Synthesis and electrochemistry of new thienyl - Schiff base complexes

Article abstract of DOI:10.1139/V08-143

The synthesis and characterization of nickel(II), copper(II), and vanadyl ([V=O]²⁺) complexes of two new thienyl-substituted Schiff base ligands are reported. Cyclic voltammetry of some of these complexes showed oxidation waves, but none of the complexes formed conductive polymer films upon repeated cycling. UV-vis absorption spectros-copy shows that some of the complexes exhibit enhanced conjugation, and the radical cations formed on these chromo-phores appear to be too stable to undergo oxidative coupling.

Full text of DOI:10.1139/V08-143

314
Synthesis and electrochemistry of new thienyl –
Schiff base complexes1
A. Pietrangelo, B.N. Boden, M.J. MacLachlan, and M.O. Wolf
Abstract: The synthesis and characterization of nickel(II), copper(II), and vanadyl ([V=O]2+) complexes of two new
thienyl-substituted Schiff base ligands are reported. Cyclic voltammetry of some of these complexes showed oxidation
waves, but none of the complexes formed conductive polymer films upon repeated cycling. UV–vis absorption spectros-
copy shows that some of the complexes exhibit enhanced conjugation, and the radical cations formed on these chromo-
phores appear to be too stable to undergo oxidative coupling.
Key words: Schiff base, salphen, conjugated polymer, electrochemistry.
Résumé : On a effectué la synthèse et on a caractérisé les complexes du nickel(II), du cuivre(II) et du vanadyle
([V=O]2+) de deux ligands dérivés de bases de Schiff substituées par de groupes thiényles. La voltampérométrie cy-
clique a permis de montrer que quelques-uns de ces complexes présentent des vagues d’oxydation, mais aucun de ces
complexes ne forme de films de polymères conducteurs après des cycles voltampérométriques répétés. La spectroscopie
d’absorption UV/vis montre que certains de ces complexes donnent lieu à une conjugaison exaltée et que les cations
radicaux qui se forment sur ces chromophores semblent trop stables pour subir des couplages oxydants.
Mots-clés : base de Schiff, salphène, polymère conjugué, électrochimie.
[Traduit par la Rédaction] Pietrangelo et al. 320
Introduction
R = H to larger groups such as R = Ph increases interchain
spacing resulting in a reduction in conductivity for Cu(II)-
Conjugated polymers containing metal complexes are of
interest because they combine the electronic properties of a
highly delocalized π-system with the catalytic, magnetic,
and optical properties of a metal (1). Schiff base complexes
are a particularly intriguing class of metal complexes be-
cause they have large second-order and third-order NLO re-
sponses, are stable to over 300 °C, and have electronic or
magnetic characteristics that permit additional functionality,
such as chemical sensing, catalysis, and supramolecular or-
ganization (2–4). Both conjugated and non-conjugated poly-
mers incorporating Schiff base complexes have been reported
(5). Schiff base complexes containing a range of transition
metals with pendant thiophene units have been electro-
polymerized to generate conductive polymer films that ex-
hibit catalytic, sensing, and nonlinear optical properties (6).
The groups of both Swager and Reynolds have synthesized
thiophene-containing Schiff base monomers and studied their
electropolymerization. Oxidative coupling of monomers 1
and 2 (M = Co) gave conductive polymers where the metal
does not contribute to conductivity but is necessary for elec-
tropolymerization (6b). Changing the substituents on 2 from
containing
polymers
(6c).
Reynolds
investigated
electropolymerization of monomers 3 and 4, and found that
polymerization occurs at the phenylene group for 3 (6f, 6g).
In the case of 4, polymerization could occur at either the
thienyl or phenylene ring, except when R = CH3, in which
case polymerization occurs exclusively through the
oligothiophene moiety.
Received 21 April 2008. Accepted 24 July 2008. Published
on the NRC Research Press Web site at canjchem.nrc.ca on
12 November 2008.
A. Pietrangelo, B.N. Boden, M.J. MacLachlan,2 and
M.O. Wolf.2 Department of Chemistry, University of British
Columbia, Vancouver, BC V6T 1Z1, Canada.
1This article is part of a Special Issue dedicated to Professor
R. Puddephatt.
2Corresponding authors (e-mail: mmaclach@chem.ubc.ca;
mwolf@chem.ubc.ca).
We recently reported the electropolymerization of substi-
tuted Schiff base complexes 5–7 in microgravity (6a). In
some cases, improved film order was observed when film
Can. J. Chem. 87: 314–320 (2009)
doi:10.1139/V08-143
© 2008 NRC Canada

Pietrangelo et al.
315
Scheme 1.
growth occurred in the absence of gravity-driven convection
currents as evidenced by higher χ3 susceptibilities.
While electropolymerization is known for salphen com-
plexes formed from 5-(2-thienyl)salicylaldehyde, such as 5–
7, it has not been studied for salphens made from 4-(2-
thienyl)salicylaldehyde. In compounds with the general
structure A, the relative meta arrangement between the
thienyl and imine substituents on the phenyl ring leads to
less effective conjugation than para arrangements (structure
B). Visually it may be noted that the π-conjugation pathway
between the thienyl substituents for A cannot be drawn with
alternating single and double bonds in any important reso-
nance structure, whereas in structure B the conjugation ap-
pears to be improved, inasmuch as this model is an
indication of delocalization. Thus, we set out to probe
whether 4-substituted structures polymerize and whether the
resulting materials show significantly different electronic
properties from those made from 5-substituted monomers.
1
Fig. 1. H NMR (300 MHz, CDCl3) spectrum of 11b.
Another possible approach to a fully conjugated monomer
involves replacing the terminal phenyl rings with thiophene
groups, as in structure C. Here, we report a series of new
conjugated monomers, along with electrochemistry and elec-
tronic absorption data.
Results and discussion
Scheme 2.
Synthesis
To prepare 4-(2-thienyl)salicylaldehyde 9, 4-iodosalicyl-
aldehyde 8 was coupled to 2-tributylstannylthiophene via
Stille coupling affording 9 as a beige product in 92% yield
(Scheme 1). Schiff base condensation of 9 with diamine 10a
gave salphen 11a as an orange solid. With longer alkoxy
chains, a longer reaction time was required for complete
conversion to the product (11b and 11c). The 1H NMR spec-
trum of 11b shows an imine resonance at δ 8.56 and a
hydroxyl resonance at δ 13.34 (Fig. 1).
Heating 11b at reflux in THF with the appropriate metal
salt yielded the salphen metal complexes 12b–14b. All three
metal complexes crystallized readily, but the resulting crys-
tals were thin and unsuitable for single crystal X-ray diffrac-
tion studies. The 1H NMR spectrum of the diamagnetic
Ni(II) complex 12b was consistent with its structure, and all
three complexes gave satisfactory mass spectrometry data
and elemental analysis.
Thienolphenylenediimine (thienphen) complexes 19a and
19b were prepared by the route shown in Scheme 2. 3-
Methoxythiophene 16 was prepared by Cu(I)-catalyzed
Ullmann-type coupling of sodium methoxide with 3-bromo-
thiophene 15 (7). Ortho-directed lithiation followed by
quenching with DMF yielded 2-formyl-3-methoxythiophene
17 after work-up (8). Deprotection with BBr3 afforded air-
sensitive 2-formyl-3-hydroxythiophene 18 (9). Condensation
of 18 with diamine 10c in the presence of a metal salt gave
thienphen complexes 19a and 19b in 72% yield.
Electrochemistry
Electropolymerization of the three metal complexes 12b–
14b was attempted, but only the Ni(II) complex 12b and
Cu(II) complex 14b showed oxidation waves within the sol-
vent window. Repeated cycling through the first oxidation
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316
Can. J. Chem. Vol. 87, 2009
Fig. 2. Cyclic voltammetry of 14b. (a) 10 scans to 1.0 V. (b) 10
scans to 1.4 V. Only scans 1, 5 and 10 are shown. Pt-disc work-
ing electrode, 0.1 mol/L [n-Bu4N]PF6 in CH2Cl2, 100 mV/s scan
rate.
Fig. 3. Formation of the radical cations of A and B, showing
one resonance structure for each monomer.
Fig. 4. Cyclic voltammetry of 19a. The red trace (light trace in
print version) shows scan reversal after the first oxidation wave;
the black trace (heavy) shows a scan to 2 V. Pt-disc working
electrode, 0.1 mol/L [n-Bu4N]PF6 in CH2Cl2, 100 mV/s scan rate.
wave (~1 V vs. SCE) for both compounds resulted in identi-
cal cyclic voltammograms (CVs) on each sweep (Fig. 2a).
No film growth was visible on either Pt-disc or gold-on-
glass working electrodes. Cycling through both the first and
second oxidation waves (1.4 V vs. SCE) resulted in signifi-
cant changes in sequential CVs (Fig. 2b). An increase in cur-
rent and positive shift of the oxidation wave was observed,
along with the formation of a red film on the electrode sur-
face. CVs of these films showed no oxidation or reduction
features in the solvent window.
To explain these results, we consider the radical cations
expected to form upon one electron oxidation of the
dithienylsalphen monomers (Fig. 3). The radical cation in
the oxidized species B·+ is more delocalized than in the oxi-
dized species A·+; as a result, the radical cation of B may be
stable enough to prevent polymerization. This explains the
lack of polymerization observed when scanning only to the
first oxidation wave in 12b and 14b. There are no known ex-
amples of electropolymerization of thiophene-substituted
benzene with an imine para to the thienyl group. Upon scan-
ning to higher potentials, a redox-inactive film is formed.
The cyclic voltammetry differs from that observed upon
electropolymerization of 5–7 where a lower potential feature
attributed to reversible oxidation of the polymer backbone is
observed. It is possible that at high potentials monomers 12b
and 14b undergo coupling at the alkoxy substituted phenyl
rings as has been observed previously in related species pre-
pared by Reynolds and coworkers (6f, 6g).
Cyclic voltammetry of 19a (Fig. 4) shows a quasi-
reversible wave at 0.7 V vs. SCE, as well as two higher-
potential irreversible waves. These waves are attributed to
oxidation of the metal centre as well as ligand-based oxida-
tions. No sign of electropolymerization is observed with re-
peated scanning to potentials up to 2.0 V. Complex 19b also
does not electropolymerize and shows an anodic wave at
0.9 V vs. SCE with a large associated cathodic wave. It is
possible that the oxidized species generated here are also
stabilized via resonance stabilization of the radical cations
(Fig. 5).
The electronic absorption spectra of the monomers can be
used to provide insight into the degree of conjugation, be-
cause increased conjugation is expected to result in a
bathochromic shift. The spectra for complexes 12b–14b are
shown in Fig. 6. At higher energy, the spectrum is domi-
nated by peaks associated with the ligand (e.g., π–π* transi-
tions) whereas the lower energy peaks are attributed to n–π*
and metal-based transitions (metal to ligand charge transfer
bands, d–d transitions). Comparison of UV–vis spectra of
the 5-substituted monomers (5–7) with the corresponding 4-
substituted species (12b–14b) reveals that, as expected, the
low energy charge transfer absorption bands are shifted only
slightly. The higher energy bands, on the other hand, are
consistently shifted to lower energy in the 4-substituted
monomers (cf. 320 nm for 5b vs 350 nm for 12b). These
bands, attributed to π–π* transitions on the conjugated back-
© 2008 NRC Canada

Pietrangelo et al.
317
Fig. 5. Formation of the radical cations of 19 (metal-based oxi-
dation is not considered).
Fig. 7. Absorption spectra of monomers in DCM (a) 19a and
(b) 19b.
Fig. 6. Normalized absorption spectra of dithienylsalphen mono-
mers in DCM (concentration 4.0 – 5.0 × 10–6 mol/L), where
(a) 5b (----), 12b (—); (b) 6b (----), 13b (—); (c) 7b (----), 14b
(—).
enhanced stabilization of the oxidized species owing to the
extended conjugation. Similar observations were made for
the thienolphenylenediimine complexes, and were also at-
tributed to enhanced resonance stabilization of the oxidized
species. Zotti has previously demonstrated that alkoxy-
substituted hexathiophene oligomers do not polymerize well
because of stabilization of the radical cation by the substitu-
ents (11). These results demonstrate that in order for electro-
polymerization to occur, the oxidized species cannot be too
stable or the desired coupling reaction will not occur. The ir-
reversibility of the oxidation waves associated with the or-
ganic groups suggests that other decomposition pathways
may be available for the oxidized species. These results will
guide future development of polymerizable thienyl – Schiff
base complexes.
bone, shift in a manner consistent with enhanced conjuga-
tion.
The absorption spectra of 19a and 19b both have a higher
energy band (~300 nm) attributed to the π–π* transition of
the conjugated system (Fig. 7). This absorption is close in
energy to the π–π* transition in 5b and 6b suggesting a sim-
ilar extent of conjugation in these complexes. It is reason-
able to conclude, based on these observations, that the
conjugation is localized primarily over the diarylimine unit,
regardless of whether the terminal aryl group is a substituted
benzene or thiophene. The lower energy transitions in the
spectra of 19a and 19b are attributed to CT transitions. The
intensity of these transitions is comparable to the π–π* tran-
sition, possibly owing to an increase in the transition dipole
moments as has been previously observed in similar com-
plexes (10).
Experimental3
Compounds 8 (12) and 10a–10c (13) were prepared ac-
cording to literature procedures. Tetrahydrofuran (THF) was
distilled over Na and benzophenone under N2. All other
chemicals were purchased from Sigma-Aldrich, TCI, or
Fisher and used as received. All reactions were carried out
under nitrogen unless otherwise noted. UV–vis spectra were
obtained on a Varian Cary 5000 UV–vis NIR spectrometer
using a 1 cm cuvette. Infrared spectra were obtained using
KBr discs or on NaCl plates with a Bomem MB-100 spec-
trometer or a Nicolet 4700 FTIR spectrometer. 1H NMR
(300 or 400 MHz) and 13C NMR (75.5 or 100.7 MHz) spec-
tra were recorded on Bruker Avance 300 or Bruker Avance
400 spectrometers and were referenced internally to residual
protonated solvent. Electrospray ionization (ESI) mass spec-
tra were obtained on a Micromass LCT time-of-flight (TOF)
mass spectrometer equipped with an electrospray ion source.
Samples were analyzed in methanol–dichloromethane at
1 µmol/L. EI spectra were obtained with a double focusing
Conclusions
Two strategies for exploring the factors important in con-
trolling electropolymerization of salphen complexes are re-
ported. Extending the conjugation via substitution of the
terminal phenyl ring at the 4-position with a thiophene group
leads to a red-shift in the absorption spectrum, but results in
species that do not electropolymerize. This is attributed to
3 Supplementary data for this article are available on the journal Web site (canjchem.nrc.ca) or may be purchased from the Depository of
Unpublished Data, Document Delivery, CISTI, National Research Council Canada, Ottawa, ON K1A 0R6, Canada. DUD 3839. For more
information on obtaining material refer to cisti-icist.nrc-cnrc.gc.ca/cms/unpub_e.shtml.
© 2008 NRC Canada

318
Can. J. Chem. Vol. 87, 2009
mass spectrometer (Kratos MS-50) coupled with a MASPEC
data system with EI operating conditions of: source tempera-
tures 120–220 °C and ionization energy 70 eV. Elemental
analyses were obtained at the Microanalytical facility at the
University of British Columbia. Melting points were re-
corded on a Fisher John’s melting point apparatus.
11b
Mp 176–178 °C. UV–vis (CH2Cl2, nm (L mol–1cm–1))
λmax (ε): 360 (5.0 × 104). IR (KBr, cm–1) ν: 2950, 2928,
2853, 1608, 1510, 1375, 1263, 1189, 850, 804, 695. 1H
NMR (300 MHz, CDCl3) δ: 13.34 (s, 2H, OH), 8.56 (s, 2H,
HC=N), 7.39 (dd, 2H, J1 = 3.7 Hz, J2 = 0.9 Hz, aromatic
CH), 7.35 (d, 2H, J = 8.0 Hz, aromatic CH), 7.32 (m, 4H,
aromatic CH), 7.16 (dd, 2H, J1 = 8.0 Hz, J2 = 1.7 Hz, aro-
matic CH), 7.08 (dd, 2H, J1 = 5.0 Hz, J2 = 3.7 Hz, aromatic
CH), 6.79 (s, 2H, aromatic CH), 4.05 (t, 4H, OCH2), 1.86–
0.88 (m, 22H, hexyl chain). 13C NMR (75.5 MHz, CDCl3) δ:
161.7, 161.1, 149.3, 143.7, 138.7, 135.6, 132.7, 128.4,
126.3, 124. 6, 118.8, 116.8, 114.3, 105.0, 70.0, 31.8, 29.5,
25.9, 22.8, 14.2. ESI–MS m/z: 681 ([M + H]+). Anal. calcd.
for C40H44N2O4S2: C 70.56, N 4.11, H 6.51; found C 70.36,
N 4.43, H 6.43.
Synthesis of 4-(2-thienyl)salicylaldehyde 9
A solution of 2-tributylstannylthiophene (8.0 mL, 25.2 mmol)
in DMF (40 mL) was added to
a mixture of 4-
iodosalicylaldehyde 8 (4.095 g, 16.5 mmol) and trans-
dichlorobis(triphenylphosphine) palladium (II) (0.606 g,
0.863 mmol). After heating for 16 h, the reaction solution
was diluted with ether (100 mL) and washed with aqueous
ammonium chloride (3 × 150 mL). The organic layer was
filtered through silica and the solvent was removed under
vacuum to obtain a beige solid, which was washed with hex-
anes and filtered to yield 3.088 g (0.794 mmol, 92%) of
product; mp 92–94 °C. UV–vis (CH2Cl2, nm (L mol–1cm–1)):
λmax (ε): 331 (2.7 × 104). IR (KBr, cm–1) ν: 3098, 3074,
2834, 2748, 1650, 1625, 1557, 1529, 1492, 1431, 1312,
11c
1H NMR (400 MHz, CDCl3) δ: 13.31 (s, 2H, OH), 8.58
(s, 2H, HC=N), 7.39 (d, 2H, J = 3.7 Hz, aromatic CH), 7.35
(d, 2H, J = 8.0 Hz, aromatic CH), 7.32 (m, 4H, aromatic
CH), 7.17 (dd, 2H, J1 = 8.0 Hz, J2 = 1.6 Hz, aromatic CH),
7.08 (dd, 2H, J = 5.0 Hz, J = 3.7 Hz, aromatic CH), 6.81 (s,
2H, aromatic CH), 4.06 (t, 4H, OCH2), 1.86–0.88 (m, 46H,
dodecyl chain). 13C NMR (100.7 MHz, CDCl3) δ: 161.7,
161.0, 149.4, 143.6, 139.1, 135.2, 133.0, 128.4, 126.4,
124.7, 118.6, 116.9, 114.4, 105.0, 70.1, 32.2, 29.9, 29.9,
29.7, 29.6, 29.5, 26.3, 22.9, 14.3. EI–MS m/z: 848 (M+).
HRMS calcd. for C52H68N2O4S2: 848.46205; found:
848.46226.
1
1235, 1207, 1184, 995, 852, 800, 694. H NMR (400 MHz,
CDCl3) δ: 11.12 (s, 1H, OH), 9.84 (s, 1H, CHO), 7.53 (d,
1H, J = 8.1 Hz, aromatic CH), 7.45 (d, 1H, J = 3.9 Hz, aro-
matic CH), 7.40 (d, 1H, J = 4.8 Hz, aromatic CH), 7.25 (dd,
1H, J1 = 8.1 Hz, J2 = 1.5 Hz, aromatic CH), 7.21 (s, 1H, aro-
matic CH), 7.11 (dd, 1H, J1 = 4.8 Hz, J2 = 3.9 Hz, aromatic
CH). 13C NMR (75.5 MHz, CDCl3) δ: 195.7, 162.3, 142.7,
142.6, 134.5, 128.7, 127.7, 125.9, 119.8, 117.6, 114.1. ESI–
MS m/z: 227 ([M + Na]+). Anal. calcd. for C11H8O2S: C
64.69, H 3.95; found C 64.30, H 3.99.
12b
To a mixture of 11b (0.137 g, 0.201 mmol) and nickel(II)
acetate tetrahydrate (0.226 g, 0.908 mmol) was added 10 mL
of distilled THF. The red solution was heated to reflux for
16 h. After cooling, MeOH was added to precipitate a red
solid, which was subsequently filtered and washed with
MeOH and petroleum ether. Yield: 0.095 g, 0.13 mmol,
64%; mp > 300 °C. UV–vis (CH2Cl2, nm (L mol–1cm–1))
Synthesis of N,N′-Phenylenebis(4-(2-thienyl)salicyl-
ideneimine 11b
1,2-Dihexyloxy-4,5-diaminobenzene 10b (0.297 g,
0.962 mmol) and 4-thienylsalicylaldehyde 9 (0.486 g,
2.37 mmol) were combined in a 100 mL Schlenk flask under
nitrogen. To this mixture was added 20 mL of dry THF to
form an orange solution. The solution was heated to reflux
overnight and was cooled to room temperature, after which
the volume of solution was reduced. Addition of methanol to
the solution caused precipitation of an orange solid, which
was collected on a Büchner funnel and washed with addi-
tional methanol. Yield: 0.587 g, 0.86 mmol, 89%. Com-
pounds 11a and 11c were synthesized in an analogous
fashion using 10a and 10c with yields of 0.355 g
(0.66 mmol, 77%) and 0.525 g (0.61 mmol, 66%), respec-
tively.
λ
max (ε): 361 (4.3 × 104), 403 (5.6 × 104), 489 (2.2 × 104). IR
(KBr, cm–1) ν: 2953, 2930, 2859, 1607, 1584, 1501, 1475,
1
1438, 1362, 1282, 1188, 699. H NMR (400 MHz, CDCl3)
δ: 7.87 (s, 2H, HC=N), 7.43 (s, 2H, aromatic CH), 7.39 (d,
2H, J = 3.4 Hz, aromatic CH), 7.32 (d, 2H, J = 5.0 Hz, aro-
matic CH), 7.26 (d, 2H, J = 8.3 Hz, aromatic CH), 7.07 (m,
2H, aromatic CH), 7.02 (s, 2H, aromatic CH), 6.88 (d, 2H,
J = 8.3 Hz, aromatic CH), 3.97 (t, 4H, OCH2), 1.81–0.88
(m, 22H, hexyl chain). 13C NMR (75.5 MHz, CDCl3) δ:
165.4, 151.4, 149.7, 144.0, 139.9, 136.3, 133.7, 128.4,
126.4, 124.8, 119.7, 117.9, 114.1 98.8, 64.2, 31.9, 29.4,
25.9, 22.8, 14.3. ESI–MS m/z: 759 ([M + Na]+). Anal. calcd.
for C40H42N2O4S2Ni: C 65.13, H 5.74; found C 65.16, H
5.82.
11a
1H NMR (400 MHz, CDCl3) δ: 13.21 (s, 2H, OH), 8.62
(s, 2H, HC=N), 7.39 (dd, 2H, J1 = 3.7 Hz, J2 = 1.0 Hz, aro-
matic CH), 7.36 (d, 2H, J = 8.0 Hz, aromatic CH), 7.35–
7.32 (m, 6H, aromatic CH), 7.25 (m, 2H, aromatic CH), 7.17
(dd, 2H, J1 = 8.0 Hz, J2 = 1.7 Hz, aromatic CH), 7.08 (dd,
2H, J1 = 5.0 Hz, J2 = 3.7 Hz, aromatic CH). 13C NMR
(100.7 MHz, CDCl3) δ: 162.9, 162.0, 143.6, 142.6, 139.3,
133.1, 128.4, 128.0, 126.5, 124.8, 119.8, 118.6, 116.9,
13b
To a mixture of 11b (0.166 g, 0.244 mmol) and vanadyl
acetylacetonate (0.191 g, 0.720 mmol) was added 10 mL of
distilled THF. The red solution was heated to reflux for 16 h.
After cooling, the volume of the solution was reduced and
MeOH was added to precipitate a red-brown solid. The
product was subsequently filtered and washed with MeOH
114.5. EI–MS: m/z
C28H20N2O2S2: 480.09662; found: 480.09674.
=
480 (M+). HRMS calcd for
© 2008 NRC Canada

Pietrangelo et al.
319
and petroleum ether. Yield: 0.136 g, 0.18 mmol, 75%; mp
293 °C (dec.). UV–vis (CH2Cl2, nm (L mol–1cm–1)) λmax (ε):
364 (4.6 × 104), 422 (5.0 × 104). IR (KBr, cm–1) ν: 2956,
2927, 2857, 1604, 1577, 1509, 1479, 1430, 1377, 1275,
1191, 980, 696. ESI–MS m/z: 768 ([M + Na]+). Anal. calcd.
for 13bqH2O (C40H44N2O6S2V): C 62.89, H 5.81, N 3.67;
found C 63.09, H 5.87, N 3.91.
electrode was a Pt disk, an indium tin oxide (ITO) thin film
on glass, or Au (1000 Å) deposited on Si using a Cr (50 Å)
adhesion layer. The counter electrode was a Pt mesh and the
reference electrode a silver wire. An internal reference
(decamethylferrocene) was added to correct the measured
potentials with respect to saturated calomel electrode (SCE).
[(n-Bu)4N]PF6 was used as a supporting electrolyte and was
purified by triple recrystallization from ethanol and dried at
90 °C under vacuum for 3 days. Dichloromethane used for
CV was purified by passing the solvent through an activated
alumina tower. Polymerizations were carried out in a solu-
tion containing 0.1 mol/L electrolyte, and 1 mM monomer.
Polymers were grown by cycling a potential between 0 V
and the onset of monomer oxidation (= 1.6 V) for a total of
10 cycles, at a scan rate of 100 mV/s.
14b
To a mixture of 11b (0.158 g, 0.232 mmol) and copper(II)
acetylacetonate (0.186 g, 0.710 mmol) was added 20 mL of
distilled THF. The brown solution was heated to reflux for
16 h. After cooling, the solution was reduced and MeOH
was added to precipitate the product. Subsequent filtration
afforded a red solid which was washed with MeOH and pe-
troleum ether. The product was recrystallized from DCM
and MeOH. Yield: 0.118 g, 0.16 mmol, 69%; mp > 300 °C.
UV–vis (CH2Cl2, nm (L mol–1cm–1)) λmax (ε): 356 (4.2 ×
104), 383 (4.0 × 104), 432 (4.3 × 104). IR (KBr, cm–1) ν:
2952, 2925, 2856, 1608, 1587, 1500, 1474, 1374, 1275,
1187, 696. MALDI-TOF-MS m/z:742 (M+). Anal. calcd. for
C40H42N2O4S2Cu: C 64.71, H 5.70, N 3.77; found C 64.99,
H 5.80, N 4.00.
Acknowledgement
We thank the Canadian Space Agency (CSA) and Natural
Sciences and Engineering Research Council of Canada
(NSERC) for funding. We thank Dr. Bryan Sih for cyclic
voltammetry measurements.
19a
Under
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thiophene 18 (200 mg, 1.56 mmol), 4,5-didodecyloxy-1,2-
phenylenediamine 10c (300 mg, 0.629 mmol), and nickel
acetylacetonate tetrahydrate (232 mg, 0.932 mmol) were dis-
solved in anhydrous THF (40 mL) and heated to reflux for
48 h. The red solution was then cooled to room temperature
and concentrated under vacuum. Addition of methanol to the
solution precipitated a red solid, which was collected by
centrifugation, then washed with methanol. The product was
a red solid (300 mg, yield 63%); mp > 210 °C. UV–vis
(CH2Cl2, nm (L mol–1cm–1)) λmax (ε): 231 (27000), 295
(17500), 373 (21500), 416 (25000). IR (cm–1) ν: 2918, 2850,
1600, 1571, 1518, 1487, 1469, 1443, 1338, 1281, 1190,
1142, 1076, 1041, 1032, 918, 812, 759, 698, 669, 593, 534,
3. (a) P.G. Lacroix. Eur. J. Inorg. Chem. 339 (2001); (b) P.G.
Lacroix, S. Di Bella, and I. Ledoux. Chem. Mater. 8, 541
(1996).
4. For recent examples, see: (a) X. Lu, W.-Y. Wong, and W.-K.
Wong. Eur. J. Inorg. Chem. 523 (2008); (b) S. Manivannan, R.
Prabhakaran, K.P. Balasubramanian, V. Dhanabal, R. Karvembu,
V. Chinnusamy, and K. Natarajan. Appl. Organomet. Chem. 21,
952 (2007); (c) M.S. Shongwe, B.A. Al-Rashdi, H. Adams,
M.J. Morris, M. Mikuriya, and G.R. Hearne. Inorg. Chem. 46,
9558 (2007); (d) H. Zhou, Z.-H. Peng, Z.-Q. Pan, Y. Song,
Q.-M. Huang and X.-L. Hu. Polyhedron, 26, 3233 (2007).
5. (a) C.W. Leung and M.J. MacLachlan. J. Inorg. Organomet.
Polym. Mater. 17, 57 (2007); (b) D. Vitalini, P. Mineo, S. Di
Bella, I. Fragala, P. Maravigna, and E. Scamporrino. Macro-
molecules, 29, 4478 (1996).
1
466. H NMR (400 MHz, DMSO-d6) δ: 7.81 (2H, s, aro-
matic CH), 7.40 (2H, d, J = 5.7 Hz, aromatic CH), 6.97 (2H,
s, aromatic CH), 6.58 (2H, d, J = 5.5 Hz, aromatic CH), 3.84
(4H, t, J = 6.7 Hz, OCH2), 1.65 (4H, m, CH2), 1.11 (36H, m,
CH2), 0.71 (6H, t, J = 6.8 Hz, CH3). EI–MS m/z: 752 (M+,
100%). Anal. calcd. for C40H58S2N2O4Ni: C 63.74, H 7.76,
N 3.72; found: C 63.35, H 7.90, N 4.08.
19b
6. (a) A. Pietrangelo, B.C. Sih, B.N. Boden, Z. Wang, Q. Li,
K.C. Chou, M.J. MacLachlan, and M.O. Wolf. Adv. Mater. 20,
2280 (2008); (b) R.P. Kingsborough and T.M. Swager. Adv.
Mater. 10, 1100 (1998); (c) R.P. Kingsborough and T.M.
Swager. J. Am. Chem. Soc. 121, 8825 (1999); (d) R.P.
Kingsborough and T.M. Swager. Chem. Mater. 12, 872 (2000);
(e) J.L. Reddinger and J.R. Reynolds. Synth. Met. 84, 225
(1997); ( f ) J.L. Reddinger and J.R. Reynolds. Macro-
molecules, 30, 673 (1997); (g) J.L. Reddinger and J.R.
Reynolds. Chem. Mater. 10, 3 (1998); (h) T. Shioya and T.M.
Swager. Chem. Commun. (Cambridge), 1364 (2002).
7. J. Sicé. J. Am. Chem. Soc. 75, 3697 (1953).
The same procedure was used as for the preparation of
19a. The product was isolated as a red solid, yield 72%; mp
> 210 °C. UV–vis (CH2Cl2, nm (L mol–1cm–1)): λmax (ε): 320
(14000), 388 (18000), 444 (17700). IR (cm–1) ν: 2917, 2849,
1600, 1566, 1521, 1487, 1436, 1401, 1338, 1260, 1216,
1081, 1032, 982, 950, 796, 764, 720, 697, 681, 526, 489,
459. EI–MS m/z: 761 (M+, 100%). Anal. calcd. for
C40H58N2O5S2V: C 63.05, H 7.67, N 3.68; found: C 62.89,
H 7.74, N 3.95.
Electrochemistry
Cyclic voltammetry experiments were conducted using ei-
ther a Pine AFCBP1 or Autolab potentiostat. The working
8. (a) G. Henrio, G. Ple, and J. Morel. Comptes Rendus des
Séances de l’Académie des Sciences, 278, 125 (1974); (b) P.
© 2008 NRC Canada

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11. G. Zotti, R.A. Marin, and M.C. Gallazzi. Chem. Mater. 9,
2945 (1997).
9. This compound has been previously prepared (see ref. 8b), but
via deprotection with pyridine hydrochloride. We found that
BBr3 was more effective.
10. J. Gradinura, A. Forni, V. Druta, F. Tessore, S. Zecchin, S.
Quici, and N. Garbalau. Inorg. Chem. 46, 884 (2007).
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13. D.-H. Kim, M.J. Choi, and S.-K. Chang. Bull. Korean Chem.
Soc. 21, 145 (2000).
© 2008 NRC Canada