Theoretica chimica acta

, Volume 63, Issue 3, pp 177–194 | Cite as

TheT1 state ofp-nitroaniline and related molecules: A CNDO/S study

  • Richard W. Bigelow
  • Hans-Joachim Freund
  • Bernhard Dick
Original Investigations


The nature of the lowest energy triplet state (T1) ofp-nitroaniline (PNA), N,N-dimethyl-p-nitroaniline (DMPNA) and nitrobenzene (NB) is reexamined using the semiempirical CNDO/S-CI method with selected parameter options. The present results indicate that in the case of theunperturbed molecules the short-axis polarized π* ←n(π) triplet largely localized at the acceptor end of the molecule may lie lower in energy than the triplet manifold counterpart of the intense intramolecular charge-transferD+Asinglet excitation. Computations suggest, however, that polar solvents strongly stabilize the PNA and DMPNA π* ← π charge-transfer triplet relative to other excitations, whereas specific solvent hydrogen-bonded interactions stabilize the π* ←n(σ) triplet of NB below those of π* ← π character. These assignments allow a rationalization of phosphorescence lifetime data,T n T1 absorption measurements and relative photochemical behavior.

Key words

p-nitroaniline Nitrobenzene Triplet state Photo reductions Quantum Yield Solvent shifts 


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Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • Richard W. Bigelow
    • 1
  • Hans-Joachim Freund
    • 2
  • Bernhard Dick
    • 2
  1. 1.Xerox Webster Research CenterWebsterUSA
  2. 2.Lehrstuhl für Theoretische Chemie der Universität zu KölnKölnFederal Republic of Germany

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