Configuration interaction and density functional study of the influence of lithium cation complexation on vertical and adiabatic excitation energies of enones

R. B. Sunoj, P. Lakshminarasimhan, V. Ramamurthy, J. Chandrasekhar

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The changes in the excited state energies of representative cyclic enones (cyclopentenone and cyclohexenone) induced by lithium ion coordination have been examined using ab initio and DFT methods. Quantitative estimates of the vertical triplet state energies were obtained using configuration interaction calculations at the CIS and CIS(D) levels with the 6-31+G(d) basis. Inclusion of perturbative doubles corrections has a marked effect on the relative energies of the n-π* and π-π* triplet states. At both CI and CIS(D) levels, lithium complexation is predicted to raise the energy of the n-π* triplet state much more than the π-π* triplet. The trends obtained at the CIS(D) level are reproduced using B3LYP/6-31+G(d) calculations. Adiabatic excitation energies were also computed by carrying out geometry optimization of the triplet states at the B3LYP level. While the separation between the geometry optimized n-π* and π-π* triplet states is very small for the parent enones, the π-π* triplet is clearly favored in the lithium complexes. These results suggest the possibility of reversing the reactive photoexcited state in enones through cation complexation. The conclusions provide a rationale for interesting variations in product distributions observed for enones in cation exchanged zeolites.

Original languageEnglish (US)
Pages (from-to)1598-1604
Number of pages7
JournalJournal of Computational Chemistry
Volume22
Issue number13
DOIs
StatePublished - Oct 1 2001
Externally publishedYes

Keywords

  • CI
  • DFT
  • Enones
  • Excited states
  • Lithium ion complexation

ASJC Scopus subject areas

  • Chemistry(all)
  • Safety, Risk, Reliability and Quality

Fingerprint Dive into the research topics of 'Configuration interaction and density functional study of the influence of lithium cation complexation on vertical and adiabatic excitation energies of enones'. Together they form a unique fingerprint.

Cite this