Photodimerization of phenanthrene-9-carbonitrile and methyl phenanthrene-9-carboxylate

Frederick D. Lewis*, Steven V. Barancyk, Eric L. Burch

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The fluorescence self-quenching and photodimerization of three phenanthrene derivatives have been investigated. Methyl phenanthrene-9-carboxylate undergoes self-quenching with a rate constant of 1.2 × 109 M-1 s-1 in dichloromethane solution to form a weakly bound, nonfluorescent excimer from which the syn head-to-tail dimer is formed efficiently. The well-known photodimerization of phenanthrene-9-carbonitrile is found to occur predominantly via the excitation of a ground-state π-complex or aggregate. The structure and stability of the π-complex have been investigated using both 1H NMR spectroscopy and molecular mechanics. The failure to observe self-quenching for either the nitrile or N,N-dimethylphenanthrene-9-carboxamide is attributed to an enthalpy of excimer formation for these and other phenanthrenes which is too small to overcome the entropy of excimer formation at room temperature in fluid solution.

Original languageEnglish (US)
Pages (from-to)2548-2553
Number of pages6
JournalJournal of physical chemistry
Issue number6
StatePublished - 1992

ASJC Scopus subject areas

  • General Engineering
  • Physical and Theoretical Chemistry


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