Supplementary Material for
Bromination of graphene with pentagonal, hexagonal zigzag and armchair, and
heptagonal edges
Jungpil Kim, Yasuhiro Yamada*, Ryo Fujita, Satoshi Sato
Graduate School of Engineering, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
*
Corresponding author. Tel/Fax: +81-43-290-3376. E-mail address:y-yamada@faculty.chiba-u.jp (Y.
Yamada).
S1. Experimental (Empirical and simulated UV-Vis)
The brominated naphthalene and azulene as well as bromine-substituted naphthalene such as
1-bromonaphtahlene (Tokyo Chemical Industry Co., Ltd.), 2-bromonaphthalene (Tokyo Chemical
Industry Co., Ltd.), 1,4-dibromonaphthalene (Wako Pure Chemical Industries, Ltd.), and 2,7dibromonaphthalene (Sigma-Aldrich Co., Ltd.) were analyzed by UV-Vis spectroscopy (UV-1240
Shimadzu Corp.). n-Hexane was used as a solvent for UV-Vis spectroscopy. The absorption wavelengths
were calculated by means of time-dependent density functional theory [S1] using B3LYP/6-31+G(d,p)
integral=grid=ultrafine level (solvent=hexane). Charge was set as 0 and spin multiplicity (M) was set as
1. The scaling factor of 1.02 was multiplied with the simulated UV-Vis spectra to compensate for the
difference between empirical and simulated spectra. Proposed peak shifts of absorption were calculated
by dividing the simulated peak shifts of absorption by 1.90 to apply the simulated peak shifts to actual
peak shifts (Tables S1 and S2).
S2. Results
The brominated position on naphthalene and azulene was examined by empirical and
1
simulated UV-Vis spectroscopies. The difference of peak positions of absorption between empirical and
simulated UV-Vis spectra was obtained using naphthalene, 1-bromonaphtahlene, 2-bromonaphthalene,
1,4-dibromonaphthalene, and 2,7-dibromonaphthalene. Figure S1 shows the actual and simulated peak
shifts
of
1-bromonaphtahlene,
2-bromonaphthalene,
1,4-dibromonaphthalene,
and
2,7-
dibromonaphthalene from the peak top of naphthalene. Empirical and simulated peak positions of
absorbance were compared and a liner relationship was obtained (Fig. S1). Thus, we utilized the
simulated peak positions (y), adjusted by a scaling factor obtained from the intercept of this liner
relationship in Fig. S1 (1.90) using the equation written in Fig. S1 (y = 1.90 x), for assignment of
empirical peak positions (x).
Figure S2 shows actual UV-Vis spectra of naphthalene and azulene before and after
bromination. The peak top of naphthalene (217 nm) was shifted to high wavelength (223 nm) by
bromination (Fig. S2a). The peak top of azulene (275 nm) was also shifted to high wavelength (280 and
284 nm) by bromination (Fig. S2b). These empirical values of positive shifts by bromination were
compared with simulated values. Table S1 shows peak shifts of simulated and proposed UV-Vis spectra
of mono- and di-bromonaphthalene from a peak top of naphthalene. Table S2 shows peak shifts of
simulated and proposed UV-Vis spectra of mono- and di-bromoazulene from a peak top of azulene.
Proposed peak shifts of absorption of 1-bromonaphthalene (+7 nm in Table S1), 1,4dibromonaphthalene (+5 nm in Table S1), and 1,5-dibromonaphthalene (+9 nm in Table S1) from a peak
top of naphthalene were close to an actual peak shift of absorption of brominated naphthalene (+6 nm in
Fig. S2a) from the peak top of naphthalene, indicating the existence of 1-bromonaphthalene, 1,4dibromonaphthalene, and 1,5-dibromonaphthalene in brominated naphthalene. Proposed peak shifts of
absorption of mono-bromoazulene such as 1-bromoazulene (+5 nm in Table S2), 2-bromoazulene (+7
nm in Table S2), and 6-bromoazulene (+8 nm in Table S2) from a peak top of azulene were close to an
actual peak shift of absorption of brominated azulene (+5 and +9 nm in Fig. S2b) from a peak top of
2
azulene. Among di-bromoazulenes (Table S2), there are many possible structures which have a close
peak shift to an actual peak shift of absorption of brominated azulene, indicating the difficulty of
distinction of brominated positions of di-bromoazulenes.
Calculated Ef values based on two proposed mechanisms were compared. One mechanism is
reaction of arene with a Br radical (Fig. S3a) and another mechanism is formation of an arene radical
and a hydrogen radical (Fig. S3b). Ef value calculated from the mechanism through formation of an arene
radical and a hydrogen radical was much larger than that calculated from the mechanism through
reaction of arene with a Br radical (Fig. S3). Thus, the mechanism of Fig. S3a was utilized in the main
manuscript of this work.
References
[S1] Stratmann RE, Scuseria GE, Frisch MJ (1998) An efficient implementation of time-dependent
density-functional theory for the calculation of excitation energies of large molecules. J Chem Phys
109:8218-8224.
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Table S1 Peak shifts of simulated and proposed UV-Vis spectra of mono- and di-bromonaphthalene
from a peak top of naphthalene.
Structures
1-Monobromonaphthalene
2-Monobromonaphthalene
1,2-Dibromonaphthalene
1,3-Dibromonaphthalene
1,4-Dibromonaphthalene
1,5-Dibromonaphthalene
1,6-Dibromonaphthalene
1,7-Dibromonaphthalene
1,8-Dibromonaphthalene
2,3-Dibromonaphthalene
2,6-Dibromonaphthalene
2,7-Dibromonaphthalene
Simulated absorption peak shifts
a
Proposed absorption peak shifts
from a peak top of naphthalene / nm
from a peak top of naphthaleneb / nm
13
21
26
25
10
18
21
27
22
29
29
31
7
11
14
13
5
9
11
14
12
15
15
16
a
The peak top of naphthalene (217 nm) was used as a reference peak.
b
These values were calculated by dividing simulated absorption peak shifts by 1.90.
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Table S2 Peak shifts of simulated and proposed UV-Vis spectra of mono- and di-bromoazulene from a
peak top of azulene.
Structures
1-Bromoazulene
2-Bromoazulene
4-Bromoazulene
5-Bromoazulene
6-Bromoazulene
1,2-Dibromoazulene
1,3-Dibromoazulene
1,4-Dibromoazulene
1,5-Dibromoazulene
1,6-Dibromoazulene
1,7-Dibromoazulene
1,8-Dibromoazulene
2,4-Dibromoazulene
2,5-Dibromoazulene
2,6-Dibromoazulene
4,5-Dibromoazulene
4,6-Dibromoazulene
4,7-Dibromoazulene
4,8-Dibromoazulene
5,6-Dibromoazulene
5,7-Dibromoazulene
Simulated absorption peak shifts
a
Proposed absorption peak shifts
from a peak top of azulene / nm
from a peak top of azuleneb / nm
10
13
-1
2
15
25
20
21
13
27
16
12
16
21
21
15
17
-1
12
19
3
5
7
-1
1
8
13
10
11
7
14
8
6
8
11
11
8
9
-1
6
10
2
a
The peak top of azulene (275 nm) was used as a reference peak.
b
These values were calculated by dividing simulated absorption peak shifts by 1.90.
5
Fig. S1 Actual and simulated peak shifts of UV-Vis spectra of 1-bromonaphtahlene, 2bromonaphthalene, 1,4-dibromonaphthalene, and 2,7-dibromonaphthalene from the peak of
naphthalene.
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Fig. S2 Actual UV-Vis spectra of PAHs and brominated PAHs. (a) Naphthalene (bold black line) and
brominated naphthalene (thin red line). Naphthalene was brominated in 10 wt.% bromine solution. (b)
Azulene (bold black line) and brominated azulene (thin red line). Azulene was brominated in 1.0 wt.%
bromine solution.
Fig. S3 Calculated Ef values based on two proposed mechanisms. (a) Reaction of an arene with a Br
radical. (b) Formation of an arene radical and a hydrogen radical. White spheres hydrogen atom. Gray
spheres carbon atom. Red spheres bromine atom.
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