Fluorine-containing dibenzoanthracene and benzoperylene-type polycyclic aromatic hydrocarbons: Synthesis, structure, and basic chemical properties

Article abstract of DOI:10.3390/molecules23123337

Intramolecular photocyclization of stilbene derivatives (Mallory reaction) is one of the efficient methods for building polycyclic aromatic hydrocarbon (PAH) frameworks, and is also expected to be applicable to synthesis of fluorine-containing PAHs (F-PAHs). In this study, dibenzoanthracene-type (4a) and benzoperylene-type (4b) F-PAHs were synthesized using the Mallory reaction of the 1,4-distyrylbenzene-type π-conjugated molecule (3a), which was prepared by addition-defluorination of available octafluorocyclopentene (OFCP) and aryllithium in three steps. The structure of 4a originating from π–π interaction was characterized by X-ray crystallographic analysis. The absorption maxima of UV-Vis spectra and emission maxima of photoluminescence spectra of the PAHs were positioned at a longer wavelength compared to those of the corresponding unsubstituted PAHs, presumably due to the electron-withdrawing nature of perfluorocyclopentene (PFCP) units. The effect of PFCP units in F-PAHs was also studied by time-dependent density functional theory (TD-DFT) calculation.

Full text of DOI:10.3390/molecules23123337

molecules
Article
Fluorine-Containing Dibenzoanthracene and
Benzoperylene-Type Polycyclic Aromatic
Hydrocarbons: Synthesis, Structure, and Basic
Chemical Properties
Otohiro Gotsu 1, Tomomi Shiota 1, Hiroki Fukumoto 1,
*
, Tomoko Kawasaki-Takasuka 2,
and Toshio Kubota 1,
Takashi Yamazaki 2, Tomoko Yajima 3, Tomohiro Agou 1,
*
*
1
Department of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University,
4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan; 16nd105r@vc.ibaraki.ac.jp (O.G.);
tomo.514a@gmail.com (T.S.)
Division of Applied Chemistry, Institute of Engineering, Tokyo University of Agriculture and Technology,
2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan; takasuka@cc.tuat.ac.jp (T.K.-T.);
tyamazak@cc.tuat.ac.jp (T.Y.)
2
3
Department of Chemistry, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610,
Japan; yajima.tomoko@ocha.ac.jp
*
Correspondence: hiroki.fukumoto.chem@vc.ibaraki.ac.jp (H.F.);
tomohiro.agou.mountain@vc.ibaraki.ac.jp (T.A.); toshio.kubota.organicchem@vc.ibaraki.ac.jp (T.K.);
Tel.: +81-294-38-5071 (H.F.)
Academic Editor: Pierre-Antoine Bouit
Received: 20 November 2018; Accepted: 11 December 2018; Published: 16 December 2018
ꢀꢁꢂꢀꢃꢄꢅꢆꢇ
ꢀꢁꢂꢃꢄꢅꢆ
Abstract: Intramolecular photocyclization of stilbene derivatives (Mallory reaction) is one of
the efficient methods for building polycyclic aromatic hydrocarbon (PAH) frameworks, and is
also expected to be applicable to synthesis of fluorine-containing PAHs (F-PAHs). In this study,
dibenzoanthracene-type (4a) and benzoperylene-type (4b) F-PAHs were synthesized using the
Mallory reaction of the 1,4-distyrylbenzene-type
addition-defluorination of available octafluorocyclopentene (OFCP) and aryllithium in three steps.
The structure of 4a originating from interaction was characterized by X-ray crystallographic
π-conjugated molecule (3a), which was prepared by
π–π
analysis. The absorption maxima of UV-Vis spectra and emission maxima of photoluminescence
spectra of the PAHs were positioned at a longer wavelength compared to those of the corresponding
unsubstituted PAHs, presumably due to the electron-withdrawing nature of perfluorocyclopentene
(PFCP) units. The effect of PFCP units in F-PAHs was also studied by time-dependent density
functional theory (TD-DFT) calculation.
Keywords: polycyclic aromatic hydrocarbons; dibenzoanthracene; benzoperylene; π-conjugated
molecules; Mallory reaction; addition-defluorination; octafluorocyclopentene
1. Introduction
Fluorine-containing polycyclic aromatic hydrocarbons (F-PAHs) [
in the field of material chemistry as n-type semiconductors for fabrication of electronic and optical
devices [ ]. In order to synthesize F-PAHs in short steps, it is inevitable to introduce fluorine or
organofluorine groups into the PAH framework. Direct fluorination of PAH with a fluorinated
reagent [ ] is a typical and simple synthetic method, however it requires expensive XeF2 [ ] or
1] have attracted much attention
2
3,4
3
treatment of a fluorinated reagent (e.g., N-fluoro-2,4-dinitroimidazole) using F2 gas [4]. Furthermore,
this method usually yields a mixture of regioisomers of F-PAHs, due to the difficulty of selective
Molecules 2018, 23, 3337; doi:10.3390/molecules23123337
www.mdpi.com/journal/molecules

Molecules 2018, 23, 3337
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fluorination to the mother PAH skeleton, except for a few cases [
5
,6
]. On the other hand, the ring-closing
process of fluorine-containing aromatic compounds can basically achieve the desired regiospecific
F-PAH. For example, Ichikawa and his coworkers reported metal-catalyzed Friedel–Crafts-type
intramolecular cyclization of difluoroalkene and the nearest phenyl unit [7–9]. In this case, fluorine was
pinpoint introduced to a phenacene skeleton. Kikuzawa and his groups developed a synthesis of
hexafluoro-hexa-peri-hexabenzocoronene, which showed an n-type character in a fabricated FET
(field effect transistor) device, using chemical oxidative intramolecular cyclization (Scholl reaction) of
the corresponding hexaphenylbenzene [10].
The Mallory reaction is a useful intramolecular photocyclization of stilbene derivatives
for synthesis of phenanthrenes via cis-trans isomerization [11
to the formation of F-PAHs. In recent years, regiospecific F-PAHs have been synthesized by
photocyclization of 1,2-diarylfluoroalkenes via Julia Kocienski olefination [14] or the Wittig
–13], which is also applicable
−
reaction [15]. Our group also reported fluorine-containing phenanthrenes [16] using the Mallory
reaction of the corresponding stilbene-type precursor, which were obtained by the reaction of
available octafluorocyclopentene (OFCP) with two equivalents of aryllithium under milder conditions
(addition-defluorination [17]). The merit of addition-defluorination toward fluorine-containing alkene
is the stepwise introduction of two different aromatic rings to give an asymmetric diarylethene in only
two steps. Therefore, a combination of the Mallory reaction and addition-defluorination has the ability
to supply a wide variety of F-PAHs containing perfluorocyclopentene (PFCP) unit(s).
Herein, we report the synthesis of 1,4-distyrylbenzene-like
π-conjugated molecule bearing
PFCP units by reaction of available OFCP with aryllithium derivatives. We also describe
fluorine-containing dibenzoanthracene and benzoperylene using the sequential Mallory reaction
of the synthesized precursor.
2. Results
2.1. Synthesis of Fluorine-Containing Dibenzoanthracene (4a) and Benzoperylene (4b)
The synthetic route to fluorine-containing dibenzoanthracene 4a and benzoperylene 4b is shown
in Scheme 1. Preparation of 1-phenyl-heptafluorocyclopentene
out by reaction of OFCP and 1 equiv. of phenylmagnesium bromide, according to the literature [17].
Treatment of with 4-bromophenyllithium in THF gave unsymmetric diarylethene as a colorless
oil in 52% yield. Lithiated , generated from in THF to afford the
and nBuLi, was reacted with
precursor for the following Mallory reaction, giving 3 as white powder in 22% yield.
Mallory reaction of in benzene was carried out under light irradiation ( = 365 nm) at room
1 (64%, literature 29% [17]) was carried
1
2
2
2
1
3
λ
temperature (rt) for 3 h in the presence of iodine (1.6 equiv.) as an oxidant and excess amounts of
1,2-epoxybutane as a scavenger of the formed hydrogen iodide to give the mixture of the ring-closed
1
products 4a and 4b, confirmed by H-NMR spectroscopy. Benzoperylene-type 4b in the reaction
◦
mixture was sublimed under reduced pressure (0.1 kPa) at 160 C, however the sublimate still contained
a small amount of dibenzoanthracene-type 4a. The sublimate was purified by preparative layer
chromatography (PLC) (silica) to afford pure 4a and 4b (13% yield). After removal of the first sublimate,
the residue was heated up to 250 ◦C under 0.1 kPa to result in sublimation of 4a (22% as total yield);
the low yields were due to loss of the products in repeated purification (PLC and sublimation).
Compared to the solubility of 3, both 4a and 4b have quite low solubility in organic solvents, such as
chloroform and dichloromethane. Formation of [5]helicene-type compound was not detected after
the Mallory reaction. It is known that photocyclization of 1,4-distyrylbenzene derivatives preferably
gives benzoperylene, [5]helicene, or both, whereas photocyclization affords dibenzoanthracene in low
yields [13,18,19]. The above Mallory reaction of 3 indicates that formation of dibenzoanthracene-like
structure, and rotation of one of the PFCP units to form benzoperylene-like structure, are competitive as
the second photocyclization. It is also supposed that the third photocyclization spontaneously occurred
to give benzoperylene-like 4b once the second photocyclization proceeded in [5]helicene-type form.

Molecules 2018, 23, 3337
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F F
F F
F
F
F
F
F F
F
F
F
F
F
F
F
F
Li
Br
(1.0 equiv)
PhMgBr (1.0 equiv)
F
THF, -78 ºC, 20 min to rt, 1 h
F
F
THF, 0 ºC, 1 h to rt, 20 h
Br
1 (64%)
2 (52%)
OFCP
F F
F
F
F
F
1) nBuLi (1.0 equiv), THF, -78 ºC, 30 min
2) 1 (1.0 equiv), THF, -78 ºC, 1 h to rt, 1 h
F
F
F
F
F F
3 (22%)
F F
F F
F
F
F
F
F
F
F
F
I2 (1.6 equiv), 1,2-epoxybutane (excess)
h , benzene, rt, 3 h
+
F
F
F
F
F
F
F
F
F
F F
F
4a (22%)
4b (13%)
Scheme 1. Synthetic route to fluorine-containing 4a and 4b.
1H-NMR spectra of
(Figure S4), signals of two terminal phenyl and central phenylene protons are observed in the
typical aromatic region. For spectra of 4a and 4b (Figures S7 and S9), all the peaks clearly appear at a
lower magnetic field than those observed in that of , owing to the magnetic deshielding effect of the
extended -conjugated PAH framework. In particular, the singlet observed at 9.77 ppm in the spectrum
3, 4a, and 4b are depicted in the Supporting Information. In the spectrum
of
3
3
π
of 4a is assignable to the protons bound to the carbons of the central ring in the dibenzoanthracene
framework, due to the induced effect originating from the neighborhood fluorines in the PFCP units.
2.2. Molecular Structures of 3, 4a, and 4b
The molecular structures of
Figure 1. The structures of precursor
molecules in the unit cell, respectively. One of the independent molecules (molecule A for
and molecule E for 4a in Figure 1b) is depicted in Figure 1 for clarity. Benzoperylene 4b (Figure 1c)
and (molecules C and D in Figure 1a) show disorder in fluorine atoms. Precursor takes a flexible
3
,
4a, and 4b revealed by X-ray crystallographic study are shown in
and dibenzoanthracene 4a have four and two independent
in Figure 1a
3
3
3
3
backbone with dihedral angle between the central phenylene plane (C3–C8–C21–C3*–C8*–C21*)
and the terminal phenyl plane (C25–C34–C44–C49–C45–C33) of 60.2◦, to result in no face-to-face
π–π interactions between neighborhood molecules (Figure 1a). The C=C bond distance between C5
and C12 in the five-membered unit is 1.353(5) Å (molecule A), which is comparable to the reported
similar diarylethene derivatives [20]. For 4a, two independent molecules (molecules E and F) are
herringbone-like packed in the unit cell, and one of two independent molecules (molecule E) partly
overlaps to make a pair with terminal naphthalene units (C2-C3-C4-C5-C8–C9–C10–C11–C6–C7) in
the neighboring molecule; the distance between the centroids in the dibenzoanthracene skeleton is
7.15 Å. The distance between dibenzoanthracene planes is 3.55 Å, due to the π–π interaction (Figure 1b).
The shortest intermolecular fluorine–fluorine (F2-F5) distance between the pairing molecules is ca.
2.67 Å, which is shorter than the sum of the van der Waals radius (2.94 Å), indicating that not only the
π
–
π
interaction, but also the F–F interaction partly contribute to the packing of the molecules of 4a
[21].
The length of the C=C bond (C(3)–C(4)) fused with the perfluorocycloalkane unit is 1.354(5) Å. In the

Molecules 2018, 23, 3337
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case of 4b, the molecules construct a columnar structure extended to a axis in the crystal (Figure 1c).
In sharp contrast to the case of 4a, the nearest two molecules of 4b fully overlap where possible,
to avoid steric repulsion between the bulky PFCP units, Such overlap of benzoperilene skeletons is
observed in unsubstituted benzoperylene [22] and 1,2-disubstituted benzoperylene [23].
(a)
F19
F15
C43
molecule C
molecule B
F10
F11
C27
C32
F7
F4
C12
C25
molecule A
C5
C8
C34
C44
C3
C21*
molecule D
C33
C45
C21
C3*
C8*
C49
(b)
F3
C13
F4
F1
F6
molecule E
F5
2.67 Å
F2
F2
b
c
C12
C3
C2
C14
C4
C8 C5
a
F5
C1
C9
C6
C11
C7
C10
3.53 Å
molecule F
c
a
(c)
F6
C3
F8
a
F5
C2
F4
C14
c
b
F10
F7
C15
C16
C13
F9
b
C4
C26
C27
F3
F2
C1
C17
C18
C25
C24
C12
C5
C28
C23
F11
F1
C6
C7
F12
C11
C10
C22
C21
C19
C20
C9
C8
Figure 1. Molecular structures and packing modes of (a) 3, (b) 4a, and (c) 4b. One of the independent
molecules ( : molecule A, 4a: molecule E) is shown for clarity. Two fluorine atoms (F9 and F10) bound
to CF2 carbon (C27) in 4b and some fluorine atoms in two independent molecules (molecules C and D)
of are disordered (see Figures S13 and S15). For 4a, the face-to-face distance is calculated between
the polyaromatic hydrocarbon (PAH) cores, which are optimized by the least square method. For 4b
3
3
,
its crystallographic data are not satisfied to discuss the bond lengths and short-contacts distances
(see Section 3.5).
2.3. UV-Vis and Photoluminescence Spectra of 3, 4a, and 4b
UV-Vis and photoluminescence (PL) spectra of 4a and 4b are shown in Figure 2a,b, respectively,
and the optical data are summarized in Table 1. For comparison, UV-Vis and PL spectra of the
corresponding precursor
max) in the spectrum of
backbone of . In contrast, the spectra of 4a and 4b in CH2Cl2 exhibit
respectively. This longer wavelength shift presumably originates from extension of the
3
3
were also measured, as depicted in Figure S12. The absorption maximum
appears at 262 nm, due to localization of -electrons along the flexible
at 301 nm and 309 nm,
(λ
π
3
λ
max
π
-conjugated
system on the molecules of 4a and 4b. The spectrum of dibenzoanthracene 4a exhibits three−m1edium
−1
−1
)
peaks (
ε
= ca. 10,000 M
·
cm−1) at 322, 336, and 352 nm, and two small peaks (
ε
= ca. 1000 M
·
cm
around 390 nm, as comparable to those observed in unsubstituted dibenzoanthracene [24]. On the
other hand, the spectrum of benzoperylene 4b gives two clear peaks (
= ca. 7000 M−1 cm−1) around
ε
·
380 and 400 nm, which is similar to those of the reported analogues [23]. Time-dependent density
functional theory (TD-DFT) calculation supports assignments of absorption peaks in the UV-Vis
spectrum of organic molecules. The TD-DFT calculation was carried out at the B3LYP/6-311G(d)
level, and the initial structures of 4a and 4b were obtained using their X-ray crystallographic data.
The results indicate that the bands that appeared at 401 and 309 nm in the spectrum of 4b correspond to

Molecules 2018, 23, 3337
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the transition from HOMO (the highest occupied molecular orbital) to LUMO (the lowest unoccupied
molecular orbital) with oscillator strength (f) of 0.2041 (λcalc = 399 nm), and the HOMO LUMO +
1 (f = 0.3049, λcalc = 307 nm) transition, respectively (Table S1). The DFT calculation also suggests
→
that the HOMO
(
→
LUMO + 1 (f = 0.5972, λcalc = 305 nm) transition corresponds to the large peak
ε = 64,000 M−1·cm−1) at 301 nm in the spectrum of 4a, and the weak band (
ε )
= 1120 M−1 cm−1
around 380 nm is thought to be the HOMO→LUMO transition (f = 0.0146, λcalc = 381 nm).
Figure 2. UV-Vis (A) and photoluminescence (B) spectra of 4a (blue line) and 4b (red line) in CH2Cl2.
Table 1. UV-Vis and photoluminescence spectral data of 4a and 4b a.
−1
−1
)
F-PAH
4a
UV-Vis a
λ
max, nm (ε, M cm
Photoluminescence λem, nm
292 (47000), 301 (64000), 322 (10400), 336
(10000), 352 (11000), 380 (1120), 401 (750)
284 (13400), 298 (14600), 309 (17600), 379
(6600), 401 (7100)
411, 433
418, 440
4b
a
b
Measured in CH2Cl2. [4a] = 1.6 × 10−5 M and [4b] = 3.1 × 10−5 M.
The Mallory reaction products are photoluminescent in CH2Cl2 (Figure 2b). The main PL peaks
em) of 4a and 4b appear at 411 and 418 nm, respectively. The peak positions of both 4a and
(λ
λ
em
4b shift to longer wavelengths than those of the corresponding unsubstituted dibenzoanthracene
= 398 nm) [24] and benzoperylene ( em = 408 nm) [23], respectively. In recent years, it has been
reported that introduction of electron-withdrawing methoxycarbonyl group(s) into the C1 and C2
carbons of benzoperylene causes a longer wavelength shift of their PL spectra [23]. In the case of 4b
PFCP units may contribute to the red-shift of the λ peak, although the PFCP units are fused on the
(λ
em
λ
,
em
C3, C4, C11, and C12 carbons of 4b. In contrast, the PL spectrum of precursor
band at approximately 430 nm in CHCl3 (Figure S12), due to the small effective
3
exhibited a very weak
-conjugation length
π
along the distorted molecule of 3.

Molecules 2018, 23, 3337
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2.4. Computational Study
To evaluate effect of the introduction of PFCP units to the PAH backbone, a computational study
was carried out by DFT at the B3LYP/6-311G(d) level, together with 4a-H* and 4b-H*, in which all the
fluorine atoms of 4a and 4b are replaced with hydrogen atoms for comparison (Figure 3). As shown in
this diagram, the LUMOs in 4a and 4b are extended to the PFCP units, and their LUMO levels (
for 4a and 3.12 eV for 4b) are remarkably lower than those of 4a-H* 1.60 eV) and 4b-H*
The HOMO levels of 4a 6.75 eV) and 4b 6.57 eV) are also lower than those of 4a-H* 5.36 eV) and
4b-H* 5.22 eV), due to electro-negative fluorine groups in PFCP units. The HOMO–LUMO gap of
−
2.96 eV
1.77 eV).
−
(
−
(
−
(
−
(
−
(
−
(
−
benzoperylene-type 4b (3.45 eV) is smaller than that of dibenzoanthracene-type 4a (3.79 eV). This trend
is consistent with the difference in the UV-Vis absorption peaks between 4a and 4b, as described above.
Figure 3. Molecular orbital diagram for fluorine-containing PAHs (F-PAHs) (4a and 4b) and their
corresponding PAH (4a-H* and 4b-H*), in which all fluorine atoms in 4a and 4b are replaced with
hydrogen atoms.
3. Materials and Methods
3.1. General
All manipulations were conducted by standard Schlenk techniques in argon atmosphere. 1H-, 13C-,
and 19F-NMR spectra were measured with a Bruker AVANCE III 400 spectrometer (1H-NMR:
400 MHz, 19F-NMR: 376 MHz, 13C-NMR: 100 MHz; Bruker Corporation, Billerica, MA, USA).
1
SiMe4 was used as an internal standard for H- and 13C-NMR spectra, and CFCl3 was adopted
as an external standard for 19F-NMR spectra. UV-Vis and photoluminescence spectra were recorded
on a Shimadzu UV-3100PC spectrometer (Shimadzu Corporation, Kyoto, Japan) and a Hitachi F-4500
spectrometer (Hitachi High-Technologies Corporation, Tokyo, Japan), respectively. Elemental analysis
was carried out using a J-Science Lab JM10 microanalyzer (J-Science Lab Co., Ltd., Kyoto, Japan).
High resolution mass spectra (HRMS) were taken using a JEOL JMS-700 analyzer (JEOL Ltd., Akishima,
Japan). Mallory reaction of
3 was conducted using a USHIO Optical Modulex Multi-purpose
lighting unit (irradiation wavelength = 365 nm, light power = 20 mW/cm2; USHIO INC., Tokyo,
Japan). Octafluorocyclopentene (OFCP) was purchased and used without further purification.
1-Phenyl-heptafluorocyclopentene (1) was prepared according to the literature [17].

Molecules 2018, 23, 3337
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3.2. Synthesis of 1-(4-bromophenyl)-2-phenyl-3,3,4,4,5,5-hexafluorocyclopentene (2)
To a THF (10 mL) solution of 1,4-dibromobenzene (0.71 g, 3.0 mmol), nBuLi (1.6 M hexane solution,
1.9 mL, 3.0 mmol) at
78 ◦C was added, and the reaction temperature was kept at 78 ◦C for 20 min.
(0.81 g, 3 mmol) was added to the reaction mixture at
78 ◦C, then the reaction temperature was
−
−
1
−
raised up to rt for 1 h. The reaction mixture was poured into saturated NH4Cl aqueous solution
(ca. 10 mL) and extracted with ethyl acetate (ca. 60 mL). The organic layer was washed with distilled
water and dried over MgSO4. The solvent was removed at reduced pressure, and the resulting residue
was purified by column chromatography on silica (eluent = hexane) to afford
2
as a colorless oil (0.63 g,
1
52%). H-NMR (400 MHz, CDCl3):
13C{1H}-NMR (100 MHz, CDCl3):
δ
7.50–7.55 (m, 2H), 7.44–7.30 (m, 5H), 7.20 (d, J = 8.8 Hz, 2H).
δ 140.26 (m), 138.50 (m), 132.26, 130.84, 130.54, 129.21, 129.06, 127.46,
126.66, 125.04, 116.33 (triplet of triplets (tt), J = 255.7 and 23.9 Hz), 111.07 (tt, J = 269.7 and 25.0 Hz).
The central CF2 carbon in the five-membered ring was not clearly observed, presumably because the
intensity of the peak with multicity became very weak. 19F-NMR (376 MHz, CDCl3): δ −110.38 (m, 2F),
−
110.60 (m, 2F),
−
131.66 (m, 2F). HRMS (FAB positive, m/z): Found, 406.9868; calcd. for C17H10BrF6
([M + H]+), 406.9825.
3.3. Synthesis of 1,10-[1,4-phenylenebis(3,3,4,4,5,5-hexafluorocyclopent-1-ene-2,1-diyl)]dibenzene (3)
To a THF (5 mL) solution of
78 C was added, and the reaction temperature was kept at
2
(0.63 g, 1.5 mmol), nBuLi (1.6 M hexane solution, 0.9 mL, 1.5 mmol)
◦
◦
at
of
−
−
78 C for 30 min. After consumption
2
,
1
(0.41 g, 1.5 mmol) was added to the reaction mixture at
−
78 ◦C. The reaction temperature was
◦
kept at
−
78 C for 1 h, and then raised up to rt for 1 h. The reaction mixture was poured into saturated
NH4Cl aqueous solution (ca. 5 mL) and extracted with ethyl acetate (ca. 60 mL). The organic layer was
washed with distilled water and dried over MgSO4. The solvent was removed at reduced pressure,
and the resulting residue was purified by column chromatography on silica (eluent = hexane) to give
3
1
as white powder (0.19 g, 22%). H-NMR (400 MHz, (CD3)2CO):
4H). 13C{1H}-NMR (100 MHz, (CD3)2CO):
δ
7.58–7.45 (m, 10H), 7.43 (d, J = 7.6 Hz,
δ 141.33 (m), 138.87 (m), 130.83, 130.00, 129.63, 129.24, 129.08,
127.04, 116.42 (tt, J = 256.4 and 21.8 Hz), 111.29 (tt, J = 269.6 and 24.9 Hz). The central CF2 carbon in
the five-membered ring was not clearly observed, presumably because the intensity of the peak with
multicity became very weak. 19F-NMR (376 MHz, (CD3)2CO): δ −110.04 to
−
110.07 (m, 4F),
−
110.37 to
−
111.41 (m, 4F),
−
132.36 (quint, J = 4.5 Hz, 4F). Found: C, 58.17; H, 2.68. Calcd. for C28H14F12: C,
58.14; H, 2.44.
3.4. Synthesis of 1,1,2,2,3,3,9,9,10,10,11,11-dodecafluoro-1,2,3,9,10,11-
hexahydrobenzo[k]dicyclopenta[f,m]tetraphene (4a) and 1,1,2,2,3,3,10,10,11,11,12,12-dodecafluoro-
1,2,3,10,11,12-hexahydrobenzo[pqr]dicyclopenta[b,n]perylene (4b)
To a mixture of
3 (0.042 g, 0.073 mmol) and benzene (30 mL), iodine (0.029 g, 0.12 mmol) at rt was
added in Ar atmosphere. After stirring for 30 min, 1,2-epoxybutane (0.3 mL, 3.5 mmol) was added to
the mixture, which was stirred under light irradiation at rt for 3 h. The reaction mixture was poured
into saturated sodium thiosulfate aqueous solution (10 mL), and the resulting organic layer was washed
with distilled water (10 mL) and brine (10 mL). After separation and drying of the layer, the solvent
◦
was evaporated at reduced pressure. The resulting residue was heated under 0.1 kPa at 160 C, and the
sublimate was separated by column chromatography on silica (eluent: ethyl acetate/hexane = 1/4)
to afford 4a and 4b. The residue after the first sublimation was heated again under 0.1 kPa at 250
1
◦C to sublime 4a
.
4a—colorless powder (10 mg, 22%). H-NMR (400 MHz, CDCl3):
δ
9.77 (s, 2H),
9.01 (d, J = 8.0 Hz, 2H), 8.49 (d, J = 7.2 Hz, 2H), 8.07 (t, J = 7.2 Hz, 2H), 7.93 (t, J = 8.0 Hz, 2H). 19F-NMR
(376 MHz, CDCl3): δ −105.45 (m, 4F),
−
106.06 (m, 4F),
−
128.75 (quint, J = 3.8 Hz, 4F). HRMS (FAB
positive, m/z): Found, 574.0552; Calcd. for C28H10F12 ([M]+), 574.0591. 4b—colorless powder (6 mg,
1
13%). H-NMR (400 MHz, CDCl3):
δ 9.34 (d, J = 8.0 Hz, 2H), 9.05 (s, 2H), 8.83 (d, J = 8.0 Hz, 2H),
8.35 (t, J = 8.0 Hz, 2H). 19F-NMR (376 MHz, CDCl3): δ −105.61 (m, 4F),
−
106.17 (m, 4F),
−
128.7
(t, J = 3.8 Hz, 4F). HRMS (FAB positive, m/z): Found, 572.0458; Calcd. for C28H8F12 ([M]+), 572.0434.

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3.5. X-Ray Crystallographic Analysis of 3, 4a, and 4b
Single crystals of
evaporation of the saturated CH2Cl2 (for 4a and 4b) or hexane (for
mounted on a Rigaku XtaLabMini diffractometer (Rigaku Corporation, Akishima, Japan) using Mo
radiation ( = 0.71073 Å). Processing of the collected reflection data was carried out using the
3,
4a, and 4b suitable for X-ray crystallographic analysis were obtained by slow
3
) solution at rt. The crystals were
K
α
λ
CrysAlisPro program (version 1.171.38.46, Rigaku Corporation, Akishima, Japan) [25]. The structure
was solved by a direct method (SHELXT-2014/5) and refined by the full-matrix least square method on
F2 for all reflections (SHELXTL-2014/7) [26]. All hydrogen atoms were placed using AFIX instructions,
and all the other atoms were refined anisotropically. Precursor
disorder in fluorine atoms (F25, F26, F27, F28, in ; F9 and F10 in 4b). Dibenzoanthracene 4a and
have two and four independent molecules in the unit cell, respectively. Crystallographic data of 4a
and 4b are deposited on the system of The Cambridge Crystallographic Data Centre: CCDC-1822475
(for ), CCDC-1822473 (for 4a), and CCDC-1822474 (for 4b). These crystal data can be obtained free of
3 and benzoperylene 4b showed
3
3
3,
,
3
charge from the center via https://www.ccdc.cam.ac.uk/structures/.
◦
Crystal data for
3
: C28H14F12, FW 578.39, –100 C, 0.130
×
0.120
×
0.120 mm3, Triclinic, P-1,
a = 10.1230(5) Å, b = 13.9273(9) Å, c = 18.2364(11) Å, V = 2414.6(3) Å3,
γ
α β
= 70.087(6)◦, = 88.323(5)◦,
= 87.402(5)◦, Z = 4, Dcalcd = 1.591 g cm−3
,
µ
= 0.157 mm−1, F(000) = 1160, 2.014◦ ≤ θ ≤ 25.500◦,
reflection collected 21,605, independent reflections 8993 (Rint = 0.0373), completeness to
θ
100.0%,
max
data/restraints/parameters 8993/48/793, GOF on F2 1.027, R1 [I > 2
σ
(I)] 0.0710, wR2 (all data) 0.2046,
largest diffraction peak and hole 0.871 and −0.464 e Å−3
.
Crystal data for 4a: C28H10F12, FW 574.36,
−
100 ◦C, 0.230
×
0.180
×
0.150 mm3, Triclinic, P-1,
a = 7.1452(7) Å, b = 9.4617(7) Å, c = 17.8343(15) Å, V = 1088.81(18) Å3,
α β
= 79.109(7)◦, = 79.718(8)◦,
γ
= 67.831(8)◦, Z = 2, Dcalcd = 1.752 g cm−3
,
µ
= 0.174 mm−1, F(000) = 572, 2.342◦ ≤ θ ≤ 25.492◦,
reflection collected 9765, independent reflections 4065 (Rint = 0.0508), completeness to
θ
99.9%,
max
data/restraints/parameters 4065/0/361, GOF on F2 1.031, R1 [I > 2
σ
(I)] 0.0634, wR2 (all data) 0.1985,
largest diffraction peak and hole 0.365 and −0.357 e Å−3
.
◦
Crystal data for 4b: C28H8F12, FW 572.34,
−
100 C, 0.210
×
0.080
×
0.050 mm3, Triclinic, P-1,
a = 7.438(3) Å, b = 11.078(3) Å, c = 13.181(3) Å, V = 1024.6(6) Å3,
α β
= 72.22(3)◦, = 82.50(3)◦,
γ
= 89.76(3)◦, Z = 2, Dcalcd = 1.855 g cm−3
,
µ
= 0.184 mm−1, F(000) = 568, 1.638◦ ≤ θ ≤ 25.495◦,
reflection collected 9075, independent reflections 3811 (Rint = 0.1310), completeness to
data/restraints/parameters 3811/54/379, GOF on F2 1.058, R1 [I > 2
largest diffraction peak and hole 0.963 and
θ
100.0%,
max
σ
(I)] 0.1448, wR2 (all data) 0.4404,
−
0.676 e Å−3. The ratio of observed unique reflection is 45%
and R value is over 10%. Thus, crystallographic data of 4b can only be used for molecular structure
identification as shown in Figure 1c and as the starting molecule for DFT optimization (Figure 3).
3.6. Computational Method
DFT calculations were performed using the Gaussian 16 program package (Gaussian, Inc.,
Wallingford, CT, USA) [27]. The initial geometry of the structures of 4a and 4b using their X-ray
crystallographic data was optimized at the B3LYP/6-311G(d) level of theory. The computational time
was provided by the Super Computer Laboratory, Institute for Chemical Research, Kyoto University.
Frequency calculations confirmed that all the optimized geometries are the equilibrium structures.
Excited energies and oscillator strengths were calculated on the optimized structures by the TD-DFT
method at the B3LYP/6-311G(d) level. Tables S2, S3, S4, and S5 in the supporting information show
Cartesian coordinates of the optimized geometries of 4a, 4a-H*, 4b, and 4b-H*, respectively.
4. Conclusions
In conclusion, we investigated efficient synthesis of fluorine-containing dibenzoanthracene
(4a) and benzoperylene (4b) using Mallory reaction of the corresponding 1,4-distyrylbenzene-type
precursor ( ), which was prepared using addition-defluorination of available OFCP and aryllithium
3

Molecules 2018, 23, 3337
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derivatives. The structure of 4a originating from intermolecular
π–
π
interactions was characterized
by X-ray crystallographic analysis. In the structure of 4a, the F–F interaction between the nearest
molecules was observed. UV-Vis spectra of 4a and 4b in CH2Cl2 exhibited at 301 and
309 nm, respectively. The main PL peaks ( em) of 4a and 4b in CH2Cl2 appeared at 411 and
λ
max
λ
418 nm, respectively, which shifted to longer wavelengths compared to those of the corresponding
unsubstituted dibenzoanthracene and benzoperylene. The effect of electron-withdrawing PFCP units
in 4a and 4b skeletons was also evaluated by computational study; TD-DFT calculation of 4a and
4b revealed that both HOMO and LUMO levels became lower than those of the corresponding
non-fluorinated 4a-H* and 4b-H*. This finding will contribute to the design of new n-type F-PAHs.
Supplementary Materials: The following are available online. Figure S1. 1H NMR spectrum of
Figure S2. 19F NMR spectrum of in CDCl3. Figure S3. 13C NMR spectrum of
spectrum of
in (CD3)2CO. Figure S5. 19F NMR spectrum of
2
in CDCl3.
1
2
2
in CDCl3. Figure S4. H NMR
3
3
in (CD3)2CO. Figure S6. 13C NMR spectrum of
3
in (CD3)2CO. Figure S7. 1H NMR spectrum of 4a in CDCl3. Figure S8. 19F NMR spectrum of 4a in CDCl3.
Figure S9. 1H NMR spectrum of 4b in CDCl3. Figure S10. 19F NMR spectrum of 4b in CDCl3. Figure S11. 1H
NMR spectrum of the first sublimate after sublimation of the crude product in CDCl3. Figure S12. UV-vis (A)
and photoluminescence (B) spectra of 3 in CHCl3. Figure S13. Molecular structures of 3. Figure S14. Molecular
structures of 4a. Figure S15. Molecular structure of 4b. Table S1. Excited states and oscillator strengths of (a)
dibenzoanthracene 4a and (b). benzoperylene 4b, calculated at B3LYP/6-611G(d) level. Table S2. Cartesian
coordinates of the optimized geometry of 4a (in Å). Table S3. Cartesian coordinates of the optimized geometry
of 4a-H* (in Å). Table S4. Cartesian coordinates of the optimized geometry of 4b (in Å). Table S5. Cartesian
coordinates of the optimized geometry of 4b-H* (in Å).
Author Contributions: In this study, O.G., T.S., T.K., and H.F. conceived and designed the experiment;
the contributions of O.G and T.S. were the synthesis and characterization of basic chemical properties of F-PAHs;
T.A. determined the molecular structure of 3, 4a, and 4b by X-ray crystallographic study; T.Y. (Takashi Yamazaki)
and T.K.-T. measured the mass spectra of the compounds. T.Y. (Tomoko Yajima) contributed with research and
discussion of recent studies concerned with F-PAHs. The manuscript was written and edited by O. G and H.F.
Funding: This work was partly supported by JSPS KAKENHI (No. 15K05513), the Izumi Science and Technology
Foundation (H.F.), the Ibaraki University Priority Research Grants (H.F. and T.A.) and the AGC Research
Collaboration Program (Takashi Yamazaki, Tomoko Yajima, and T.K.).
Acknowledgments: The authors thank Kyoko Yamamoto at the Research Center, AGC Inc. for her technical
support. The computational time was provided by the Super Computer Laboratory, Institute for Chemical
Research, Kyoto University.
Conflicts of Interest: The authors declare no conflict of interest.
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2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
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