Combined experimental and computational study of intramolecular charge transfer in p-N,N-dimethylamino-p′-cyano-diphenylacetylene

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DOIResolve DOI: http://doi.org/10.1021/jp109674t
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TypeArticle
Journal titleJournal of Physical Chemistry A
Volume115
Issue5
Pages586592; # of pages: 7
AbstractA concerted experi-mental (time-resolved spectroscopies) and computational (TDDFT) study of p-N,N-dimethylamino-p′-cyano-diphenylacetylene (DACN-DPA) has been carried out to probe the intramolecular charge transfer (ICT) reaction that occurs in polar solvents. The picosecond transient absorption, as well as fluorescence, in acetonitrile reveals the formation of a twisted ICT(σ*) state, which involves transfer of an electron from the 4-(dimethylamino)benzethyne moiety (DMAB) to the benzonitrile (BN) group. This ICT(σ*) state, with a large dipole moment (24.7 D) and a geometry in which the plane of electron-accepting BN group is perpendicular to the plane electron-donating DMAB moiety and the angles of C(DMAB)C≡C is 135.0°, is responsible for the greatly Stokes-shifted (8000 cm−1) fluorescence and the transient absorption bands (with peaks at about 630 and 425 nm), which decays with the same lifetime (780 ps). It is proposed that the 630 nm picosecond transient absorption of the ICT state represents the absorption spectrum of dimethylaminobenzethyne radical cation and the 425 nm transient represents the absorption spectrum of benzonitrile radical anion. In nonpolar n-hexane, most of the fluorescence as well as the major component of the transient absorption originate from the S1 (ππ*) state.
Publication date
LanguageEnglish
AffiliationNRC Steacie Institute for Molecular Sciences; National Research Council Canada
Peer reviewedYes
NPARC number19739612
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Record identifiereaf4e54a-ce5f-4ff2-9973-20b2249d67fb
Record created2012-03-30
Record modified2016-05-09
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