Synthesis and functional properties of symmetrically naphthyl-Based oligoarylenes with high glass-transition temperatures

Article abstract of DOI:10.1002/cjoc.201090162

Symmetrically naphthyl-based π-conjugated oligoarylenes, OPP(4)Ph-TNp, OPP(4)An-TNp and OPP(4)OXTNp have successfully been synthesized by a divergent approach using Pd-catalyzed Suzuki cross-coupling reaction of diiodo- or dibromo-oligoarylene and arylboronic acid as a key step. Their optical, electrochemical and thermal properties have also been characterized. These newly synthesized naphthyl-based oligoarylenes show highly morphological (T_g 149-187 °C) and thermal (T_dec 509-597 °C) stabilities as well as exhibit potential applications in optoelectronic fields.

Full text of DOI:10.1002/cjoc.201090162

FULL PAPER
Synthesis and Functional Properties of Symmetrically
Naphthyl-Based Oligoarylenes with High
Glass-Transition Temperatures
a
a
a
Zhang, Xiaoling (张小玲)
Sun, Kang (孙康)
Liu, Yurong (刘玉容)
b
a
Xiong, Mojun (熊茉君)
Xia, Pingfang (夏萍芳)
,
a
,a
Li, Zhonghui* (李仲辉)
Cao, Zijian* (曹子建)
a
Department of Chemistry and Institute of Applied Chemistry, Sichuan College of Education,
Chengdu, Sichuan 610041, China
b
West China School of Pharmacy, Sichuan University, Chengdu, Sichuan 610041, China
Symmetrically naphthyl-based π-conjugated oligoarylenes, OPP(4)Ph-TNp, OPP(4)An-TNp and OPP(4)OX-
TNp have successfully been synthesized by a divergent approach using Pd-catalyzed Suzuki cross-coupling reaction
of diiodo- or dibromo-oligoarylene and arylboronic acid as a key step. Their optical, electrochemical and thermal
properties have also been characterized. These newly synthesized naphthyl-based oligoarylenes show highly mor-
phological (T 149— 187 ℃) and thermal (T 509— 597 ℃) stabilities as well as exhibit potential applications in
g
dec
optoelectronic fields.
Keywords naphthyl-based oligoarylenes, synthesis, properties, amorphous materials
Introduction
have been investigating the structural factors that would
enhance the technologically useful functional and mate-
1
Organic π-conjugated molecular materials such as
low molar mass molecules and oligomers have con-
tinuously drawn considerable attentions for their poten-
tial applications in next-generation electronic and opto-
electronic devices such as organic light-emitting diodes
12
rial properties of oligophenylvinylenes (OPVs), oligo-
13
14
(
p-phenylenes) (OPPs), oligofluorenes (OFs), oli-
15 16
gothiophenes (OTs), and dendrimers as they are es-
sential towards a rational design and an optimization of
functional organic and polymeric materials.
2
3
(
OLEDs) and field effect transistors as well as in the
Recently, the naphthalene has already been used as
an efficient structural moiety that facilitates the forma-
tion of morphologically stable glassy state of the mo-
lecular materials obtained to build optoelectronic mo-
4
emerging photonic technologies such as plastic laser
and three-dimensional optical storage in the past few
5
years. Tremendous progress has already been made in
understanding and optimizing the electronic and optical
properties of linear π-conjugated molecules or oli-
7,17
lecular materials. Moved alonged this idea and based
on the concepts that the incorporation of rigid moieties
6
gomers. Recently, there is a great interest to increase
18
increases glass-transition temperature (T
g
) and that the
the structural or spatial dimensions of π-conjugated
molecules in order to tune and acquire more favorable
physical i.e. morphological and functional properties of
enlargement of molecular size enhances the stability of
19
amorphous glassy state, we report herein a facile syn-
thesis and functional properties of symmetrically
naphthyl-based π-conjugated oligoarylenes (Figure 1) as
morphologically stable amorphous molecular materials,
OPP(4)Ph-TNp, OPP(4)An-TNp and OPP(4)OX-TNp,
7
a material. For instance, various novel structures of
8
conjugated molecules such as star-burst molecules,
9
tetrahedral-arranged chromophores, spiro-linked oli-
1
0
11
gomers and dendritic macromolecules have been
designed and synthesized in order to prevent molecular
aggregation and facilitate amorphous glass formation of
electroluminescent materials, which would enhance the
fluorescence efficiency and stability of OLEDs as well
as induce the formation of morphologically stable
glassy states of photonic molecular materials, which
could prevent light scattering caused by grain bounda-
ries in optical waveguides. Over the last few years, we
g
which exhibit a high glass transition temperature (T )
and thermal stability as well as show potential applica-
tions in optoelectronic fields.
Experimental
Apparatus and conditions
All the solvents were dried by the standard methods
*
E-mail: zhonghli@yahoo.cn
Received September 10, 2009; revised December 10, 2009; accepted February 10, 2010.
Project supported by Sichuan Science & Technology Supported Project (No. 2008GZ0041) from Sichuan Province, China.
1034
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Chin. J. Chem. 2010, 28, 1034— 1040

Synthesis and Functional Properties of Symmetrically Naphthyl-Based Oligoarylenes
(
1
DMSO-d , 100 MHz) δ: 134.1, 133.8, 128.5, 128.3,
6
＋
28.0, 126.4, 126.3, 126.0; MS (FAB) m/z: 172 (M ＋1).
3
,5-Bis(1-naphthyl)-1-bromobenzene (2) A mix-
ture of 1,3,5-tribromobenzene (2.52 g, 8 mmol), palla-
dium(II) acetate (90 mg, 0.4 mmol), tri-o-tolylphos-
phine (243 mg, 0.8 mmol), toluene (40 mL), methanol
－
1
(20 mL), 2 mol•L
2 3
K CO (16 mL), 1-naphthylboronic
acid (1, 2.75 g, 16 mmol) was heated at 75 ℃ over-
night under nitrogen atmosphere while maintaining a
good stirring. After the reaction mixture was cooled to
room temperature, it was poured into a large amount of
water and extracted with dichloromethane (50 mL×3).
The combined organic layer was dried over anhydrous
Figure 1 Structures of naphthyl-based oligoarylenes.
wherever needed. Thermal stabilities were determined
by thermal gravimetric analyser with a heating rate of
1
0 ℃/min under N
2
. The glass transitions and melting
transitions were extracted from the second run DSC
traces which were determined by differential scanning
2 4
Na SO and evaporated to dryness. The crude product
was further purified by silica gel column gradient chro-
matography using petroleum ether as eluent affording a
white solid 2 in 32% yield and a by-product white solid
calorimeter with a heating rate of 10 ℃/min under N
2
.
All the photophysical measurements were performed in
1,3,5-tri(1-naphthyl)benzene in 30% yield. m.p. 156—
1
CHCl
3
including electronic absorption (UV-Vis) and
157 ℃; H NMR (CDCl
3
, 270 MHz) δ: 7.97—8.01 (m,
fluorescence spectra. The fluorescence quantum yields
in chloroform were determined by dilution method us-
ing quinine sulfate monohydrate (λexc＝313 nm, Ф＝
2H), 7.86—7.92 (m, 4H), 7.72 (d, J＝4.0 Hz, 2H), 7.57
1
3
(t, J＝4.0 Hz, 1H), 7.46—7.55 (m, 8H); C NMR
3
(CDCl , 66 MHz,) δ: 142.5, 138.3, 133.7, 131.6, 131.2,
0
.48) as a standard. The fluorescence decay curves were
130.4, 128.3, 128.2, 127.1, 126.4, 125.9, 125.5, 125.3,
＋
recorded at room temperature using nitrogen laser as
excitation. The lifetimes were estimated from the meas-
122.1; MS (FAB) m/z: 410 (M ＋1). Anal. calcd for
C
26
H17Br: C 76.29, H 4.19; found C 76.36, H 4.28.
ured fluorescence decay using iterative fitting procedure.
1,3,5-Tri(1-naphthyl)benzene m.p. 203—204 ℃;
＋
1
E
1/2 (vs. Fc /Fc) was estimated by cyclic voltammetric
H NMR (CDCl
3
, 270 MHz) δ: 8.20—8.23 (m, 2H),
method using platinum disc electrode as a working
electrode, platinum wire as a counter electrode, and
SCE as a reference electrode with an agar salt bridge
7.86—7.97 (m, 6H), 7.76 (s, 2H), 7.46—7.63 (m, 12H),
1
3
7.16—7.26 (m, 2H); C NMR (CDCl
3
, 66 MHz) δ:
140.6, 139.7, 133.8, 131.4, 130.6, 128.3, 127.8, 127.2,
＋
connecting to the oligomer solution dissolved in CH
2
Cl
2
126.1, 125.9, 125.8, 125.4; MS (FAB) m/z: 457 (M ).
－
1
using 0.1 mol•L of Bu
4
NPF
6
as a supporting electro-
3,5-Bis(1-naphthyl)-1-phenylboronic acid (3)
The synthetic procedure of 1-naphthylboronic acid was
followed using 3,5-bis(1-naphthyl)-1-bromobenzene
(851 mg, 2.1 mmol), n-BuLi (2 mL, 3.15 mmol), and
trimethyl borate (0.4 mL, 3.15 mmol). The crude prod-
uct was purified by precipitation with petroleum ether
lyte with a scan rate of 100 mV/s and all the potentials
＋
were calibrated with ferrocene, E1/2(Fc/Fc )＝0.45 V
(
vs. SCE) as an external standard.
Synthesis
1
-Naphthylboronic acid (1) To a 100.0 mL
affording a white solid 3 in 94% yield. m.p. 197—199
1
two-necked flask containing the solution of 1-naphthyl
bromide (4.14 g, 20 mmol) in 40 mL dry THF equipped
with a magnetic stirrer, a N
tone-dry ice bath were added 1.5 mol•L of n-butyl
lithium (n-BuLi, 16 mL, 24 mmol) while maintaining a
good stirring. After stirring for 1 h, 1.2 equiv. of
trimethyl borate (2.7 mL, 24 mmol) was added. After
stirring for a further 2 h, cool water was first added to
the reaction mixture to quench the reaction and diluted
℃; H NMR (DMSO-d
6
, 270 MHz) δ: 8.26 (s, 2H),
1
3
7.96—8.03 (m, 8H), 7.53—7.64 (m, 9H); C NMR
purge and a －78 ℃ ace-
6
(DMSO-d , 66 MHz) δ: 139.3, 139.1, 134.5, 133.3,
2
－
1
130.7, 128.3, 127.6, 127.0, 126.4, 125.8, 125.5, 125.2;
＋
MS (FAB) m/z: 375 (M ). Anal. calcd for C26
H19BO
2
: C
83.44, H 5.12; found C 83.40, H 5.19.
Terphenylene (4) The synthetic procedure of 2
was followed using 1220 mg (10 mmol) of phenylbo-
ronic acid and 944 mg (4.0 mmol) of 1,4-dibromo-
benzene. The pure product was precipitated by petro-
－
1
hydrochloric acid (6 mol•L
HCl) was then added
dropwise until an acidic mixture obtained. The reaction
mixture was poured into a large of water and extracted
with dichloromethane (50 mL×3). The combined or-
leum ether affording 878 mg (91%) of a milky white
1
solid. m.p. 211—212 ℃; H NMR (CDCl
3
, 400 MHz)
δ: 7.67 (s, 4H), 7.62—7.65 (m, 4H), 7.43—7.47 (m, 4H),
1
3
ganic layer was dried over anhydrous Na
evaporated to dryness. Petroleum ether was added to
remove the starting raw material and solidify the prod-
2
SO
4
and
7.34—7.38 (m, 2H); C NMR (CDCl
3
, 66 MHz) δ:
140.7, 140.1, 128.8, 127.5, 127.3, 127.0; MS (FAB) m/z:
＋
230 (M ). Anal. calcd for C18
found C 93.90, H 6.18.
H14: C 93.87, H 6.13;
uct. The product boronic acid is a white solid in 74%
1
yield. m.p. 167—169 ℃; H NMR (DMSO-d
6
, 400
4,4'-Diiodoterphenylene (5) A mixture of ter-
phenylene, 4 (0.84 mg, 3.6 mmol), glacier acetic acid
(20 mL), water (2 mL), concentrated sulfuric acid (2
MHz) δ: 8.36 (s, 2 H), 8.35 (s, 1H), 7.87—7.91 (m, 2H),
13
7
.72 (d, J＝6.8 Hz, 1H), 7.45—7.50 (m, 3H); C NMR
Chin. J. Chem. 2010, 28, 1034— 1040
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1035

Zhang et al.
FULL PAPER
mL), iodine (1.02 g, 4.03 mmol), iodic acid (1.38 g,
1
white solid. m.p. 219—220 ℃; H NMR (CDCl
3
, 400
6.05 mmol), and carbon tetrachloride (5 mL) was heated
MHz) δ: 7.98 (d, J＝6.8 Hz, 4H), 7.66 (d, J＝6.8 Hz,
1
3
at 80 ℃ for 4 h with a good magnetic stirring. After
the product slurry was cooled to room temperature, it
was poured into water and extracted with dichloro-
methane (50 mL×3). The combined dark purple or-
ganic layer was decolourized with sodium sulfite,
4H); C NMR (CDCl
3
, 100 MHz) δ: 164.0, 132.5,
＋
128.3, 126.6, 122.6; MS (FAB) m/z: 381 (M ＋1). Anal.
calcd for C14
H, 2.20.
8 2 2
H Br N O: C 44.25, H 2.12; found C 44.35,
4,4'-Bis[3,5-di(1-naphthyl)phenyl-1-yl]terphenyl-
ene (OPP(4)Ph-TNp) The Suzuki cross coupling
procedure for synthesis of 2 was followed using
4,4'-diiodoterphenylene (214 mg, 0.5 mmol), 3,5-bis(1-
naphthyl)-1-phenylboronic acid (3, 449 mg, 1.2 mmol),
palladium(II) acetate (11 mg), tri-o-tolylphosphine (30
2 3
K CO (3 mL), toluene (30 mL) and
methanol (15 mL). The crude product was purified by
2 4
washed with water, dried over anhydrous Na SO , fil-
tered and evaporated to dryness. The pure product was
precipitated by petroleum ether affording 1540 mg
1
(
(
4
89%) of a yellow solid. m.p. 231—233 ℃; H NMR
CDCl
3
, 400 MHz) δ: 7.77 (d, J＝8.8 Hz, 4H), 7.61 (s,
13
－1
H), 7.35 (d, J＝8.4 Hz, 4H); C NMR (CDCl
3
, 66
mg), 2 mol•L
MHz) δ: 138.5, 135.4, 135.1, 130.1, 129.1, 94.1; MS
＋
(FAB) m/z: 482 (M ). Anal. calcd for C18
H
12
I
2
: C 44.84,
silica gel chromatography using 2∶1 (V∶V) petroleum
H 2.51; found C 44.90, H 2.60.
,10-Bis (4-bromophenyl) anthracene (6) A mix-
ether dichloromethane affording 350 mg (79%) of a
1
9
white solid. m.p. 318—319 ℃; H NMR (CDCl
3
, 400
ture of 9,10-diiodoanthracene (0.86 g, 2 mmol), tetra-
kis(triphenylphosphine)palladium (0) (116 mg, 0.1
mmol), dried tetrahydrofuran (20 mL), p-bromophenyl
MHz) δ: 8.13 (d, J＝8.0 Hz, 4H), 7.88—7.94 (m, 12H),
7.81 (d, J＝8.0 Hz, 4H), 7.74 (d, J＝6.8 Hz, 8H), 7.66
13
(s, 2H), 7.54— 7.60 (m, 8H), 7.46—7.53 (m, 8H);
C
－
1
boronic acid (0.96 g, 4.8 mmol) and 2 mol•L
K
2
CO
3
3
NMR (CDCl , 66 MHz) δ: 141.3, 140.5, 139.8, 139.7,
(
4 mL) was heated at 75 ℃ under the atmosphere of
139.6, 139.5, 133.8, 131.5, 130.7, 128.3, 127.8, 127.6,
nitrogen overnight while maintaining a good stirring.
After the reaction mixture was cooled to room tempera-
ture, it was poured into a large amount of water and ex-
tracted with dichloromethane (50 mL×3). The com-
127.5, 127.4, 127.1, 126.2, 125.9, 125.8, 125.4; MS
＋
(FAB) m/z: 888 (M ). Anal. calcd for C70
H
46: C 94.77,
H 5.23; found C 94.80, H 5.28.
9,10-Bis[3,5-di(1-naphthyl)phenyl-1-phenyl-4-yl]]-
anthracene (OPP(4)An-TNp) The Suzuki cross cou-
pling procedure for synthesis of 2 was followed using
9,10-bis(4-bromophenyl)anthracene (6, 155 mg, 0.31
mmol), 3,5-bis(1-naphthyl)-1-phenylboronic acid (3,
285 mg, 0.76 mmol), palladium(II) acetate (11 mg),
2 4
bined organic layer was dried over anhydrous Na SO
and evaporated to dryness. The crude product was fur-
ther purified by silica gel column gradient chromatog-
raphy using petroleum ether as eluent affording a
1
light-yellow solid in 45% yield. m.p. 222—224 ℃; H
－
1
NMR (CDCl
3
, 270 MHz) δ: 7.71—7.74 (m, 4H),
tri-o-tolylphosphine (30 mg), 2 mol•L
2 3
K CO (3 mL),
1
3
7
.60—7.66 (m, 4H), 7.32—7.36 (m, 8H); C NMR
toluene (40 mL) and methanol (20 mL). The crude
product was purified by silica gel chromatography using
6∶1 (V∶V) petroleum ether dichloromethane affording
(
CDCl
3
, 66 MHz) δ: 137.7, 135.9, 132.9, 131.6, 129.6,
＋
1
26.6, 125.3, 121.7; MS (FAB) m/z: 488 (M ). Anal.
1
calcd for C26
.35.
N,N-Bis(4-bromobenzoyl)hydrazine (7) A solu-
tion of p-bromobenzoyl chloride (4.83 g, 22 mmol) in
0 mL of chloroform was added dropwise to a solution
H
16Br
2
: C 63.96, H 3.30; found C 63.70, H
150 mg (50%) of a white solid. m.p. 321—321 ℃; H
3
NMR (CDCl
3
, 400 MHz) δ: 8.18—8.20 (m, 4H), 8.00 (d,
J＝1.6 Hz, 4H), 7.90—7.97 (m, 12H), 7.79 (d, J＝6.8
Hz, 4H), 7.71 (t, J＝1.6 Hz, 2H), 7.63—7.65 (m, 4H),
7.58 (t, J＝7.6 Hz, 8H), 7.50—7.54 (m, 8H), 7.35 (d,
3
13
of hydrazide monohydrate (0.5 g, 10 mmol) and
triethyl-amine (2.2 g, 24 mmol) in 50 mL of chloroform
at an ice-water bath. The resulting mixture was stirred
for further 2 h at room temperature. The solvent was
removed and the solid was washed with petroleum ether
J＝6.8 Hz, 4H); C NMR (CDCl
3
, 100 MHz) δ: 141.5,
140.8, 139.9, 139.8, 138.4, 136.8, 133.9, 131.9, 131.7,
130.8, 129.9, 128.4, 127.9, 127.8, 127.3, 127.2, 127.0,
126.3, 126.0, 125.9, 125.5, 125.1; MS (FAB) m/z: 988
＋
(M ). Anal. calcd for C78
H50: C 94.90, H 5.10; found C
first and then a large amount of water, affording 2.71 g
94.85, H 5.13.
1
(
68%) of a white solid. m.p. 251—254 ℃; H NMR
2,5-Bis[3,5-di(1-naphthylphenyl)-1-phenyl-4-yl]-
1,3,4-oxadiazole (OPP(4)OX-TNp) The Suzuki cross
coupling procedure for synthesis of 2 was followed us-
ing 2,5-bis(4-bromophenyl)-1,3,5-oxadiazole (8, 190
mg, 0.5 mmol), 3,5-bis(1-naphthyl)-1-phenyl boronic
acid (3, 561 mg, 1.5 mmol), palladium(II) acetate (11
(CDCl
3
, 270 MHz) δ: 7.59 (d, J＝8.1 Hz, 8H), 4.09 (s,
＋
2
H); MS (FAB) m/z: 398 (M ).
2
,5-Bis(4-bromophenyl)-1,3,4-oxadiazole (8)
A
reaction mixture of 2.71 g (6.81 mmol) of N,N-bis(4-
bromobenzoyl)hydrazine (7) in 20 mL of SOCl was
was dis-
2
－
1
refluxed under nitrogen for 3—4 h. The SOCl
2
mg), tri-o-tolylphosphine (30 mg), 2 mol•L
2 3
K CO (3
tilled and the residue was extract with dichloromethane
and water. The organic layer was dried over anhydrous
mL), toluene (30 mL) and methanol (15 mL). The crude
product was purified by silica gel chromatography using
1∶2 (V∶V) petroleum ether dichloromethane affording
2 4
Na SO and evaporated to dryness. The crude product
was purified by silica column chromatography using
dichloromethane as eluent affording 1.63 g (63%) of a
1
376 mg (86%) of a white solid. m.p. 308—309 ℃; H
NMR (CDCl
3
, 400 MHz) δ: 8.23 (d, J＝8.4 Hz, 4H),
1
036
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Chin. J. Chem. 2010, 28, 1034— 1040

Synthesis and Functional Properties of Symmetrically Naphthyl-Based Oligoarylenes
8
.11 (d, J＝7.6 Hz, 4H), 7.87—7.94 (m, 16H), 7.70 (t,
glass-transition temperatures are 149, 187 and 155 ℃,
respectively and their melting points are 319, 321 and
309 ℃, respectively, which is a rare phenomenon for
the same molecular size.
J＝1.6 Hz, 2H), 7.56—7.59 (m, 8H), 7.47—7.54 (m,
13
8
1
1
8
3
H); C NMR (CDCl , 100 MHz) δ: 144.0, 141.6,
39.8, 139.6, 133.8, 131.5, 128.4, 128.0, 127.9, 127.7,
27.2, 126.3, 125.9, 125.8, 125.4, 122.9; MS (FAB) m/z:
＋
Photophysical properties
80 (M ). Anal. calcd for C66
H
42
N
2
O: C 90.18, H 4.82,
N 3.19; found C 90.23, H 4.90, N 3.20.
The photophysical properties of these naphthyl-
based oligoarylenes were examined by UV-Vis and
fluorescence spectroscopy in chloroform solution (Fig-
ure 3 and Table1). In view of electronic absorption
spectra, the absorption bands/maxima of these mole-
cules are generally structureless and all show similar
absorption bands peaking at ca. 290 nm arising from
π-π* transition, indicating that they have similar ground-
state electronic structures. Except for OPP(4)An-TNp
that exhibits identical absorption bands of anthracene
peaking at 398, 378 and 358 nm, OPP(4)Ph-TNp and
OPP(4)OX-TNp show a single absorption band peaking
at 309 and 311 nm, respectively. Like absorption spectra,
these naphthyl-based oligoarylenes exhibit similar
emission spectra in chloroform, which bave two emis-
sion peaks and emit blue-violent light peaking at
370—420 nm (Figure 4 and Table 1). The fluorescence
quantum yields of these compounds are 76%, 55% and
79%, respectively. On the other hand, the fluorescence
Results and discussion
Synthesis
The strategy for preparation of symmetrically naph-
thyl-based oligoarylenes OPP(4)Ph-TNp, OPP(4)An-
TNp and OPP(4)OX-TNp is outlined in Scheme 1. All
the newly synthesized naphthyl-based oligoarylenes
1
13
were fully characterized with H NMR, C NMR, MS,
and elemental analysis and found to be in good agree-
ment with their structures.
Thermal properties
The thermal properties of symmetrically naphthyl-
based π-conjugated oligoarylenes were examined by
thermogravimetric analysis (TGA) and differential
scanning calorimetry (DSC). All the newly synthesized
molecular materials show high decomposition tempera-
tures (Tdec) in the range of 509—597 ℃ (Figure 2 and
Table 1). The molecular weights of newly synthesized
compounds OPP(4)Ph-TNp, OPP(4)An-TNp and
OPP(4)OX-TNp are 887, 987 and 879, respectively;
however the Tdeco values of them are 597, 559 and 509
℃
, respectively, indicating that the thermal stability of
these molecules is related not only to its molecular
weight, but also to its molecular structure, especially the
replace ment of phenyl ring in OPP(4)Ph-TNp by
oxadiazolyl ring in OPP(4)OX-TNp leads reduction a to
of decomposition temperature by about 100 ℃. All the
newly synthesized naphthyl-based oligoarylenes
OPP(4)Ph-TNp, OPP(4)An-TNp and OPP(4)OX-TNp
can form morphologically stable glassy state and show
high glass-transition temperatures. Based on their simi-
lar DSC curves at the second heating scan, their
Figure 3 Absorption spectra of naphthyl-based oligoarylenes.
Figure 2 TGA analyses of symmetrically naphthyl-based oli-
goarylenes at heating rate of 10 ℃/min.
Figure 4 Photoluminescence spectra of naphthyl-based oli-
goarylenes.
Chin. J. Chem. 2010, 28, 1034— 1040
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1037

Zhang et al.
FULL PAPER
Scheme 1 Synthetic route of symmetrically naphthyl-based oligoarylenes
1
038
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Chin. J. Chem. 2010, 28, 1034— 1040

Synthesis and Functional Properties of Symmetrically Naphthyl-Based Oligoarylenes
Table 1 Summaries of physical data of naphthyl-based oligoarylenes
a
4
－1
－1
a,b
a,c
d
e
f
g
g
h
Compound
λ /nm [ε/(10 L•mol •cm )]
λ
em /nm
Φ
E1/2 /V
HOMO /eV
E
g
/eV
T
g
/℃
T
m
/℃
T
dec /℃
3
3
70
89
OPP(4)Ph-TNp
309 (5.50)
0.76 －1.03
0.55 －0.88
0.79 －1.08
－5.83
－5.68
－5.88
3.52
3.04
3.54
149
187
155
319
321
309
597
559
509
3
98 (1.51)
378 (1.60)
58 (1.02)
3
4
70
23
OPP(4)An-TNp
3
3
78
00
OPP(4)OX-TNp
311 (5.65)
4
c
a
b
d
＋
Measured in CHCl
3
. Excited at the absorption maxima. Using quinine sulfate monohydrate (Ф313＝0.48) as a standard. E1/2 vs. Fc /
Fc estimated by CV method using platinum disc electrode as a working electrode, platinum wire as a counter electrode, and SCE as a
reference electrode with an agar salt bridge connecting to the oligomer solution and all the potentials were calibrated with ferrocene,
＋
e
f
g
E1/2(Fc/Fc )＝0.45 V (vs. SCE). HOMO＝E ＋4.8 V. Optical energy gaps estimated from the electronic absorption onset. Deter-
1/2
h
mined by differential scanning calorimeter from re-melt after cooling with a heating rate of 10 ℃/min under N . Determined by thermal
2
gravimetric analyser with a heating rate of 10 ℃/min under N
2
.
lifetimes of all newly synthesized naphthyl-based oli-
goarylenes are very similar which are in the nanosecond
timescale indicating that emission comes from the
singlet excited state.
(b) Martin, R. E.; Diederich, F. Angew. Chem., Int. Ed. 1999,
38, 1350.
(c) Berresheim, A. J.; Müller, M.; Müllen, K. Chem. Rev.
1999, 99, 1747.
(
1
d) Sheats, J. R.; Barbara, P. F. Acc. Chem. Res. 1999, 32,
91.
Electrochemical properties
To investigate the electrochemical properties of
these naphthyl-based oligoarylenes and estimate their
HOMO and LUMO energy levels, cyclic voltammetry
(e) Segura, J. L.; Martin, N. J. Mater. Chem. 2000, 10, 2403.
(f) Bunz, U. H. F. Chem. Rev. 2000, 100, 1605.
(a) Kraft, A.; Grimsadle, A. C.; Holmes, A. B. Angew.
Chem., Int. Ed. 1998, 37, 402.
2
(CV) was carried out using a platinum disk electrode as
the working electrode, a platinum wire as the counter
electrode, and a SCE as the quasi-reference electrode
with an agar salt bridge connecting to the naphthyl-
based oligoarylenes dichloromethane solution and all
(b) Friend, R. H.; Gymer, R. W.; Holmes, A. B.;
Burroughes, J. H.; Marks, R. N.; Taliani, C.; Bradley, D. D.
C.; dos Santos, D. A.; Brédas, J. L.; Lögdlund, M.; Salaneck,
W. R. Nature 1999, 397, 121.
the potentials were calibrated with ferrocene, E1/2(Fc/
(c) Mitschke, U.; Bäuerle, P. J. Mater. Chem. 2000, 10,
1471.
＋
Fc )＝0.45 V (vs. SCE). Generally, the naphthyl-based
oligoarylenes exhibit one reversible one-electron anodic
redox couple which corresponds to removal of electron
from the molecular skeleton forming radical cation. The
HOMO-LUMO energy gaps of these newly synthesized
molecules were estimated to be 3.04—3.54 eV from the
energy thresholds of their electronic absorption spectra
3
(a) Katz, H. E. J. Mater. Chem. 1997, 7, 369.
(b) Horowitz, G. Adv. Mater. 1998, 10, 365.
(c) Garnier, F. Acc. Chem. Res. 1999, 32, 209.
Maillou, T.; Le Moigne, J.; Dumarcher, V.; Rocha, L.; Gef-
froy, B.; Nunzi, J. M. Adv. Mater. 2002, 14, 1297.
Parthenopoulos, D. A.; Rentzepis, P. M. Science 1989, 245,
843.
Müllen, K.; Wegner, G. Electronic Materials: The Oligomer
Approach, Wiley-VCH, Weinheim, 1998.
Strohriegl, P.; Grazulevicius, J. V. Adv. Mater. 2002, 14,
4
5
6
7
8
(
Table 1).
Conclusion
A novel class of symmetrically naphthyl-based oli-
goarylene molecular materials OPP(4)Ph-TNp, OPP(4)-
An-TNp and OPP(4)Ox-TNp with high glass-transition
temperatures, have been developed and were fully
1
439.
(a) Shirota, Y. J. Mater. Chem. 2000, 10, 1.
b) Xiong, M. J.; Li, Z. H.; Wong, M. S. Aust. J. Chem.
007, 60, 603.
(
2
1
13
characterized with H NMR, C NMR, MS, and ele-
mental analysis and found to be in good agreement with
their structures. Their optical, electrochemical and
thermal properties have also been characterized. These
naphthyl-based oligoarylenes show high morphological
9
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(
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T
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＝149—187 ℃) and thermal (Tdec＝509—597 ℃)
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(
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10
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Chin. J. Chem. 2010, 28, 1034— 1040