Synthesis and electrochemical characterization of a new benzodioxocine-fused poly(: N -methylpyrrole) derivative: A joint experimental and DFT study

Article abstract of DOI:10.1039/d0nj03992f

In this study, our findings from experimental studies were presented on the synthesis of a new electropolymerizable monomer, 2-methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-c]pyrrole (XyPMe), regarding the cyclization reaction of diethyl N-methyl-3,4-dihydroxypyrrole-2,5-dicarboxylate and 1,2-bis(bromomethyl)benzene with concomitant hydrolysis and decarboxylation reactions. The critical step in this synthetic pathway was to determine the optimal temperature of decarboxylation utilizing TGA analysis, which decreases in situ polymerization side-product formation significantly. Following the preparation of the target monomer, the electropolymerization reaction was then conducted, and the optoelectronic properties were investigated in detail. In order to better illuminate the effects of N-alkylation and the heterocyclic ring system on the polymer backbones, we have included and theoretically studied the electronic properties of two monomers already synthesized in our laboratory, possessing the butyl group on the pyrrole ring (XyPBu) and the thiophene scaffold on its structure (XyT), and their corresponding oligomers (n = 2 to 11, n indicates the consecutive unit number). This combined experimental and theoretical research provides a pathway for advanced conjugated systems with predictable electronic and structural properties to be established.

Full text of DOI:10.1039/d0nj03992f

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Yellowish and blue luminescent graphene oxide quantum dots
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DOI: 10.1039/D0NJ03992F
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Synthesis and Electrochemical Characterization of a New
Benzodioxocine-fused Poly(N-methylpyrrole) Derivative: A Joint
Experimental and DFT Study
Received 00th January 20xx,
Accepted 00th January 20xx
Gülbin KURTAY,*a Tuğba SOĞANCI,b Kübra SARIKAVAK,c Metin AK,d and Mustafa GÜLLÜ *a
DOI: 10.1039/x0xx00000x
In this study, our findings from the experimental studies were presented on the synthesis of a new electropolymerizable
monomer, 2-methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-c]pyrrole (XyPMe) regarding the cyclization reaction of
diethyl N-methyl-3,4-dihydroxypyrrole-2,5-dicarboxylate and 1,2-bis(bromomethyl)benzene with concomitant hydrolysis
and decarboxylation reactions. The critical step in this synthetic pathway was to determine the optimal temperature of
decarboxylation utilizing the TGA analysis, which decreases in situ polymerization side-product formation significantly.
Following the preparation of the target monomer, the electropolymerization reaction was then conducted, and the
optoelectronic properties were investigated in detail. In order to better enlighten the effects of N-alkylation and heterocyclic
ring system on polymer backbones, we have included and theoretically studied the electronic properties of two already
synthesized monomers in our laboratory, possessing the butyl group on pyrrole ring (XyPBu) and the thiophene scaffold on
its structure (XyT) and their corresponding oligomers (n=2 to 11, n indicates the consecutive unit numbers). This combined
experimental and theoretical research provides a pathway for advanced conjugate systems with predictable electronic and
structural properties to be established.
pyrrole-cored conductive polymers have fueled several
potential applications in supercapacitors26–29, batteries30,31, fuel
cells32–35, electrochromic pH and CO2 sensors36, drug delivery
Introduction
Electrochemical synthesis of conducting polymers with diverse
functionalities has received growing attention due to their
systems37–39, and anti-static coatings40,41
.
potential use in the fields of organic photovoltaics1–3
,
Besides, N-alkylpyrrole derivatives are suitable as synthons for
synthesizing natural products, and they are used to prepare
biosensors4,5
,
transistors6, light-emitting diodes7–9
Currently, the
,
and
advanced electrochromic materials10–13
.
pharmaceuticals42–44, dyes45,46, photographic chemicals47,48
,
electropolymerization approach offers significant advantages,
such as enhancing film thickness and morphology control over
oxidative chemical polymerization14–16. Among the various kind
of heteroaromatic subunits containing polymers known to date,
polypyrrole derivatives (PPys) and of subsequent structural
variants are preferred due to their higher environmental
and other organic compounds49,50. These products are also used
as a precursor for the polymerization process and corrosion
inhibition51–53 and are therefore known to concur with other
low bandgap polymers. Today, an enormous variety of pyrrole
derivatives are prepared by using different synthetic
methodologies. However, in order to perform a successful
electropolymerization process and to obtain the target polymer
film on the surface of the working electrode, it is crucial to avoid
the blocking effect of the corresponding substituents, especially
if these groups are in the N-substituted position54.
stability, redox properties, and electrical conductivity17–19
.
According to this strategy, the conductivity term reflects two
essential factors: the number of potential electron or hole
carriers and the mobility of these carriers, which signify the ease
of the carrier movements through the material20,21. As a result,
several research studies have been reported in the literature
a focus on developing effective organic synthesis
approaches aimed at obtaining PPys with electrical properties
similar to those of inorganic semiconductors22–25. Therefore,
Within this concept, we have designated a new monomer; 2-
methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-
with
c]pyrrole (XyPMe) in order to enlighten the influence and steric
hindrance effect of N-substitution on its synthesis and
electropolymerization processes. Following the completion of
the synthetic steps, we have performed FT-IR, GC-MS, TGA, 1H-
NMR, and elemental analysis techniques to characterize the
a. Ankara University, Faculty of Science, Department of Chemistry, Ankara, Turkey.
b. Eskisehir Technical University, Graduate School of Sciences, Department of
Advanced Technologies, Eskisehir, Turkey.
c. Hacettepe University, Faculty of Science, Department of Chemistry, Ankara, Turkey. synthesized compounds, including the target monomer,
d. Pamukkale University, Faculty of Art and Science, Chemistry Department, Denizli,
XyPMe. The electrochemical polymerization of the XyPMe has
Turkey.
been potentiostatically achieved in the following part of the
study utilizing different electrolyte-solvent couples. Then, the
Electronic Supplementary Information (ESI) available. See DOI: 10.1039/x0xx00000x
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electrochemical and electrochromic properties were multiplet (m), and the coupling constants (J) are given in Hz.
View Article Online
investigated with complementary experimental and Melting points (up to 350 °C, uncorrectedD)OwI:e1r0e.1o0b39ta/Din0eNdJ0o3n99a2nF
computational studies. To better predict the impact of the N- Electrothermal Programmable Melting Point Apparatus
alkylation and divergent heteroaromatic systems on the (IA9300) (Bibby Scientific Limited, OSA, U.K.) using open
polymer backbone, we have also included two monomers capillary tubes. Elemental analyses were carried out on a
(already synthesized in our laboratory; one of them containing Eurovector model EA3000 CHNS elemental analyzer
n-butyl substitution on pyrrole ring’s nitrogen (XyPBu)55, and (EuroVector SpA, Italy) and found to be within the range of ±
the other contains the thiophene subunit instead of pyrrole 0.4% of calculated values. Thin-layer chromatography (TLC) was
(XyT)12 and their corresponding oligomer structures (n=2 to 11, used to track the progress of the experiments steadily. For this
n indicating the consecutive unit number) while performing our purpose, aluminum sheets (Merck, 20x20, Silica Gel 60 F254)
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theoretical calculations.
were utilized. Plates were visualized under UV light (at 254 nm)
or by staining with vanillin/sulphuric acid. Purification of the
XyPMe (monomer) was performed by column chromatography,
and to this purpose, silica gel (SiO2) (Merck, Silica Gel 60, 0,063-
0,200mm, 70-230 mesh ASTM) was used as the column
stationary phase. The TG-DTA analysis was used to determine
the temperature at which the decarboxylation reaction was to
be conducted, and to this purpose, Shimadzu DTG-60H
(Shimadzu Corp., Kyoto, Japan) apparatus was used. The
thermogravimetric analyzes were performed in atmosphere N2
and using Pt pan at a gas flow of 100 ml/min. The cyclic
voltammetry and electrochemical polymerization studies were
performed using an Ivium CompactstatTM e20250
electrochemical potentiostat/galvanostat workstation (Ivium
Technologies B.V., Eindhoven, The Netherlands). Accordingly,
Gamry Reference 600 potentiostat (Gamry Instruments,
Warminster, PA, USA) was used in order to perform
spectroelectrochemical studies. Accordingly, UV-vis-NIR spectra
were recorded on an Agilent 8453 spectrophotometer (Agilent
Technologies, Germany) coupled with UV-vis Chemstation
software (Version 13.04.01-G1). All electrochemical
experiments were carried out in a one-component quartz cell.
The indium tin oxide (ITO) coated glass plates of a thickness of
Experimental Section
Materials
Commercial anhydrous methanol (ACS reagent, ≥ 99.8%, Sigma-
Aldrich) was purified following Lund and Bjerrum’s process56.
Acetonitrile (ACN) (Sigma-Aldrich) was distilled over CaH2. N,N-
Dimethylformamide (DMF) (Sigma-Aldrich) was preserved
before use on 4A molecular sieves and vacuum-distilled.
Anhydrous potassium carbonate (Fluka) was dried for 3 to 4
hours in an oven. All of the other required reagents, solvents,
and catalyzers including acetic acid (glacial, Merck), acetone
(ACS reagent, ≥ 99.5%, Sigma-Aldrich), benzoyl peroxide
(Sigma-Aldrich), N-bromosuccinimide (Sigma-Aldrich), carbon
tetrachloride
(Fluka),
copper
(dust,
Sigma-Aldrich),
dichloromethane (Sigma-Aldrich), diethyl ether (Sigma-Aldrich),
diethyl oxalate (Sigma-Aldrich), ethanol (absolute, Sigma-
Aldrich), ethyl acetate (Sigma-Aldrich), hydrochloric acid (ACS
reagent, 37%, Sigma-Aldrich), iminodiacetic acid (Sigma-
Aldrich), lithium perchloride (LiClO4)(Sigma-Aldrich), potassium
hydroxide (ACS reagent, 85%, Sigma-Aldrich), propylene
carbonate (Sigma-Aldrich), sodium (Merck), sodium hydroxide
0.7 mm with the resistance of 8–12
Limited, USA) was used as

.sq-1 (Delta Technologies
working electrode. The
(Sigma-Aldrich),
sodium
sulfate
(Sigma-Aldrich),
a
tetrabutylammonium hexafluorophosphate (TBAPF6)(Sigma-
Aldrich), thionyl chloride (Sigma-Aldrich), triethanolamine
(Sigma-Aldrich), o-xylene (Sigma-Aldrich) were used from their
specified suppliers without any further purification.
corresponding polymer films were electrochemically deposited
on these ITO plates. Pt was used as a counter electrode, and
silver wire (Fc/Fc+ (0.3V)) was used as a pseudo-reference
electrode. Conductivity measurement of the prepared films in
different electrolyte solutions was performed with Keithley
2700 model multimeter.
Instrumentation
The corresponding FT-IR spectra were obtained by the Perkin-
Elmer Spectrum 100 Series FT-IR spectrometer (Perkin Elmer
Co., Beaconsfield, Bucks, UK). The required measurements were
collected in ATR mode using an average of 10 scans. The mass
spectral (MS) analyses were carried out with an Agilent
Technologies 6890N Network G.C. System and Agilent
Technologies 5975B VL MSD Mass Spectrometer (Agilent
Technologies, Santa Clara, CA, USA) running at an ionization
potential (E.I.) of 70 eV. 1H-NMR spectra were recorded at room
temperature on a Varian-Mercury 400MHz High-Performance
digital Fourier Transform (F.T.)-NMR Spectrometer (Mercury-
400BB)(Varian, Fort Collins, CO, USA) and CDCl3 was used as the
solvent. The 1H-NMR chemical shifts were reported as δ values
in parts per million (ppm) relative to tetramethylsilane (TMS, δ:
0) as the internal standard. Proton coupling patterns were
described as singlet (s), doublet (d), triplet (t), quartet (q),
2 | J. Name., 2012, 00, 1-3
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to 70 °C, where it was maintained for 4 hours. InVtiehwisArpticrloe cOenlsinse,
DOI: 10.1039/D0NJ03992F
the formation of a pale-yellow chunk was observed. The
Synthetic procedures
Starting compounds and the target monomer XyPMe were
prepared via the synthetic route shown in Scheme 1.
reaction then quenched by pouring it into cold water. The pH of
the solution was adjusted to about 5 by the addition of glacial
acetic acid. The precipitated solids were then separated by
vacuum filtration on a sintered glass Buchner funnel and
washed with water. The crude product was purified by
recrystallization from acetone to yield 68% of diethyl 3,4-
dihydroxy-1-methyl-1H-pyrrole-2,5-dicarboxylate as white solid
(m.p: 93-95 °C). 1H-NMR (400 MHz, CDCl3) δH/ppm: 1.40 (t,
J=6.8 Hz, 6H, ester -CH3), 3.97 (s, 3H, N-CH3), 4.41 (q, 4H, J=7.1
Hz, ester –CH2), 7.60 (s, 2H, -OH). MS (EI) m/z (%) calcd. for
C11H15NO6: 257.2; found: 257.1 (M+, 37), 211 (93), 182 (3), 165
(100), 137 (6), 82 (5.5), 69 (21), 42 (11). IR (ATR), νmax/cm-1:
3415, 3282 (O-H stretching), 2973-2874 (aliphatic C-H
stretching), 1708, 1658 (ester C=O stretching), 1491-1321
(aliphatic C-H bending), 1232 (ester C-O-C asymmetric
stretching), 1104 (ester, C-O-C symmetric stretching), 904, 856,
769, 733. Elemental analysis: anal. calcd. for C11H15NO6 (257.2):
C, 51.36; H, 5.88; N, 5.45; O, 37.32 found: C 51.02 H 5.66 N 5.27.
1,2-Bis(bromomethyl)benzene (3). This compound was
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Dimethyl iminodiacetate (1). Anhydrous methanol (100 mL)
was poured into a two-necked round bottom flask equipped
with a pressure-equalizing dropping funnel and water-cooled
condenser. The flask was flushed with N2. Iminodiacetic acid
(10.00 g, 62 mmol) was added and stirred until a homogeneous
solution was obtained. The solution was then cooled in an ice
bath, and the reaction was initiated by slowly adding thionyl
chloride (32.70 g, 277 mmol, 20.00 mL, 1.69 g/cm3) with cooling
(exothermic reaction). Stirring was continued in the ice bath for
an additional 30 minutes, then the ice bath was replaced with
an oil bath (65 ± 0.5 °C), and the mixture was refluxed for 7
hours (caution: the released HCl gas was absorbed by passing
into sodium hydroxide solution). The excess of methyl alcohol
was removed by distillation. The remaining crude product
(white) was dissolved in water and treated with a saturated KOH
solution until pH reached 7-8. It was then extracted with CH2Cl2
and dried over Na2SO4. After the drier was filtered, the solvent
was recovered from the rotary evaporator, and the oily product
was purified by vacuum distillation to yield 75% of dimethyl
iminodiacetate as a slightly yellow liquid (bp: 175-180 °C/10-15
mmHg). MS (EI) m/z (%) calcd. for C7H13NO4: 175.2; found: 175.1
(M+, 6), 161 (7.5), 129 (8), 116 (48), 102 (100), 88 (11), 74 (26),
58 (7), 42 (60). IR (ATR), νmax/cm-1: 2955-2867 (aliphatic C-H
stretching), 1737 (ester, C=O stretching), 1437 (aliphatic C-H
bending), 1198 (ester, C-O-C asymmetric stretching), 1177,
1033 (ester, C-O-C symmetric stretching).
synthesized in accordance with
a previously described
procedure10. To this aim, o-xylene (5.80 g, 54.0 mmol) and N-
bromosuccinimide (NBS) (20.00 g, 112.3 mmol) were dissolved
in 25 ml of carbon tetrachloride. Benzoyl peroxide (0.01 g, 0.04
mmol) was then introduced to the flask in small portions, and
the reaction mixture started to reflux. After 20 minutes, a
second benzoyl peroxide partition (0.01 g, 0.04 mmol) was
added, and the resultant mixture was refluxed for about 6
hours, and then the solution was allowed to cool to room
temperature. The precipitated succinimide solids were filtered
under suction, and the recovery of the excess carbon
tetrachloride was accomplished by vacuum distillation. The
crude mixture was chilled in the refrigerator, and the crude
product (white crystals) was separated by filtration. The
recrystallization was made from diethyl ether to yield 65% of
1,2-bis(bromomethyl)benzene (observed m.p: 97 °C, lit m.p: 99
°C). MS (EI) m/z (%) calcd. for C8H8Br2: 264.0; found: 264.0 (M+,
11), 183.1 (97), 104.2 (100), 78.2 (19). IR (ATR), νmax/cm-1:
3052-3021 (w, aromatic, C-H stretching), 2965 (w, aliphatic C-H
stretching), 1489 (m, aliphatic C-H bending), 768 (s, aromatic C-
H bending). Elemental analysis: anal. calcd. for C8H8Br2 (264.0):
C 36.40 H 3.05 Br 60.54; found: C 35.20 H 2.41.
Diethyl 2-methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-
c]pyrrole-1,3-dicarboxylate (4). In a 100 ml round-bottomed flask,
diethyl 3,4-dihydroxy-1-methyl-1H-pyrrole-2,5-dicarboxylate
(2) (0.77 g, 3.0 mmol) was introduced, and then dissolved in
anhydrous DMF (20 ml). K2CO3 (1.45 g, 10.5 mmol) was added,
and the reaction mixture was stirred vigorously for 0.5 h under
inert N2 atmosphere. Following this step, 1,2-
bis(bromomethyl)benzene (0.80 g, 3.0 mmol) was introduced to
the solution, and the mixture was heated at 110 °C for 5 h. The
reaction was followed by TLC, and after the termination of the
reaction, the excess DMF was removed by vacuum distillation.
Diethyl 3,4-dihydroxy-1-methyl-1H-pyrrole-2,5-dicarboxylate (2).
Under nitrogen atmosphere, absolute ethanol (20 ml) was
carefully added into the two-necked round-bottom reaction
flask containing freshly cut sodium metal (0.86 g, 37.5 mmol). A
mixture of dimethyl iminodiacetate (1) (3.00 g, 17.2 mmol) and
diethyl oxalate (2.50 g, 2.33 mL, d: 1.08 g / mL, 12.1 mmol) was
added dropwise to the ice-cold sodium ethoxide solution with
vigorous stirring. Upon completion of the addition, the ice-bath
was removed, and the temperature of the solution was brought
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The residue was poured into 75 ml ice-water yielding a bright
yellow solid. The recrystallization of the crude product was
accomplished from diethyl ether to afford the target compound
(yield: 77%, m.p: 72-75 °C). MS (EI) m/z (%) calcd. for C19H21NO6:
359.1; found: 359.1 (M+, 65), 314 (17), 302 (14), 286 (17), 258
(20), 245 (45), 230 (40), 212 (9), 200 (12.5), 184 (11), 171 (9),
156 (8), 143 (10), 131 (4), 115 (14), 104 (100), 78 (26), 42 (26),
28 (17). IR (ATR), νmax/cm-1: 2992, 2981, 2974, 2872 (aliphatic
analysis: anal. calcd. for C13H13NO2 (215.25): C, 72.54; H, 6.09;
N, 6.51; O, 14.87 found: C, 71.83 H, 5.88 N, 6.37.
View Article Online
DOI: 10.1039/D0NJ03992F
Cyclic voltammetry (CV) and Electrochemical Polymerization
In this part of the research work, the electrochemical behavior
of XyPMe was examined by performing cyclic voltammetry (CV)
technique. The corresponding electrochemical experiments
were conducted using an Ivium CompactstatTM e20250
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C-H stretching), 1709, 1680 (ester, C=O stretching), 1416 electrochemical potentiostat/galvanostat workstation (Ivium
Technologies B.V., Eindhoven, The Netherlands). The
corresponding voltammograms were collected at
temperature of 25±0.5 °C by using a conventional three-
electrode cell configuration consisting of an ITO-coated glass
electrode as a working electrode, a Pt wire, and an Ag wire were
used as counter and pseudo-reference electrodes, respectively
(aliphatic C-H bending), 1349, 1249 (ester, C-O-C asymmetric
stretching), 1160 (ester, C-O-C symmetric stretching), 1055,
1033 (ether, C-O symmetric stretching).
2-Methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-c]pyrrole-
1,3-dicarboxylic acid (5). Into a 50 ml round-bottomed flask fitted
with a reflux condenser, diethyl 2-methyl-5,10-dihydro-2H-
a
(
Scheme 2). The effects of preliminary operational parameters,
benzo[6,7][1,4]dioxocino[2,3-c]pyrrole-1,3-dicarboxylate
(4)
including the utilization of different supporting
(0.50 g, 1.39 mmol) and 10 ml ethanol were added. Following
the addition of KOH (85%, 0.28 g, 4.9 mmol) and 1 ml distilled
water, the mixture was refluxed in a hot water bath for 6 hours.
The excess of ethanol was removed by distillation. The
unreacted diester derivative (4) was separated by extraction
with Et2O, and then the residue was poured into the crushed
ice. The cooled water phase was acidified with concentrated HCl
(pH: 2-3). The resulting gray-colored product was separated by
filtration to yield 85% of 2-methyl-5,10-dihydro-2H-
electrolyte/solvent couples (TBAPF6/DCM, TBAPF6/PC, and
LiClO4/ACN), were also taken into consideration. To this
purpose, 0.05M of TBAPF6 or LiClO4 solutions were prepared by
dissolving the adequate amount of electrolytes in freshly
distilled solvents. During
a
regular application, the
electrochemical cell was filled with the appropriate solution,
and it was de-aerated by highly pure nitrogen gas bubbling for
at least 10 minutes before each measurement. During the
process, a blanket of the nitrogen atmosphere was maintained
above the solution. Accordingly, a background voltammogram
was also executed to ensure that no impurity remained before
that XyPMe was added. In the concomitant step, the
electrochemical polymerization of the target monomer was
accomplished under constant potential conditions. To this aim,
XyPMe (50 mg) was dissolved in 10 ml of 0.05M LiClO4/ACN
(most convenient supporting electrolyte/solvent couple was
predicted from the cyclic voltammetry studies). The
electropolymerization of the XyPMe on ITO-coated glass slide
was conducted in a quartz cell equipped with Pt wire as a
counter electrode and Ag wire as a pseudo-reference electrode
at +1.0 V for 0.5h. The free-standing films were then washed
several times with ACN to remove the unreacted monomer and
the excess TBAPF6.
benzo[6,7][1,4]dioxocino[2,3-c]pyrrole-1,3-dicarboxylic acid (5)
(m.p: 136-137 °C). IR (ATR), νmax/cm-1: 3200-2500 (O-H
stretching), 2938-2876 (aliphatic C-H stretching), 1705
(carboxylic acid, C=O stretching), 1651, 1426 (aliphatic C-H
asymmetric bending), 1265, 1241 (C-O asymmetric stretching),
1033 (s, C-O symmetric stretching).
2-Methyl-5,10-dihydro-2H-benzo[6,7][1,4]dioxocino[2,3-
c]pyrrole (XyPMe) (6). The corresponding dicarboxylic acid
derivative (5) (0.50 g, 1.65 mmol) was placed into a round-
bottomed flask and dissolved into triethanolamine (5 ml).
Following the addition of the copper dust (5 mg), the reaction
mixture was stirred under a continuous nitrogen flow in a
preheated oil bath at 135 °C. The reaction was monitored by
TLC. Following the completion of the reaction -approximately
30 minutes-, the flask content was allowed to cool to room
temperature and poured into the ice-water mixture, and then,
extracted with ethyl acetate, concomitant work-up steps
included the treatment of the combined organic layers with
brine and water, respectively. The organic layer was dried over
Na2SO4, and the solvent was removed under reduced pressure.
The crude product was then purified by column
chromatography (SiO2, DCM) to give the target monomer as
white colored oily solid in 52% yield. 1H-NMR (400 MHz, CDCl3)
δH/ppm: 3.40 (s, 3H), 5.30 (s, 4H), 6.10 (s, 2H), 7.20-7.30 (m, 4H,
arom.). MS (EI) m/z (%) calcd. for C15H13N3O2: 215.1; found:
215.1 (M+, 96), 186 (5.5), 173 (5), 158 (25), 144 (73), 128 (50),
116 (36), 104 (100), 83 (16), 78 (41), 42 (70). IR (ATR), νmax/cm-
1: 3051-3024 (aromatic C-H stretching), 2961, 2928, 2901, and
2868 (aliphatic C-H stretching), 1356 (C-H symmetric bending),
1057, 1017 (ether, C-O symmetric stretching). Elemental
Spectroelectrochemistry
In order to enlighten the optoelectronic and electrochromic
properties of the conducting polymers, it is crucial to perform
spectroelectrochemical studies. Therefore, we accomplished
the required spectroelectrochemical data by using Agilent 8453
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UV-vis-NIR spectrophotometer
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(Agilent
Technologies, polymer, we have performed the oligomer apprVoieawcAhrt6ic3le–6O5n,linine
DOI: 10.1039/D0NJ03992F
Germany) integrated with the Gamry Reference 600 which the physical properties of the oligomers containing an
potentiostat (Gamry Instruments, Warminster, PA, USA) upon increasing number of repeating units (in our case from n = 1 to
applied potentials varying between -0.4 V and +1.2 V. The setup 11) are first calculated, and then extrapolated to infinite
for the spectroelectrochemical experiments compromised the polymeric chains. During the geometry optimization studies,
usage of a quartz cell with 1 cm of optical path length which was the alkyl groups on XyPMe and XyPMe were not fixed and
assembled with an optically transparent ITO working electrode investigated polymer backbones were altered consecutively.
(thickness: 0.7 mm, sheet resistance: 8–12 Ω.sq-1, (Delta Therefore, various input geometries differentiated by the
Technologies Limited, USA). During these studies, in the values of the torsion angles around the single bonds have been
presence of 0.05M LiClO4/ACN supporting electrolyte/solvent studied for corresponding dimers in order to define the
couple, the monomer-free P(XyPMe) was electrodeposited on appropriate conformational space and lowest-energy
the ITO electrode by applying +1.0 V for 1h and used as the conformation. Then, we have replicated and designed the
working electrode, Pt wire, and Ag wire were also chosen as the starting geometries of increasingly large oligomers according to
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counter and pseudo-reference electrode, respectively.
the pre-defined geometries of the corresponding dimer units.
Switching
Results and Discussion
Preparation of the XyPMe
Double potential step spectrochronoamperometry was
performed to elucidate the long-term electrochromic switching
stability and contrast of the XyPMe polymer film in 0.05M
LiClO4/ACN supporting electrolyte-solvent system. In order to
perform this study, the initial potential was set to -0.4 V [where
the P(XyPMe) film was in its reduced state] for 5 seconds, and
then the potential was stepped to the second potential value
(+1.2 V) [where the (P(XyPMe) film was in its oxidized state] for
another 5 seconds before switching back to the initial potential
value (-0.4 V). The obtained data were used to calculate the
percent transmittance (T%), and the corresponding switching
times were predicted by using UV-vis-NIR spectrophotometer at
λmax of the polymer film.
As mentioned before, the diester derivative of the XyPMe (
was successfully synthesized from the condensation reaction of
diethyl N-methyl-3,4-dihydroxypyrrole-2,5-dicarboxylate
and 1,2-bis(bromomethyl)benzene ( ). This step was then
followed by the concomitant hydrolysis and decarboxylation
reactions to yield the desired monomer, XyPMe ( ). It should be
4)
(2)
3
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emphasized that the key-step in this synthetic pathway involves
the utilization of the TGA analysis to predict the optimum
temperature for the decarboxylation step, which is generally
responsible for the decrease of the overall reaction yield due to
the formation of in-situ polymerization side-products. In order
to justify our proposition, we have also performed the
corresponding TGA analyses for the XyPBu and XyT, two
different o-xylene ring possessing monomers, which were
previously synthesized by our research group.12,55 The obtained
data proved the convenience of the TGA analysis to determine
the optimum conditions for the decarboxylation reactions (Fig.
S1-3, ESI†).
Computational studies
The quantum chemical calculations were performed using the
Gaussian 09 package57. During the studies, all of the structure
drawings were modeled, and representation of the geometries
was visualized with GaussView 5.058. The required equilibrium
geometries were calculated by full optimization of the
conformations at the density functional theory (DFT) level by
applying the B3LYP/6-31G(d,p) method. The corresponding DFT
studies were performed in vacuum and also in acetonitrile (ε =
35.94) mediums using the polarizable continuum solvation
model (PCM) developed by Cossi and co-workers to take
account of the environmental dielectric effects59. The choice of
basis set was justified by previously published studies where
reasonable agreements were found between calculated
geometries and experimental data for particularly poly(pyrrole)
and poly(thiophene) derivatives60–62. The optimized molecular
structures were depicted in ESI†. The equilibrium geometry
ensures a minimum energy state by confirming the second
derivatives of energy (NIMAG=0). Harmonic frequencies
obtained were used to calculate the zero-point vibrational
energies (ZPVE). It should be pointed out that when we
performed our calculations, we only focused on a one-
dimensional oligomer chain, to wit, the possible influence of the
defects and interchain interactions were not taken into
account. In order to propound a realistic correlation between
the chemical structure and electronic behavior of the target
Electrochemical studies
Cyclic voltammetry. Fig. 1 shows the corresponding CVs
obtained from the potentiodynamic polymerization (5 cycles) of
the XyPMe on the ITO electrode using three different
supporting
TBAPF6/PC, and LiClO4/ACN) in the potential window from -0.3
to +1.0V. Careful examination of corresponding
electrolyte/solvent
couples
(TBAPF6/DCM,
voltammograms revealed that from the first cycle onwards, in
all three operational conditions, the current due to both
oxidation and reduction peaks were increased, which endues
the oxidation of XyPMe undergoes in each oxidative potential
scan, and therefore the deposition of the electroactive
P(XyPMe) on the working electrode surface. Besides, as the
number of potential cycles was increased, the observed anodic
peak potentials were shifted in a more positive direction.
Presumably, this observation might due to the ohmic potential
drop caused by the growing formation of the polymer film over
the subsequent scans. In this respect, the polymer film obtained
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in LiClO4/ACN provided the highest oxidation current, and we determined for the film prepared in the ACN (3.7V4iexw10Ar-t2icSle/Ocnmlin)e,
-3
DOI: 10.1039/D0NJ03992F
observed
a considerably lower polymerization rate in whereas the conductivity is decreased to4.35x10 S/cm in DCM,
TBAPF6/DCM and TBAPF6/PC. As a result, the obtained data and the lowest conductivity value has been determined for the
revealed that, compared to other examined supporting film prepared in PC (1.87x10-3 S/cm).
electrolyte/solvent systems, LiClO4/ACN is capable of offering a
better electron transfer rate and, meanwhile, higher Scan rate dependence of the peak currents. The correlation
8
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conductivity.
between the peak current and scan rate is an effective way to
characterize a redox system with electrochemical reversibility.
Therefore, in order to explore this phenomenon, we have
studied divergent scan rate values from 50mV/s to 700mV/s. It
is well known that the variation of the scan rate could give an
important diagnostic information particularly with respect to
kinetics of the investigated redox system. For a reversible
couple, separation of peaks is 0.059V/n (Equation 1).
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a
∆Ep=Epa-Epc=(0.059)/n
(Equation 1)
Ideally, the ratio of the Ipa to Ipc should be close to one, ie
reversible couples are characterized by Ipa/Ipc = 1. When a
reversible peak is observed, Ipa/Ipc is close but not exactly
equal to 1. Many redox processes observed by CV are quasi-
reversible or non-reversible. The irreversibility is indicated by
Ipa/Ipc ≠ 1. For reversible system the peak currents Ipa and Ipc
are defined by Randles-Sevcik equation. The important
relationship here is that the Ip is directly proportional to the
square root of the scan rate for a diffusion limited process. If the
peak current is directly proportional to the scan rate, this
confirms that the polymer film is redox active and well-adhered
onto the electrode surface. The observed relationship between
the potential and root of scan-rate values confirmed that the
formation of the polymer film was diffusion-controlled, and
therefore, the polymer film could be oxidized or reduced
reversibly even at remarkably higher scan rates. Accordingly,
the higher r2 values obtained from the anodic and cathodic peak
current values of P(XyPMe) indicated that the polymer had a
good adsorption capacity on the ITO surface (Fig. 2).
b
c)
Conductivity of the polymer films prepared through
electrochemical polymerization technique highly depends on
the electrolyte environment (solvent, supporting electrolyte,
applied potential etc.). The highest conductivity has been
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Spectroelectrochemical
properties.
The
corresponding Electrochromic switching. As previously described, the square-
View Article Online
DOI: 10.1039/D0NJ03992F
optoelectrochemical plot of the P(XyPMe) was shown in Fig. 3. wave potential step technique coupled with optical
Accordingly, the π-π* transition wavelength (λmax
) was spectroscopy, was used to examine the switching time and
determined as 481 nm and also, the optical bandgap (Eg) was contrast of the obtained polymer film. In compliance with this
calculated according to the Planck equation [Eg = 1241(eV definition, the maximum contrast (∆T%) and switching time (s)
nm)/λonset (nm)]66 and it was found to be 2.02 eV. During the were determined from Fig. 4 as 17% and 1 s for 1000 nm by
detailed investigation of the P(XyPMe) oxidation process, a adjusting the potential between -0.4 and +1.2 V with the
significant decrease in absorption values was observed in the residence time of 5 s.
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corresponding UV-vis spectrum. Accordingly, due to the
formation of the conducting polymer layer on the electrode
surface, charge carriers with lower energy (polaron and
bipolaron, respectively) were detected in the visible and near-
IR regions. It could be depicted from the Fig. 3 that while the
resultant polymer film was forming, the valence-conduction
band at 481 nm started to decrease, and a new band could be
seen to intensify at ~ 577 nm, and also the formation of new
broadband was detected at ~ 905 nm.
As
mentioned
before,
electropolymerization
and
spectroelectrochemical investigation of XyPBu and XyT were
already investigated by our research group. Therefore, in order
to notice the differences among the spectroelectrochemical
properties of these monomers, the obtained data from the
corresponding studies were tabulated in Table 1.
The observed values indicate that
Table 1 Spectroelectrochemical data for o-xylene bearing pyrrole/thiophene derivatives
Monomer
XyPMe
XyPBu
XyT
λmax(nm)
481
395
Egap (eV)
2.02
2.38
∆T% (nm)‡
Reference
17
39
62.5
this study
55
12
585
1.69
‡
the maximum contrast values were predicted at 1000nm.
Stability. The electrochemical stability is explicitly related to
electrochromic stability by the lack of the electrochromic
contrast because of the depletion of the active redox couple.
Repetitive cyclic voltammetric data of the prepared polymer in
monomer-free LiClO4/ACN supporting electrolyte/solvent
system were provided in Fig. 5. It was estimated that the
On the other hand, the homopolymer of XyPMe was observed
in two different colors in different potential ranges: light gray (-
0.4 V) and light blue (+1.3 V).
current response after 100 consecutive cycles decreased by
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about 13%, and this finding showed that P(XyPMe) had
adequate redox and environmental stability.
compare its physical properties with a homologVcieownAtraticinleiOnnglinae
longer alkyl chain. On the other hand, preDvOioIu: 1s0s.1t0u3d9i/eDs0rNeJv0e3a9l9e2dF
that several thiophene derivatives showed better conductivity
and stability in their thin films contrasting to their pyrrole
reciprocals67–69. Therefore, the computational properties of two
additional monomers previously synthesized by our group
containing pyrrole and thiophene systems (XyPBu and XyT,
respectively) were also investigated in the theoretical part of
this study, in order better to propound and compare the subunit
effects (Fig. 6).
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Computational studies
Geometrical properties. Experimental studies followed by
computational methods provide a particular insight into the
structural and electronic properties of polymeric target
systems. Therefore, we have focused on three different types
of monomers, all possessing the o-xylene subunit in their
backbones. The inclusion of longer alkyl chains in the
heteroaromatic structures has been already reported to
increase the solubility of the polymers studied in organic
solvents. In our case, the newly synthesized monomer, XyPMe,
was designed now to foresee the realistic effect of the smallest
alkyl group substitution onto the pyrrole ring system and
Table 2 Inter-ring torsion angles of studied monomers and their oligomers
n=2
Φ1
n=11
Entry
Φ1
Φ2
Φ3
Φ4
Φ5
Φ6
Φ7
Φ8
Φ9
Φ10
XyPMe
XyPBu
XyT
-124.76
121.64
179.62
-125.04
-127.77
179.66
-124.18
-116.22
179.83
-121.76
-116
179.86
-123.85
-112.80
-179.63
-124.72
-118.17
-179.29
-121.60
-115.09
-179.29
-124.67
-112.98
-179.63
-123.44
-112.57
179.86
-122.93
-113.43
179.83
-124.87
-98.21
179.66
It should be noted herewith that the calculated inter-ring ~1.43 Ao for XyT, ~1.45 Ao for XyPMe, and ~1.46 Ao for XyPBu.
distances for all investigated monomers and their oligomers are An accurate representation of conformations is crucial to
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identify the physical properties of the designated polymer charge. These findings are expected because ESP correlates very
systems. In this perspective, the relative inter-ring torsion closely with electronegativity and partial DchOaI:r1g0e.1.039/D0NJ03992F
angles between two consecutive units are evaluated to be
View Article Online
about ~180 Ao (a quasi-planar conformation) for XyT, and in the
case of XyPMe and XyPBu with a twist angle between 100-125
Ao. This deviation is probably caused by the charge flux and
chain interactions induced by the longer alkyl group stretch
along the polymer chain. Apparently, the geometry
optimization studies reveal that XyPMe oligomers are slightly
more planar than the oligomers of XyPBu (Table 2). According
to preceding studies, it is well known that the increase in torsion
angles is liable with the increased values of bandgaps.
Therefore, it could be concluded that the XyT, which promotes
the flatness of the conjugate oligomer system is more favorable
for strong intermolecular interaction comparing with XyPMe
and XyPBu. The corresponding electrostatic potential (ESP) V(r)
maps estimate the possible location of the charge throughout
the polymer chains. In other terms, the charge distribution in
examined structures must be understood to foresee better the
electrostatic interaction, bonding orientation, and chemical
reactivity. As shown in Fig. 7, the most negative electrostatic
potential (ESP) of the studied monomers is around the two
oxygen atoms connected to 3- and 4- positions, whereas the
most positive ESP is around the o-xylene unit in XyT, howbeit
close to the N-alkylpyrrole moieties in XyPMe and XyPBu. The
spatial distribution of negative charge is inhomogeneous in
pyrrole-based oligomers and distributed along the polymer
chain, especially around the electronegative atoms. In contrast,
the corresponding ESP map of the XyT’s undecamer gives
intuitive guidance about the centrosymmetric distribution of
Global density-based descriptors. The pivotal parameters to
improve the electrical properties and, therefore, the
electrochromic performance of conducting polymers are the
Highest Molecular Orbital (HOMO), Lowest Unoccupied
Molecular Orbital (LUMO), and especially the bandgap energy
(Eg) calculated from the corresponding frontier molecular
orbital energies (Eg=ELUMO-EHOMO). The relative order of
occupied and virtual orbitals provides an objective indicator of
the excitation properties and the efficiency of hole or electron
transfer. According to the calculated HOMO and LUMO
energies, the theoretical Eg values as a function of reciprocal
unit numbers are found in the order of XyT (1.921) < XyPMe
(3.975) < XyPBu (4.124), and these results correlate, in a good
agreement with the experimental observations (Table 3). DFT
calculations do not include the solid-state packing patterns that
influence associated HOMO and LUMO energy levels. The
overestimation of theoretical bandgap values compared to the
electrochemical and optical measurements is therefore
consistent with the findings of previous theoretical studies. It
could be interpreted from the obtained data that with the
increased number of monomer units, the bandgap energies
became smaller and displayed definite convergence. The
bandgap value of XyT had the narrowest among the
investigated monomers, and on the contrary, XyPBu had the
highest bandgap energy (Fig. 8).
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Table 3 Theoretical EHOMO, ELUMO, and bandgap (ΔE) values (eV) of XyPMe, XyPBu, and XyT.
View Article Online
DOI: 10.1039/D0NJ03992F
XyPMe
ELUMO
XyPBu
ELUMO
XyT
unit
number
n=1
n=2
n=3
n=4
n=5
n=6
n=7
n=8
n=9
n=10
n=11
n=∞
EHOMO
ΔE
EHOMO
ΔE
EHOMO
ELUMO
ΔE
-5.495
-4.947
-4.761
-4.701
-4.676
-4.652
-4.639
-4.630
-4.654
-4.639
-4.642
-4.507
-0.464
-0.490
-0.512
-0.518
-0.519
-0.522
-0.523
-0.524
-0.524
-0.524
-0.524
-0.532
5.030
4.457
4.249
4.183
4.157
4.130
4.116
4.106
4.130
4.115
4.117
3.975
-5.480
-4.897
-4.825
-4.839
-4.830
-4.778
-4.619
-4.811
-4.781
-4.817
-4.812
-4.661
-0.465
-0.496
-0.515
-0.521
-0.522
-0.524
-0.523
-0.526
-0.531
-0.532
-0.530
-0.537
5.016
4.401
4.310
4.318
4.308
4.254
4.096
4.285
4.250
4.285
4.282
4.124
-6.202
-5.342
-4.963
-4.764
-4.637
-4.553
-4.498
-4.453
-4.424
-4.398
-4.380
-4.222
-0.550
-1.203
-1.580
-1.793
-1.917
-2.001
-2.064
-2.106
-2.139
-2.164
-2.184
-2.301
5.652
4.139
3.383
2.971
2.720
2.552
2.435
2.348
2.285
2.234
2.196
1.921
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q
These results show that the thiophene scaffold on the XyT has compelling delocalization profile throughout the pyrrole and
considerably improved the hole creation. The pictorial diagram thiophene centroids, howbeit the pure effect of the LUMOs
of the calculated HOMO and LUMO orbitals for the monomers could be depicted from the Fig. 10, wherein the case of the XyT
(n=1) and undecamers (n=11) are shown in Fig. 9, and Fig. 10
,
undecamer, the LUMO exhibit an orientation toward the bonds
strong
respectively (See the ESI† for the contour plots of smaller between the consecutive units and displays
a
oligomer units), where HOMOs of the monomers accumulates delocalization. The isovalue of the calculated wave functions is
over the donor heterocyclic units (N-alkyl-3,4-dioxypyrrole or depicted by blue and metallic gray colors indicating the positive
3,4-dioxythiophene), and LUMOs accumulates on the acceptor and negative phases, respectively.
(o-xylene) subunits. For oligomeric systems, HOMOs display a
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C. C. Chang, C. P. Chen, H. H. Chou, C. Y. Liao, VSi.ewH.ACrtihclaenOnalninde
C. H. Cheng, J. Polym. Sci. Part A PDoOlyIm: 1.0.C10h3e9m/D.,02N0J1033,99521F,
4550–4557.
E. Lahiff, C. Lynam, N. Gilmartin, R. O’Kennedy and D.
Diamond, Anal. Bioanal. Chem., 2010, 398, 1575–1589.
M. Rahman, X.-B. Li, N. Lopa, S. Ahn and J.-J. Lee, Sensors,
2015, 15, 3801–3829.
C. B. Nielsen and I. McCulloch, Prog. Polym. Sci., 2013, 38,
2053–2069.
T. Bin Song and N. Li, Electron., 2014, 3, 190–204.
J. E. Yoo, K. S. Lee, A. Garcia, J. Tarver, E. D. Gomez, K.
Baldwin, Y. Sun, H. Meng, T.-Q. Nguyen and Y.-L. Loo, Proc.
Natl. Acad. Sci., 2010, 107, 5712–5717.
D. Luo, Q. Chen, B. Liu and Y. Qiu, Polymers (Basel)., 2019,
11, 384.
M. Ak, M. S. Ak, G. Kurtay, M. Güllü and L. Toppare, Solid
State Sci., 2010, 12, 1199–1204.
T. Soganci, H. C. Soyleyici, E. Giziroglu and M. Ak, J.
Electrochem. Soc., 2016, 163, H1096–H1103.
T. Soganci, G. Kurtay, M. Ak and M. Güllü, RSC Adv., 2014, 5,
2630–2639.
T. Soganci, S. Soyleyici, H. C. Soyleyici and M. Ak, Polymer
(Guildf)., 2017, 118, 40–48.
C. L. Heth, D. E. Tallman and S. C. Rasmussen, J. Phys. Chem.
B, 2010, 114, 5275–5282.
A. Palma-Cando, G. Brunklaus and U. Scherf,
Macromolecules, 2015, 48, 6816–6824.
K.-Y. Lin, L.-W. Hu, K.-L. Chen, M.-D. Siao, W.-F. Ji, C.-C. Yang,
J.-M. Yeh and K.-C. Chiu, Eur. Polym. J., 2017, 88, 311–319.
K. Ishii, K. Sato, Y. Oaki and H. Imai, Polym. J., 2019, 51, 11–
18.
T. P. Kaloni, G. Schreckenbach and M. S. Freund, Sci. Rep.,
2016, 6, 36554.
P. Camurlu, RSC Adv., 2014, 4, 55832–55845.
L. Yang, A.-M. Ren, J.-K. Feng and J.-F. Wang, J. Org. Chem.,
2005, 70, 3009–3020.
H. A. Al Attar and A. P. Monkman, Adv. Funct. Mater., 2006,
16, 2231–2242.
U. Salzner, J. B. Lagowski, P. G. Pickup and R. A. Poirier,
Synth. Met., 1998, 96, 177–189.
S. Kim, J. S. Oh, T. Hwang, H. W. Seo, D.-C. Jeong, J.-H. Lee,
L. Wen, C. Song, J. G. Han and J.-D. Nam, Macromol. Res.,
2019, 27, 243–249.
U. Geissler, D. E. Lynch, N. Rohde, M. L. Hallensleben and D.
J. Walton, Synth. Met., 1997, 84, 171–172.
K. B. Vu, V. V. Vu, H. P. Thi Thu, H. N. Giang, N. M. Tam and
S. T. Ngo, Synth. Met., 2018, 246, 128–136.
Y. Yan, Int. J. Electrochem. Sci., 2017, 12, 9320–9334.
P. A. Basnayaka, M. K. Ram, L. Stefanakos and A. Kumar,
Graphene, 2013, 02, 81–87.
H. A. Abdul Bashid, H. N. Lim, S. Kamaruzaman, S. Abdul
Rashid, R. Yunus, N. M. Huang, C. Y. Yin, M. M. Rahman, M.
Altarawneh, Z. T. Jiang and P. Alagarsamy, Nanoscale Res.
Lett., 2017, 12, 246.
H. Zhuo, Y. Hu, Z. Chen and L. Zhong, Carbohydr. Polym.,
2019, 215, 322–329.
J. Zhang, B. Sun, H.-J. Ahn, C. Wang and G. Wang, Mater. Res.
Bull., 2013, 48, 4979–4983.
Y. Fu and A. Manthiram, RSC Adv., 2012, 2, 5927.
S. Ben Jadi, A. El Guerraf, E. A. Bazzaoui, R. Wang, J. I.
Martins and M. Bazzaoui, J. Solid State Electrochem., 2019,
23, 2423–2433.
Conclusions
The present study proposes the synthesis of a new and stable
N-methyl pyrrole derivative, namely XyPMe, bearing
a
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benzodioxocino-fused system on the 3,4-positions of the
pyrrole ring. In the following section, the target electrofilm of
the XyPMe was obtained by applying the electrochemical
polymerization technique. At first glance, the supporting
electrolyte/solvent couple reliance on electrofilm formation
was examined and the results reveal that LiClO4/ACN provided
the highest electron transfer rate. In concomitant steps, scan
rate dependence, spectroelectrochemistry, electrochromic
switching and stability tests were also conducted to reveal the
electrochromic properties of the target P(XyPMe)
homopolymer.
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It is well known that molecular design, synthesis, and
electropolymerization of the organic conductive materials are
time-consuming and expensive processes. Hence, in order to
enlighten and compare the optoelectronic properties of the
similar polypyrrole and polythiophene derivatives, a detailed
computational benchmark study was also carried out.
Our studies have demonstrated strong alignment between the
experimental and calculated bandgap values of the conducting
polymers comprising the pyrrole or thiophene scaffolds under
investigation. The results obtained from this study are
promising to demonstrate the efficacy of the computational
techniques to forecast and compare the electronic properties of
designated poly-conjugated systems. The HOMO and LUMO
delocalization profiles in the polythiophene system was found
revealing to explain the comparably lowest bandgap value
obtained in the case of the P(XyT) homopolymer.
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The novelty of this study resides on the determination of the
steric hindrance impact of the N-alkylation on the pyrrole unit
even that this group is small, like the methyl group, as in our
case, which could substantially alter the homopolymerization
kinetics.
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Conflicts of interest
There are no conflicts to declare.
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Acknowledgments
The quantum chemical calculations described in this study have
been conducted at TUBITAK/ULAKBIM (High Performance and
Grid Computing Center: TRUBA).
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References
1
D. Baran, F. M. Pasker, S. Le Blanc, G. Schnakenburg, T.
Ameri, S. Höger and C. J. Brabec, J. Polym. Sci. Part A Polym.
Chem., 2013, 51, 987–992.
31
32
2
T. Sagawa, S. Yoshikawa and H. Imahori, J. Phys. Chem. Lett.,
2010, 1, 1020–1025.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 13
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 14 of 15
ARTICLE
Journal Name
1
2
3
4
5
6
7
8
9
33
I. Carrillo, T. J. Leo, O. Santiago, F. Acción, E. Moreno-
Gordaliza and M. A. Raso, Int. J. Hydrogen Energy, 2018, 43, 61
16913–16921.
S. S. Rikame, A. A. Mungray and A. K. Mungray, Electrochim. 62
Acta, 2018, 275, 8–17.
N. Zhao, Z. Ma, H. Song, Y. Xie and M. Zhang, Electrochim. 63
Acta, 2019, 296, 69–74.
V. Ratautaite, G. Bagdziunas, A. Ramanavicius and A. 64
Ramanaviciene, J. Electrochem. Soc., 2019, 166, B297–B303.
S. Shah, M. Firlak, S. Berrow, N. Halcovitch, S. Baldock, B. 65
Yousafzai, R. Hathout and J. Hardy, Materials (Basel)., 2018,
Chem., 2015, 2015, 1–12.
S. Zor, F. Kandemirli, E. Yakar and T.DAOrsI:la10n.,10P3ro9/tD. M0NeJt0.3P9h9y2sF.
Chem. Surfaces, 2010, 46, 110–116.
M. Bouachrine, T. Abram, R. Kacimi, L. Bejjit and M. Nassiri
Bennani, Turkish Comput. Theor. Chem., 2018, 2, 36–48.
L. Zhang, M. Yu, H. Zhao, Y. Wang and J. Gao, Chem. Phys.
Lett., 2013, 570, 153–158.
M. Wykes, B. Milián-Medina and J. Gierschner, Front. Chem.,
2013, 1.
K. Honda, Y. Furukawa and H. Nishide, Vib. Spectrosc., 2006,
40, 149–154.
T. Soganci, J. Electrochem. Soc., 2019, 166, 1112–1118.
J. Casanovas and C. Alemán, J. Phys. Chem. C, 2007, 111,
4823–4830.
J. Wang, K. G. Neoh and E. T. Kang, Thin Solid Films, 2004,
446, 205–217.
P. Audebert, J. M. Catel, G. Le Coustumer, V. Duchenet and
P. Hapiot, J. Phys. Chem. B, 1998, 102, 8661–8669.
View Article Online
34
35
36
37
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
11, 1123.
66
38
39
40
S. Geetha, C. R. K. Rao, M. Vijayan and D. C. Trivedi, Anal. 67
Chim. Acta, 2006, 568, 119–125.
B. Alshammary, F. C. Walsh, P. Herrasti and C. Ponce de 68
Leon, J. Solid State Electrochem., 2016, 20, 839–859.
J. H. Johnston, M. J. Richardson, J. Moraes, F. Kelly and T. 69
Borrmann, Appita Annu. Conf., 2005, 1, 167–171.
J. R. Byrom, ProQuest Diss. Theses, 2018, 179.
V. Bhardwaj, D. Gumber, V. Abbot, S. Dhiman and P. Sharma,
RSC Adv., 2015, 5, 15233–15266.
41
42
43
44
45
46
47
48
J. A. Jackson, M. Braud and S. Neathery, J. Orthomol. Med.,
2010, 25, 39–42.
T. Sun, J. Qi, M. Zheng, Z. Xie, Z. Wang and X. Jing, Colloids
Surfaces B Biointerfaces, 2015, 136, 201–206.
Y. Saito, T. Azechi, T. Kitamura, Y. Hasegawa, Y. Wada and S.
Yanagida, Coord. Chem. Rev., 2004, 248, 1469–1478.
H. Li, L. Yang, R. Tang, Y. Hou, Y. Yang, H. Wang, H. Han, J.
Qin, Q. Li and Z. Li, Dye. Pigment., 2013, 99, 863–870.
R. Kaur, S. K. Manjal, R. K. Rawal and K. Kumar, J. Pharm.
Chem. Chem. Sci., 2017, 1, 17–32.
Y. Chen, L. Zhou, J. Wei, C. Mei, S. Jiang, M. Pan and C. Xu, J.
Electron. Mater., 2019, 48, 3157–3168.
49
50
A. Ajayaghosh, Acc. Chem. Res., 2005, 38, 449–459.
D. E. Lynch, I. R. Peterson, M. Floersheimer, D. Essing, L. F.
Chi, H. Fuchs, N. J. Calos, B. Wood, C. H. L. Kennard and G. J.
Langley, J. Chem. Soc. Perkin Trans. 2, 1998, 779–784.
A. Zarrouk, B. Hammouti, T. Lakhlifi, M. Traisnel, H. Vezin
and F. Bentiss, Corros. Sci., 2015, 90, 572–584.
C. Verma, E. E. Ebenso, I. Bahadur, I. B. Obot and M. A.
Quraishi, J. Mol. Liq., 2015, 212, 209–218.
İ. Çakmakcı, B. Duran, M. Duran and G. Bereket, Corros. Sci.,
2013, 69, 252–261.
S. Kumar, S. Krishnakanth, J. Mathew, Z. Pomerantz, J.-P.
Lellouche and S. Ghosh, J. Phys. Chem. C, 2014, 118, 2570–
2579.
G. Kurtay, T. Soganci, M. Ak and M. Gullu, J. Electrochem.
Soc., 2016, 163, H896–H905.
H. Lund and J. Bjerrum, Berichte der Dtsch. Chem.
Gesellschaft (A B Ser., 1931, 64, 210–213.
M. J. Frisch, G. W. T., H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci,
G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P.
Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, Sonnenberg, J.
L. Hada and F. D. J., Gaussian, Inc., Wallingford, CT, 2009,
1988.
J. Dennington, Roy; Keith, Todd; Millam, Semichem Inc. ,
Shawnee Mission. KS, 2009.
M. Cossi, N. Rega, G. Scalmani and V. Barone, J. Comput.
Chem., 2003, 24, 669–681.
51
52
53
54
55
56
57
58
59
60
S. M. Bouzzine, G. Salgado-Morán, M. Hamidi, M.
Bouachrine, A. G. Pacheco and D. Glossman-Mitnik, J.
14 | J. Name., 2012, 00, 1-3
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