Synthesis of a polypseudorotaxane, polyrotaxane, and polycatenane using 'click' chemistry

Article abstract of DOI:10.1016/j.tet.2008.10.005

The synthesis of a polypseudorotaxane, polyrotaxane, and polycatenane containing the electron-deficient cyclophane cyclobis(paraquat-p-phenylene) (CBPQT⁴⁺) subunit in the side chain is described. These interlocked supramolecular polymers have b

Full text of DOI:10.1016/j.tet.2008.10.005

Tetrahedron 65 (2009) 400–407
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of a polypseudorotaxane, polyrotaxane, and polycatenane
using ‘click’ chemistry
,
b
c
Marc Bria a, Julien Bigot b, Graeme Cooke c , Joe¨l Lyskawa , Gouher Rabani ,
*
,
Vincent M. Rotello d, Patrice Woisel b
*
a
´
´
CCM-RMN Lille 1 Universite des Sciences et Technologies de Lille, F-59655 Villeneuve d’Ascq Cedex, France
UMR 8009 Chimie Organique et Macromole´culaire, Laboratoire de Chimie Organique et Macromole´culaire, Batiment C6(1),
b
ˆ
Universite´ des Sciences et Technologies de Lille, F-59655 Villeneuve d’Ascq Ce´dex, France
c Glasgow Centre for Physical Organic Chemistry, WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow,
Glasgow, G12 8QQ, UK
d Department of Chemistry, University of Massachusetts at Amherst, Amherst, MA 01003, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of a polypseudorotaxane, polyrotaxane, and polycatenane containing the electron-de-
ficient cyclophane cyclobis(paraquat-p-phenylene) (CBPQT4þ) subunit in the side chain is described.
These interlocked supramolecular polymers have been prepared from an azide-functionalized
polystyrene derivative and an acetylene-functionalized [2]rotaxane, [2]catenane and their parent tet-
racationic cyclophane via Cu(I)-catalyzed 1,3 dipolar cycloadditions (‘click chemistry’). The synthesis and
characterization of the polymers and intermediates has been described using IR, 1H NMR, UV
spectroscopies, and voltammetry. We have shown that the CBPQT4þ unit of the side chain polystyrene
derivative has the ability to reversibly undergo complexation with a complementary dialkoxynaph-
thalene derivative.
Received 6 August 2008
Received in revised form
17 September 2008
Accepted 2 October 2008
Available online 10 October 2008
Keywords:
Interlocked molecules
Polymers
Ó 2008 Published by Elsevier Ltd.
Click chemistry
Cyclobis(paraquat-p-phenylene)
1. Introduction
alkyne-functionalized building blocks.7 Recently, this ‘click’
methodology has been extended to feature interlocked structures
The synthesis of interlocked1 supramolecular polymers2 (e.g.,
polyrotaxanes and polycatenanes) has received considerable
attention in attempts to synthesize novel macromolecular archi-
tectures. Indeed the juxtaposition of covalent and mechanical
bonds in systems of this type has led to the creation of macro-
molecules with interesting new topologies and function.3 Although
a number of synthetic methods exist for synthesizing main-chain
and side-chain interlocked polymers, there still remains significant
scope for developing new protocols with improved convenience,
applicability, and effectiveness.
‘Click’ chemistry is a generic term describing a range of
chemical transformations characterized by high efficiency, mild
conditions, and convenient purification.4,5 This methodology has
led to the bespoke synthesis of a range of systems with applica-
tions encompassing biological5 to materials chemistry.6 Possibly
the most versatile method is based upon the Huisgen Cu(I)-cata-
lyzed 1,3-cycloaddition of appropriately functionalized azide and
(e.g., rotaxanes and catenanes).8 This methodology is particularly
attractive for the synthesis of systems of this type, as it offers
advantages over more traditional methods in terms of improved
yields and increased sophistication of the resulting structures.
Here, we extend this methodology to include polymeric structures
by reporting the synthesis of new alkyne-functionalized cyclo-
phane 1 and its corresponding [2]rotaxane 2 and [2]catenane 3,
and their ability to be conveniently ‘clicked’ onto an azide-func-
tionalized polystyrene derivative. Moreover, the ability of the
CBPQT4þ pendant side chain polystyrene to reversibly undergo
complexation with a complementary dialkoxynaphthalene de-
rivative is reported.
2. Results and discussion
The synthesis of the alkyne-functionalized building blocks 1–3
is shown in Scheme 1. Derivative 5 is conveniently prepared from
1-pentynoic acid and alcohol 4, and proved to be a versatile
building block for the construction of cyclophane 1 and its cor-
responding interlocked structures 2 and 3.9 Cyclophane 1 was
synthesized from compounds 5 and 610 using a template-directed
* Corresponding authors. Tel.: þ0141 330 5500.
E-mail address: graemec@chem.gla.ac.uk (G. Cooke).
0040-4020/$ – see front matter Ó 2008 Published by Elsevier Ltd.
doi:10.1016/j.tet.2008.10.005

M. Bria et al. / Tetrahedron 65 (2009) 400–407
401
O
O
O
O
Si
O
O
Si
O
N
N
N
N
Si
O
O
N
N
N
N
O
O
8
O
2 PF6
O
4 PF6
O
O
O
6
O
DMF, rt, 10 d
2
O
+
Si
Br
Br
Br
Br
O
O
O
OH
O
O
O
COOH
9
O
O
O
O
O
O
4
5
DMF, rt, 10 d
MeO
O
O
O
O
DMF, rt, 10 d
O
O
O
O
O
O
O
7
OMe
N
N
N
N
4 PF6
O
O
O
O
O
O
O
3
N
N
N
1
N
4 PF6
Scheme 1. Synthesis of cyclophane 1, rotaxane 2, and catenane 3.
clipping methodology using 7.11 The interlocked structures 2 and 3
were synthesized by using the naphthalene-based axle 812 and
macrocycle 913 as templates, respectively. The cyclophane 1 and
interlocked structures 2 and 3 were purified by column chroma-
tography (MeOH/NH4Cl (2 M)/MeNO2, 4:4:2); and following
counterion exchange with NH4PF6 were isolated either as a white
solid (for 1) or deep purple solids (for 2 and 3).
1H NMR spectra is the significant upfield position of the resonances
of the 1,5-dialkyloxynaphthalene protons of 2 and 3, compared to
the same protons of the corresponding free templates 8 and 9,
respectively (Fig. 1). This fact is particularly evident for the reso-
nances of the protons attached to the 4- and 8- positions, which
shift by Ddz5.3 ppm for both interlocked structures.
We next investigated whether we could use standard Huisgen
‘click’ chemistry to graft the alkyne-functionalized building blocks
1–3 onto an azide-functionalized polystyrene derivative (Scheme
2).14 Polymer 13 was readily synthesized from styrene 11 and
Structures 1–3 were characterized by UV–vis, MS, 1H NMR and
13C NMR spectroscopies, which gave data that are consistent with
the proposed structures 1–3. For example, a notable feature in the

402
M. Bria et al. / Tetrahedron 65 (2009) 400–407
O
O
O
O
O
Si
O
Hα
Hβ
N
N
N
N
H8
H4
4PF6
O
O
O
2
O
-OCH2CH2O-
Si
H2/6,Η3,7
CH2Ph
HPhenyl
Hα
H4/8
Hβ
9.0
8.0
7.0
6.0
5.0
4.0
3.0
Figure 1. Partial 1H NMR of 2 in CD3CN.
p-chloromethyl styrene 12. The chlorine was readily substituted by
sodium azide to afford polymer 14.14a This polymer underwent
Cu(I)-catalyzed 1,3-cycloadditions with derivatives 2 and 3 to af-
ford the pink-colored polymers 15 and 16, respectively. We have
investigated the use of either CuSO4/ascorbic acid (Method 1) or
CuI (Method 2) as catalyst. Moreover, we have also explored the
application of catalytic amounts (e.g., 5 mol % CuSO4$5H2O and
10 mol % ascorbic acid; 10% CuI) or non-catalytic amounts of the
copper catalyst.
(Fig. 3). This fairly low grafting density is likely to be due to
a combination of Coulombic repulsion of the cyclophane units and
steric congestion between the reactive groups in the side-chains
and the polymeric backbone.14g 1H NMR spectra of 15 and 16 dis-
played new resonances consistent with methylene group adjacent
to the triazole moiety at w5.7–5.8 ppm and the triazole hydrogen
at w8.7–8.8 ppm, further providing evidence for the proposed
structures.
We have exploited the electrochemical signature of the electro-
active cyclophane moiety to further confirm the attachment of the
catenane unit to polymer 13 (Fig. 4). The cyclic voltammogram of
parent catenane 3 recorded in DMF indicated that the catenation
process provided similar electrochemical data to that obtained for
related [2]catenanes.15 In particular, two one-electron reduction
waves were obtained for the formation of the diradical dication
species, whereas the subsequent loss of two electrons resulting in
the formation of the fully reduced macrocycle occurred at a more
negative potential. Similar redox waves were observed for polymer
16, however, two notable differences were observed. Firstly, the
redox waves were broader and less well resolved for the macro-
molecule and secondly the reduction waves for the polymer
became significantly more reversible as the scan rate was lowered,
in accordance with the slower electron transfer rate of 16 compared
to 3.16 The shape of the voltammograms when recorded using
a scan rate of 100 mV sꢀ1 did not change significantly with repeated
cycling (five cycles), suggesting that decomposition did not occur to
any significant extent under the conditions examined. Thus, the
electrochemical data are in accordance with the aforementioned
spectroscopic data and are consistent with the catenane being co-
valently bound to the polystyrene backbone.
1H NMR spectroscopy of the products from these reactions
clearly revealed that an excess of the copper catalyst was required
for Method 1 to achieve effective functionalization of the azide
groups of the polymer, whereas when excess copper catalyst was
used in Method 2, a noticeable change in color of both the reaction
solution and the resulting polymers was observed (purple to
brown) indicating possible decomposition of the interlocked
structures. Overall, the most effective method for synthesizing
polymers 15 and 16, with regard to proportion of grafted inter-
locked structure and convenient purification, proved to be Method
1 using an excess of CuSO4$5H2O and ascorbic acid.
The differing solubility characteristics of derivatives 2 and 3
(compared to the ‘clicked’ polymers) in THF conveniently allowed
preliminary separation of unreacted reagents from polymers 15
and 16. Subsequent precipitation of these polymers into methanol
provided macromolecules free from their parent interlocked
structures 2 and 3 as judged by thin layer chromatography experi-
ments (silica gel: MeOH/NH4Cl(2 M)/MeNO2, 4:4:2). Although in
both cases resonances for the interlocked structures could be seen
in the 1H NMR spectra of the polymers, the broad nature of the
signals for the polymer backbone and the grafted interlocked
moieties prevented accurate determination of the ratio of inter-
locked structures ‘clicked’ onto the polymer versus unreacted azido
groups to be determined (Fig. 2). However, we estimate that around
40–50% of available azido groups were functionalized.
We next investigated whether the parent cyclophane 1 could
also be grafted onto polymer 13 using click chemistry. We have
explored Method 1 and Method 2 (Scheme 2), however, the best
methodology proved to be the use of CuI (10 mol %) to achieve ef-
fective grafting. Polymer 17 was purified in the same manner as
that described for polymers 15 and 16. 1H NMR spectroscopy in-
dicated that approximately w50% of the available azide units were
FTIR spectroscopy clearly revealed the presence of azide groups
in polymers 15 and 16, thereby further indicating that complete
functionalization of all of the available azide groups did not occur

M. Bria et al. / Tetrahedron 65 (2009) 400–407
403
AIBN,
95%
N
x%
N3
y%
NaN3,
DMF
95%
N3
5%
95%
Cl
5%
chlorobenzene
2 or 3, 1
+
Method 1:
CuSO4.5H2O,
ascorbic acid,
DMF, 20 °C,
48h
Cl
R
N
N
Method 2:
CuI, DMF, 20 °C,
48h
14
11
12
13
15-17
15 R =
16 R =
17 R =
O
O
O
O
O
O
O
O
O
O
O
O
O
Si
O
O
N
N
N
N
N
N
N
N
N
N
N
N
O
O
O
O
O
O
O
O
4 PF6
4 PF6
4 PF6
O
Si
O
HO
O
O
OH
18
O
Scheme 2. Attachment of 1, 2, or 3 onto a polystyrene derivative using the ‘click’ reaction.
x%
y%
95%
Harom (PS)
H
b
N
H
a
N
3
N
N
O
O
O
O
O
O
O
H
N
N
H
8
Harom (PS)
CH (PS
2
)
CH (PS)
N
N
O
O
O
O
O
4 PF
6
Hphenyl
H
H
H
Ha
Hb
9
8
7
6
5
4
3
2
1
ppm
Figure 2. 1H NMR of polymer 16 (acetone-d6).

404
M. Bria et al. / Tetrahedron 65 (2009) 400–407
100
75
50
25
unreacted azide
bands due
to clicked catenane
2100 1900 1700 1500 1300 1100
Wavenumber
900
700
500
Figure 3. FTIR spectrum of a thin film polymer 16.
Figure 5. Cyclic voltammetry of polymer 17 (20 mg). Recorded in acetone at 298 K at
different scan rates (scan rate¼1 V sꢀ1 (largest peak current), 0.5 V sꢀ1, 0.1 V sꢀ1, and
0.05 V sꢀ1 (smallest peak current)).
functionalized. We have exploited the redox active nature of the
cyclophane to further prove the structure of polymer 17 (Fig. 5).
Cyclic and square wave voltammetry clearly shows the formation of
two redox waves, presumably corresponding to the sequential
formation of the diradical dication and fully reduced states of the
cyclophane, respectively.10 Cyclic voltammetry indicated that the
reversibility of the redox waves increased as the scan rate was
lowered, which is consistent with its polymeric nature.
It is well established that naphthalene derivatives based upon
structure 18 are effective guests for cyclobis(paraquat-p-phenyl-
ene)-based cyclophanes.11 The addition of complementary guest 18
to a solution of polymer 17 resulted in the following observations.
Firstly, the solution changed from colorless to purple resulting from
an absorption around 520 nm characteristic of pseudorotaxane
formation (Fig. 6). Secondly, the addition of 18 to a solution of 17 in
an electrochemical cell immediately resulted in the first redox wave
being shifted by w60 mV to a more negative potential, consistent
with donor–acceptor interactions between 18 and the cyclophane
destabilizing the diradical dication state of the latter (Fig. 7). The
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
500
600
700
800
Wavelength (nm)
900
1000
1100
Figure 4. Cyclic voltammograms of (a) 3 recorded in DMF at scan rate 0.1 V sꢀ1 and (b)
polymer 16 recorded in DMF at different scan rates (scan rate¼1 V sꢀ1 (largest peak
current), 0.5 V sꢀ1, and 0.1 V sꢀ1 (smallest peak current)).
Figure 6. UV–vis spectrum of polymer 17 (10 mg in 10 mL of acetone) ( ), and in the
presence of 18 (w8ꢁ10ꢀ4 M) ( ).

M. Bria et al. / Tetrahedron 65 (2009) 400–407
405
described in the literature. Solvents were purified and dried by the
literature methods. The stabilizers present in styrene and chloro-
methylstyrene were removed by elution over a basic Al2O3.
4.3. Synthesis of 5
A solution of the alcohol 4 (1 g, 3.40 mmol), 4-pentynoic
acid (0.33 g, 3.40 mmol), 1,3-dicyclohexylcarbodiimide (0.70 g,
3.40 mmol), and 4-dimethylaminopyridine (catalytic amount) in
CH2Cl2 (40 mL) was stirred under N2 for 6 h at room temper-
ature. The resulting suspension was filtered, and the filtrate
was evaporated and subjected to column chromatography
(SiO2: petroleum ether/EtAc, 2:18) to furnish 5 as a white solid.
Yield: 68%. Mp¼68–69 ꢂC. 1H NMR (CDCl3, 300 MHz, 298 K):
d
¼7.43 (s, 1H), 7.37 (s, 2H), 5.29 (s, 2H), 4.56 (s, 2H), 4.47 (s,
2H), 2.67–2.62 (m, 2H), 2.57–2.51 (m, 2H), 1.99 (t, J¼2.7 Hz,
1H); 13C NMR (CDCl3, 75 MHz, 298 K):
d
¼29.9, 32.4, 33.3, 63.3,
69.3, 82.3, 100.0, 129.7, 130.7, 131.2, 134.9, 136.5, 138.7, 171.4. MS
(ES): C14H14Br2O2 m/z¼397 [MþNa]. Elemental analysis: calcd
(%) for C14H14Br2O2: C 44.95, H 3.77; found: C 45.11, H 3.99.
4.4. Synthesis of 1
Figure 7. Square wave voltammetry of polymer 17 (13 mg in 6 mL) recorded in acetone
(d) at 298 K and upon the addition of 18 (w9ꢁ10ꢀ3 M) (/).
A solution of 6 (0.76 g, 1.1 mmol), 5 (0.4 g, 1.1 mmol), and 7
(1.17 g, 3.2 mmol) in dry DMF (30 mL) was stirred under N2 at
room temperature for 10 days. The solvent was removed under
vacuum and the residue was subjected to a liquid–liquid extrac-
tion (CHCl3/H2O). The aqueous layer was concentrated and the
residue was purified using column chromatography (SiO2: MeOH/
NH4Cl (2 M)/MeNO2, 4:4:2). The fractions containing the product
were combined and concentrated under vacuum. The residue was
dissolved in hot water and an aqueous NH4PF6 solution was
added. The precipitate was collected by filtration, washed with
water and Et2O, and finally dried under vacuum, yielding a white
solid. Yield: 24%. Mp>300 ꢂC; 1H NMR (DMSO-d6, 300 MHz,
second redox wave is largely unaffected by this process, indicating
that 18 decomplexes from the cyclophane upon the formation of the
diradical dicationic state of the polymer-immobilized cyclophane.10
3. Conclusion
In conclusion, we have shown that we can readily synthesize
alkyne-functionalized systems 1–3, and that these building blocks
can undergo Huisgen ‘click’ chemistry to conveniently attach these
units onto a pre-formed azide-functionalized polystyrene de-
rivative. We have shown that polymer 17 has the propensity to
undergo electrochemically tunable interactions with compound 18.
We are currently further exploiting the synthetic versatility of
‘click’ chemistry as a means of attaching building blocks 1–3 onto
other macromolecules and biomacromolecules. Our results from
these investigations will be disclosed in due course.
298 K):
d
¼9.47 (d, J¼6.6 Hz, 4H), 9.40 (d, J¼6.9 Hz, 2H), 9.28 (d,
J¼6.6 Hz, 2H), 8.68–8.57 (m, 8H), 7.75–7.72 (m, 5H), 7.55–7.45 (m,
2H), 5.99 (s, 2H), 5.86 (s, 2H), 5.83 (s, 2H), 5.82 (s, 2H), 5.34 (s,
2H), 2.42 (t, J¼6.6 Hz, 2H), 2.26 (t, J¼2.4 Hz, 1H), 2.22–2.16 (m,
2H); 13C NMR (DMSO-d6, 100 MHz, 298 K):
d¼13.4, 32.5, 62.8,
63.2, 70.9, 82.2, 123.3, 126.6, 127.0, 129.1, 129.8, 131.2, 134.6, 135.6,
136.3, 136.5, 144.9, 145.1, 145.6, 147.9, 148.2, 148.3, 170.9. Ele-
mental analysis: calcd (%) for C42H38F24N4O2P4: C 41.66, H 3.16, N
4.63; found: C 41.89, H 3.22, N 4.85.
4. Experimental section
4.1. Instrumentation
4.5. Synthesis of 2
Infrared spectra were obtained on a Perkin–Elmer Lambda 25
instrument. Optically matched 1 cm cuvettes were used in the ex-
periments. Spectra were recorded at 23 ꢂC. The relative molecular
weight of polymer 13 was determined using a Polymer Labs GPC50
(RI detector) gel permeation chromatography (GPC) equipment
using tetrahydrofuran and polystyrene standards. All electro-
chemical experiments were performed using a CH Instruments 440
electrochemical workstation. The electrolyte solution (0.1 M) was
prepared from recrystallized Bu4NPF6 and dry DMF or dry acetone.
A three-electrode configuration was used with a platinum disc
(2 mm diameter) working electrode, an Ag/AgCl reference elec-
trode and a platinum wire as the counter electrode. The solution
was purged with nitrogen prior to recording the electrochemical
data, and all measurements were recorded under a nitrogen
atmosphere.
A solution of component 8 (2.36 g, 3.2 mmol), 5 (0.40 g,
1.1 mmol), and 6 (0.76 g, 1.1 mmol) in dry DMF (30 mL) was stirred
under N2 at room temperature for 10 days. The solvent was re-
moved under vacuum and the residue was purified using column
chromatography (SiO2: MeOH/NH4Cl(2 M)/MeNO2, 4:4:2). The
fractions containing the product were combined together and
concentrated under reduced pressure. The residue was dissolved in
hot water and an aqueous NH4PF6 solution was added. The pre-
cipitate was collected by filtration, washed with water and Et2O,
and finally dried under vacuum, yielding 2 as a purple solid. Yield:
42%. Mp>300 ꢂC; 1H NMR (CD3CN, 400 MHz, 298 K):
d
¼9.08 (br s,
4H), 8.80–8.51 (br m, 4H), 8.24–7.92 (br s, 7H), 7.51–7.16 (br m, 8H),
6.31 (br s, 2H), 6.09–5.40 (br m, 12H), 4.49–4.14 (br m, 8H), 4.13–
4.02 (br m, 4H), 4.01–3.93 (br m, 4H), 3.88 (t, J¼5.3 Hz, 4H), 3.71 (t,
J¼5.3 Hz, 4H), 2.93–2.76 (br m, 2H), 2.75–2.61(br m, 2H), 2.51 (br s,
2H), 2.41–2.33(br m, 1H), 1.05–0.94 (m, 42H); 13C NMR (CD3CN,
4.2. Materials
100 MHz, 298 K):
70.7, 71.9, 72.3, 73.7, 83.9, 105.4, 109.4, 125.5, 125.8, 127.3, 128.7,
129.2, 132.4, 133.4, 134.3, 137.6, 137.9, 145.3, 146.2, 146.8, 152.2,
d
¼12.8, 15.0, 18.4, 34.2, 62.9, 63.7, 65.9, 66.1, 69.5,
Alcohol 4,9 component 8,12 macrocyclic polyether 9,13 bipyri-
dium salt 6,10 and 711 were obtained following the procedures

406
M. Bria et al. / Tetrahedron 65 (2009) 400–407
172.4 HRMS (ESI): m/z calcd C82H110F18N4O10P3Si2 [MꢀPF6]:
4.10. Synthesis of polymer 16
1802.8351; found: 1802.8360.
To a stirred solution of polymer 14 (0.1 g), 3 (0.03 mmol) in DMF
(20 mL) at 20 ꢂC were added CuSO4$5H2O (0.05 g, 0.2 mmol) dis-
solved in DMF (1 mL) and ascorbic acid (0.07 g, 0.4 mmol) dissolved
in DMF (1 mL). The solution was stirred for 48 h in the dark, and the
solvent was carefully removed under high vacuum. THF (100 mL)
was added and the mixture was filtered to remove unreacted
starting materials. The filtrate was concentrated under reduced
pressure and precipitated into a vigorously stirred solution of
methanol (200 mL). The solid was collected by filtration and dried
under high vacuum to yield 16 (0.9 g) as a pink powder.
4.6. Synthesis of 3
A solution of the macrocyclic polyether 9 (0.26 g, 0.48 mmol), 6
(0.14 g, 0.19 mmol), and 5 (0.07 g, 0.19 mmol) in dry DMF (15 mL)
was stirred at room temperature for 10 days. The solvent was
removed under reduced pressure and chloroform was added
(40 mL). The precipitate was isolated by filtration and was purified
using column chromatography (SiO2: MeOH/NH4Cl (2 M)/MeNO2,
4:4:2). The fractions containing the product were combined to-
gether and concentrated under reduced pressure. The residue was
dissolved in hot water and an aqueous NH4PF6 solution was added.
The precipitate was collected by filtration, washed with water and
Et2O, and finally dried under vacuum, yielding 3 as a purple solid.
Yield: 63%. Mp>300 ꢂC; 1H NMR (CD3CN, 400 MHz, 298 K):
4.11. Synthesis of polymer 17
To a stirred solution of 1 (0.05 g, 0.04 mmol) in DMF (10 mL) at
20 ꢂC was added polymer 14 (0.1 g). Then, CuI (0.8 mg,
0.004 mmol, 10 mol %) was added. The solution was stirred for
48 h in the dark, and the solvent was carefully removed under high
vacuum. THF (100 mL) was added and the mixture was filtered to
remove unreacted starting materials. The filtrate was concentrated
under reduced pressure and precipitated into a vigorously stirred
solution of methanol (200 mL). The solid was collected by filtra-
tion and dried under high vacuum to yield 17 (0.9 g) as a white
powder.
d
¼8.95–8.70 (br m, 4H), 8.43–8.17 (br s, 4H), 8.14–8.02 (br m, 1H),
8.01–7.92 (br s, 3H), 7.87–7.78 (br m, 3H), 7.12–6.98 (m, 5H), 6.84
(br s, 5H), 6.31–6.23 (m, 2H), 6.04–5.92 (m, 2H), 5.86–5.68 (m, 5H),
5.62–5.46 (m, 6H), 5.36 (d, J¼17.6 Hz, 1H), 4.23–3.58 (m, 34H),
2.79–2.70 (br m, 2H), 2.65–2.56 (br m, 2H), 2.41 (d, J¼11.6 Hz, 1H),
2.31 (br s, 1H), 2.20 (d, J¼11.6 Hz, 1H); 13C NMR (CD3CN, 100 MHz,
298 K):
d¼15.0, 34.2, 62.7 63.9, 65.8, 66.1, 68.8, 69.1, 70.7, 71.0, 71.1,
71.8, 72.0, 72.2, 72.4, 74.4, 104.8, 105.0, 106.6, 106.7, 109.3, 114.9,
124.5, 124.9, 125.3, 126.2, 126.6, 126.9, 128.6, 129.2, 132.0, 132.1,
132.5, 133.4, 137.7, 144.8, 145.3, 152.1, 154.4, 154.5, 172.4. HRMS
(ESI): m/z calcd C78H82F18N4O12P3 [MꢀPF6]: 1702.3978; found:
1702.3985.
Acknowledgements
We thank the EPSRC and US NSF (CHE-0518487) for funding this
work. G.C. thanks the Royal Society of Edinburgh for the award of
a Support Research Fellowship.
4.7. Synthesis of polymer 13
References and notes
AIBN (2 g, 12 mmol) was added to a solution of styrene (25.0 g,
240 mmol) and p-(chloromethyl)styrene (1.9 g, 12 mmol) in
chlorobenzene (100 mL). The reaction mixture was stirred at
78 ꢂC for 20 h. The reaction mixture was then cooled to room
temperature and then added drop-wise to vigorously stirred
methanol (700 mL). The precipitate was filtered and washed with
copious amounts of methanol. The product was dried under high
vacuum to afford 13 as a white solid. Yield: 64%; Mn¼3578,
Mw¼6270 g molꢀ1, PD¼1.75.
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4.8. Synthesis of polymer 14
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4.9. Synthesis of polymer 15
To a stirred solution of polymer 14 (0.1 g), 2 (0.05 g, 0.03 mmol)
in DMF (20 mL) at 20 ꢂC were added CuSO4$5H2O (0.05 g,
0.2 mmol) dissolved in DMF (1 mL) and ascorbic acid (0.07 g,
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