D. Zhenming et al. / Spectrochimica Acta Part A 78 (2011) 1143–1148
1147
shift, as a consequence of the similar geometries in the S0 and S1
states. It was 2487 cm−1 in CH3CN solution. As shown in Table 5, the
emission peak of MPBQ can be described as originating from –*
excited states with ICT character. On the basis of the calculated ver-
tical excited energies and their corresponding oscillator strengths,
the continuous emission spectrum was simulated with the help of
SWIZARD software with the width at half-height of 2500 cm−1. As
shown in Fig. 5, the simulated emission spectrum is in relatively
good agreement with the experimental fluorescence spectrum of
the compound. The maximum emission wavelengths of MPBQ are
386 and 402 nm in CH3CN solution.
1.0
0.8
0.6
0.4
0.2
0.0
Exp
Cal
4. Conclusions
200
300
400
500
600
In this paper, a new benzo[h]quinoline derivative, namely, 10-
methoxy-2-phenylbenzo[h]quinoline (MPBQ) was synthesized and
characterized by NMR, MS as well as elemental analysis. The
single-crystal X-ray crystallographic analysis indicated that MPBQ
adopts a planar conformation in crystal structure and contains one
molecule in the asymmetric unit. The absorption and fluorescence
spectra of MPBQ in CH3CN calculated by quantum chemistry com-
putations were in good agreement with the experimental data.
With good thermal stability, MPBQ could be potentially used as an
excellent luminescent material. Such studies are currently under
way in our laboratory, and the results will be released soon.
Wavelength (nm)
Fig. 5. Experimental and calculated emission spectra of MPBQ in CH3CN.
Table 4
Fluorescence spectral data of MPBQ in CH3CN solvent.
Emission
energy
Emission
wavelength
(nm)
Stokes shift
MO/character
Transition
(cm−1
)
(cm−1
)
25,906
24,875
386
402
2422
2079
LUMO ← HOMO
S1 → S0
Acknowledgements
LUMO. The absorption peak at the longest wavelength is assigned
to the electronic transition from HOMO to LUMO according to the
calculation in CH3CN solvent. It can be assigned to –* transition
with intramolecular charge transfer (ICT) character. On the basis
of the calculated vertical excitation energies and their correspond-
ing oscillator strengths, the continuous absorption spectrum was
simulated with the help of SWIZARD software with the width at
half-height of 2500 cm−1. As shown in Fig. 4, the simulated absorp-
spectrum of the compound.
All the calculations have been performed using the advanced
computing facilities of supercomputing center of computer net-
work information center of Chinese Academy of Sciences. All the
authors express their deep thanks.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
3.2.3. Fluorescence spectra
References
CH3CN solution excited at 353 nm. The spectrum consists of two
emission bands with peaks at 386 and 402 nm attributed to the
–* electronic transitions. Values of the emission peak energy
and Stokes shifts are given in Table 4. The higher energy peak in
the emission spectrum occurs at 25,906 cm−1 with small Stokes
shift, which can be assigned to the S1 → S0 electronic transition.
In order to gain insight into the nature of the fluorescence emis-
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state (S1) was optimized for the compound. The optimized geome-
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25,723 cm−1 and its oscillator strength was 0.5161. This transition
was also allowed. Moreover, TDDFT calculations gave small Stokes
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