Influence of heteroaryl group on electrochemical and spectroscopic properties of conjugated polymers

Article abstract of DOI:10.1016/j.electacta.2012.08.020

During our search for novel conjugated compounds, novel monomers and their polymers with selenophene and tellurophene group were synthesized and characterized. Conjugated poly(p-phenylenevinylenes)s (PPV) derivatives attracted a large attention due to their photolouminescence properties. The stereocontrolled synthesis of 1,4-bis(2-(heteroar-2-yl) ethenyl)benzenes and 1,4-bis(heteroar-2-yl)benzenes with tellurophene, selenophene, thiophene and furan-based monomers has been successfully performed. Eight of p-phenylene derivatives have been synthesized, electrochemically polymerized and characterized.

Full text of DOI:10.1016/j.electacta.2012.08.020

Electrochimica Acta 83 (2012) 271–282
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Electrochimica Acta
journal homepage: www.elsevier.com/locate/electacta
Influence of heteroaryl group on electrochemical and spectroscopic properties of
conjugated polymers
P. Dataa,b, M. Lapkowskia,b,∗, R. Motykaa, J. Suwinskia
a Faculty of Chemistry, Silesian University of Technology, M. Strzody 9, 44-100 Gliwice, Poland
b Center of Polymer and Carbon Materials, Polish Academy of Science, Sowinskiego 5, 44-100 Gliwice, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 May 2012
Received in revised form 3 August 2012
Accepted 6 August 2012
Available online 14 August 2012
During our search for novel conjugated compounds, novel monomers and their polymers with
selenophene and tellurophene group were synthesized and characterized. Conjugated poly(p-
phenylenevinylenes)s (PPV) derivatives attracted a large attention due to their photolouminescence
properties. The stereocontrolled synthesis of 1,4-bis(2-(heteroar-2-yl) ethenyl)benzenes and 1,4-
bis(heteroar-2-yl)benzenes with tellurophene, selenophene, thiophene and furan-based monomers has
been successfully performed. Eight of p-phenylene derivatives have been synthesized, electrochemically
polymerized and characterized.
Keywords:
Thiophenes
Selenophenes
Tellurophenes
Spectroelectrochemistry
Synthesis
© 2012 Elsevier Ltd. All rights reserved.
1. Introduction
decreasing of conjugation length conjugated spacer like vinyl group
is applied. The conjugated spacer between mers in conjugated
Organic semiconductor materials based on extended linear
␲-conjugated systems have been intriguing and significantly devel-
oped over the past several years [1–3], but there are always
difficulties with synthesis of compounds with proper properties. By
manipulation of their chemical structure it is possible to make them
suitable for use in liquid form for spin-coating or printing process
[4–7]. Since the 1960s, polyphenylenes and their derivatives have
been developed and used many important applications [8–10]. A
number of PPV polymers and their derivatives have been exten-
sively studied. Coupling benzene molecules via their para positions
is the easiest pathway to enhance the conjugation but this influence
on other properties. Typical unsubstituted linear polyphenylenes
have low solubility and because of that have practically no indus-
trial application. The main requirement of optoelectronics is the
ability to prepare a well defined material, featuring desirable
electronic properties, stable, durable and preferably soluble in com-
mon organic solvents for inkjet printing, or low molecular weight
molecules for PVD deposition [11–15]. The main modification of
molecular structure is adding alkoxy groups to enhance solubil-
ity which influence on torsion within polymer and unfortunately
decreasing conjugation length [16–18]. To avoid problems with
polymers influence on conjugation length, narrows the energy
gap of polymer and providing color tuning for optoelectronic
applications. Bisubstituted poly(thienylenevinylene)s exhibited
significant bathochromic shifts in comparison with their hete-
rocyclic analogs [19–21]. Conjugated poly(p-phenylenevinylene)s
(PPV) derivatives attracted
a large attention due to their
photoluminescence properties. PPV is the first reported poly-
mer used in organic light-emitting diode applications [22]. Its
derivatives remain the most popular conjugated polymers for
this application and continue to generate considerable inter-
est and much research form photovoltaic applications. Pure
PPV is insoluble substance and therefore difficult to process
into the solid state. The previous electrochemical investigation
of MEH-PPV (poly[2-methoxy-5-(2ꢀ-ethylhexyloxy)-p-phenylene
vinylene]) showed band gap of 2.18 eV stable p-doping pro-
cess [23,24]. Substitution of heteroarylphenylene derivatives with
long alkoxy group influence on solubility and processability of
synthesized polymers [25–32]. Heteroaryl-p-phenylenevinylenes
derivatives are shifted bathochromic than his phenylenevinylenes
analog and shifted hypochromic than his heteroaryl analogs
[33]. Elongation of alkoxy chain in poly[1,4-bis(2-(thien-2-
yl)ethenyl)benzenes] influenced by increasing on band gap value
and polaron absorption wavelength peak [34]. Formerly we
have shown that monomers with conjugated system of multiple
bonds bearing two terminal residues of chalcogens (furan, thio-
phene, and selenophene) with free positions in C5 are able to
∗
Corresponding author at: Faculty of Chemistry, Silesian University of Technol-
ogy, M. Strzody 9, 44-100 Gliwice, Poland.
E-mail address: Mieczyslaw.Lapkowski@polsl.pl (M. Lapkowski).
0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.electacta.2012.08.020

272
P. Data et al. / Electrochimica Acta 83 (2012) 271–282
Fig. 1. Investigated compounds.
electropolymerize leading to linear PPV-type conducting systems
that show strong electroluminescence [34–37]. The (E,E)-1,4-
diethoxy-2,5-bis[2-(tellurophen-2- yl)ethenyl]benzene presenting
higher absorption peak and fluorescence wavelength than thio-
phene and selenophene analogs [38]. There are many techniques to
determine properties of materials for optoelectronic applications
[39]. The electrochemical and spectroelectrochemical analyses
give a possibility to determine oxidation and reduction poten-
tials of compounds which are directly related to HOMO and LUMO
values, kind of charge carriers responsible for the process of con-
ductivity and other parameters for optoelectronic applications
[39–41].
The synthesis of investigated compound (Fig. 1) was associ-
ated with examination of influence of heteroaryl and vinyl group
to obtained polymer during electrochemical polymerization. Typi-
cally benzene ring in the middle of heteroaryl group influences on
decreasing of oxidation potential but influence of vinyl linker was
not fully characterized.
charge and capacitance were measured on 10 MHz Au coated elec-
trode with 0.209 cm2 active area, on UELKO M106 QCM combined
with AUTOLAB PGSTAT20 potentiostat. UV–vis spectroscopy was
performed on HP Agilent 8453 spectrometer. Fluorescence mea-
surements were conducted on Hitachi F-2500 Fluorimeter.
2.3. General synthesis of 1,4-bis(2-(heteroar-2-yl)
ethenyl)benzenes (5)
A stereocontrolled three steps synthesis of a furan, thio-
phene, selenophene, tellurophene-based monomers of 1,4-bis(2-
(heteroar-2-yl)ethenyl)benzenes (5) has been successfully per-
formed starting from 1,4-dialkoxybenzene (1) as it is shown in
Scheme 1. Compound 1 was treated with paraformaldehyde and
gaseous hydrogen chloride in the solution of glacial acetic acid
and concentrated hydrochloric acid to give 2,5-bis(chloromethyl)-
1,4-dialkoxybenzene (3). The latter compound on heating at
150 ◦C with ca 20% excess of triethoxyphosphine afforded 2,5-
bis(diethoxyphosphononomethyl)-1,4-dialkoxybenzene. Furan-2-
carboaldehyde (4a) and thiophene-2-carboaldehyde (4b) were
bought from Sigma–Aldrich Company.
2. Experimental
Therefore,
a stereocontrolled condensation of 3 with 2-
2.1. Materials
heteroarylcarbaldehyde leading to the most stable EE isomer was
a method of choice for the synthesis of 5.
All solvents for synthesis were dried and then distilled before the
use. Other commercial substances and reagents were used with-
out purification. Electrochemical measurements were conducted in
1.0 mM concentration of all monomers for all of cyclic voltamper-
ometry measurements. Electrochemical studies were conducted in
0,1 M solution of Bu4NBF4 (Sigma–Aldrich 99%) in dichloromethane
(DCM) solvent (anhydrous for HPLC) at room temperatures. UV–vis
spectroelectrochemical measurements were conducted on poly-
meric layers synthesized on indium tin oxide (ITO) quartz glass
working electrode in condition compared to cyclic voltammetric
measurements. Fluorescence was measured for 10 ␮M concentra-
tion of all monomers in DCM solvent.
2.3.1. 1,4-Dibutoxybenzene (1) [42]
To a stirred solution of 50 cm3 DMSO, 5.50 g (0.05 mole) hydro-
quinone and 5.00 g (0.12 mole) NaOH under nitrogen 20.24 g
(0.11 mole) butyl iodide was added drop wise. Stirring was contin-
ued with precipitating product of reaction, after 2 h mixture was
poured on 400 cm3 of cold distilled water. Precipitated product
was filtered off under vacuum, washed with water and dried under
2.2. Measurements
Melting points (not corrected) were determined on Boetius HMK
apparatus. NMR spectra were taken in CDCl3 with TMS as an inter-
nal reference by Varian XL-300 at 300 MHz for 1H and at 75.5 MHz
for 13C. EA results were obtained using Perkin-Elmer CHN auto-
matic analyzer. Electrochemical investigation has been carried out
using Eco Chemie Company’s AUTOLAB potentiostat “PGSTAT20”.
All measured spectra have been collected using GPES (General Pur-
pose Electrochemical System) software. The electrochemical cell
comprised platinum wire with 1 mm diameter of working area and
ITO glass as working electrode, Ag/AgCl electrode as reference elec-
trode and platinum coil as auxiliary electrode. Cyclic voltammetric
measurements were conducted at 50 mV/s potential rate and cal-
ibrated versus ferrocene/ferrocenium redox couple. The specific
Scheme 1. A stereocontrolled three steps synthesis of (E,E)-1,4-dialkoxy-2,5-bis [2-
(heteroar-2-yl)ethenyl]benzene (5).

P. Data et al. / Electrochimica Acta 83 (2012) 271–282
273
nitrogen. Dried product was recrystalized from methanol and dried
in vacuo (8.38 g, 37.69 mmol, 56%). Product as white flakes with
tm = 45–46 ◦C. 1H NMR (300 MHz, CDCl3) ı (ppm) 0.97 (t, J = 7.20 Hz,
6H, 2× CH3), 1.42–1.54 (m, 4H, 2× CH2 ), 1.69–1.79 (m, 4H,
2× CH2 ), 3.90 (t, J = 6.30 Hz, 4H, 2× CH2O ), 6.82 (s, 2H, 2×
5-bis(diethoxyphosphonomethyl)benzene was added and next
0.15 g (0.13 cm3, 1.56 mmol) of furfural in 10 cm3 DMF was added
drop wise. Reaction mixture was stirred for 3 h in room temper-
ature. Reaction mixture was poured on 100 cm3 of cold distilled
water with ice and 2 cm3 of concentrated hydrochloric acid.
Suspension was extracted with dichloromethane (3 × 50 cm3).
Organic layer was dried with MgSO4 and after solvent distillation
under low pressure, crude product (0.19 g, 0.47 mmol, 70%) was
obtained as yellow solid with tm = 124–126 ◦C. 1H NMR (300 MHz,
CDCl3) ı (ppm) 1.03 (t, J = 7.50 Hz, 6H, 2× CH3), 1.58 (sext.,
J = 7.50 Hz, 4H, 2× CH2 ), 1.85 (q, J = 6.60 Hz, 4H, 2× CH2 ),
4.03 (t, J = 6.60 Hz, 4H, 2× OCH2 ), 6.35 (d, J = 3.30 Hz, 2H, C4H3O,
2× C3 H), 6.21–6.42 (m, 2H, C4H3O, 2× C4 H), 6.81–7.06 (m,
2H, 2× Hvinyl), 7.01 (s, 2H, 2× HAr), 7.32 (d, J = 16.50 Hz, 2H,
2× Hvinyl), 7.41 (d, J = 1.20 Hz, 2H, C4H3O, 2× C5 H). 13C NMR
(75 MHz, CDCl3) ı (ppm) 14.08 (2× CH3), 19.56 (2× CH2 ),
31.69 (2× CH2 ), 69.28 (2× OCH2 ), 108.33 (C4H3O, C3), 110.94
(C4H3O, 2× C4), 111.76 (2× Cvinyl), 117.14 (2× CAr H), 122.44
(2× Cvinyl), 126.56 (2× CAr), 142.19 (C4H3O, 2× C5), 151.26 (2×
COAlk), 154.14 (C4H3O, 2× C2). UV–vis (CH2Cl2): ꢀ = 401.0 nm,
H
Ar). 13C NMR (75 MHz, CDCl3) ı (ppm) 13.89 (2× CH3), 19.27
(2× CH2 ), 31.47 (2× CH2 ), 68.33 (2× OCH2 ), 115.38 (2×
CAr H), 153.20 (2× COAlk).
2.3.2. 1,4-Bis(chloromethyl)-2,5-dialkoxybenzene (2) [35]
To a stirred solution of 60 cm3 acetic acid and 15 cm3 con-
centrated hydrochloric acid filled with gaseous hydrochloric acid,
2.70 g (90.00 mmol) paraformaldehyde was added. After clarifica-
tion of stirred solution 3.33 g (15.00 mmol) dibutoxybenzene was
added. Stirring was continued with precipitating product of reac-
tion for 24 h and then mixture was poured on 300 cm3 of cold
distilled water. Precipitated white product was filtered under vac-
uum, washed with water and dried under vacuum and P4O10. Crude
product was recrystallized from methanol (4.37 g, 13.69 mmol,
91%) as white solid with tm = 81–82 ◦C. 1H NMR (300 MHz, CDCl3)
ı (ppm) 0.98 (t, J = 7.20 Hz, 6H, 2× CH3), 1.46–1.58 (m, 4H, 2×
CH2 ), 1.74–1.83 (m, 4H, 2× CH2 ), 3.99 (t, J = 6.60 Hz, 4H, 2×
OCH2 ), 4.63 (s, 4H, 2× CH2Cl), 6.91 (s, 2H, 2× HAr). 13C NMR
(75 MHz, CDCl3) ı (ppm) 13.85 (2× CH3), 19.28 (2× CH2 ), 31.41
(2× CH2 ), 41.35 (2× CH2Cl), 68.80 (2× OCH2 ), 114.29 (2×
CAr H), 127.03 (2× CAr), 153.56 (2× COAlk).
ε = (4.47 0.28) × 104;
ꢀ = 346.5 nm,
ε = (2.40 0.15) × 104;
ꢀ = 236.5 nm,
C(76.82%) H(7.44%), found C(76.64%) H(7.51%).
ε = (1.47 0.10) × 104 [dm3/mol cm].
EA
calc.
2.3.6. (EE)-1,4-dibutoxy-2,5-bis[2-(tiophen-2-
yl)ethenyl]benzene (5b)
To a stirred solution of 10 cm3 DMF and 1.02 g (9.20 mmol)
t-BuOK in ice bath 0.40 g (0.77 mmol) 1,4-dibutoxy-2,5-
bis(diethoxylphosphonomethyl)benzene was added and next
0.20 g (0.20 cm3, 1.77 mmol) of 2-thienyl aldehyde in 10 cm3 DMF
was added drop wise. Reaction mixture was stirred for 3 h in room
temperature. Reaction mixture was poured on 100 cm3 of cold dis-
tilled water with ice and 2 cm3 of concentrated hydrochloric acid.
Suspension was extracted with dichloromethane (3 × 50 cm3).
Organic layer was dried with MgSO4 and after solvent distillation
under low pressure, crude product (0.23 g, 0.52 mmol, 67%) was
obtained as yellow solid with tm = 159–160 ◦C. 1H NMR (300 MHz,
CDCl3) ı (ppm) 1.03 (t, J = 7.50 Hz, 6H, 2× CH3), 1.57 (sext.,
J = 7.50 Hz, 4H, 2× CH2 ), 1.85 (q, J = 6.60 Hz, 4H, 2× CH2 ), 4.04
(t, J = 6.00 Hz, 4H, 2× OCH2 ), 7.00 (dd, J = 3.60 Hz, J = 5.10 Hz,
2H, C4H3S, 2× C4 H), 7.03 (s, 2H, 2× HAr), 7.06 (d, J = 3.60 Hz, 2H,
C4H3S, 2× C3 H), 7.18 (d, J = 5.10 Hz, 2H, C4H3S, 2× C5 H), 7.24 (d,
J = 16.20 Hz, 2H, 2× Hvinyl). 7.31 (d, J = 16.20 Hz, 2H, 2× Hvinyl). 13C
NMR (75 MHz, CDCl3) ı (ppm) 14.11 (2× CH3), 19.61 (2× CH2 ),
31.69 (2× CH2 ), 69.35 (2× OCH2 ), 110.82 (2× CAr H), 122.26
(2× Cvinyl), 123.54 (2× Cvinyl), 124.32 (C4H3S, 2× C3), 125.83
(C4H3S, 2× C4), 126.52 (2× CAr), 127.72 (C4H3S, 2× C5), 143.97
(C4H3S, 2× C2), 151.17 (2× COAlk). UV–vis (CH2Cl2) ꢀ = 398.5 nm,
2.3.3. 1,4-Dibutoxy-2,5-bis(diethoxyphosphonomethyl)benzene
(3) [43]
A solution of 0.32 g (1.00 mmol) 2,5-bis(chloromethyl)-1,4-
dibutoxybenzene and 0.50 g (0.52 cm3, 3.00 mmol) triethoxyphos-
phine was stirred at 150 ◦C for 4 h. Triethoxyphosphine excess was
distilled off under low pressure and obtained product was purified
chromatographically (2.5% vol. methanol in chloroform) to gave
light yellow oil liquid (0.75 g, 1.44 mmol, 92%). 1H NMR (300 MHz,
CDCl3) ı (ppm) 0.97 (t, J = 7.30 Hz, 6H, 2× CH3), 1.24 (t, J = 7.30 Hz,
12H, 4× CH3), 1.49 (sekst., J = 7.50 Hz, 4H, 2× CH2 ), 1.75 (q,
J = 7,50 Hz, 4H, 2× CH2 ), 3.23 (d, J = 20.40 Hz, 4H, 2× CH2P ),
3.93 (t, J = 6.50 Hz, 4H, 2× OCH2 ), 4.00 (q, J = 7.30 Hz, 8H, 4×
OCH2 ), 6.92 (s, 2H, 2× CAr H). 13C NMR (75 MHz, CDCl3) ı
(ppm) 13.97 (2× CH3), 16.42 (2× CH2 ), 19.38 (4× CH3), 26.57
1
(d, JP–C = 139.50 Hz, 2× CH2P ), 31.62 (2× CH2 ), 61.91 (4×
OCH2 ), 68.72 (2× OCH2 ), 114.96 (2× CAr H), 119.51 (2× CAr),
150.41 (2× COAlk).
2.3.4. Selenophene-2-carboaldehyde (4c) [44]
The solution of 2.71 g (2.47 cm3; 20.00 mmol) N-
methylformanilide and 3.07 g (1.87 cm3, 20.00 mmol) POCl3
under nitrogen was stirred for 30 min. Mixture was cooled to
15 ◦C and 2.50 g (19.10 mmol) selenophene was added drop wise.
Reaction was conducted in room temperature under nitrogen for
12 h. Reaction mixture was poured on 300 cm3 of cold distilled
water with ice. Obtained solution extracted three times with
diethyl ether. Ether layer was flushed with NaHCO3 solution and
dried with MgSO4. After solvent evaporation the crude product
was obtained (1.95 g, 12.30 mmol, 64%) as orange liquid. 1H NMR
(300 MHz, CDCl3) ı (ppm) 7.48 (dd, J = 3.90 Hz, J = 5.40 Hz, 1H,
C4H3Se, H4), 8.03 (dd, J = 1.20 Hz, J = 3.90 Hz, 1H, C4H3Se, H3), 8.50
(dt, J = 1.20 Hz, J = 5.40 Hz, 1H, C4H3Se, H5), 9.82 (d, J = 1.20 Hz, 1H,
CHO). 13C NMR (75 MHz, CDCl3) ı (ppm) 130.87, 139.57, 141.14,
150.39 (C2), 184.38 ( CHO).
ε = (4.42 0.27) × 104,
ꢀ = 341.0 nm,
ε = (2.11 0.14) × 104,
ꢀ = 246.5 nm, ε = (1.15 0.08) × 104 [dm3/mol cm].
2.3.7. (EE)-1,4-dibutoxy-2,5-bis[2-(selenophen-2-
yl)ethenyl]benzene (5c)
To a stirred solution of 10 cm3 DMF and 0.99 g (8.83 mmol)
t-BuOK in ice bath 0.27 g (0.54 mmol) 1,4-dibutoxy-2,5-
bis(diethoxylphosphonomethyl)benzene was added and next
0.14 g (0.88 mmol) of 2-selenophenyl aldehyde in 10 cm3 DMF
was added drop wise. Reaction mixture was stirred for 3 h in room
temperature. Reaction mixture was poured on 100 cm3 of cold dis-
tilled water with ice and 2 cm3 of concentrated hydrochloric acid.
Suspension was extracted with dichloromethane (3 × 50 cm3).
Organic layer was dried with MgSO4 and after solvent distil-
lation under low pressure, crude product (0.08 g, 0.15 mmol,
29%) was obtained as yellow solid with tm = 173–175 ◦C. 1H NMR
(300 MHz, CDCl3) ı (ppm) 1.03 (t, J = 7.50 Hz, 6H, 2× CH3), 1.58
2.3.5. (EE)-1,4-dibutoxy-2,5-bis[2-(furan-2-yl)etenyl]benzene
(5a) [43]
To a stirred solution of 10 cm3 DMF and 1.02 g (9.20 mmol)
t-BuOK in ice bath 0.35 g (0.67 mmol) 1,4-dibutoxy-2,

274
P. Data et al. / Electrochimica Acta 83 (2012) 271–282
Scheme 2. A stereocontrolled three steps synthesis of 1,4-dialkoxy-2,5-bis (heteroar-2-yl)benzene (10).
(sext., J = 7.50 Hz, 4H, 2× CH2 ), 1.85 (pent., J = 6.60 Hz, 4H, 2×
CH2 ), 4.04 (t, J = 6.30 Hz, 4H, 2× OCH2 ), 7.03 (s, 2H, 2×
HAr), 7.14 (d, J = 16.50 Hz, 2H, 2× Hvinyl), 7.33 (d, J = 16.50 Hz,
2H, 2× Hvinyl), 7.22–7.34 (m, 4H, C4H3Se, 2× C3 H, 2× C4 H),
7.82 (d, J = 4.50 Hz, 2H, C4H3Se, 2× C5 H). 13C NMR (75 MHz,
CDCl3) ı (ppm) 14.12 (2× CH3), 19.64 (2× CH2 ), 31.68 (2×
CH2 ), 69.38 (2× OCH2 ), 110.89 (2× CAr H), 124.78 (2×
2.4.1. 1,4-Dibutoxy-2,5-dibromobenzene (6) [45]
To a stirred solution of 2.07 g (9.31 mmol) 1,4-dibutoxybenzene,
1.90 g (23.16 mmol) sodium acetate and 15 cm3 acetic acid, a
3.02 g (0.96 cm3, 18.90 mmol) Br2 in 2 cm3 acetic acid was added
drop wise. After 3 h of stirring in room temperature, mixture was
poured on 50 cm3 of cold distilled water with ice and filtered
under vacuum. Precipitate as crude product was recrystallized from
dichloromethane to obtained (2.67 g, 7.02 mmol, 78%) white solid
with tm = 70–72 ◦C. 1H NMR (300 MHz, CDCl3) ı (ppm) 0.98 (t,
J = 7.20 Hz, 6H, 2× CH3), 1.52 (sekst., J = 7.50 Hz, 4H, 2× CH2 ),
1.79 (q, J = 6.90 Hz, 4H, 2× CH2 ), 3.95 (t, J = 6.30 Hz, 4H, 2×
OCH2 ), 7.09 (s, 2H, 2× HAr). 13C NMR (75 MHz, CDCl3) ı (ppm)
13.96 (2× CH3), 19.34 (2× CH2 ), 31.35 (2× CH2 ), 70.15
(2× OCH2 ), 111.29 (2× CAr Br), 118.63 (2× CAr H), 150.25 (2×
COAlk).
C
vinyl), 124.87 (2× Cvinyl), 126.62 (2× CAr), 128.63 (C4H3Se, 2×
C5), 128.83 (C4H3Se, 2× C4), 130.30 (C4H3Se, 2× C3), 150.23
(C4H3Se, 2× C2), 151.19 (2× COAlk). UV–vis (CH2Cl2) ꢀ = 413.5 nm,
ε = (4.82 0.31) × 104,
ꢀ = 356.0 nm,
ε = (2.03 0.13) × 104,
ꢀ = 291.0 nm,
ε = (0.93 0.06) × 104 [dm3/mol cm].
EA
calc.
C(58.65%) H(5.68%), found C(58.09%) H(5.93%).
2.3.8.
(EE)-1,4-diethoxy-2,5-bis[2-(tellurophen-2-yl)ethenyl]benzene
(5d)
2.4.2. 1,4-Diethoxy-2,5-diiodobenzene (7) [46]
Synthesis and characterization were previously reported in pub-
lication [38].
To
a
stirred solution of 2.00 g (12.01 mmol) 1,4-
diethoxybenzene in 20 cm3 acetic acid and 5 cm3 CCl4, a 3.05 g
(12.03 mmol) I2, 1 cm3 of conc. H2SO4, 1 cm3 of water and 2.57 g
(12.03 mmol) KIO3 were added in order. After 24 h of stirring under
reflux, mixture was poured on 200 cm3 of cold distilled water
with ice and extracted with chloroform (3× 50 cm3). Organic layer
was dried with MgSO4 and after solvent distillation under low
pressure, crude product (3.32 g, 7.78 mmol, 65%) was obtained
as white solid with tm = 144–146 ◦C. 1H NMR (300 MHz, CDCl3) ı
(ppm) 1.44 (t, J = 6.90 Hz, 6H, 2× CH3), 4.01 (q, J = 6.90 Hz, 4H, 2×
OCH2 ), 7.18 (s, 2H, 2× HAr). 13C NMR (75 MHz, CDCl3) ı (ppm)
14.94 (2× CH3), 66.19 (2× OCH2 ), 86.63(2× CAr I), 123.17 (2×
CAr H), 152.95 (2× COAlk).
2.4. General synthesis of 1,4-bis(heteroar-2-yl) benzenes (10)
A two steps synthesis of a furan, thiophene, selenophene,
tellurophene-based monomers of 1,4-bis(heteroar-2-yl) ben-
zenes (10) has been successfully performed starting from
1,4-dialkoxybenzene (1) as it is shown in Scheme 2. Compound
1 was treated with bromine in acetic acid to give 2,5-dibromo-
1,4-dibutoxybenzene (6). The synthesis of tellurophene derivatives
only works with 2,5-iodo-1,4-alkoxybenzenes (7) as starting mate-
rials. Furan and thiophene derivatives were synthesized by Suzuki
coupling reaction and selenophene derivative by Still coupling.
2-Furylboronic acid (8a) was bought from Maybridge company
and 2-thienylboronic acid (8b) was bought from Acros Organics
Company.
2.4.3. Tri-n-butyl(selenophen-2-yl)tin (9c) [47]
To
a
stirred solution of 1.54 g (1.02 cm3, 11.75 mmol)
selenophene in10 cm3 dried diethyl ether under nitrogen at

P. Data et al. / Electrochimica Acta 83 (2012) 271–282
275
Fig. 2. Cyclic voltammetry of investigated monomers of polymerization. Measurement conditions: scan rate 50 mV/s, Ag/AgCl – quasireference electrode, calibrated against
ferrocene/ferrocenium redox couple.
temperature −10 ◦C 0.75 g (1.06 cm3, 11.71 mmol) n-butyllithium
2.4.5. 1,4-Dibutoxy-2,5-bis(furan-2-yl)benzene (10a)
The reaction mixture of 0.31 g (0.82 mmol) 2,5-dibromo-1,4-
dibutoxybenzene, 0.20 g (1.79 mmol) 2-furanboronic acid, 0.02 g
(0.014 mmol) Pd(PPh3)4, 3 cm3 2 M Na2CO3 (3.39 mmol) in 10 cm3
THF was stirred for 24 h at temperature 70 ◦C. Solution after
synthesis was extracted (50 cm3 water, 50 cm3 dichloromethane)
and organic layer was washed with water (2×), salty water (1×)
and dried by MgSO4. Solvent was evaporated and crude prod-
uct was purified by column chromatography method (hexane
– eluent) to obtained light green solid (0.29 g, 0.82 mmol, 83%)
with tm = 140–141 ◦C. 1H NMR (300 MHz, CDCl3) ı (ppm) 1.02 (t,
J = 7.50 Hz, 6H, 2× CH3), 1.57 (sext., J = 7.50 Hz, 4H, 2× CH2 ),
1.90 (q, J = 7.20 Hz, 4H, 2× CH2 ), 4.14 (t, J = 6.30 Hz, 4H, 2×
OCH2 ), 6.51 (dd, J = 1.80 Hz, J = 3.30 Hz, 2H, C4H3O, 2× C4 H),
7.03 (d, J = 3.30 Hz, 2H, C4H3O, 2× C3 H), 7.45 (s, 2H, 2× HAr),
7.47 (d, J = 1.80 Hz, 2H, C4H3O, 2× C5 H). 13C NMR (75 MHz,
CDCl3) ı (ppm) 14.09 (2× CH3), 19.67 (2× CH2 ), 31.74 (2×
CH2 ), 68.71 (2× OCH2 ), 109.50 (C4H3O, 2× C3), 110.35
(C4H3O, 2× C4), 112.13 (2× CAr H), 118.91 (2× CAr), 141.08
(C4H3O, 2× C5), 149.08 (C4H3O, 2× C2), 150.47 (2× COAlk).
UV–vis (CH2Cl2) ꢀ = 368.0 nm, ε = (2.12 0.14) × 104, ꢀ = 351.5 nm,
(2.5 M hexane) was added drop wise. Mixture was stirred for
1.5 h at room temperature and next reaction were cooled down
to 0 ◦C for adding 3.83 g (3.19 cm3, 11.77 mmol) of tri-n-butyltin
chloride in 10 cm3 dried diethyl ether. Reaction was conducted
for 1 h at room temperature and filtered under vacuum. Solvent
was evaporated and crude product (3.50 g, 8.34 mmol, 71%) was
obtained as light yellow oil liquid.
2.4.4. Tri-n-butyl(tellurophen-2-yl)tin (9d)
To a stirred solution of 1.00 g (5.57 mmol) tellurophene[33] in
10 cm3 dried diethyl ether under nitrogen at temperature −10 ◦C
0.36 g (2.23 cm3, 5.57 mmol) of n-butyllithium (2.5 M hexane) was
added drop wise. Mixture was stirred for 1.5 h at room tempera-
ture and as next step reaction was cooled down to 0 ◦C for adding
1.81 g (1.59 cm3, 5.57 mmol) of tri-n-butyltin chloride in 10 cm3
dried diethyl ether. Reaction was conducted for 1 h at room tem-
perature and filtered under vacuum. Solvent was evaporated and
crude product (2.56 g, 5.47 mmol, 98%) was obtained as light yel-
low oil liquid. 1H NMR (300 MHz, CDCl3) ı (ppm) 0.90 (t, J = 7.30 Hz,
9H, 3× CH3), 0.95–1.20 (m, 6H, 3× CH2 ), 1.34 (sext., J = 7.20 Hz,
6H, 3× CH2 ), 1.45–1.65 (m, 6H, 3× CH2 ), 8.00 (dd, J = 3.60 Hz,
J = 6.40 Hz, 1H, H4Ar), 8.12 (dd, 1H, J = 0.80 Hz, J = 3.60 Hz, H3Ar), 9.25
(dd, 1H, J = 0.80 Hz, J = 6.40 Hz, H5Ar). 13C NMR (75 MHz, CDCl3) ı
(ppm) 11.72, 13.80, 27.47, 29.14, 130.12, 140.08, 145.66.
ε = (2.18 0.14) × 104,
ꢀ = 295.0 nm,
ꢀ = 309.5 nm,
ε = (2.25 0.14) × 104,
ꢀ = 247.0 nm,
ε = (1.68 0.11) × 104,
ε = (0.91 0.06) × 104 [dm3/mol cm]. EA calc. C(68.35%) H(6.78%),
found C(68.15%) H(6.79%).

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P. Data et al. / Electrochimica Acta 83 (2012) 271–282
Fig. 3. Cyclic voltammetry of electrochemical doping–dedoping process of the electrodeposited polymers in monomer free medium. Measurement conditions: scan rate
50 mV/s, Ag/AgCl – quasireference electrode, calibrated against ferrocene/ferrocenium redox couple.
0.66 g (1.57 mmol) tributyl(selenophen-2-yl)tin in 2 cm3 was
added drop wise. Reaction was conducted under nitrogen for 18 h
at temperature 75 ◦C. Rection mixture was poured into 50 cm3 of
concentrated KF solution with 20 cm3 of dichloromethane and
stirred for 1 h. Aqueous layer was extracted with dichloromethane
(3 × 10 cm3) and collected organic phases were washed by KF
solution and water. Organic phase was dried by MgSO4 and
solvent was evaporated. Crude product was purified by column
chromatography (hexane) to give yellow solid (0.18 g, 0.37 mmol,
48%) with tm = 120–121.5 ◦C (hexane), 120–122 ◦C (methanol),
121–122 ◦C (diethyl ether). 1H NMR (300 MHz, CDCl3) ı (ppm) 1.02
(t, J = 7.20 Hz, 6H, 2× CH3), 1.51 (sext., J = 7.20 Hz, 4H, 2× CH2 ),
1.94 (pent., J = 7.20 Hz, 4H, 2× CH2 ), 4.14 (t, J = 6.60 Hz, 4H, 2×
OCH2 ), 7.26 (s, 2H, 2× HAr), 7.36 (dd, J = 3.90 Hz, J = 5.70 Hz,
2H, C4H3Se, 2× C4 H), 7.72 (d, J = 3.90 Hz, 2H, C4H3Se, 2× C3 H),
8.06 (d, J = 5.70 Hz, 2H, C4H3Se, 2× C5 H). 13C NMR (75 MHz,
CDCl3) ı (ppm) 13.92 (2× CH3), 19.57 (2× CH2 ), 31.56 (2×
CH2 ), 69.48 (2× OCH2 ), 111.06 (2× CAr H), 124.59 (2×
CAr), 125.83 (C4H3Se, 2× C3), 128.86 (C4H3Se, 2× C4), 131.76
(C4H3Se, 2× C5), 143.06 (C4H3Se, 2× C2), 148.59 (2× COAlk).
UV–vis (CH2Cl2) ꢀ = 374.0 nm, ε = (2.57 0.16) × 104, ꢀ = 323.5 nm,
2.4.6. 1,4-Dibutoxy-2,5-bis(thiophen-2-yl)benzene (10b)
0.50 g (1.32 mmol) 2,5-dibromo-1,4-dibutoxybenzene, 0.37 g
(2.89 mmol) 2-thienylboronic acid, 0.03 g (0.026 mmol) Pd(PPh3)4,
3 cm3 (3.39 mmol) 2 M Na2CO3, 10 cm3 THF-u. Reaction time 24 h.
Received product 0.28 g (0.72 mmol, 54%) as white solid with
tm = 93–95 ◦C. 1H NMR (300 MHz, CDCl3) ı (ppm) 1.00 (t, J = 7.50 Hz,
6H, 2× CH3), 1.56 (sext., J = 7.50 Hz, 4H, 2× CH2 ), 1.82 (q,
J = 6.60 Hz, 4H, 2× CH2 ), 4.09 (t, J = 6.30 Hz, 4H, 2× OCH2 ),
7.09 (dd, J = 3.60 Hz, J = 5.10 Hz, 2H, C4H3S, 2× C4 H), 7.26 (s, 2H,
2× HAr), 7.34 (dd, J = 0.90 Hz, J = 5.10 Hz, 2H, C4H3S, 2× C5 H),
7,53 (dd, J = 0.90 Hz, J = 3.60 Hz, 2H, C4H3S, 2× C3 H). 13C NMR
(75 MHz, CDCl3) ı (ppm) 14.07 (2× CH3), 19.63 (2× CH2 ),
31.65 (2× CH2 ), 69.51 (2× OCH2 ), 112.91 (2× CAr H),
123.09 (2× CAr), 125.27 (C4H3S, 2× C3), 125.82 (C4H3S, 2× C4),
126.85 (C4H3S, 2× C5), 139.44 (C4H3S, 2× C2), 149.36 (2× COAlk).
UV–vis (CH2Cl2) ꢀ = 361.5 nm, ε = (2.26 0.14) × 104, ꢀ = 305.0 nm,
ε = (1.61 0.10) × 104, ꢀ = 256.5 nm, ε = (0.94 0.06) × 104 [dm3/
mol cm].
2.4.7. 1,4-Dibutoxy-2,5-bis(selenophen-2-yl)benzene (10c)
ε = (1.37 0.09) × 104,
ꢀ = 313.0 nm,
ε = (1.38 0.09) × 104,
To
a stirred solution of 0.30 g (0.79 mmol) 2,5-dibromo-
ꢀ = 290.0 nm,
ε = (0.93 0.06) × 104 [dm3/mol cm].
EA
calc.
1,4-dibutoxybenzene, 0.02 g (0.024 mmol) Pd(PPh3)2Cl2, 0.03 g
(0.13 mmol) triphenylphosphine in 3 cm3 DMF and 3 cm3 THF,
C(55.01%) H(5.46%), found C(54.64%) H(5.38%).

P. Data et al. / Electrochimica Acta 83 (2012) 271–282
277
Fig. 4. Cyclic voltammetry of investigated monomers of polymerization. Measurement conditions: scan rate 50 mV/s, Ag/AgCl – quasireference electrode, calibrated against
ferrocene/ferrocenium redox couple.
2.4.8. 1,4-Diethoxy-2,5-bis(tellurophen-2-yl)benzene (10d)
To stirred solution of 0.42 g (1.00 mmol) 2,5-diiodo-
1,4-diethoxybenzene, 0.04 g (0.035 mmol) Pd(PPh3)4,
3. Results and discussion
a
3.1. Electrochemical properties
0.01 g (0.05 mmol) CuI in 5 cm3 DMF, 0.94 g (2.00 mmol)
tributyl(tellurophen-2-yl)tin in 3 cm3 DMF was added drop
wise. Reaction was conducted under nitrogen for 18 h at tempera-
ture 75 ◦C. As next step reaction mixture was poured into 50 cm3
of concentrated KF solution and 20 cm3 of dichloromethane and
stirred for 1 h. Aqueous layer was extracted with dichloromethane
(3× 15 cm3) and collected organic phases were washed by KF
solution and water. Organic phase was dried by MgSO4 and
solvent was evaporated. Crude product was purified by column
chromatography (hexane) to give yellow solid (0.24 g, 0.46 mmol,
46%) with tm = 214–216 ◦C (hexane). 1H NMR (300 MHz, CDCl3) ı
(ppm) 1.62 (t, J = 6.90 Hz, 6H, 2× CH3), 4.29 (q, J = 6.90 Hz, 4H,
2× OCH2 ), 7.44 (s, 2H, 2× HAr), 7.94 (dd, J = 4.50 Hz, J = 7.20 Hz,
2H, C4H3Te, 2× C4 H), 8.15 (dd, J = 0.90 Hz, J = 4.50 Hz, 2H, C4H3Te,
2× C3 H), 8.98 (dd, J = 0.90 Hz, J = 7.20 Hz, 2H, C4H3Se, 2× C5 H).
13C NMR (75 MHz, CDCl3) ı (ppm) 15.52 (2× CH3), 65.63 (2×
OCH2 ), 108.63 (2× CAr H), 127.39 (2× CAr), 129.32 (C4H3Te,
2× C3), 131.82 (C4H3Te, 2× C4), 136.29 (C4H3Te, 2× C5), 136.62
(C4H3Te, 2× C2), 147.63(2× COAlk). UV–vis (CH2Cl2) ꢀ = 406.0 nm,
To understand influence of heteroatom in the electronic struc-
tures of the molecules, cyclic voltammetry (CV) measurements
were performed. Fig. 2 shows the results of electrochemical mea-
surements of the monomers in the potential ranges from −0.7 V
up to 0.8 V for thiophene derivative. Cyclic voltammetric curves
in positive potentials range show multistep irreversible oxidation
process, and both the shape of the curves and the individual oxida-
tion potentials of peaks depend on the type of heteroatom. Series
of reduction peaks are observed at lower potentials than the first
oxidation peak, which indicates that the reactions give us products
with a higher conjugation degree compared to the initial monomer.
The reduction process is irreversible, although less complicated,
but in the case of monomers containing tellurophene several inde-
pendent peaks are shown. In order to better visualize of individual
processes and to obtain the absolute values of the peaks of oxidation
and reduction differential pulse voltammetry (DPV) measurements
in Fig. 6 are shown.
The synthesized monomers were electropolymerized by
cyclic voltammetric process in the dichloromethane solutions
(Fig. 2). In all of investigated monomers electropolymerization
ε = (3.00 0.19) × 104;
ꢀ = 388.0 nm,
ε = (3.23 0.20) × 104,
ꢀ = 322.0 nm, ε = (1.63 0.11) × 104 [dm3/mol cm].

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P. Data et al. / Electrochimica Acta 83 (2012) 271–282
Fig. 5. Cyclic voltammetry of electrochemical doping–dedoping process of the electrodeposited polymers in monomer free medium. Measurement conditions: scan rate
50 mV/s, Ag/AgCl – quasireference electrode, calibrated against ferrocene/ferrocenium redox couple.
process occurred only above first oxidation peak potentials. Dur-
ing electropolymerization, the current is growing in successive
scans what corresponding to formation of conducting species
on working electrode as polymer layer (Figs. 2 and 4). The
monomers electropolymerization under potentiostatic control pro-
vides information about the formation and polymer growth
stages on electrode. Electrochemical investigation of compounds
in dichloromethane showed that all molecules undergo multi-
electron oxidation processes but the initial potentials depend on
the molecular structure and were found 0.15 V for (5a), 0.26 V for
(5b), 0.23 V for (5c) and 0.21 V for (5d), respectively, as shown in
Fig. 3. The first oxidation peak potentials of compounds occur at
0.43 V (5a), 0.46 V (5b), 0.44 V (5c) and 0.53 V (5d). The peak of tel-
lurophene monomer is not clearly shown because of large peak of
second oxidation step of decomposition of tellurophene ring, which
was described in previous investigations [38].
As is shown in Fig. 3 the poly(5a) with bifuran unit has two
oxidation peaks and two reduction peaks at potentials 0.12 V,
0.31 V and 0.18 V, −0.46 V. The poly(5b) with bithiophene have
similar two oxidation and two reduction peaks at 0.10 V, 0.36 V
and 0.23 V, 0.16 V, the sharp peak shape suggesting high speed
of doping–dedoping process. Oxidation and reduction peaks of
poly(5c) are 0.12 V, 0.28 V and 0.23 V, −0,09 V. Peaks from redox
process of poly(5d) are 0.37 V and 0.32 V. The poly(5b) had the
lowest oxidation potential what was observed in previous inves-
tigations. Normally the poly(5d) should have lowest oxidation
potential, but probably tellurium twist molecule structure, similar
process was observed in selenophene compounds [48,49].
In all poly(5) and poly(10) we observed shifting of oxidation
peak which was related with activation barrier of neutral poly-
mers. In first cycle the polymer must oxidize from neutral state
at different equilibrium state than in second and successive scans
(Figs. 3 and 5).
Electrochemical investigation of monomers 10 showed that all
molecules undergo similar electrochemical processes. The initial
potentials were found 0.35 V for (10a), 0.41 V for (10b), 0.39 V for
(10c) and 0.24 V for (10d) and the first oxidation peak potentials
of compounds occurred at voltage 0.56 V (10a), 0.58 V (10b), 0.57 V
(10c), and 0.49 V (10d) which are shown in Fig. 4.
The poly(10a) with bifuran unit has two peaks of the oxidation
and reduction process at 0.10 V, 0.28 V and 0.23 V, −0.18 V which
is shown in Fig. 5. The poly(10b) with bithiophene spacer have
two oxidation and two reduction peaks at higher potential (0.34 V,
0.54 V and 0.47 V, 0.29 V) than polymer with bifuran unit. Oxida-
tion and reduction peaks of poly(10c) are −0.44 V, 0.44 V and 0.38 V,
−0,51 V and the peaks of electrochemical processes of poly(10d) are
0.30 V and 0.22 V. The poly(10a) has the lowest oxidation potential
what was similar in previous investigations.
Specific charges of polymer doping calculated by area under
CV’s curve are shown in Table 1. Measured values in comparison
with chemically synthesized polythiophene 352.8 C/g are lower
but in the range of investigated electrochemically synthesized

P. Data et al. / Electrochimica Acta 83 (2012) 271–282
279
Table 1
tellurophene monomers are lower. Redox processes at the poten-
tial near of 0.50 V concerns the first oxidation step of benzene unit.
In respect of that, peaks of monomers with vinyl linker have lower
potential than analogs without vinyl linker, which is connected to
higher conjugation length in monomer.
Similar dependence is for shifting of first reduction
peak, value is increasing due to higher conjugation of
molecule. First oxidation potential is increasing in tel-
lurophene < selenophene < thiophene < furan series, first reduction
peak is decreasing tellurophene < selenophene < thiophene < furan
series in both of cases. That means tellurophene monomers had
lowest band gap in investigated series.
Electrical properties of investigated polymers.
Specific charge (C/g)
Specific capacitance (F/g)
Poly(5a)
Poly(5b)
Poly(5c)
Poly(5d)
Poly(9a)
Poly(9b)
Poly(9c)
Poly(9d)
Polythiophene
Polypyrrole
33
56
67
73
75
26
49
101
27
20
61
86
125
10
15
129
260 [51]
–
352.8 [50]
44.5 [52]
3.2. Spectroelectrochemical properties of poly(5) and poly(10)
materials like polypyrrole 44.5 C/g. The specific capacitance of poly-
mers measured by ratio of mean value of current to CV’s scan rate
of doping process are much lower than for chemically synthesized
polythiophene (260 F/g).
The specific charge of poly(5d) doping increased by half and
specific capacitance by three times from previous investigation [38]
only by controlling of polymerization process. The specific charge
should increase with heteroatom mass in both cases but there is
large influence on charge transfer when furan is directly connected
to the chain without vinyl linker. Probably chain is more rigid what
influence on electrical properties. The specific charge is 2.5 times
larger and specific capacitance is 5 times larger than monomer with
vinyl linker.
Differential pulse voltammetry (DPV) spectra (Fig. 6) are show-
ing absolute peaks of oxidation and reduction processes. In
correlation to the molecular band, oxidation peak is connected to
the HOMO band and reduction peak is connected to the LUMO band.
Electrochemical band gap value for monomers is the range between
those peaks. DPV spectra showed that peaks of oxidation pro-
cess are similar for all p-phenylene derivatives, only potentials for
In order to find relation between redox processes and UV–vis
absorption, the spectroelectrochemical properties of polymers
prepared on ITO coated glass electrode were investigated. The
absorption spectra of poly(5a–d) films on ITO glass were rep-
resented in Fig. 7. As a result of the spectroelectrochemical
measurements, both electronic structure of the poly(5) and their
optical behavior upon doping were clarified. The neutral poly(5a) is
characterized by two overlapping broad absorption peaks located
at ꢀmax1 = 369 nm and ꢀmax2 = 413 nm and poorly marked shoul-
der. During the oxidation process of poly(5a) film, by increasing
potential and electrochemical doping the band at 300–550 nm
diminished and a new broad band developed between 500 and
1000 nm. This is indicating the formation of polarons and bipo-
larons in conducting polymers, while the ␲ → ␲* transitions of the
neutral polymer appear in higher energies (Fig. 7a). The neutral
polymer 5b shows a maximum of absorbance at 517 nm related to
the interband ␲ → ␲* transitions of the aromatic form of neutral
polythiophene derivative. When the oxidation starts, new pola-
ronic and bipolaronic levels are generated inside this band gap.
The UV–vis set of spectrum recorded during the poly(5b) oxidation
revealed the absorption band (400–650 nm) correlated with the
polymer (Fig. 7b), gradually losing its intensity as the applied poten-
tial increased. In the same time the new defined absorption band
occurred (600–1100 nm), owing the formation of radical cation of
bithiophene and p-phenylenevinylene.
The neutral polytellurophene derivative poly(5d) shows
two broad absorption peaks located at ꢀmax1 = 347 nm and
ꢀmax2 = 513 nm. During anodic process UV–vis set of spectrum
showed that the absorption band from 450 to 700 nm correlated
with the polymer (Fig. 7d), gradually losing its intensity as the
applied potential increased. In the same time the new defined
polaron absorption band is formed at 750–1100 nm with maximum
at 805 nm. Under doping polymers 5 from red for poly(5a,b) and
violet for poly(5c,d) turns to dark violet and dark blue.
The absorption spectra of poly(10a–d) films on ITO glass were
represented in Fig. 8. The neutral poly(10a) is characterized by
two overlapping absorption peaks located at ꢀmax1 = 478 nm and
ꢀmax2 = 517 nm. During the oxidation process of poly(10a) film, the
band at 400–550 nm diminished and a new broad band of polarons
developed between 500 and 800 nm (Fig. 8a). Formation of bipo-
laron band occurs with absorption band formation from 1000 to
beyond 1100 nm. Bipolarons are formed by oxidation of polarons.
Electrons require an average lower energy to be transferred to those
bipolaronic levels from the fundamental state ꢀmax > 850 nm. The
neutral polymer 10b shows a maximum of absorbance at 442 nm
related to the interband ␲ → ␲* transitions. The next UV–vis set
of spectrum recorded during the poly(10b) oxidation showed the
absorption band (350–550 nm) from neutral polymer (Fig. 8b),
gradually losing its intensity as the applied potential increased.
In the same time the formation of polarons and bipolarons in
conducting polymer occurred by forming new absorption band
Fig. 6. DPV spectra of investigated monomers. Measurement conditions: scan
rate 50 mV/s, Ag/AgCl – quasireference electrode, calibrated against ferrocene/
ferrocenium redox couple.

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P. Data et al. / Electrochimica Acta 83 (2012) 271–282
Fig. 7. UV–vis spectra recorded during electrochemical oxidation of poly(5a), poly(5b), poly(5c) and poly(5d) films.
(550–800 nm). The bipolaron band occurs with absorption band
formation from 900 to beyond 1100 nm.
3.3. Photoluminescent properties of monomers
Spectroelectrochemical processes were similar in all of poly-
mers, differences were only in shifting of polymer and polaron
band. The electrochromic properties are usually described by
behavior of those bands. The color change characterization should
be analyzed for materials for electrochemical windows applica-
tions, e.g. colorless layer fully turns to red or other color. Under
oxidation polymers 10a–c layer from red turns to dark violet.
Poly(10d) turns from golden red to dark blue.
The photophysical characteristic of p-phenylene derivatives
(5, 10) was investigated by photoluminescence (PL) in diluted
dichloromethane solution (1 × 10−5 mol/L) at ultraviolet-visible
(UV–vis) maximum absorption peak of excitation. It is strictly
showed that fluorescence emission is shifted to lower ener-
gies with increasing of heteroatom radius in heterocyclic ring.
Heteroatom influence on separation of molecular band and it is pos-
sible to distinguished two fluorescence peaks for selenophene and
Table 2
Electrochemical and optical band-gap.
EHOMO (eV)
ELUMO (eV)
Eg (eV)
Eg (eV)
Op.
El
Poly(5a)
Poly(5b)
Poly(5c)
Poly(5d)
Poly(10a)
Poly(10b)
Poly(10c)
Poly(10d)
−4.91
−4.87
−4.77
−4.76
−4.75
−4.69
−4.67
−4.63
−2.70
−2.78
−2.90
−3.00
−2.34
−2.45
−2.65
−2.80
2.21
2.09
1.87
1.76
2.41
2.24
2.02
1.83
2.10
1.91
1.82
1.75
2.25
2.21
2.14
1.94

P. Data et al. / Electrochimica Acta 83 (2012) 271–282
281
Fig. 8. UV–vis spectra recorded during electrochemical oxidation of poly(10a), poly(10b), poly(10c) and poly(10d) films.
tellurophene molecules. The vinyl p-phenylene derivatives are
more conjugated and have higher absorption and emission peak
than non-vinyl analogs (Fig. 9).
Thank to electrochemical characterization of polymers by ana-
lyzing oxidation and reduction processes it is possible to estimation
of electrochemical band-gap value. In correlation to the molecular
band, oxidation peak is related to the HOMO band and reduction
peak is related to the LUMO band. Electrochemical band-gap value
is the range between those peaks (Table 2) [53,54]. Optical band-
gap was calculated from onset of polymer absorption by conversion
Fig. 9. Fluorescence spectra recorded at maximum absorption peak of monomers.

282
P. Data et al. / Electrochimica Acta 83 (2012) 271–282
of wavelength to the energy [53,54]. The lowest electrochemical
and optical band-gap have polymer contain bitellurophene and p-
phenylenevinylene unit. The largest electrochemical and optical
band-gap have polymer with bifuran and without vinyl unit.
[13] R. Tipnis, J. Bernkopf, S. Jia, J. Krieg, S. Li, M. Storch, D. Laird, Solar Energy
Materials and Solar Cells 93 (2009) 422.
[14] M. Lapkowski, P. Data, S. Golba, J. Soloducho, A. Nowakowska-Oleksy, S. Roszak,
Materials Chemistry and Physics 131 (2012) 757.
[15] S.U. Pandya, H.A. Al Attar, V. Jankus, Y. Zheng, M.R. Bryce, A.P. Monkman, Journal
of Materials Chemistry 21 (2011) 18439.
[16] L.M. Leung, Plastics Engineering 41 (1997) 817.
4. Conclusions
[17] A.C. Grimsdale, K. Mullen, Advances in Polymer Science 199 (2006) 1.
[18] A.C. Grimsdale, K. Mullen, Advances in Polymer Science 212 (2008) 1.
[19] M.L. Blohm, J.E. Pickett, P.C. Van Dort, Macromolecules 26 (1993) 2704.
[20] E.E. Havinga, C.M.J. Mutsaers, L.W. Jenneskens, Chemistry of Materials 8 (1996)
769.
[21] H.E. Kwan-Yue Jen, T.R. Jow, L.W. Shacklette, R.L. Elsenbaumer, Journal of the
Chemical Society, Chemical Communications 3 (1988) 215.
[22] J.H. Burroghes, D.D.C. Bradley, A.R. Brown, R.N. Marks, K. Mackay, R.H. Friend,
P.L. Burns, A.B. Holmes, Nature 347 (1990) 539.
[23] L.F. Santos, R.C. Faria, L. Gaffo, L.M. Carvalho, R.M. Faria, D. Goncalves, Elec-
trochimica Acta 52 (2007) 4299.
[24] Y.-C. Nah, S.-S. Kim, J.-H. Park, D.-Y. Kim, Electrochemical and Solid-State Letters
10 (2007) J12.
New derivatives of p-phenylene containing different het-
eroaryl group were synthesized according to Suzuki and
Stille condensation. Presented results show that (E,E)-1,4-
dialkoxy-2,5-bis[2-(tellurophen)-2-yl)ethenyl]benzene can be
obtained by condensation of 2-tellurophenecarbaldehyde with
tetraethyl
The 1,4-dialkoxy-2,5-bis(selenophen-2-yl)benzenes and 1,4-
dialkoxy-2,5-bis(tellurophen-2-yl)benzenes could be only
[2,5-dialkoxy-1,4-bis(methylene)]diphosphonate.
synthesized from proper tri-n-butyltin derivative with 1,4-
dialkoxy-2,5-bromobenzene for selenophene compound and
1,4-dialkoxy-2,5-diiodobenzene for tellurophene compound.
Presented results show influence of heteroatom and vinyl
group in conjugated monomers and polymers on photo and elec-
trochemical properties. All monomers electropolymerize during
oxidative polymerization and formed polymers were elec-
tro and optically active. The band-gap were decreasing in
furan > thiophene > selenophene > tellurophene series.
Fluorescence emission is shifted to lower energies with
increasing of heteroatom radius in heterocyclic ring. Heteroatom
influence on separation of molecular band and it is possible
to distinguished two fluorescence peaks for selenophene and
tellurophene molecules. The vinyl p-phenylene derivatives are
more conjugated and have higher wavelength of absorption and
emission peak than non-vinyl analogs.
[25] A.D. Child, B. Sankaran, F. Larmat, J.R. Reynolds, Macromolecules 28 (1995)
6571.
[26] J.R. Reynolds, J.P. Ruiz, A.D. Child, K. Nayak, D.S. Marynick, Macromolecules 24
(1991) 678.
[27] J.P. Ruiz, J.R. Dharia, J.R. Reynolds, L.J. Buckley, Macromolecules 25 (1992) 849.
[28] F. Larmat, J. Soloducho, A.R. Katritzky, J.R. Reynolds, SyntheticMetals124 (2001)
329.
[29] J.R. Reynolds, A.D. Child, J.P. Ruiz, S.Y. Hong, D.S. Marynick, Macromolecules 26
(1993) 2095.
[30] J.R. Reynolds, A.R. Katritzky, J. Soloducho, S. Belyakov, G.A. Sotzing, M. Pyo,
Macromolecules 27 (1994) 7225.
[31] G.A. Sotzing, J.R. Reynolds, A.R. Katritzky, J. Soloducho, S. Belyakov, R. Musgrave,
Macromolecules 29 (1996) 1679.
[32] K. Aydemir, S. Tarkuc, A. Durmus, G.E. Gunbas, L. Toppare, Polymer 49 (2008)
2029.
[33] J.F.A. Van Der Looy, G.J.H. Thys, P.E.M. Dieltiens, D.De Schrijver, C. Van Alsenoy,
H.J. Geise, Tetrahedron 53 (1997) 15069.
[34] M. Lapkowski, K. Waskiewicz, R. Gabanski, J. Zak, J. Suwinski, Russian Journal
of Electrochemistry 42 (2006) 1267.
[35] R. Gabanski, K. Waskiewicz, J. Suwinski, ARKIVOC V (2005) 58.
[36] K. Waskiewicz, R. Gabanski, J. Zak, M. Lapkowski, J. Suwinski, Electrochemical
and Solid-State Letters 8 (2005) E24.
[37] P. Data, M. Lapkowski, R. Motyka, J. Suwinski, Electrochimica Acta 59 (2012)
567.
Acknowledgment
[38] P. Data, M. Lapkowski, R. Motyka, J. Suwinski, Macromolecular Chemistry and
Physics 213 (2012) 29.
[39] G. Inzelt, Conducting Polymers – A New Era in Electrochemistry, Springer,
Berlin, 2012.
Research funded by Ministry of Higher Education and Science of
Poland. Research project no. N N205 106935.
[40] C.G. Zoski, Handbook of Electrochemistry, Elsevier, Amsterdam, 2007.
[41] R. Reghu, J. Grazulevicius, J. Simokaitiene, A. Miasojedovas, K. Kazlauskas, S.
Jursenas, P. Data, K. Karon, M. Lapkowski, G. Valentas, V. Jankauskas, Journal of
Physical Chemistry C 116 (2012) 15878.
[42] R.A.W. Johnston, M.E. Rose, Tetrahedron 35 (1979) 2169.
[43] I. Brehm, S. Hinneschiedt, H. Meier, European Journal of Organic Chemistry 18
(2002) 3162.
[44] A.W. Weston, R.J.J. Michaels Jr., American Chemical Society 72 (1950) 1422.
[45] N. Kuhnert, A. Lopez-Periago, G.M. Rossignolo, Organic & Biomolecular Chem-
istry 3 (2005) 524.
References
[1] G.R. Hutchison, M.A. Ratner, R.J. Marks, Journal of Physical Chemistry B 109
(2005) 3126.
[2] J.A. Merlo, C.R. Newman, C.P. Gerlach, T.W. Kelley, D.V. Muyres, S.E. Fritz, M.F.
Toney, C.D. Frisbie, Journal of the American Chemical Society 127 (2005) 3997.
[3] H.E. Katz, Chemistry of Materials 16 (2004) 4748.
[4] G. Gustafsson, Y. Cao, G.M. Treacy, F. Klavetter, N. Colaneri, A.J. Heeger, Nature
357 (1992) 477.
[46] N. Marshall, S.K. Sontag, J. Locklin, Macromolecules 43 (2010) 2137.
[47] M. Bouachrine, J.-P. Lere-Porte, J.J.E. Moreau, F. Serein-Spirau, Ch. Torreilles,
Journal of Materials Chemistry 10 (2000) 263.
[5] R.H. Friend, R.W. Gymer, A.B. Holmes, J.H. Burroughes, R.N. Marks, C. Taliani,
D.D.C. Bradley, D.A. Dos Santos, J.L. Bredas, M. Logdlund, W.R. Salaneck, Nature
397 (1999) 121.
[48] A. Patra, M. Bendikov, Journal of Materials Chemistry 20 (2010) 422.
[49] S.S. Zade, M. Bendikov, Chemistry – A European Journal 13 (2007) 3688.
[50] P. Novak, K. Muller, K.S.V. Santhanam, Chemical Reviews 97 (1997) 207.
[51] Y.W. Chen-Yang, J.L. Li, T.L. Wu, W.S. Wang, T.F. Hon, Electrochimica Acta 49
(2004) 2031.
[52] A. Lafourge, P. Simon, C. Sarrazin, J.F. Fauvarque, Journal of Power Sources 80
(1999) 142.
[53] J. Pei, W.-L. Yu, J. Ni, Y.-H. Lai, W. Huang, A.J. Heeger, Macromolecules 34 (2001)
7241.
[6] M.M. Alam, S.A. Jenekhe, Chemistry of Materials 14 (2002) 4775.
[7] J.H. Lee, D.-H. Hwang, Chemical Communications 22 (2003) 2836.
[8] S.B. Mainthia, P.L. Kronickk, H. Ur, E.F. Chapman, M.M. Labes, Polymer Preprints
4 (1963) 208.
[9] M. Akiyama, Y. Iwakura, S. Shiraishi, Y. Imai, Journal of Polymer Science Part B:
Polymer Letters 4 (1966) 305.
[10] P. Kovacic, J. Oziomek, Macromolecular Synthesis 2 (1966) 23.
[11] J. Jensen, H.F. Dam, J.R. Reynolds, A.L. Dyer, F.C. Krebs, Journal of Polymer Science
Part B: Polymer Physics 50 (2012) 536.
[54] M. Lapkowski, P. Data, S. Golba, J. Soloducho, A. Nowakowska-Oleksy, Optical
Materials 22 (2011) 1445.
[12] R. Sondergaard, M. Hosel, D. Angmo, T.T. Larsen-Olsen, F.C. Krebs, Materials
Today 15 (2012) 36.