivatives is extended to four additional substituted coumarins in order to investigate substituent effects on T-T absorption in these molecules. A steady cross Illumination technique is used in EPA glass at 77° K. Measurements of the decay of T-T absorption are carried out with a flash technique and a comparison made with phosphorescence lifetimes to verify the triplet nature of the absorption. The observed T-T spectra show a marked dependence on the presence and position of hydroxy substitution. An explanation is developed based on the mixing of nπ*character into the lowest ππ*triplet state. The effect of methyl substitution is also investigated and, although it leads to relatively small changes in the T-T spectra, the results suggest that it plays a role in the susceptibility of the molecules to photochemical change. © 1973.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Bryan R. Henry

  • Edward A. Lawler

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free