Triplet recombination of radical ion pairs: CIDNP effects and DFT calculations on 1,2-dicyanoethylene

Heinz Roth, Ronald S. Sauers

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Radical ion pairs generated by electron transfer from photo-excited aromatic hydrocarbons to maleo- and fumaronitrile (cis- and trans-1,2- dicyanoethylene, 1) undergo back electron transfer from singlet and triplet pairs. The pair energies relative to the reactant ground states and to the triplet state, respectively, determine the competition between the recombination pathways. Cross sections through the potential surfaces of the radical anion and the triplet state of 1 have been examined by density functional theory calculations. The radical anion surface has minima in which the carbon and nitrogen skeleton is essentially planar; the central C-C bond is lengthened (weakened), but the barrier to geometric isomerization is still sizeable (31.2 kcal mol-1). The triplet energy surface has a minimum at a bisected geometry (plus its enantiomer); rotation of the H-C-CN segments of the triplet yields a syn-periplanar and an anti-periplanar point 9.3 kcal mol-1 and 8.2 kcal mol-1 above the minimum, respectively.

Original languageEnglish (US)
Pages (from-to)2036-2042
Number of pages7
JournalPhotochemical and Photobiological Sciences
Volume12
Issue number11
DOIs
StatePublished - Jan 1 2013

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Discrete Fourier transforms
Anions
Ions
Aromatic Hydrocarbons
atomic energy levels
Enantiomers
Electrons
electron transfer
Isomerization
Interfacial energy
Ground state
anions
Density functional theory
ions
Nitrogen
Carbon
enantiomers
musculoskeletal system
isomerization
surface energy

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

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abstract = "Radical ion pairs generated by electron transfer from photo-excited aromatic hydrocarbons to maleo- and fumaronitrile (cis- and trans-1,2- dicyanoethylene, 1) undergo back electron transfer from singlet and triplet pairs. The pair energies relative to the reactant ground states and to the triplet state, respectively, determine the competition between the recombination pathways. Cross sections through the potential surfaces of the radical anion and the triplet state of 1 have been examined by density functional theory calculations. The radical anion surface has minima in which the carbon and nitrogen skeleton is essentially planar; the central C-C bond is lengthened (weakened), but the barrier to geometric isomerization is still sizeable (31.2 kcal mol-1). The triplet energy surface has a minimum at a bisected geometry (plus its enantiomer); rotation of the H-C-CN segments of the triplet yields a syn-periplanar and an anti-periplanar point 9.3 kcal mol-1 and 8.2 kcal mol-1 above the minimum, respectively.",
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Triplet recombination of radical ion pairs : CIDNP effects and DFT calculations on 1,2-dicyanoethylene. / Roth, Heinz; Sauers, Ronald S.

In: Photochemical and Photobiological Sciences, Vol. 12, No. 11, 01.01.2013, p. 2036-2042.

Research output: Contribution to journalArticle

TY - JOUR

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T2 - CIDNP effects and DFT calculations on 1,2-dicyanoethylene

AU - Roth, Heinz

AU - Sauers, Ronald S.

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N2 - Radical ion pairs generated by electron transfer from photo-excited aromatic hydrocarbons to maleo- and fumaronitrile (cis- and trans-1,2- dicyanoethylene, 1) undergo back electron transfer from singlet and triplet pairs. The pair energies relative to the reactant ground states and to the triplet state, respectively, determine the competition between the recombination pathways. Cross sections through the potential surfaces of the radical anion and the triplet state of 1 have been examined by density functional theory calculations. The radical anion surface has minima in which the carbon and nitrogen skeleton is essentially planar; the central C-C bond is lengthened (weakened), but the barrier to geometric isomerization is still sizeable (31.2 kcal mol-1). The triplet energy surface has a minimum at a bisected geometry (plus its enantiomer); rotation of the H-C-CN segments of the triplet yields a syn-periplanar and an anti-periplanar point 9.3 kcal mol-1 and 8.2 kcal mol-1 above the minimum, respectively.

AB - Radical ion pairs generated by electron transfer from photo-excited aromatic hydrocarbons to maleo- and fumaronitrile (cis- and trans-1,2- dicyanoethylene, 1) undergo back electron transfer from singlet and triplet pairs. The pair energies relative to the reactant ground states and to the triplet state, respectively, determine the competition between the recombination pathways. Cross sections through the potential surfaces of the radical anion and the triplet state of 1 have been examined by density functional theory calculations. The radical anion surface has minima in which the carbon and nitrogen skeleton is essentially planar; the central C-C bond is lengthened (weakened), but the barrier to geometric isomerization is still sizeable (31.2 kcal mol-1). The triplet energy surface has a minimum at a bisected geometry (plus its enantiomer); rotation of the H-C-CN segments of the triplet yields a syn-periplanar and an anti-periplanar point 9.3 kcal mol-1 and 8.2 kcal mol-1 above the minimum, respectively.

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