Novel perylene liquid crystals: Investigation of the influence of bay-substituents on mesomorphism and photophysical property

Article abstract of DOI:10.1016/j.dyepig.2016.06.021

A series of perylene liquid crystals with H, Br, phenyl and tert-butylphenyl on bay-positions were synthesized in yields of 50-70%. Their mesomorphic properties and photophysical properties were investigated. The perylene derivatives 6, 7 and 8 with Br, phenyl and tert-butylphenyl at bay-positions have the hexagonal columnar liquid crystalline phase and wider scopes of phase transfer temperatures in comparison with similar perylene liquid crystal 5 with no substituent on bay-position. Compounds 6, 7 and 8 showed stronger fluorescence intensities, larger Stokes shifts and higher quantum yields than that of compound 5. These results indicated that the suitable substituents on bay-positions of perylene liquid crystals were favorable for producing excellent mesomorphic properties and good fluorescence properties.

Full text of DOI:10.1016/j.dyepig.2016.06.021

Accepted Manuscript
Novel perylene liquid crystals: Investigation of the influence of bay- substituents on
mesomorphism and photophysical property
Mingguang Zhu, Hongyu Guo, Fafu Yang, Zusheng Wang
PII:
S0143-7208(16)30272-8
10.1016/j.dyepig.2016.06.021
DYPI 5305
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 15 April 2016
Revised Date: 11 June 2016
Accepted Date: 14 June 2016
Please cite this article as: Zhu M, Guo H, Yang F, Wang Z, Novel perylene liquid crystals: Investigation
of the influence of bay- substituents on mesomorphism and photophysical property, Dyes and Pigments
(2016), doi: 10.1016/j.dyepig.2016.06.021.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Novel perylene liquid crystals: Investigation of the influence of bay-
substituents on mesomorphism and photophysical property
a
a
a,b
a
Mingguang Zhu, Hongyu Guo, Fafu Yang,* and Zusheng Wang
a
5
College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou 350007, P. R. China ;Tel: +0086-591-83465225; E-mail:
yangfafu@fjnu.edu.cn
b
Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, P. R. China
A series of perylene liquid crystals with H, Br, phenyl and
semiconductor materials possessing high electron affinity and
excellent photoluminescence [1, 2]. They were promising
1
1
2
0
tert-butylphenyl on bay-positions were synthesized in
yields of 50~70%. Their mesomorphic properties and 30 candidates for the potential application in organic electronic
photophysical properties were investigated. The perylene
derivatives 6, 7 and 8 with Br, phenyl and tert-butylphenyl
at bay-positions have the hexagonal columnar liquid
crystalline phase and wider scopes of phase transfer
devices [3, 4]. Usually, the high ordering PBI materials are
favorable for good exciton diffusion length and charge carrier
mobility [5, 6]. In order to obtain this kind of PBI materials,
PBI liquid crystals (LC) were paid much attention because
5
temperatures in comparison with similar perylene liquid 35 liquid crystals have good π-π stacking action and improve the
crystal 5 with no substituent on bay-position. Compounds
, 7 and 8 showed stronger fluorescence intensities, larger
supramolecular self-assembling processes [7, 8]. Up to now,
all kinds of PBI liquid crystals, especially, the ordered
columnar PBI liquid crystals with efficient and directional
charge migration, were synthesized and their mesomorphic
6
Stokes shifts and higher quantum yields than that of
compound 5. These results indicated that the suitable
0
substituents on bay-positions of perylene liquid crystals 40 properties were investigated [9-12]. By modifying imide
were favorable for producing excellent mesomorphic
properties and good fluorescence properties.
groups with polyoxyethylene chain [13], siloxane [14, 15],
alkyl esters [16], organosilica [17], dendritic peptides [18],
fluoro-pentenyl groups [19], alkoxyl or alkyl groups [20, 21],
phenyl substituents [22, 23], and triphenylene groups [24-26],
series of perylene discotic liquid crystals were prepared
conveniently. Recently, the perylene derivatives with 3,4,5-
trialkoxyphenyl substitution on imides groups attracted much
Keywords: Perylene; Synthesis; Bay-substituent; Mesophase;
Fluorescence
2
5
45
1
. Introduction
Perylene bisimide (PBI) derivatives were important

research interests due to their facile format
hexagonal mesophases or organogelator [27-30]. The survey
of these literatures suggested that most of perylene liquid 35 according to standard anhydrous methods before use. TLC
A
ion
C
o
C
f
E
co
P
lu
T
m
E
na
D
r
MAsup
N
pl
U
ier
S
s
C
an
R
d
I
u
P
s
T
ed without further purification. The other
organic solvents and inorganic reagents were purified
crystals were synthesized by the introduction functional
groups on imides position. The substituent on bay-position
was seen as unfavorable factor which produce the hindrance
and depress the π-π stacking action of perylene core for
analysis was performed using pre-coated glass plates. Column
chromatography was performed using silica gel (200-300
5
mesh). NMR spectra were recorded in CDCl on a Bruker-
3
o
ARX 400 instrument at 25 C. Chemical shifts are reported in
columnar stacking. However, several perylene derivatives 40 ppm, using tetramethylsilane (TMS) as internal standard. MS
with substituents on bay-positions also showed mesomorphic
properties or formed organogelator aggregates, although some
others did not exhibit mesomorphism [23, 31-33]. These
results implied that a complex balance between the hindrance
spectra were obtained from Bruker MALDI-TOF mass
spectrometer. UV-Vis and fluorescence spectra were recorded
on Varian spectrometer. Fluorescence spectra were measured
1
0
o
in a conventional quartz cell (10×10×45 nm) at 25 C on a
of bay-substituent and the mesomorphic property. Thus, a 45 Hitachi F-4500 spectrometer equipped with a constant-
question appears obviously—Is it possible that the suitable
temperature water bath, with excitation and emission slits
0nm wide. The fluorescence absolute Φ values of solution
1
1
5
bulky substituents on bay-positions result in a twisting of the
aromatic perylene core, which does not destroy the mesophase
but improves the mesomorphic property such as wider scope
of mesomorphic temperature? However, no paper concerned
this study up to now.
F
were measured by using an Edinburgh Instruments FLS920
Fluorescence Spectrometer with a 6-inch integrating sphere.
The excitation wavelengths were at λmax of the adsorption
spectra of each compound. POM (Leica DMRX) was used
along with a hot stage (Linkam THMSE 600) to examine
phase transitions. Thermal analysis of the materials was
5
5
6
0
5
0
2
0
In the present research, we synthesized series of perylene
liquid crystals with H, Br, phenyl and tert-butylphenyl on
bay-positions and investigated systematically the influences of
substituents on mesomorphism for the first time. The results
showed that the bigger bulky groups resulted in wider scopes
of mesomorphic temperature and kept high fluorescence in
solution. The structures and synthetic routes of series of
perylene liquid crystals with substituents on bay-positions
were shown in Scheme 1.
carried out using DSC (Thermal Analysis Q100) at a scanning
o
rate of 10 C/min under N atmosphere. XRD experiments
2
were performed on SEIFERT-FPM (XRD7), using Cu Kα
1
.5406Å as the radiation source with 40 kV, 30 mA power.
Compounds 3 and 5 were synthesized by the literature method
27]. Compound 4 was prepared by the reported procedure
[34].
2
5
[
3
0
2. Experimental
2
2
.2. Synthesis
.2.1. The synthetic procedure of compound 6
2
.1 General
All chemical reagents were obtained from commercial

The mixture of 1,7-dibromoperylen
A
e
C
t
C
etr
E
ac
P
ar
T
bo
E
xy
D
licMA
t
N
he
U
pr
S
od
C
uc
R
t
I
w
P
as extracted with 40 mL of CHCl . The organic
T
3
anhydride (0.274g, 0.5 mmol) and compound 3 (0.72 g, 1
layer was washed with brine solution and dried over
anhydrous MgSO4. The solution was filtrated and
mmol) were stirred in DMF (30 mL) under N atmosphere at
2
o
1
10 C for 20h. TLC detection suggested the disappearance of 35 concentrated. The residue was purified by column
5
0
5
0
5
0
compound 3. After cooling, 50 mL of distilled water was
added in the reaction mixture, and the red precipitates were
obtained. Then the red precipitates were filtered and washed
with methanol. The crude product was purified by column
chromatography (CH Cl / ethyl acetate (9/1, v/v)). The
2 2
compound 7 was obtained as red solid in yield of 72%.
-
1
Compound 7: FT-IR (KBr), v/cm : 3730 (N-H), 1697,1662
1
(C=O); H NMR (400 MHz, CDCl ) δ ppm: 9.60 (d, J = 8.0
3
chromatography (CH Cl / ethyl acetate (6/1, v/v)). The 40 Hz, 2H, ArH), 8.61 (d, J = 8.0 Hz, 2H, ArH), 8.35 (s, 2H,
2
2
1
1
2
2
3
compound 6 was obtained as red solid in yield of 52%.
ArH), 7.41-7.52 (m, 6H, ArH), 6.99 (bs, 2H, NH), 6.92 (s, 4H,
ArH), 7.14 (d, J = 8.0 Hz, 4H, ArH), 4.51 (bs, 4H, NCH2),
3.95 (m, 12H, OCH ), 3.83 (bs, 4H, NCH ), 1.18-1.85 (m,
-
1
Compound 6: FT-IR (KBr), v/cm : 3730(N-H), 1702, 1666
1
(
C=O). H NMR (400 MHz, CDCl ) δ ppm: 9.45 (d, J = 8.0
3
2
2
13
Hz, 2H, ArH), 8.72 (s, 2H, ArH), 8.69 (d, J = 8.0 Hz, 2H,
120H, CH ), 0.87 (t, J = 8.8Hz, 18H, CH ); C NMR (100
2 3
ArH), 6.92 (s, 4H, ArH), 6.85 (bs, 2H, NH), 4.56 (t, J = 8.8 45 MHz, CDCl ) δppm: 167.51, 164.28, 163.32, 156.17, 155.24,
3
Hz, 4H, NCH ), 3.99 (m, 12H, OCH ), 3.90 (t, J = 8.8 Hz, 4H,
155.02, 153.15, 146.37, 140.75, 133.67, 130.56, 130.36,
129.30, 129.11, 125.34, 124.61, 124.20, 123.61, 121.83,
119.21, 105.37, 73.43, 69.08, 40.00, 39.75, 31.93, 30.29,
29.74, 29.66, 29.59, 29.42, 29.35, 29.29, 26.04, 22.68, 14.09;
2
2
NCH ), 1.20-1.88 (m, 120H, CH ), 0.86 (t, J = 8.8Hz, 18H,
2
2
13
CH3); C NMR (100 MHz, CDCl ) δppm: 167.59, 163.53,
3
1
63.01, 152.94, 140.93, 138.25, 133.27, 133.05, 130.22,
1
29.23, 129.09, 128.62, 127.05, 122.89, 122.49, 120.93, 50 MALDI-TOF-MS Calcd. for m/z = 1997.8, found: m/z =
+
+
105.44, 73.46, 69.27, 69.08, 40.00, 39.91, 31.93, 31.91, 29.74,
1997.4 (MNa ). HR-MS (ESI) (C126H180N O ) [MNa] :
4 14
2
9.70, 29.66, 29.58, 29.45, 29.41, 29.38, 29.35, 26.17, 22.68,
Calcd.: 1997.3422. found:1997.3453.
1
4.09; MALDI-TOF-MS Calcd. for m/z = 1948.4, found: m/z
+
+
=
1949.4 (MH ). HR-MS (ESI) (C114H170Br N O ) [M+H] :
2.2.3. The synthetic procedure of compound 8
2
4
12
Calcd.: 1949.1279. found:1949.1283.
55
The mixture of compound 6 (0.195 g, 0.1 mmol), tert-
butylphenol (0.045 g, 0.3 mmol) and anhydrous K CO (0.050
2
3
2
.2.2. The synthetic procedure of compound 7
The mixture of compound 6 (0.195 g, 0.1 mmol), phenol
0.028g, 1 mmol) and anhydrous K CO (0.050g, 0.36 mmol)
g, 0.036 mmol) were stirred in DMF (20 mL) under N2
o
atmosphere at 95 C for 12h. TLC detection implied the
(
disappearance of compound 6. After cooling, 50 mL of HCl
2
3
o
were stirred in DMF (20 mL) under N atmosphere at 95 C for 60 solution (1M) was added and the product was extracted with
2
8h. TLC detection suggested the disappearance of compound
. After cooling, 50 mL of HCl solution (1M) was added and
40 mL of CHCl . The organic layer was washed with brine
3
6
solution and dried over anhydrous MgSO . After filtration, the
4

solution was concentrated and purifie
A
d
C
b
C
y
EPco
T
lu
E
m
D
n
MAam
N
mo
U
no
S
ly
C
si
R
s
I
derivative 3 was obtained by refluxing
P
T
chromatography (CH Cl / ethyl acetate (8/1, v/v)). The
compound 2 with excess ethylenediamine in yield of 86%. By
2
2
compound 8 was obtained as red solid in yield of 63%.
treating compound 3 with perylene tetracarboxylic anhydride
-
1
0
Compound 8: FT-IR (KBr), v/cm : 3731 (N-H), 1697,1661 35 in formdimethylamide (DMF) at 110 C overnight, the target
1
5
0
5
0
5
0
(C=O); H NMR (400 MHz, CDCl ) δ ppm: 9.62 (d, J = 8.0
compound 5 was synthesized in yield of 65% [27]. On the
other hand, the 1,7-dibrominated perylene bisanhydride 4 was
prepared by the published procedure [34]. Synthesis of target
3
Hz, 2H, ArH), 8.59 (d, J = 8.0 Hz, 2H, ArH), 8.38 (s, 2H,
ArH), 7.47 (d, J = 8.0 Hz, 4H, ArH), 7.08 (d, J = 8.0 Hz, 4H,
ArH), 7.0 (s, 2H, CONH), 6.93 (s, 4H, ArH), 4.51 (bs, 4H,
compound 6 was fulfilled through the ammonolysis reaction
0
NCH ), 3.97 (m, 12H, OCH ), 3.83 (t, J=8.8Hz, 4H, NCH ), 40 of compound 4 with compound 3 in DMF solution at 110 C
2
2
2
1
1
2
2
3
1.76 (m, 12H, CH ), 1.43 (m, 12H, CH ), 1.37 (s, 18H, CH ),
for 20h. The red solid 6 was obtained in yield of 52% after
2
2
3
13
1
.24 (m, 96H, CH ), 0.86(t, J = 8.8 Hz, 18H, CH ); C NMR
column chromatography (CH Cl / ethyl acetate (6/1, v/v)). By
2
3
2
2
(
100 MHz, CDCl ) δppm: 167.52, 164.02, 163.29, 155.46,
further treating compound 6 with phenol or tert-butylphenol
in K CO /DMF system, target compounds 7 and 8 were
3
1
1
52.91, 152.33, 148.25, 140.74, 133.63, 130.11, 129.08,
2
3
28.76, 127.30, 124.80, 124.05, 123.68, 123.26, 124.45, 45 prepared after column chromatography in yields of 72% and
118.97, 118.69, 105.24, 73.25, 68.85, 39.66, 39.43, 34.35,
63%, respectively. The new perylene derivatives 6, 7 and 8
were characterized by IR, NMR, and high-resolution mass
spectral analysis. The mass spectrometry spectra of
compounds 6, 7 and 8 showed corresponding molecular ion
3
2
2.00, 31.12, 30.19, 29.61, 29.45, 29.31, 29.27, 29.15, 25.91,
2.55, 13.90; MALDI-TOF-MS Calcd. for m/z = 2087.0,
+
+
found: m/z = 2087.8 (M ). HR-MS (ESI) (C134H196N O ) [M] :
4
14
1
Calcd.: 2086.4776. found: 2086.4771.
50 peaks at 1949.4, 1997.4 and 2087.8, respectively. In the H
NMR spectra of compounds 6, 7 and 8, all signals of protons
were assigned well for the proposed structures. Especially, the
ArH of perylene skeleton exhibited two symmetrical doublets
3
. Results and discussion
3
.1. Synthesis and characterization
In order to investigate the influences of different bulky
and one singlet, indicating the substituents were on the 1,7-
1
bay-substituents on mesomorphism, a series of perylene 55 positions of perylene skeleton (the representative H NMR
1
3
imides with H, Br, phenyl and tert-butylphenyl on bay-
position were designed as target compounds, in which the
bulks of substituents increased orderly. The synthetic routes
were illustrated in Scheme 1. According to the report methods
spectrum of compound 6 was illustrated in Figure 1). The C
NMR also supported the 1,7-bis-substituents structures. All
these characteristic data were in accordance with the proposed
structures of compounds 6, 7 and 8. These results suggested
[
27, 35], gallic derivative 2 with three long alkyl chains was 60 that the small quantities of isomers for brominated product
prepared by reacting methyl gallate 1 with bromodecane in
(such as 1,6-dibrominated isomers) were removed completely
by column chromatography [34]. The obtained perylene
K CO /MeCN system in yield of 80%. Subsequently, the
2
3

derivatives showed good soluble in all
A
k
C
ind
C
s
E
o
P
f
T
or
E
ga
D
nicMA
s
N
co
wide as 133.9, 161.5, 176.3 and 186.2 C for compounds 5, 6,
and 8, respectively. These scopes of phase transfer
temperatures not only were wider than that of most of
U
pe
S
s o
C
f
R
ph
I
a
P
se
T
transfer temperatures after calculation were as
o
solvents (CHCl , toluene, THF, DMF, etc).
3
7
3
.2. Mesomorphic properties
The thermotropic properties of compounds 5, 6, 7 and 8
3
4
4
5
5
6
5
0
5
0
5
0
5
0
5
0
36
reported perylene liquid crystals, but also displayed the same
changes that the scopes of phase transfer temperatures became
wider with the increase of the bulk of substituents on bay-
positions. Based on these DSC traces, it could be concluded
that compounds 5, 6, 7 and 8 had good liquid crystalline
behaviours. The phase transitions temperatures and the scopes
of phase transfer temperatures increased gradually with the
increases of the bulk of substituents on bay-positions. These
phenomena might be explained by that the bigger bulk of the
substituents on bay-positions enlarge the area of rigid
perylene cores and result in the higher phase transfer
temperatures. On the other hand, the substituents on bay-
positions might produce steric hindrances to twist the plane of
rigid perylene core, which enhance the different values of Cr-
Col and Col-Iso phase transition temperatures, and increase
the scopes of phase transfer temperatures finally. According
to these explanations, it could be deduced that, the liquid
crystal behaviors would disappear eventually if the steric
hindrances of substituents on bay-positions were too large and
destroyed the plane of rigid perylene core. Indeed, this
deduction had been confirmed by no mesomorphic property of
similar perylene derivative with four phenyls on bay 1, 6, 7,
were investigated by DSC as shown in Figure 2. The phase
transition temperatures and associated enthalpies were listed
in Table 1. One can see that all of them exhibited good
reversible phase transitions on heating and cooling with
similar phase transitions temperatures. The two obvious phase
transition temperatures on heating and cooling could be
observed, suggesting that the crystal phase-mesophase-
isotropic phase exists on the heating and cooling process.
These results implied that, besides compound 5 with no
substituent on bay-position, compounds 6, 7 and 8 with
substituents on bay-positions also possess good mesomorphic
properties. It can be seen that a small exothermal peak at
1
1
2
o
o
1
90.1 C or 212.7 C, near their mesophase-isotropic phase
transition temperatures, was appeared for compounds 6 and 7,
respectively. These small thermal effects might correspond to
phase transition of the hexagonal columnar mesophase to
nematic phase, which were further confirmed by XRD
analysis and the textures changes from clear pseudo-confocal
conic textures to cloudy and schlieren textures observed
under POM. Moreover, the phase transition temperatures of
2
5
o
compounds 5, 6, 7 and 8 were -1.5, 41.3, 55.3, 61.7 C for Cr-
o
Col and 132.4, 202.8, 231.6, 247.9 C for Col-Iso phase
1
2-positions [33].
transition processes, respectively. It was interesting that they
showed orderly changes, i.e. the phase transitions
temperatures increased gradually with the increases of the
bulk of substituents on bay-positions. On the other hand, the
Furthermore, POM was used to study the mesomorphic
textures of compounds 5, 6, 7 and 8 based on the DSC results.
The phase transitions of Cr-Col and Col-Iso phase were
clearly observed. Their phase transition temperatures were in
3
0

accordance with the DSC data approximately
A
. F
C
or
C
co
E
m
P
po
T
u
E
nd
D
s
MAcom
N
p
U
ou
S
nd
C
s
R
6,
I
7 and 8 suggested the spacing of 3.83 Å, 3.77 Å
P
T
6
and 7, the clear columnar textures turn into cloudy and
and 3.85Å, respectively, which corresponded to the typical
characteristic of intracolumnar distance of ordered hexagonal
columnar liquid crystals with π-π interactions. Figure 5
o
o
schlieren textures gradually at 190 C and 210 C
approximately, indicating the transition of ordered hexagonal
columnar mesophase to nematic mesophase. Figure 3
35
0
showed the XRD traces of compound 8 measured at 25 C,
5
0
5
0
5
0
0
0
0
9
0 C and 280 C, respectively. Comparing with the clear
exhibited their mesomorphic textures at 90 C. All of them
0
0
reflections of Col phase at 90 C, the reflections at 25 C was
possessed the pseudo-confocal conic textures, which are
typical textures for columnar mesophase.
h
0
complicated for Cr-phase and no obvious reflection at 280 C
40
was observed for Iso-phase of compound 8. Figure 6
The mesomorphic structures of compounds 5, 6, 7 and 8
o
illustrated the XRD trace and the texture of compound 7 at
1
1
2
2
3
were also established by XRD studies at mesophase of 90 C.
o
2
2
10 C. The weak reflection at low angle and the broad halo at
The results were exhibited in Figure 4. As analyzed in
literature [27], typical peaks of columnar phase of perylene
liquid crystals were observed for compound 5 at the
o
θ = 17~30 suggested the nematic mesophase, which was in
accordance with the schlieren texture under POM. On the
o
o
o
reflections of 2θ = 3.1 , 15~25 and 23.5 , but it was difficult 45 other hand, the calculated lattice parameter ɑ for compounds 6,
to deduce the specific phase structures such as hexagonal or
rectangular liquid crystal phase. However, different from
compound 5, the perylene liquid crystals 6, 7 and 8 with
substituents on bay-positions showed more complicated peaks.
7 and 8 was 50 Å approximately, which is 25% less than the
diameters (~64 Å) of compounds 6, 7 and 8 obtained by CPK
molecular model. These differences might indicate that the
folding of the flexible alkyl chains or the possible
o
o
o
In the small angle region, three peaks at 2.0 (or 2.08 , 1.97 ), 50 interdigitation of flexible chains in the neighbouring columns.
o
o
o
o
o
o
3.48 (or 3.67 , 3.33 ), and 4.04 (or 4.25 , 3.85 ) were
observed obviously for compounds 6, 7 and 8, respectively.
According to Bragg equation, the d-spacing based on these
angles were calculated as 44.1 Å (or 42.4 Å, 44.8 Å), 25.4 Å
Thus, the proposed arrangement for the molecular stacking of
hexagonal columns of compounds 6, 7 and 8 were presented
in Figure 7. Combining all the data of DSC, POM and XRD
analyses, it could be concluded that perylene derivatives 6, 7
(
or 24.1 Å, 26.5 Å) and 21.9 Å (or 20.8 Å, 22.9 Å). These 55 and 8 with substituents on bay-positions have the hexagonal
distances were in accordance with the ratios of 1:1/√3:1/√4
approximately for (100), (110) and (200) reflections.
Therefore, the hexagonal columnar liquid crystals could be
columnar liquid crystalline phases and wider scopes of phase
transfer temperatures. The substituents on bay-positions were
favorable for not only broadening scopes of LC phase transfer
temperatures and but also producing the hexagonal mesophase.
assigned for compounds 6, 7 and 8. In the wide-angle region,
o
the broad halos at 2θ = 15~30 reflected mean distance of 60 The larger bulks of substituents result in wider scopes of
4.5Å and the very short correlation length of the molten alkyl
phase transfer temperatures before the oversize bulks or too
much substituents destroyed the mesophase [23, 33].
o
o
o
chains. The reflections at 23.18 , 23.60 and 23.11 of

ACCEPTED MA
f
N
luo
U
re
S
sc
C
en
R
ceIP
quenching and increase the fluorescence
T
3
.3. photophysical properties
quantum yields. Their fluorescences in solid state were also
investigated but no fluorescence was detected, indicating the
The photophysical properties of compounds 5, 6, 7 and 8
were studied by absorption spectra and fluorescence spectra. 35 existence of strong aggregation-caused quenching in solid
5
0
5
0
5
0
Figure 8 and 9 illustrated the representative absorption spectra
and fluorescence spectra for compound 7, respectively, which
showed obvious changes in different organic solvents. The
maximal adsorption spectra fluctuated between 490 nm and
state which was normal phenomena for perylene derivatives.
All these photophysical data suggested that the fluorescence
properties of compounds 6, 7 and 8 with bay-substituents
were more excellent than that of compound 5 with no
5
60 nm with different shoulder peaks due to the influences of 40 substituents on bay-position. The substituents on bay-
1
1
2
2
3
solvent effects. Also, the intensity and emission wavelength of
fluorescence spectra varied dramatically with the strongest
emission in DMF solution. Thus, the absorption spectra and
fluorescence spectra of compounds 5, 6, 7 and 8 in DMF
solution were investigated in details and the results were
presented in Figure 10, Figure 11 and Table 2. Comparing
with compound 5 with no substituent on bay-position,
compounds 6, 7 and 8 exhibited considerable line broadening
and whole bathochromic shift for the absorption spectra. The
emission spectra of compounds 6, 7 and 8 also showed
bathochromic shift and the intensities increased obviously.
These phenomena were attributed to the introduction of
substituents on bay-posiutions resulting in a twisting of two
naphthalene subunits of perylene and loss of planarity and
rigidity of the perylene bisimide chromophore [23, 33, 37].
On the other hand, the Stokes shifts, fluorescence quantum
yields and fluorescence lifetimes were bigger than that of
compound 5 and increased orderly with the increase of bulks
of substituents on bay-positions. These results could be
explained by that the bigger bulk of substituent causes
stronger twisting of two naphthalene subunits and reduces
orderly aggregates. The less orderly aggregates decrease the
positions of perylene liquid crystals were favorable for good
photophysical properties in reasonable range of the number
and bulk of substituents.
4
5
5
6
5
0
5
0
4. Conclusion
In summary, a series of perylene liquid crystals with H, Br,
phenyl and tert-butylphenyl on bay-positions were prepared in
reasonable yields. Their structures were confirmed by FT-IR,
NMR and MS. Their mesomorphic properties were
investigated by DSC, POM and XRD analysis. Their
photophysical properties were studied by absorption spectra
and fluorescence spectra. The results suggested that perylene
derivatives 6, 7 and 8 with substituents on bay-positions have
the hexagonal columnar liquid crystalline phases and wide
scopes of phase transfer temperatures. The scopes of phase
transfer temperatures increased with the increase of the bulks
of substituents. The photophysical results implied that the
fluorescence properties of compounds 6, 7 and 8 possess
stronger intensities, larger Stokes shifts and higher
fluorescence quantum yields than that of compound 5 with no
substituents on bay-position. All these results indicated that
the substituents on bay-positions for perylene liquid crystals

were favourable for producing excellen
A
t
C
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C
es
E
om
P
o
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rp
E
hi
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c
MAforNUwh
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e
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hybrid light-emitting diodes. Dyes Pigm
I
P
T
properties and fluorescence properties in a reasonable range of
the number and bulk of substituents. The other perylene liquid
crystals with various substituents on bay-positions will be
2015;114 :138-143.
[5] Liu SG, Sui G, Cormier RA, Leblanc RM, Gregg BA.
Self-organizing liquid crystal perylene diimide thin films:
5
further studied in the following work to investigate the 35 Spectroscopy, crystallinity, and molecular orientation. J Phys
influences of substituents on properties in more details Chem B 2002;106:1307–15.
6] Wicklein A, Lang, A, Muth M, Thelakkat M. Swallow-tail
.
[
Acknowledgment. Financial support from the National
substituted liquid crystalline perylene bisimides: Synthesis
and thermotropic properties. J Am Chem Soc 2009;131:
Natural Science Foundation of China (No: 21406036), Fujian
1
0
Natural Science Foundation of China (No. 2014J01034), the 40 14442–53.
Program for Innovative Research Team in Science and
Technology in Fujian Province University and Program of
students innovative experimental projects of FJNU
[7] Kato T, Mizoshita N, Kishimoto K. Functional liquid-
crystalline assemblies: Self-organized soft materials. Angew
Chem Int Ed 2006;45:38–68.
(201310394016) were greatly acknowledged.
[8] Hoeben, FJM, Jonkheijm P, Meijer EW, Schenning AP.
45 About supramolecular assemblies of pi-conjugated systems.
Chem Rev 2005;105:1491–46.
1
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ACCEPTED MANUSCRIPT
Scheme 1 The synthetic routes of perylene liquid crystals 5, 6, 7 and 8 with different substituents on bay-positions
1
Figure 1 The H NMR spectrum of compound 6
o
-1
5
0
5
Figure 2 The DSC traces of compounds 5, 6, 7 and 8 on second heating and cooling (scan rate 10 C min )
o
Table 1 Transition temperatures ( C) and enthalpy changes (kJ/mol) of compound 5, 6, 7 and 8
o
Figure 3 The textures of compounds 5, 6, 7 and 8 obtained with polarized optical microscopy on cooling at 90 C (×400)
0
Figure 4 XRD traces of compounds 5, 6, 7 and 8 measured at 90 C
0
0
0
Figure 5 XRD traces of compound 8 measured at 25 C (Cr phase), 90 C (Col phase) and 280 C (Iso phase)
0
1
Figure 6 XRD trace and texture of compound 7 measured at 210 C
Figure 7 The proposed arrangement for the molecular stacking of hexagonal columns of compounds 6, 7 and 8
-
5
Figure 8 Adsorption spectra of 7 in different solvents (10 M)
-
5
Figure 9 Fluorescence emission spectra of 7 in different solvents (10 M). The excitation wavelength was 518 nm.
-
5
Figure 10 Adsorption spectra of 5, 6, 7 and 8 in DMF (10 M)
-
5
1
Figure 11 Fluorescence emission spectra of compounds 5, 6, 7 and 8 in DMF (10 M). The excitation wavelength was 525 nm (5),
4
19 nm (6), 518 nm (7), 523nm (8).
Table 2 Absorption and fluorescence data for the compounds 5, 6, 7 and 8 in DMF at 298K

ACCEPTED MANUSCRIPT
1
0
5
0
C
12
H
25
O
HO
HO
HO
C12H25Br
CO , MeCNC12H25
12 25
C H O
NH
2
O
O
O
2
H N
K
2
3
O
C
12
H
25
O
NH
2
cooling
MeOH
N
OMe
OMe
C
12
H
25
O
H
8
1
C
12 25
H O
2
3
O
O
O
7
C
12
25
12
H
25
O
O
3
O
O
OC12
H
25
6
H
N
5
C
12
H
O
N
N
DMF
N
OC12
H
25
H
5
O
O
O
C
H
25
O
-5
O
O
O
OC12
H
25
6
5
Br
O
2
, H
2
SO
4
, I
2
7
O
O
Br
Br
-10
8
second heating
C
12
25
12
H
25
O
O
O
O
OC12H25
OC12H25
H
Br
3
N
300
Br
C
12
H
O
N
N
N
0
50
100
150
200
250
DMF
H
O
O
O
o
C
H
25
O
OC12H
25
Temperature ( C)
6
O
O
O
4
O
C
12
25
12
H
25
O
O
O
N
K
2
CO
3
O
H
OC12
OC12H25
OC12
H
25
Figure 2 The DSC traces of compounds 5, 6, 7 and 8 on
6
+
N
N
DMF
C
12
H
O
N
H
OH
o
-1
O
O
O
C
H
25
O
second heating and cooling (scan rate 10 C min )
H
25
O
7
O
C
12
25
12
H
25
O
O
O
K
2
CO
3
O
H
OC12
OC12H25
OC12
H
25
6
+
N
o
DMF
C
12
H
O
N
N
N
15 Table 1 Transition temperatures ( C) and enthalpy changes
OH
H
O
O
O
C
H
25
O
H
25
O
8
(kJ/mol) of compound 5, 6, 7 and 8
Scheme 1 The synthetic routes of perylene liquid crystals 5, 6,
compound Phase
transition
Heating scan
T(∆H)
Cooling scan
T(∆H)
[
a]
7
and 8 with different substituents on bay-positions
5
5
Cr-Col
-1.5(11.46)
132.4(12.25)
41.3(16.86)
190.1(1.44)
202.8(18.75)
55.3(16.21)
212.7(1.88)
231.6(22.64)
61.7(14.89)
247.9(19.34)
-7.9(13.28)
122.8(10.67)
35.6(12.74)
171.9(0.24)
188.8(14.08)
44.7(15.01)
200.4(1.62)
212.6(23.02)
59.3(13.02)
239.6(18.68)
Col-Iso
Cr-Colh
6
Col -Np
h
N -Iso
p
7
8
Cr-Colh
Col -Np
h
N -Iso
p
Cr-Colh
Col -Iso
h
[
a] Cr=crystalline, Col=columnar mesophase, Col =hexagonal
h
columnar mesophase, N =Nematic phase, Iso=isotropic
p
1
Figure 1 The H NMR spectrum of compound 6
1
0

ACCEPTED M10 ANUSCRIPT
2500
2000
1500
1000
15
5
00
0
10
20
30
40
degree (2θ)
Figure 6 XRD trace and texture of compound 7 measured at
Figure 3 The textures of compounds 5, 6, 7 and 8 obtained
0
o
20 210 C
with polarized optical microscopy on cooling at 90 C (×400)
8
6
4
2
000
000
000
000
0
6
4
2
000
000
000
0
1.97
2
.08
3.33
3.85
2
.00
3
.67
4
.25
3.48
4
.04
2
4
6
8
23.11
8
2
3.60
2
3.18
7
2
3.37
6
5
0
10
20
30
40
degree (2θ
)
5
Figure 4 XRD traces of compounds 5, 6, 7 and 8 measured at
0
9
0 C
Figure 7 The proposed arrangement for the molecular
stacking of hexagonal columns of compounds 6, 7 and 8
8
7
6
5
4
3
2
1
000
000
000
000
000
000
000
000
0
25
o
9
0 C
o
2
5 C
o
280 C
0
10
20
30
40
degree (2θ)
0
Figure 5 XRD traces of compound 8 measured at 25 C (Cr
0
0
phase), 90 C (Col phase) and 280 C (Iso phase)

ACCEPTED MANUSCRIPT
0
0
0
0
0
0
0
0
0
0
.9
.8
.7
.6
.5
.4
.3
.2
.1
.0
700
CHCl3
6
5
4
00
00
00
8
THF
6
7
5
Toluene
Acetone
DMF
300
200
100
0
4
00
500
600
700
500
600
Wavelength/nm
Wavelength/nm
-
5
Figure 8. Adsorption spectra of 7 in different solvents (10 M)
10
Figure 11. Fluorescence emission spectra of compounds 5, 6,
-
5
7
and 8 in DMF (10 M). The excitation wavelength was 525
5
4
3
2
1
00
00
00
00
00
0
nm (5), 419 nm (6), 518 nm (7), 523nm (8).
DMF
Table 2. Absorption and fluorescence data for the compounds
CHCl3
15 5, 6, 7 and 8 in DMF at 298K
Toluene
THF
Acetone
Comp.
λ
max/nm
λ
em/nm
Stokes
shift/nm
31
Ф
F
5
00
600
Wavelength/nm
5
6
7
8
525
519
518
523
556
567
572
587
0.13
0.28
0.34
0.37
48
5
Figure 9. Fluorescence emission spectra of 7 in different
54
-
5
solvents (10 M). The excitation wavelength was 518 nm.
64
0
0
0
0
0
0
0
.6
.5
.4
.3
.2
.1
.0
8
7
6
5
4
00
500
600
700
Wavelength/nm
-
5
Figure 10. Adsorption spectra of 5, 6, 7 and 8 in DMF (10 M)

ACCEPTED MANUSCRIPT
Novel perylene liquid crystals with different bay-substituents were prepared.
They have good Col mesophase and fluorescence properties.
h
They possess wide scopes of mesophase transfer temperatures.
The suitable bay-substituents were favorable for mesophase and fluorescence.