The vibrational structure of the electronic spectra of quinoxaline in shpolskii-type hydrocarbon matrices

Brenner, Karoly; Ruziewicz, Z.

doi:10.1016/0022-2313(77)90023-0

Cited by 12 publications

(1 citation statement)

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“…1,4-Diazines were reported in literature as systems showing unusual behavior in the excited electronic states, when in solution − and when surrounded by rigid, apolar environments. ,− The studies in frozen hydrocarbon matrices of Shpolskii-type have shown spectral signatures of strong coupling between adjacent excited states through an oop C–H bending vibrational mode. Other related di- and monoaza compounds without a pyrazine subunit did not exhibit these anomalous features in high-resolution fluorescence spectra. , Fluorescence and phosphorescence polarization studies of 1,4-DAT in 3-methylpentene glass at 77 K have indicated a nonplanar distortion of the lowest (π,π*) singlet state, in contrast to a planar geometry of the lowest triplet state .…”

Section: Introductionmentioning

confidence: 99%

Supersonic Jet Spectroscopy and Density Functional Theory Study of Isomeric Diazines: 1,4- and 1,8-Diazatriphenylene. Why Do They Differ So Deeply?

et al. 2016

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We report on laser-induced fluorescence excitation and dispersed fluorescence spectra of two isomeric compounds: 1,4- and 1,8-diazatriphenylene (1,4- and 1,8-DAT) isolated in supersonic molecular jets, and their 1:1 complexes with protic solvents. We found that the ground and excited state vibronic patterns of bare 1,4-DAT differ significantly from those of 1,8-DAT, and those of the complexes of both isomers. A marked activity of several out-of-plane vibrations in 1,4-DAT and the symptoms of the distortion of the S excited molecule were diagnosed from the vibronic spectra, whereas planar structures were predicted for 1,8-DAT in S and S states. An anharmonic double-minimum potential along an out-of-plane coordinate has been derived and used to predict higher overtones of the S state vibration at 113 cm. Large enhancement of fluorescence was observed upon formation of 1:1 complexes of 1,4-DAT with water or methanol, which is explained in terms of an increased separation of interacting (n,π*) and (π,π*) electronic states in the H-bonded complexes, and/or a suppression of the intersystem crossing process.

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