Synthesis of conjugated hyperbranched polytriazoles containing truxene units by click polymerization

Article abstract of DOI:10.1002/cjoc.201100339

It has been a challenge to synthesize high molecular weight and soluble conjugated hyperbranched poly(1,2,3-triazole)s (hb-PTAs). In this paper a series of soluble hyperbranched polytriazoles, whose number-average molecular weight (M_n) and poly

Full text of DOI:10.1002/cjoc.201100339

FULL PAPER
DOI: 10.1002/cjoc.201100339
Synthesis of Conjugated Hyperbranched Polytriazoles
Containing Truxene Units by Click Polymerization
Li, Dongzhi(李冬至)
Wang, Xin(王欣)
Jia, Yutao(贾玉涛)
Wang, Aiqing(王爱卿)
Wu, Yonggang*(武永刚)
College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China
It has been a challenge to synthesize high molecular weight and soluble conjugated hyperbranched
poly(1,2,3-triazole)s (hb-PTAs). In this paper a series of soluble hyperbranched polytriazoles, whose num-
ber-average molecular weight (Mn) and polydispersity index ranged in (1.2—3.3)×104 and 1.7—3.0, respectively,
were synthesized with A2＋B3 approach. In the polymerization process, diazides A1—A4 and triyne B1 were used
as A2 and B3 monomers; Cu(I)-catalyst, THF and water were used as their reaction system. At room temperature the
final molecular weight could be controlled through reaction time, so finally we obtained soluble conjugated hyper-
branched poly(1,2,3-triazole)s hb-PTAs (1—4). The polymers were soluble in common organic solvents, and all
emitted blue light; the films of polymers emitted yellow and blue light, due to the difference in the aggregation of
their chromophoric units in the solid state. The thermal properties of the final copolymers were analyzed by differ-
ential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
Keywords “click” polymerization, hyperbranched, aggregation
Introduction
the production precipitated from the reaction mix-
tures.[19,21,53] Two AB2-type monomers of azidoary-
lenediynes with a general formula of N3-Ar-(C≡CH)2
prepared by two groups in Germany and Belgium failed
to be converted into soluble polymer,[54,55] A2＋B3 type
monomers are reported by Tang groups, which also
failed to form soluble polymer using the copper Cu(I)-
catalyzed systems.[19] Recently, Li and Tang et al. have
reported the synthesis of the soluble hypebranched
polytriazoles.[56-58] The poor activity or low solubility of
the phen-monomers, which one has more influence on
the polymerization under the copper Cu(I)-catalysis? So
we brought out a series of reactions to find the best po-
lymerization condition.
Hyperbranched polymer can be obtained by the
self-condensation of ABn monomers,[48] but there are
some limitations such as tedious synthesis for asymmet-
ric functionality and self-oligomerization during storage.
The A2＋B3 type of polymerization has been demon-
strated to be a facile method to achieve hyperbranched
polymers, as the monomers are easily obtained and free
of the self-oligomerization problem encountered in the
ABn system. In our work , we took the A2＋B3 type of
polymerization to synthesize a series of conjugated hy-
perbranched polymer hb-PTAs (1 — 4) (hb-PTAs1,
Because of its remarkable features such as nearly
quantitative yields, mild reaction conditions, broad tol-
erance toward functional groups, low susceptibility to
side reactions, and simple product isolation, the “click
reaction” has been attempted to develop into a new po-
lymerization technique.[1-16] A “click reaction” can cre-
ate functional molecules with heteroatom links from
reactive modular building blocks in high efficiency un-
der benign conditions through simple isolation proce-
dures.[17-20] A number of click reactions have been ex-
plored and identified, especially, the copper Cu(I)-
catalyzed Huisgen cycloaddition, also termed as the
Sharpless “click” reaction, that is the typical example
and has been successfully applied to macromolecular
chemistry.[21-33]
Various polymeric materials including block co-
polymers, dendrimers, and complex macromolecular
structure are synthesized using the “click reaction”,[34-50]
however the conjugated hyperbranced polymers synthe-
sized by the “click reaction” are still scarcely reported,
because the Cu(I)-catalyzed polymerizations of ary-
lenediazides (N3-Ar-N3) and arylenediynes (HC≡C-Ar-
C≡CH) (Ar＝phenyl, pyridyl, fluorenyl, etc.) were
sluggish, taking as long as 7—10 d to finish, and usually
*
E-mail: wuyonggang@hbu.edu.cn
Received September 15, 2011; accepted October 31, 2011; published online March 7, 2012.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201100339 or from the author.
Chin. J. Chem. 2012, 30, 861—868
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Li et al.
FULL PAPER
hb-PTAs2, hb-PTAs3 and hb-PTAs4) (Scheme 1), the
polymers were soluble in common organic solvents, and
the number-average molecular weight (Mn) and
polydispersity index ranged in (1.2—3.3)×104 and 1.7
—3.0, respectively. The A2 monomers A1—A4 easily
react with the B3 monomer (B1) in THF/H2O and
Cu(I)-catalyzed system, moreover, the polymers will
precipitate from the solution if the reaction time is too
long. The precipitation of hb-PTAs1 and hb-PTAs2 is
difficultly dissolved, otherwise the precipitation of
hb-PTAs3 and hb-PTAs4 is easily soluble in common
solution. The soluble Polymers of hb-PTAs1 and
hb-PTAs2 can be obtained by controlling reaction time.
Finally we synthesized soluble conjugated hyper-
branched polymer by click polymerization. All the
polymer emitted blue light in solution; and the films of
polymers emitted yellow and blue light due to the dif-
ference in the aggregation.
amino-4-bromobenzene,[60] the A2-type monomer of
diazides A1,[19] and 2,7,12-triiododecaethyltruxene[61]
were prepared according to literature procedures. The
catalyst precursor Pd(PPh3)4 was prepared according to
the literature.[53] All solvents were purified and dried by
standard methods. The reactions were monitored by
TLC with silica gel 60 F254 (Merck, 0.2 mm). Column
chromatography was carried out on silica gel (200—300
1
mesh). H and 13C NMR spectra were recorded on a
Bruker AV600 spectrometer in CDCl3. The gel permea-
tion chromatography (GPC) measurements were per-
formed on a Waters 410 system using polystyrene stan-
dards with THF as an eluent at 30 ℃, a set of one col-
umn of PL gel MIX-C (500—3×106) was equipped.
Electronic absorption spectra were obtained on a SHI-
MADZU UV-visible spectrometer model UV-2500.
Fluorescence spectra were recorded on a SHIMADZU
RF-5301PC. Elemental analyses were performed on a
Flash EA 1112 analyzer. The thermal gravimetric
analysis (TGA) (Pyris 1 TGA) and differential scanning
calorimetry (DSC) (TA 2910) measurements were car-
ried out under a nitrogen atmosphere at a heating rate of
10 ℃/min. The matrix assisted laser desorption ioniza-
tion time of flight (MALDI-TOF) MS spectrometric
measurements were performed on a Bruker BIFLEXIII
mass spectrometer.
Experimental
Materials and instruments
All chemicals were purchased from Aldrich or Acros
and used without further purification. 9,9-Dihexylfluo-
rene, 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxa-borolan-
2-yl)-9,9-dihexylfluorene,[59] N-(t-butoxycarbonyl)-1-
Scheme 1 Structure of hypbranched polymers hb-PTAs (1—4)
N
N
N
N
N
N
R1
R1
R1
R1
R1
R1
N C4H8O
N N
C4H8O
N
N N
R1
R1
R1
R1
R1
R1
hp-PTAs1
N
N
N
N
N
N
hp-PTAs2
N
N
N
N
N
N
R1
R1
R1
R1
R1
R1
N
N N
N
N N
R1
R1
R1
R1
R2
R2
R1
R2
R1
R2
N
N
N
N
hp-PTAs3
N
N
hp-PTAs4
R1 = C10H21
R2 = C6H13
862
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Chin. J. Chem. 2012, 30, 861—868

Synthesis of Conjugated Hyperbranched Polytriazoles Containing Truxene Units
General procedure for the synthesis of monomers A1
—A4 from the amine precursor
13.6. MALDI-TOF m/z: calcd 364, found 364.
Synthesis of 2,7-diazide-9,9-dihexylfluorene (A3)
The amine precursor monomers were dissolved in
2% aqueous hydrochloric acid, cooled to 0 ℃, then
NaNO2 was added. The mixture was stirred for 1 h at 0
℃, NaN3 was added and stirred for 4 h at 0 ℃. Water
and CH2Cl2 (50 mL) were added, the organic layer was
separated, the aqueous layer was extracted with CH2Cl2
twice, and the combined organic layers were dried over
Na2SO4. After removal of the solvent, the crude product
was chromatographically purified on silica gel eluting
with hexane to afford A1—A4.
2,7-Diamine-9,9-dihexylfluorene (0.40 g, 1.1 mmol),
NaNO2 (0.18 g, 2.3 mmol) and NaN3 (0.16 g, 2.5 mmol)
were used, A3 was obtained as yellow solid (0.42 g,
1
92%). H NMR (CDCl3, 600 MHz) δ: 7.60 (d, J＝8.4
Hz, 2H), 7.00 (d, J＝8.4 Hz, 2H), 6.94 (s, 2H), 1.92 (t,
J＝8.4 Hz, 4H), 1.13—1.10 (m, 4H), 1.08—1.03 (m,
8H), 0.77 (t, J＝7.2 Hz, 6H), 0.59—0.55 (m, 4H); 13C
NMR (CDCl3, 150 MHz) δ: 152.6, 138.8, 137.6, 120.5,
117.9, 113.6, 55.5, 40.4, 31.5, 29.6, 23.6, 22.6, 14.0.
Anal. calcd for C25H32N6: C 72.08, H 7.74, N 20.17;
found C 72.02, H 7.47, N 19.30.
Synthesis of monomer A2
1,4-Diaminebenzene (1.00 g, 9.2 mmol), NaNO2
(1.50 g, 21.7 mmol) and NaN3 (1.50 g, 23 mmol) were
used, A2 was obtained as brown solid (1.40 g, 94%). 1H
NMR (CDCl3, 600 MHz) δ: 7.06 (s, 4H); 13C NMR
(CDCl3, 150 MHz) δ: 136.7, 120.4. Anal. calcd for
C6H4N6: C 45.00, H 2.52, N 52.48; found C 45.05, H
2.50, N 52.42.
Synthesis of compound 3
A mixture of 2,7-bis(4,4,5,5-tetramethyl-1,3,2-di-
oxaborolan-2-yl)-9,9-dihexylfluorene (0.15 g, 0.26
mmol), N-(t-butoxycarbonyl)-1-amino-4-bromobenzene
(0.15 g, 0.55 mmol), NaHCO3 (0.50 g, 5.6 mmol), H2O
(5 mL), and THF (25 mL) was carefully degassed be-
fore Pd(PPh3)4 (8 mg, 0.08 mmol) was added. The mix-
ture was refluxed for 24 h under stirring. Water and
CH2Cl2 (50 mL) were added, then the organic layer was
separated, the aqueous layer was extracted with CH2Cl2
(×2), and the combined organic layers were dried over
Na2SO4. After removal of the solvent, the crude product
was chromatographically purified on silica gel eluting
with CH2Cl2/hexane (1∶1, V/V) to afford compound 3
Synthesis of 2,7-dinitro-9,9-dihexylfluorene (1)
A mixture of 9,9-dihexylfluorene (1.00 g, 3.0 mmol),
acetic acid (80 mL), condensed sulfuric acid (10 mL)
and condensed nitric acid (2 mL) was stirred for 12 h at
95 ℃, then cooled to room temperature and the yellow
precipitation was filtered. The crude product was chro-
matographically purified on silica gel eluting with
CH2Cl2/hexane (1∶3, V/V) to afford 2,7-dinitro-9,9-
1
as a white solid (0.15 g, 81%). H NMR (CDCl3, 600
1
MHz) δ: 7.73 (d, J＝7.8 Hz, 2H), 7.60 (d, J＝8.4 Hz,
4H), 7.54 (d, J＝7.8 Hz, 2H), 7.52 (s, 2H), 7.46 (d, J＝
8.4 Hz, 4H), 6.57 (s, 2H), 2.05—2.00 (m, 4H), 1.55 (s,
18H), 1.12—1.03 (m, 12H), 0.76—0.71 (m, 10H); 13C
NMR (CDCl3, 150 MHz) δ: 152.7, 151.7, 139.8, 139.4,
137.6, 136.5, 127.7, 125.7, 121.1, 119.9, 118.8, 55.2,
40.4, 31.5, 29.7, 28.3, 23.8, 22.6, 14.0. Anal. calcd for
C47H60N2: C 78.73, H 8.43, N 3.91; found C 78.63, H
8.47, N 3.80.
dihexylfluorene (1) as a yellow solid (1.10 g, 82%). H
NMR (CDCl3, 600 MHz) δ: 8.33 (d, J＝8.4 Hz, 2H),
8.26 (s, 2H), 7.92 (d, J＝8.4 Hz, 2H), 2.12—2.09 (m,
4H), 1.12—1.08 (m, 8H), 1.03—0.97 (m, 4H), 0.76 (t,
J＝7.2 Hz, 6H), 0.57—0.54 (m, 4H); 13C NMR (CDCl3,
150 MHz) δ: 153.5, 148.5, 144.7, 123.2, 121.6, 118.5,
56.5, 39.8, 31.4, 29.4, 23.8, 22.5, 13.9. Anal. calcd for
C25H32N2O4: C 70.73, H 7.60, N 6.60; found C 70.60, H
7.44, N 6.43.
Synthesis of monomer A4
Synthesis of 2,7-diamine-9,9-dihexylfluorene (2)
A mixture of compound 3 (0.12 g, 0.17 mmol), ether
(30 mL) and condensed aqueous hydrochloric acid (20
mL) was stirred for 24 h at room temperature. After re-
moval of the ether, 2% aqueous hydrochloric acid (20
mL) was added. NaNO2 (0.025 g, 0.36 mmol) was
added and the mixture was stirred for 1 h at 0 ℃, then
NaN3 (0.035 g, 0.54 mmol) was added and stirred for 12
h under 4 ℃. Water and CH2Cl2 (50 mL) were added,
the organic layer was separated, the aqueous layer was
extracted with CH2Cl2 (×2), and the combined organic
layers were dried over Na2SO4. After removal of the
solvent, the crude product was chromatographically pu-
rified on silica gel eluting with hexane to afford com-
A mixture of 2,7-dinitro-9,9-dihexylfluorene (0.50 g,
1.2 mmol), zinc powder (2.00 g), anhydrous CaCl2 (0.30
g), alcohol (30 mL) and water (10 mL) was refluxed for
5 h, and the hot mixture was filtered to remove the zinc
powder. Water and CH2Cl2 (50 mL) were added, then
the organic layer was separated, the aqueous layer was
extracted with CH2Cl2 (×2), and the combined organic
layers were dried over Na2SO4. After removal of the
solvent, the crude product was chromatographically pu-
rified on silica gel eluting with ethyl acetate/hexane
(1∶3, V/V) to afford 2,7-diamine-9,9-dihexylfluorene
1
(2) (0.45 g, 94%). H NMR (CDCl3, 400 MHz) δ: 7.34
(d, J＝7.7 Hz, 2H), 6.62 (d, J＝7.7 Hz, 4H), 3.52 (br s,
4H), 1.84 (t, J＝8.2 Hz, 4H), 1.17—1.13 (m, 4H), 1.10
—1.03 (m, 8H), 0.78 (t, J＝7.1 Hz, 6H), 0.69—0.64 (m,
4H); 13C NMR (CDCl3, 100 MHz) δ: 158.4, 151.2,
144.0, 126.5, 118.4, 109.6, 54.2, 40.4, 31.1, 29.4, 23.1,
1
pound A4 as a yellow solid (0.076 g, 80%). H NMR
(CDCl3, 600 MHz) δ: 7.76 (d, J＝7.8 Hz, 2H), 7.66 (d,
J＝8.4 Hz, 4H), 7.55 (d, J＝7.8 Hz, 2H), 7.53 (s, 2H),
7.13 (d, J＝8.4 Hz, 4H), 2.05—2.01 (m, 4H), 1.12—
Chin. J. Chem. 2012, 30, 861—868
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FULL PAPER
1.04 (m, 12H), 0.76—0.70 (m, 10H); 13C NMR (CDCl3,
150 MHz) δ: 151.8, 140.1, 139.1, 139.0, 138.5, 128.5,
125.8, 121.2, 120.1, 119.9, 55.3, 40.4, 31.5, 29.7, 23.8,
22.5, 14.0. Anal. calcd for C37H40N6: C 78.14, H 7.09, N
14.78; found C 78.09, H 7.13, N 14.83.
used. hb-PTAs1 was obtained as yellow solid (0.11 g,
79%). H NMR (CDCl3, 600 MHz) δ: 8.45—8.31 (br s,
1
3H), 8.01—8.00 (br s, 2H), 7.93 (br s, 2H), 7.83 (br s,
2H), 7.58 (br s, 3H), 6.88 (br s, 6H), 4.58 (br s, 3H),
4.03 (br s, 3H), 2.96 (br s, 6H), 2.13 (br s, 9H), 1.64 (br
s, 3H), 1.11 (br s, 48H), 0.87 (br s, 54H), 049 (br s,
12H). Anal. calcd for C114H168N9O3: C 79.95, H 9.89, N
7.36; found C 76.33, H 9.25, N 6.52.
Synthesis of 2,7,12-trimethylsilicaethynyl-decaethyl-
truxene (compound 4)
A mixture of 2,7,12-triiododecaethyltruxene (2.10 g,
1.5 mmol), trimethylsilicaethyne (3 mmol), THF (25
mL) and diisopropylamine (13 mL) was carefully de-
gassed before Pd(PPh3)2Cl2 (0.12 g, 0.17 mmol) was
added. The mixture was refluxed for 24 h under nitro-
gen, vacuumed to dryness, and the crude product was
chromatographically purified on silica gel eluting with
hexane to afford compound 4 as a slightly yellow solid
Synthesis of polymer hb-PTAs2
A2 (40 mg, 25 mmol) and B (200 mg, 16 mmol)
were used. hb-PTAs2 was obtained as yellow solid
(0.15 g, 62%). 1H NMR (CDCl3, 600 MHz) δ: 8.49 (br s,
3H), 8.19 (br s, 5H), 8.05 (br s, 4H), 7.51 (br s, 3H),
3.05 (br s, 6H), 2.18 (br s, 6H), 1.18 (br s, 48H), 0.89
(br s, 54H), 0.58 (br s, 12H). Anal. calcd for C102H144N9:
C 81.87, H 9.70, N 8.42; found C 80.95, H 10.24, N
4.41.
1
(1.97 g, 90%). H NMR (CDCl3, 600 MHz) δ: 8.26 (d,
J＝7.8 Hz, 3H), 7.53 (s, 3H), 7.51 (d, J＝7.8 Hz, 3H),
2.87—2.83 (m, 6H), 2.07—2.02 (m, 6H), 1.19—1.14
(m, 12H), 1.12—1.07 (m, 12H), 1.06—1.02 (m, 12H),
1.00—0.96 (m, 12H), 0.90—0.87 (m, 18H), 0.83—0.80
(m, 36H), 0.47—0.40 (m, 12H), 0.31 (s, 27H); 13C
NMR (CDCl3, 150 MHz) δ: 153.5, 146.0, 140.5, 137.9,
130.4, 125.5, 124.3, 120.9, 105.9, 94.4, 55.7, 36.8, 29.8,
29.6, 29.4, 29.3, 23.9, 22.6, 14.1. Anal. calcd for
C102H162Si3: C 83.19, H 11.09; found C 83.22, H 11.15.
Synthesis of polymer hb-PTAs3
A3 (50 mg, 12 mmol) and B (100 mg, 8 mmol) were
used. hb-PTAs3 was obtained as yellow solid (0.91 g,
1
61%). H NMR (CDCl3, 600 MHz) δ: 8.46 (br s, 6H),
8.14 (br s, 3H), 7.97 (br s, 9H), 7.91 (br s, 2H), 7.50 (br
s, 3H), 3.05 (br s, 6H), 2.12 (br s, 12H), 1.96 (br s, 6H),
1.13 (br s, 66H), 0.88 (br s, 63H), 0.59 (br s, 18H). Anal.
calcd for C131H186N9: C 83.38, H 9.94, N 6.68; found C
82.41, H 9.87, N 5.23.
Synthesis of monomer 2,7,12-triethynyl-decaethyl-
truxene (B1)
TBAF in THF (8 mL, 1 mol/L) was added to the
mixture of compound 4 (1.8 g, 1.2 mmol) and di-
chloromethane (10 mL) at 0 ℃, and stirred for 1 h at 0
℃. The mixture was poured to silica gel and eluted with
dichloromethane to afford compound monomer B1 as a
Synthesis of polymer hb-PTAs4
A4 (68 mg, 12 mmol) and B (100 mg, 8 mmol) were
used. hb-PTAs4 was obtained as yellow solid (0.12 g,
1
71%). H NMR (CDCl3, 600 MHz) δ: 8.46 (br s, 3H),
1
8.14 (br s, 3H), 8.00 (br s, 8H), 7.92 (br s, 7H), 7.73 (br
s, 9H), 3.02 (br s, 6H), 2.13 (br s, 12H), 1.98 (br s, 6H),
1.11 (br s, 66H), 0.86 (br s, 63H), 0.57 (br s, 18H). Anal.
calcd for C149H198N9: C 84.61, H 9.44, N 5.96; found C
82.95, H 9.71, N 3.63.
slightly yellow solid (1.51 g, 98%). H NMR (CDCl3,
600 MHz) δ: 8.31 (d, J＝7.8 Hz, 3H), 7.60 (s, 3H), 7.56
(d, J＝7.8 Hz, 3H), 3.20 (s, 3H), 2.92—2.86 (m, 6H),
2.10—2.05 (m, 6H), 1.23—1.20 (m, 12H), 1.15—1.11
(m, 12H), 1.09—1.05 (m, 12H), 1.04—0.99 (m, 12H),
0.93—0.89 (m, 18H), 0.86—0.82 (m, 36H), 0.54—0.42
(m, 12H); 13C NMR (CDCl3, 150 MHz) δ: 153.6, 146.1,
140.7, 137.9, 130.4, 125.9, 124.4, 120.0, 84.4, 55.7,
36.8, 29.7, 29.6, 29.4, 29.3, 23.9, 22.6, 14.1. MALDI-
TOF m/z: calcd 1256, found 1255.
Results and Discussion
Synthesis of macromonomers and hyperbranched
polymers
Monomers diazides A2 (A1—A4) and triyne B3
(structure shown in Scheme 2) containing flexible alkyl
chains were designed to realize the planned A2＋B3 ap-
proach to hb-PTAs. All the monomers can be facilely
taken into consideration by click polymerizations with
Cu(I)-catalyst, and the hyperbranched polymers from
the designed monomers were easily soluble in common
solution such as dichloromethane, toluene and THF etc.
The synthetic routes to monomers are outlined in
Scheme 3. the monomers (A1—A4) were synthesized
by substitution reaction with sodium azide from the
amine precursors, 2,7-diamine-9,9-dihexylfluorene was
obtained by two step reaction of nitration and reduction
from the 9,9-dihexylfluorene in good yields of 82% and
94%; the compound 3 was synthesized by Suzuki cou-
General procedure for copper-catalyzed 1,4-regio-
regular click polymerization
A mixture of monomer A1—A4, monomer B1, THF
(5 mL) and H2O (1 mL) was carefully degassed before
fresh aqueous sodium ascorbate (50 μL, 1 mol/L) and
fresh aqueous CuSO4 (25 μL, 1 mol/L) were added. The
mixture was stirred for hours. The mixture was diluted
with methanol, and the precipitate was filtered. The
crude polymers were repurified by precipitation from
THF into hexane again and dried under vacuum to give
polymer.
Synthesis of polymer hb-PTAs1
A1 (36 mg, 12 mmol) and B (100 mg, 8 mmol) were
864
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© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2012, 30, 861—868

Synthesis of Conjugated Hyperbranched Polytriazoles Containing Truxene Units
pling reaction with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)-9,9-dihexylfluorene and N-(t-butoxy-
carbonyl)-1-amino-4-bromobenzene in yield of 81%,
and after removing the Boc-group, the intermediate was
directly used in the next diazotization reaction, finally
substituted by sodium azide to afford monomer A4 in
total yield of 80%. The monomer B1 was prepared by
coupling with (trimethylsilyl)acetylene and base-cata-
lyzed disilylation and unprotecting trimethylsilyl group
in high yields of 90% and 98%.
Scheme 3 Synthesis of monomers and hypbranched polymers
hb-PTAs (1—4)
(1) HCl, NaNO2
(2) NaN3
H2N
NH2
A2
HOAc, HNO2
NO2
NO2
H13C6
C6H13
H13C6
C6H13
1
Scheme 2 Structures of monomers A1—A4, and B1
(1) HCl, NaNO2
(2) NaN3
Zn
NH2
NH2
A3
_
_
+
OC4H8 N N
+
H13C6
C6H13
N
N N C4H8O
N
2
A1
A2
O
O
O
O
H
N
B
B
+
Br
Boc
Boc
_
N N
_
+
+
N
N N
N
H13C6
C6H13
_
N N
_
N N
H
H
N
+
+
Suzuki
Boc
N
N
N
H13C6
C6H13
H13C6 C6H13
3
A3
(1) HCl, NaNO2
_
N N
_
N N
A4
+
+
N
N
(2) NaN3
I
H
13C6 C6H13
C10H21
C10H21
A4
H21C10
Ph(PPh3)2Cl2
HC TMS
C10H21
I
H21C10
C10H21
C
H21C10
H21C10
C10H21
H21C10
I
TMS
C10H21
H21C10
B1
C10H21
C10H21
1,3-Dipolar polycycloadditions of diazides and triyne
H21C10
H21C10
TABF
B1
TMS
The click polycycloadditions can be brought out by
using thermal polymerizations and the Cu(I), Ru(II)
catalyzed polymerizations, to prepare regioregular
polymers at a fast rate. We paid attention to the metal
catalysts used in the azide-alkyne click reactions. In our
work the CuSO4/sodium ascorbate catalyst in a
THF/water mixture was used to prepared the hyper-
branched polymers. The incompatibility between the
growing hb-PTA species and the aqueous medium may
have induced the polymers to aggregate and hence pre-
cipitate. In fact all the polymers were precipitated from
the THF/water mixture, otherwise the polymers
hb-PTAs1 and hb-PTAs2 can be mostly soluble in
common solution, the polymers hb-PTAs3 and
hb-PTAs4 are all soluble in common solution, and the
molecule weights were high. The click polycycloaddi-
C10H21
H21C10
4
TMS
hb-PTAs1
B1
B1
B1
B1
+
+
A1
A2
SuzuKi
hb-PTAs2
hb-PTAs3
hb-PTAs4
A3
A4
+
+
tions were brought out under the standard click reaction
Chin. J. Chem. 2012, 30, 861—868
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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865

Li et al.
FULL PAPER
conditions, the molar ratio of the A2 and B3 was 3∶2.
Its Mn, Mw and PDI values were estimated by GPC cali-
brated by linear polystyrene standards. The yields of
polymers hb-PTAs (1—4) were 58%, 76%, 63% and
75%, respectively. The molecular structure of the poly-
Table 1 Physical properties of hypbranched ladder type poly-
mers hb-PTAs (1—4)
Polymer
Mn
Mw
PDI
Td/℃
hb-PTAs1
hb-PTAs2
hb-PTAs3
hb-PTAs4
12300
22300
27300
33400
24800
67300
47600
87200
2.16
3.00
1.74
2.61
373
351
360
342
1
mers was verified by H NMR spectroscopy, MALDI-
TOF and elemental analysis.
The IR spectra of hb-PTAs (1—4) polymers are
shown in Figure 1; those of monomers A3 and B1 are
given in the figure for comparison. Monomer B1 ab-
sorbs at 3299 and 2104 cm－ due to its ≡C—H and
1
C≡C stretching vibrations, respectively. Monomer A3
exhibits a strong absorption band at 2094 cm－ associ-
1
ated with the stretching of its azido group. All these ab-
sorption bands become weaker in intensity in the spec-
trum of hb-PTAs1, and become nearly invisible in the
spectra of higher molecular weight polymers hb-PTAs2,
hb-PTAs3 and hb-PTAs4. This suggests that most of the
ethynyl and azido groups of the monomers have been
transformed to the triazole rings of the polymer by the
polymerization reaction.
Figure 2
GPC elution traces of hypbranched polymers
hb-PTAs (1—4) and standard (Mn＝30300).
Figure 1 IR spectra of hypbranched polymers hb-PTAs (1—4).
The molecule test and thermal properties
Figure 3 TGA traces of hypbranched polymers hb-PTAs (1—
4).
The molecular weights of polymers hb-PTAs (1—4)
were determined by gel permeation chromatography
(GPC) with THF as the eluent, calibrated against poly-
styrene standards. As shown in Table 1 and Figure 2,
the GPC analysis indicated that the number-average
molecular weight (Mn) and polydispersity index of the
polymers are in the ranges (1.2—3.3)×104 and 1.7—
3.0, respectively. The elution curve of polystyrene
standards (Mn＝30300) was given in the Figure 2 as an
example.
The thermal properties of the hyperbranchced ladder
type polymers hb-PTAs (1—4) were investigated by
thermogravimetric analysis (TGA) and differential scan-
ning calorimetry (DSC) in a nitrogen atmosphere. All
polymers exhibited good thermal stability with onset
degradation temperatures (Td) above 330 ℃ (Figure 3).
Neither a glass transition process (Tg) nor other thermal
processes (such as liquid crystal phase) were observed
from 25 to 300 ℃ in the DSC trace of second heating
(10 ℃/min).
Optical properties
Figure 4 shows the absorption and PL spectra of the
hyperbranched polymers in dilute solution of chloro-
form. The polymer hb-PTAs1 exhibited an absorption
and emission band with the maximum at about 326 and
381 nm, the polymers hb-PTAs (2—4) exhibited simi-
lar absorption that were broad and peaked at around
335, 337 and 340 nm, respectively, the absorption
maxima slightly red-shifted with the increasing linear
length. The polymer hb-PTAs2 exhibited an emission
band in the blue region with the peak at 382 nm with a
shoulder at 483 nm, the polymer hb-PTAs3 shows
broad blue emission with two peaks at 382 and 403 nm,
the polymer hb-PTAs4 exhibited the blue emission
band with two peaks at 382 and 402 nm with a shoulder
at 462 nm. All the emission peaks of the polymers in
solution show no obvious change.
866
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© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2012, 30, 861—868

Synthesis of Conjugated Hyperbranched Polytriazoles Containing Truxene Units
branched polymers (hb-PTAs1, hb-PTAs, hb-PTAs, and
hb-PTAs) via the Cu(I)-catalyzed click reaction by an
“A2＋B3” approach. These hyperbranched polymers are
soluble in common organic solvents, and their num-
ber-average molecular weight (Mn) values were (1.2—
3.3)×104 g/mol with polydispersity indexes (PDI) be-
ing in the range of 1.7—3.0. All the polymers exhibited
good thermal stability with onset degradation tempera-
tures (Td) above 330 ℃ (Figure 3). Neither a glass
transition process (Tg) nor other thermal processes (such
as liquid crystal phase) were observed from 25 to 300
℃ in the DSC trace. All the polymers give strong blue
emission in solutions, and evident aggregations were
observed in film states.
Figure 4 UV-Vis absorption and PL spectra of hypbranched
polymers hb-PTAs (1—4) in chloroform.
Acknowledgements
This work was supported by National Natural Sci-
ence Foundation of China (Nos. 20904008 and
20574016), the Science Research Project of the De-
partment of Education of Hebei Province (Nos. 2009307
and B2010000214).
Solid films of polymers hb-PTAs (1—4) on quartz
plates used for UV-Vis and fluorescence were prepared
by spin-coating from a 10 mg/mL THF solution at 1500
r/min. The UV-Vis and photoluminescence spectra of
hb-PTAs (1—4) are shown in Figure 5. In contrast to
their solution spectra, the absorption bands of hb-PTAs
(1—4) in thin film were slightly broader and red-shifted
about 4 nm, and significant differences were observed
between the film and solution photoluminescence spec-
tra of the polymers hb-PTAs (1—4), which can be at-
tributed to the change in the conformation. In the re-
ported literature all the polymers were nearly nonfluo-
rescent in the solid state, although their dilute solutions
emitted UV light, suggesting that the polymer lumines-
cence was quenched by aggregate formation. The hy-
perbranched polymer hb-PTAs (1—4) exhibited an
emission band in the blue region with the peak at about
360 nm, but an evident low energy band at 470 nm is
stronger than in solution. The results showed that the
hyperbranched structure can minimize this tendency for
aggregation, but there still exist aggregations in the film.
References
[1] Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem., Int. Ed.
2001, 40, 2004.
[2] Helms, B.; Mynar, J. L.; Hawker, C. J.; Fréchet, J. M. J. J. Am.
Chem. Soc. 2004, 126, 15020
[3] Díaz, D. D.; Punna, S.; Holzer, P.; McPherson, A. K.; Sharpless, K.
B.; Fokin, V. V.; Finn, M. G. J. Polym. Sci., Part A: Polym. Chem.
2004, 42, 4392
[4] Scheel, A. J.; Komber, H.; Voit, B. I. Macromol. Rapid Commun.
2004, 25, 1175.
[5] Gress, A.; Völkel, A.; Schlaad, H. Macromolecules 2007, 40, 7928.
[6] Binder, W. H.; Sachsenhofer, R. Macromol. Rapid Commun. 2007,
28, 15.
[7] Binder, W. H.; Sachsenhofer, R. Macromol. Rapid Commun. 2008,
29, 952.
[8] Li, C. M.; Finn, G. J. Polym. Sci., Part A: Polym. Chem. 2006, 44,
5513.
[9] Such, G. K.; Quinn, J. F.; Quinn, A.; Tjipto, E.; Caruso, F. J. Am.
Chem. Soc. 2006, 128, 9318.
[10] Bu, H.-B.; Götz, G.; Reinold, E.; Vogt, A.; Schmid, S.; Blanco, R.;
Segurab, J. L.; Bäuerle, P. Chem. Commun. 2008, 1320.
[11] Codelli, J. A.; Baskin, J. M.; Agard, N. J.; Bertozzi, C. R. J. Am.
Chem. Soc. 2008, 130, 11486.
[12] Fleischmann, S.; Komber, H.; Voit, B. Macromolecules 2008, 41,
5255.
[13] Eugene, D. M.; Grayson, S. M. Macromolecules 2008, 41, 5082.
[14] Li, Z. A.; Yu, G.; Hu, P.; Ye, C.; Liu, Y. Q.; Qin, J. G.; Li, Z. Mac-
romolecules 2009, 42, 1589
[15] Qian, A. J.; Lam, J. W. Y.; Tang, B. Z. Chem. Soc. Rev. 2010, 39,
2522.
[16] Harvison, M. A.; Lowe, A. B. Macromol. Rapid Commun. 2011, 32,
779.
[17] Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B.
Angew. Chem., Int. Ed. 2002, 41, 2596.
[18] Zhang, L.; Chen, X. G.; Xue, P.; Sun, H. H. Y.; Williams, I. D.;
Sharpless, K. B.; Fokin, V. V.; Jia, G. C. J. Am. Chem. Soc. 2005,
127, 15998.
Figure 5 UV-Vis absorption and PL spectra of hypbranched
polymers hb-PTAs (1—4) in film.
Conclusions
[19] Qin, A. J.; Lam, J. W. Y.; Jim, C. K. W.; Zhang, L.; Yan, J. J.;
Häussler, M.; Liu, J. Z.; Dong, Y. Q.; Liang, D. H.; Chen, E. Q.; Jia,
We have successfully prepared a series of hyper-
Chin. J. Chem. 2012, 30, 861—868
© 2012 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
867

Li et al.
FULL PAPER
G. C.; Tang, B. Z. Macromolecules 2008, 41, 3808.
[20] Gao, H. F.; Louche, G. B.; Sumerlin, S.; Jahed, N.; Golas, P.; Maty-
jaszewski, K. Macromolecules 2005, 38, 8979.
Hawker, C. J. Chem. Commun. 2006, 2774.
[41] Mynar, J. L.; Choi, T. L.; Yoshida, M.; Kim, V.; Hawker, C. J.; Fré-
chet, J. M. J. Chem. Commun. 2005, 5169.
[21] van Steenis, D. J. V. C.; David, O. R. P.; van Strijdonck, G. P. F.;
Van Maarseveen, J. H.; Reek, J. N. H. Chem. Commun. 2005, 4333.
[22] Bertrand, P.; Gesson, J. P. J. Org. Chem. 2007, 72, 3596.
[23] Baut, N. L.; Diaz, D. D.; Punna, S.; Finn, M. G.; Brown, H. R. Poly-
mer 2007, 48, 239.
[42] Lee, J. W.; Kim, B. K.; Jin, S. H.; Kor, B. Chem. Soc. 2005, 26, 833.
[43] Lee, J. W.; Kim, J. H.; Kim, B. K.; Shin, W. S.; Jin, S. H. Tetrahe-
dron 2006, 62, 894.
[44] Papp, I.; Dernedde, J.; Enders, S.; Haag, R. Chem. Commun. 2008,
5851.
[24] Liu, Y.; Díaz, D. D.; Accurso, A. A.; Sharpless, K. B.; Fokin, V. V.;
Finn, M. G. J. Polym. Sci., Part A: Polym. Chem. 2007, 45, 5182.
[25] Ornelas, C.; Ruiz Aranzaes, J.; Cloutet, E.; Alves, S.; Astruc, D.
Angew. Chem., Int. Ed. 2007, 46, 872.
[26] O’Reilly, R. K.; Joralemon, M. J.; Wooley, K. L.; Hawker, C. J.
Chem. Mater. 2005, 17, 5976.
[45] Lee, J. W.; Kim, J. H.; Kim, B. K.; Kim, J. H.; Shin, W. S.; Jin, S. H.
Tetrahedron 2006, 62, 9193.
[46] Liu, Y.; Díaz, D. D.; Accurso, A. A.; Sharpless, K. B.; Fokin, V. V.;
Finn, M. G. J. Polym. Sci., Part A: Polym. Chem. 2007, 45, 5182.
[47] Ergin, M.; Kiskan, B.; Gacal, B.; Yagci, Y. Macromolecules 2007,
40, 4724.
[27] O’Reilly, R. K.; Joralemon, M. J.; Hawker, C. J.; Wooley, K. L. J.
Polym. Sci., Part A: Polym. Chem. 2006, 44, 5203.
[28] Johnson, J. A.; Finn, M. G.; Koberstein, J. T.; Turro, N. J. Macromol.
Rapid Commun. 2008, 29, 1052.
[29] Lau, K. N.; Chow, H. F.; Chan, M. C.; Wong, K. W. Angew. Chem.,
Int. Ed. 2008, 47, 6912.
[30] Lodge, T. P. Macromolecules 2009, 42, 3827.
[48] Saha, A.; Ramakrishnan, S. Macromolecules 2009, 42, 4028.
[49] Konkolewicz, D.; Gray-Weale, A.; Perrier, S. J. Am. Chem. Soc.
2009, 131, 18075.
[50] Semsarilar, M.; Ladmiral, V.; Perrier, S. Macromolecules 2010, 43,
1438.
[51] Lee, R. S.; Wu, K. P. J. Polym. Sci., Part A: Polym. Chem. 2011, 49,
3163.
[31] Chen, L.; Shi, N.; Qian, Y.; Xie, L. H.; Fan, Q. L.; Huang, W. Prog.
Chem. 2010, 22, 406.
[52] Kong, L. Z.; Qiao, H. M.; Jiang, B. B. Acta Chim. Sinica 2011, 69,
1817 (in Chinese).
[32] Wang, J.; He, X. P.; Gao, L. X.; Sheng, L.; Shi, X. X.; Li, J.; Chen,
G. R. Chin. J. Chem. 2011, 29, 1227 (in Chinese).
[33] Zhang, T.; Wu, Y. P.; Zhang, Z. H.; Ding, X. B.; Peng, Y. X. Chem.
J. Chin. U. 2010, 31, 2303.
[53] Bakbak, S.; Leech, P. J.; Carson, B. E.; Saxena, S.; King, W. P.;
Bunz, U. H. F. Macromolecules 2006, 39, 6793.
[54] Scheel, A. J.; Komber, H.; Voit, B. Macromol. Rapid Commun.
2004, 25, 1175.
[34] Meldal, M. Macromol. Rapid Commun. 2008, 29, 1016.
[35] Voit, B. J. Polym. Sci., Part A: Polym. Chem. 2005, 43, 2679.
[36] Häussler, M.; Tang, B. Z. Adv. Polym. Sci. 2007, 209, 1.
[37] Burley, G. A.; Gierlich, J.; Mofid, M. R.; Nir, H.; Tal, S.; Eichen, Y.;
Carell, T. J. Am. Chem , Soc. 2006, 128, 1398.
[38] Wu, P.; Feldman, A. K.; Nugent, A. K.; Hawker, C. J.; Scheel, A.;
Voit, B.; Pyun, J.; Fréchet, J. M. J.; Sharpless, K. B.; Fokin, V. V.
Angew. Chem., Int. Ed. 2004, 43, 3928.
[39] Scheel, A. J.; Komber, H.; Voit, B. I. Macromol. Rapid Commun.
2004, 25, 1175.
[40] Malkoch, M.; Vestberg, R.; Gupta, N.; Mespouille, L.; Dubois, P.;
Mason, A. F.; Hedrick, J. L.; Liao, Q.; Frank, C. W.; Kingsbury, K.;
[55] Smet, M.; Metten, K.; Dehaen, W. Collect. Czech. Chem. Commun.
2004, 64, 1097.
[56] Li, Z. A.; Yu, G.; Hu, P.; Ye, C.; Liu, Y. Q.; Qin, J. G.; Li, Z. Mac-
romolecules 2009, 42, 1589.
[57] Li, Z. A.; Wu, W. B.; Qiu, G. F.; Yu, G.; Liu, Y. Q.; Ye, C.; Qin, J.
G.; Li, Z. J. Polym. Sci., Part A: Polym. Chem. 2011, 49, 1977.
[58] Wang, J.; Mei, J.; Yuan, W. Z.; Lu, P.; Qin, A. J.; Sun, J. Z.; Ma, Y.
G.; Tang, B. Z. J. Mater. Chem. 2011, 21, 4056.
[59] Chen, H.; He, M. Y.; Pei, J.; Liu, B. Anal. Chem. 2002, 74, 6252.
[60] Tour, J. M.; Lamba, J. J. S. J. Am. Chem. Soc. 1993, 115, 4935.
[61] Cao, X. Y.; Zhou, X. H.; Zi, H.; Pei, J. Macromolecules 2004, 37,
8874.
(Pan, B.; Qin, X.)
868
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Chin. J. Chem. 2012, 30, 861—868