Triplet state dipole moments of aminobenzonitriles

A. Demeter, Klaas A. Zachariasse

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The triplet state dipole moments μ(T) of a series of 4-amino- and 3-aminobenzonitriles in cyclohexane, benzene, and 1,4-dioxane are recalculated from previously published [J. Phys. Chem. 1992, 96, 10809] time-resolved microwave conductivity data, on the basis of newly measured intersystem crossing yields. For 4-(dimethylamino)benzonitrile (DMABN), the following values are now determined for μ(T): 8.3 D (cyclohexane), 8.9 D (benzene), and 9.7 D (1,4-dioxane), as compared with the previously reported dipole moment of 12 D for the first and the last solvent. With the other aminobenzonitriles, similar μ(T) data are obtained, between 6.9 D for 4-aminobenzonitrile (ABN) in n-hexane and 10.0 D for 4-(di-n-decylamino)benzonitrile (DDABN) in 1,4-dioxane. The increase of μ(T) observed for all aminobenzonitriles when going from cyclohexane via benzene to 1,4-dioxane may indicate that their triplet dipóle moments become larger with increasing solvent polarity. The present μ(T) of DMABN, between 8.3 and 9.7 D, although larger than the ground state dipóle moment μ(0) of 6.6 D, is somewhat smaller than that of the locally excited (LE) state (9.9 D) but considerably smaller than the dipóle moment of the intramolecular charge transfer (ICT) state (17 D). By comparing these ,M(X) data with the frequency ṽ(C≡N) of the cyano vibration in each state, it appears that at least for DMABN in the triplet state ṽ(C≡N) is not a reliable indication of the extent of charge transfer as compared with the other states S0, LE, and ICT.

Original languageEnglish
Pages (from-to)1359-1362
Number of pages4
JournalJournal of Physical Chemistry A
Volume112
Issue number7
DOIs
Publication statusPublished - Feb 21 2008

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Dipole moment
cyclohexane
atomic energy levels
dipole moments
Benzene
benzene
charge transfer
moments
Charge transfer
polarity
indication
Excited states
Ground state
microwaves
vibration
conductivity
ground state
Microwaves
excitation
1,4-dioxane

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Triplet state dipole moments of aminobenzonitriles. / Demeter, A.; Zachariasse, Klaas A.

In: Journal of Physical Chemistry A, Vol. 112, No. 7, 21.02.2008, p. 1359-1362.

Research output: Contribution to journalArticle

Demeter, A. ; Zachariasse, Klaas A. / Triplet state dipole moments of aminobenzonitriles. In: Journal of Physical Chemistry A. 2008 ; Vol. 112, No. 7. pp. 1359-1362.
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abstract = "The triplet state dipole moments μ(T) of a series of 4-amino- and 3-aminobenzonitriles in cyclohexane, benzene, and 1,4-dioxane are recalculated from previously published [J. Phys. Chem. 1992, 96, 10809] time-resolved microwave conductivity data, on the basis of newly measured intersystem crossing yields. For 4-(dimethylamino)benzonitrile (DMABN), the following values are now determined for μ(T): 8.3 D (cyclohexane), 8.9 D (benzene), and 9.7 D (1,4-dioxane), as compared with the previously reported dipole moment of 12 D for the first and the last solvent. With the other aminobenzonitriles, similar μ(T) data are obtained, between 6.9 D for 4-aminobenzonitrile (ABN) in n-hexane and 10.0 D for 4-(di-n-decylamino)benzonitrile (DDABN) in 1,4-dioxane. The increase of μ(T) observed for all aminobenzonitriles when going from cyclohexane via benzene to 1,4-dioxane may indicate that their triplet dip{\'o}le moments become larger with increasing solvent polarity. The present μ(T) of DMABN, between 8.3 and 9.7 D, although larger than the ground state dip{\'o}le moment μ(0) of 6.6 D, is somewhat smaller than that of the locally excited (LE) state (9.9 D) but considerably smaller than the dip{\'o}le moment of the intramolecular charge transfer (ICT) state (17 D). By comparing these ,M(X) data with the frequency ṽ(C≡N) of the cyano vibration in each state, it appears that at least for DMABN in the triplet state ṽ(C≡N) is not a reliable indication of the extent of charge transfer as compared with the other states S0, LE, and ICT.",
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AB - The triplet state dipole moments μ(T) of a series of 4-amino- and 3-aminobenzonitriles in cyclohexane, benzene, and 1,4-dioxane are recalculated from previously published [J. Phys. Chem. 1992, 96, 10809] time-resolved microwave conductivity data, on the basis of newly measured intersystem crossing yields. For 4-(dimethylamino)benzonitrile (DMABN), the following values are now determined for μ(T): 8.3 D (cyclohexane), 8.9 D (benzene), and 9.7 D (1,4-dioxane), as compared with the previously reported dipole moment of 12 D for the first and the last solvent. With the other aminobenzonitriles, similar μ(T) data are obtained, between 6.9 D for 4-aminobenzonitrile (ABN) in n-hexane and 10.0 D for 4-(di-n-decylamino)benzonitrile (DDABN) in 1,4-dioxane. The increase of μ(T) observed for all aminobenzonitriles when going from cyclohexane via benzene to 1,4-dioxane may indicate that their triplet dipóle moments become larger with increasing solvent polarity. The present μ(T) of DMABN, between 8.3 and 9.7 D, although larger than the ground state dipóle moment μ(0) of 6.6 D, is somewhat smaller than that of the locally excited (LE) state (9.9 D) but considerably smaller than the dipóle moment of the intramolecular charge transfer (ICT) state (17 D). By comparing these ,M(X) data with the frequency ṽ(C≡N) of the cyano vibration in each state, it appears that at least for DMABN in the triplet state ṽ(C≡N) is not a reliable indication of the extent of charge transfer as compared with the other states S0, LE, and ICT.

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