Electronic states of pyrene single crystal and of its single molecule inserted in a molecular vessel of cyclodextrin

Takahashi, Nobuaki; Gombojav, Bold; Yoshinari, Takehisa; Nagasaka, Shin–ichiro; Takahashi, Yoshio; Yamamoto, Akio; Goto, T.; Kasuya, A.

doi:10.1016/j.jssc.2004.05.058

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…The observed fine structure of 170 meV (1370 cm À1 ) separation energy of the luminescence spectra is assigned as the breathing modes of pyrene molecular vibrations. 12) Other fine structures of 0.04 -0.05 eV (320 -400 cm À1 ) separation are close to the value of 407 cm À1 , that was reported as the FT-Raman spectra of pyrene. 17) This value is close to the separation of A g -mode molecular vibrations with a wavelength of 434 cm À1 which was calculated using WinMO-PAC.…”

Section: Resultssupporting

confidence: 82%

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Luminescences of Pyrene Single Crystal and Pyrene Molecules Inserted in a Molecular Vessel of Cyclodextrin

et al. 2007

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Highly purified single crystals of pyrene were made by a gas phase crystal growth method from 180 times of zone-refined pyrene. The dry powder of -cyclodextrin including a pyrene single molecule and that of -cyclodextrin including twin molecules were prepared under vacuum. The luminescence spectra of pyrene single molecules, twin molecules and single crystals, and their temperature dependences were measured with great care in the process of cooling the samples. It is found that the features of luminescence spectra at 2 K are quite different from each other. Pyrene twin molecules in -cyclodextrin show an excimer luminescence similar to that of single crystal. The vibronic luminescence in the range of 3.0 -3.5 eV comes from the ground-excited-state complex, or in other words, from the vibronic exciton, in contrast to the hitherto-assigned luminescence from another type of selftrapped exciton or metastable B-state which is the precursor of selftrapped excitons.

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Section: Resultssupporting

confidence: 82%

“…The absorption spectra are taken from our previous paper. 12) The absorption spectra were derived from the reflection spectra using the Kramers-Kronig formula. The luminescence spectra were observed in the range of 2.0 -3.3 eV.…”

Section: Resultsmentioning

confidence: 99%

Luminescences of Pyrene Single Crystal and Pyrene Molecules Inserted in a Molecular Vessel of Cyclodextrin

et al. 2007

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“…The line width broadening was fully reversible upon release of pressure but the Raman spectra of released crystals still showed the increased luminescence background. Because we use 630 nm excitation for our Raman measurements, which is far from the electronic transition for the pyrene crystal (absorption edge above 3 eV (∼415 nm)), 33 the observed luminescence background likely originates from excited structural defects. These defects could be formed during the phase transition at ∼0.3 GPa and also above 2 GPa.…”

Section: Resultsmentioning

confidence: 99%

High-Pressure Effects in Pyrene Crystals: Vibrational Spectroscopy

2008

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The response of pyrene crystals to high pressure was examined using Raman and FTIR spectroscopies. Raman spectra of external and internal modes were measured up to 11 GPa. Changes in the external modes were observed at approximately 0.3 GPa, indicating the onset of a phase transition. We demonstrated that at this pressure pyrene I (P2(1)/a, 4 mol/unit cell) transforms to pyrene III (P2(1)/a, 2 mol/unit cell). Further increase of pressure produced a gradual broadening of the internal modes and an increase of fluorescence background, indicating the formation of another phase above 2.0 GPa. Irreversible chemical changes were observed upon gradual compression to 40 GPa. FTIR spectroscopy of the recovered product indicated a transformation of pyrene into an amorphous hydrogenated carbon (a-C:H) structure.

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“…With their particular electronic, optical and geometric properties, pyrene and its derivatives (Garcia-Cruz et al, 2004;Takahashi et al, 2004;Borisevich et al, 1992) have attracted considerable recent interest. This is demonstrated in a great number of applications including host-guest (Vö gtle, 1996) and metal coordination chemistry (Arrais et al, 2004), as well as fluorescent sensor development (Bren, 2001).…”

Section: Commentmentioning

confidence: 99%