Excited-state dynamics of 4-dimethylamino-4′-nitrobiphenyl confined in AOT reverse micelles

Lee, Gisang; Jang, Taehyung; Lee, Sebok; Oh, Hyeongyeol; Lee, Hohjai; Pang, Yoonsoo

doi:10.1016/j.molliq.2020.112873

Cited by 11 publications

(12 citation statements)

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“…While the absorption spectra of DNBP and DNS show the solvatochromic shifts (373–409 nm for DNBP and 413–453 nm for DNS) depending on the solvent polarity, the emission bands show large Stokes shifts of 8010–11,800 cm −1 for DNBP and 7390–11,300 cm −1 for DNS in polar solvents. The strong ICT characters of DNBP and DNS in the excited states have also been reported 45 , 46 , 48 , 49 .…”

Section: Resultsmentioning

confidence: 67%

“…However, the rotation of the nitro group has also been suggested for the ICT of DNS from the excited state dynamics comparison between DNS and a constrained model compound for nitrophenyl rotation 47 , 49 . Similarly, twisted ICT structure of DNBP with the nitrophenyl rotation has been proposed by time-resolved electronic spectroscopy and theoretical simulations 45 , 46 . Nonetheless, the molecular structures of DNS and DNBP in the ICT states are not yet confirmed by any experimental evidence.…”

Section: Introductionmentioning

confidence: 78%

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Twisted intramolecular charge transfer of nitroaromatic push–pull chromophores

Lee

Jen

Jang

et al. 2022

Sci Rep

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The structural changes during the intramolecular charge transfer (ICT) of nitroaromatic chromophores, 4-dimethylamino-4′-nitrobiphenyl (DNBP) and 4-dimethylamino-4′-nitrostilbene (DNS) were investigated by femtosecond stimulated Raman spectroscopy (FSRS) with both high spectral and temporal resolutions. The kinetically resolved Raman spectra of DNBP and DNS in the locally-excited and charge-transferred states of the S1 state appear distinct, especially in the skeletal vibrational modes of biphenyl and stilbene including ν8a and νC=C. The ν8a of two phenyls and the νC=C of the central ethylene group (only for stilbene), which are strongly coupled in the planar geometries, are broken with the twist of nitrophenyl group with the ICT. Time-resolved vibrational spectroscopy measurements and the time-dependent density functional theory simulations support the ultrafast ICT dynamics of 220–480 fs with the twist of nitrophenyl group occurring in the S1 state of the nitroaromatic chromophores. While the ICT of DNBP occurs via a barrier-less pathway, the ICT coordinates of DNS are strongly coupled to several low-frequency out-of-phase deformation modes relevant to the twist of the nitrophenyl group.

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Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 78%

Twisted intramolecular charge transfer of nitroaromatic push–pull chromophores

Lee

Jen

Jang

et al. 2022

Sci Rep

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“…Similarly, 110 fs dynamics was also observed for the ultrafast decay of the δ NH2, rocking at 1145 cm −1 , and the vibrational relaxation dynamics of 3 ps is further confirmed by the population dynamics of many ICT bands including the bands at 1236, 1340, 1527, and 1590 cm −1 (see Figure S4 in the Supplementary Materials ). Furthermore, the blue-shifts of 3–5 cm −1 that are commonly observed in these vibrational modes show a similar 3 ps vibrational relaxation dynamics in the TICT state, which is generally considered as evidence for the vibrational relaxation in the anharmonic potential surface [ 55 , 58 ]. The differences between the vibrational relaxation dynamics obtained from FSRS and the transient absorption measurements are then considered as the difference between the TICT and the PICT dynamics of AAQ in the S 1 excited state.…”

Section: Resultsmentioning

confidence: 94%

Intramolecular Charge Transfer of 1-Aminoanthraquinone and Ultrafast Solvation Dynamics of Dimethylsulfoxide

Jeon

Jen

Lee

et al. 2021

IJMS

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The intramolecular charge transfer (ICT) of 1-aminoanthraquinone (AAQ) in the excited state strongly depends on its solvent properties, and the twisted geometry of its amino group has been recommended for the twisted ICT (TICT) state by recent theoretical works. We report the transient Raman spectra of AAQ in a dimethylsulfoxide (DMSO) solution by femtosecond stimulated Raman spectroscopy to provide clear experimental evidence for the TICT state of AAQ. The ultrafast (~110 fs) TICT dynamics of AAQ were observed from the major vibrational modes of AAQ including the νC-N + δCH and νC=O modes. The coherent oscillations in the vibrational bands of AAQ strongly coupled to the nuclear coordinate for the TICT process have been observed, which showed its anharmonic coupling to the low frequency out of the plane deformation modes. The vibrational mode of solvent DMSO, νS=O showed a decrease in intensity, especially in the hydrogen-bonded species of DMSO, which clearly shows that the solvation dynamics of DMSO, including hydrogen bonding, are crucial to understanding the reaction dynamics of AAQ with the ultrafast structural changes accompanying the TICT.

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“…Lee et al studied the fluorescence decay reflecting charge transfer state formation in 4-dimethylamino-4 0 -nitrobiphenyl in AOT, and again observed a slower excited state decay in the smaller micelles. 156 These approaches have been extended to the study of reaction dynamics in the cavities of supramolecular complexes. Kondo et al studied the reaction of AO in a series of cyclodextrin nanocavities.…”

Section: Other Excited State Reactions In Micellesmentioning

confidence: 99%