Synthesis, characterization and evaluation of optical band gap of new semiconductor polymers with N-aryl- 2,5-diphenyl-pyrrole units

Article abstract of DOI:10.1016/j.molstruc.2021.131012

We used chemical modification to obtain new polymers that contain pyrrole units in the main chain, with electron-withdrawing groups acting as potential organic semiconductors, by means of chemical modification of the diacetylene-containing precursors. The

Full text of DOI:10.1016/j.molstruc.2021.131012

Journal of Molecular Structure 1245 (2021) 131012
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Synthesis, characterization and evaluation of optical band gap of new
semiconductor polymers with N-aryl- 2,5-diphenyl-pyrrole units
a
a,∗
b
Olivia Monroy , Lioudmila Fomina , María-Elena Sánchez-Vergara ,
a
a
c
Giovanna Angélica Vázquez-Hernández , Larissa Alexandrova , Ruben Gaviño ,
d
a
a
Lev Rumsh , Mikhail G. Zolotukhin , Roberto Salcedo
a
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n. C.U., Delegación Coyoacán, C.P. 04510. Ciudad
de México, México
b
Facultad de Ingeniería, Universidad Anáhuac México, Avenida Universidad Anáhuac 46, Col. Lomas Anáhuac, Huixquilucan 52786, Estado de México,
México
c
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n. C.U., Delegación Coyoacán, C.P. 04510. Ciudad de México, México
d
M. M. Shemyakin and Yu. A. Ovchinnikov, Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya, 16/10, 117997 GSP,
Moscow V-437, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
We used chemical modification to obtain new polymers that contain pyrrole units in the main chain, with
electron-withdrawing groups acting as potential organic semiconductors, by means of chemical modifi-
cation of the diacetylene-containing precursors. These were prepared by oxidative coupling of terminal
diacetylenes or by superelectrophilic polycondensation of diphenoxydiacetylene with isatin. Diacetylenic
fragments in the precursors reacted with aromatic amines that bore electron-withdrawing substituents
in the presence of copper chloride, in order to yield the corresponding diphenyl-pyrrole polymers. These
were then fully characterized by NMR, IR and thermal analysis. The molecular weights of the polymers
were also determined by GPC. We used UV–vis spectroscopy to derive the optical band gap of the poly-
mers. The band gap values of synthetized polymers can be modulated by modifying the position and
type of substituent. Band gaps obtained in wafer form range from 1.35 to 2.8 eV; the range required for
polymer semiconductors, if they are to be employed in optoelectronic devices.
Received 24 March 2021
Revised 8 June 2021
Accepted 29 June 2021
Available online 3 July 2021
Keywords:
Diphenyl-pyrrole derivatives
Polymer chemical modification
Band gap
Semiconductor wafers
©
2021 Elsevier B.V. All rights reserved.
1
. Introduction
getic states, near the highest occupied molecular orbitals (HOMO)
and the lowest unoccupied molecular orbitals (LUMO) [7, 9]. Ac-
cording to the band theory, the higher energy occupied and lower
energy unoccupied bands of the polymer have their origins in the
HOMO and LUMO respectively, in their monomer units. There-
fore, the electronic band gap of the polymer is strongly depen-
dent on the energy gap between the HOMO-LUMO energy levels
of the parent monomer; however, the polymer structure also plays
a very important role in defining band gap value. Parameters such
as the length of the conjugated polymer chains and their alter-
nation, planarity of the molecular segments, presence of an elec-
tron donor and/or electron acceptor groups, as well as the stabiliz-
ing resonance energy of the aromatic rings, largely determine the
final band gap of the polymers; thus presenting possibilities for
their modulation [8, 9]. Using modern synthetic strategies, it was
possible to obtain semiconductor polymers with the band gap ≤
Success in the context of microelectronics has depended on
advances in the fabrication of silicon-based integrated circuits
[
1]. However, a number of physical and economic factors, which
threaten the production of silicon semiconductor devices [1], have
motivated the development of polymers for use in device manufac-
ture [2–4]. Currently, families of conjugated polymers exist, which
combine low density, flexibility and impact resistance, with elec-
trical properties such as semiconductivity [5, 6]. Semiconducting
polymers are classified in terms of their energy bands that origi-
nate from bonding and anti-bonding energy levels, associated with
a combination of their σ- and π-bonds [7]. The σ-bonds hold the
structure together, and π-bonds give rise to the properties that de-
fine conjugated polymers as semiconductors [7, 8]. This semicon-
ductivity is a consequence of the limited amount of possible ener-
2
eV, as is the case of trans-poly(acetylene) [7, 10]. Other exam-
ples are: poly-3-hexylthiophene with a band gap around 2 eV [9],
polyisothianaphthene (PITN) with a band gap around 1.2 eV [9],
∗
Corresponding author.
E-mail address: lioud@unam.mx (L. Fomina).
https://doi.org/10.1016/j.molstruc.2021.131012
0
022-2860/© 2021 Elsevier B.V. All rights reserved.

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
sessing the chemical modification of diacetylene-containing poly-
mers. In this context, diacetylene fragments are very interesting
chemical species, known for their chemical reactivity and useful
optical and electro-optical properties, at times producing materials
with particular electronic behavior that represent potential precur-
sors to devices [23–26]. Likewise, the method described for the se-
lective modification of the diacetylene groups in a polymer, follow-
ing a reaction with amines (reaction of Reisch-Schulte), constitutes
an important synthetic route towards the synthesis of new poly-
mers, particularly those containing pyrrole units [27–30]. This pro-
cess gives place to a large number of opportunities for the synthe-
sis of potentially soluble and processable pyrrole-containing poly-
mers [31, 32]. This study also pretends to determine the corre-
sponding band gap in pyrrole-based polymers, taking advantage
of the relationship between the absorption coefficient (α) and the
photon energy (hν) of polymers in wafer form. Currently, a sig-
nificant number of electronic devices have been integrated with
inorganic semiconductors of the silicon type, including crystalline,
semi-crystalline or amorphous silicon wafers, with the latter man-
ifesting low efficiency. This is an argument against their use, how-
ever their low cost compared to that of the crystalline type, has
enabled them to enter the electronics market. Few studies have
investigated wafer-shaped polymers. Therefore, the present work
seeks to provide important data concerning the synthesis and char-
acterization of pyrrole-based semiconductor polymers, whose low
band gap energy values in wafer form advocate their application in
optoelectronic devices.
Fig. 1. Pyrrole derivative with electron-withdrawing group (R= NO2 and CN).
poly(propylene thiophenoimine)-co-poly(ethylenedioxy thiophene)
copolymer (G1PPT-co-PEDOT) with a band gap of 1.6 eV [11],
diketopyrrolopyrrole (PDPP–TzVTz) copolymer with a band gap of
1
.32 eV [8] and thienothiophene-diketopyrrolopyrole copolymers
with band gaps between 1.72–1.82 eV [10].
Pyrrole, a five-membered aromatic hetero ring with high elec-
tron density, represents a very promising candidate for the creation
of novel organic semiconductor materials, some of which have
shown themselves apt for applications in light emitting diodes, so-
lar cells [12] and field-effect transistors [5]. However, the poor sta-
bility of pyrroles exposed to air has limited possible use of pyrrole-
based materials. To overcome this drawback and improve stability,
there are two common approaches: (1) introducing the electron-
withdrawing items adjacent to pyrrolic units or (2) fusing pyrroles
with more stable heterocycles such as thiophene and benzene [5].
Our group has developed scientific interest in diphenyl-pyrrole
based monomers (see Fig. 1) and polymers, and synthesized sev-
eral new compounds with semiconductor behavior [13, 14]. Evi-
dently, semiconductor properties can be determined with reference
to the nature of the substituent R. In this sense, the large electron-
withdrawing power of the substituents results in greater conduc-
tivity on the part of the material. Other research groups observed
similar effects and not only for pyrrole derivatives. It seems that
incorporation of various electron attracting and electron-donating
groups in heterocyclic azo dyes, significantly changed their electri-
cal properties. This was directly reflected in density-voltage char-
acteristics and the efficiency of the photovoltaic devices, related to
the active layers of these dyes [15].
2. Results and discussion
The π-conjugated polymers obtained by electrochemical meth-
ods, present advantages and disadvantages [33]. Among the advan-
tages in terms of its use in molecular electronics, electrochemical
polymerization offers the possibility of growing the polymer on the
surface of the working electrode. This surface is normally metallic
and transparent, as in the case of ITO (Indium tin oxide), propi-
tious for building the device and evaluating its electrical behav-
ior [34, 35]. However, for polymers obtained in this way, the usual
techniques are not apt for their detailed structural and chemical
characterization. If instead, the chemical methods of polymeriza-
tion are used, this latter limitation can be surmounted, especially
if the monomers manifest appropriate functions and include pro-
cessable polymers that can be obtained and characterized in de-
tail. Therefore, in the study described here, we propose the prepa-
ration of conjugated polymers using chemical methods, with the
aim of producing well-defined, soluble, processable and easy-to-
use pyrrole-based polymers. These represent promising candidates
for the construction of functional-polymer-based materials and de-
vices, with highly tunable properties.
Favorable electronic device behavior, on the part of pyrrole
derivatives, has been reported by several groups [5, 16, 17] and the
fact that these features have been found in carboxylic acid com-
pounds that correspond to those of the diphenyl-pyrrole deriva-
tives, corroborates this research. Significantly, the carboxylic group
represents one of the classic electron-withdrawing groups, when it
appears as a substituent in aromatic rings [16, 17]. Contrarily, by
2
2
.1. Polymer synthesis
.1.1. Synthesis of the polymer precursors
Synthesis of the precursor of polymer 6 is shown in Scheme 1.
Monomer 2 was prepared from propargyl chloride and bisphenol
A (1), in presence of an excess of potassium carbonate in acetone
changing the N-substituent from H, CH3 to C H , there was an ap-
2
5
∗
parent blue shift in the absorption peak related to a π-π transi-
tion, revealing a direct relationship with the conductivity of the N-
substituent [5, 18]. A final example is the synthesis of halogenated
of pyrroles, after attaching strong electron-withdrawing units (Cl
and Br) stable semiconductors are obtained [5, 19–22].
[
27, 33].
Synthesis of compound 4 was carried out by O-propargylation.
Monomer 5 for further superelectrophilic condensation was ob-
tained at 95% yield, via the oxidative coupling reaction (Scheme 2)
[
27].
This work aims to continue the synthesis and study of pyr-
role derivatives with electron-withdrawing groups, for producing
new organic materials that manifest semiconductor behavior. In
the present case, we have focused our task on the preparation of
polymers that contain pyrrole units in the main chain, and to as-
2.1.2. Oxidative polymerization
Oxidative polymerization of 2 was carried out by following
Scheme 3.
2

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Scheme 1. Alkylation of bisphenol A under basic conditions.
Scheme 2. Synthesis of monomer 5.
Scheme 3. Oxidative polymerization of monomer 2.
Scheme 4. Polycondensation of isatin with 5.
Because phenyl propargyl ethers are known to undergo Claisen
type sigmatropic rearrangements to produce 2H-chromenes [36],
the polymerization temperature was not allowed to rise above
fide to produce pyrrole and thiophene containing polymers, re-
spectively [39, 40]. However, the authors provided no solid proof
of the chemical structure. Furthermore, it cannot be assumed that
the drastic reaction conditions reported in those papers, exist in
all cases, because the diacetylenic groups may suffer cross-linking,
prior to chemical modification.
70 °C. Under these conditions, the reaction yielded a fully solu-
ble polymer. The preparation of polymer 6 has been reported pre-
viously [37], but its structural characterization was very limited.
Therefore, the polymer 6 obtained in this way was characterized
by NMR, IR and GPC in our previous work, prior to chemical mod-
ification [27]. However in this work, we managed to increase its
molecular weights and form 6 with Mw = 184,030 and polydis-
persity (PD) = 4.1.
In our previous work, we showed that reactions between di-
acetylene groups and aromatic amines, in the presence of CuCl
(I) acting as a catalyst, proceed under mild conditions [27]. Poly-
mer 6 was set to react with aromatic amines containing electron-
withdrawing substituents, under nitrogen atmosphere for 48 h,
at a temperature of 110 °C, to produce new polymers 9a-9j
(
Scheme 5). The reaction was monitored by IR spectroscopy us-
2
.1.3. Superacid catalyzed polyhydroxyalkylation
ing the characteristic C≡C band at 2140 cm 1, which gradually
decreased with the modification. The singlet at 6.38 ppm in the
1H NMR spectrum provides clear evidence of the formation of
−
The polymer 8 that contained diacetylenic moieties in the main
chain was synthesized by condensation of isatin with diacetylenic
monomer 5, in a superacid medium (Scheme 4). The polymer’s
yield was close to quantitative [27]. The synthesis proceeded as a
superelectrophilic aromatic substitution reaction and was carried
out, in a way similar to polymerizations of isatin 7 with aromatic
hydrocarbons [38].
2
, 5-disubstituted pyrroles (Fig. 2). The 13C NMR spectrum con-
firms the chemical transformation by the signal of the product at
10.82 ppm, characteristic of the pyrrole group (Fig. 3). We ob-
1
served an 83% conversion (determined by 1H NMR integration).
Polymer 8 was modified by reaction with aromatic amines with
electron withdrawing groups catalyzed by copper (I) chloride un-
der nitrogen atmosphere in order to obtain 10a-10j (Scheme 6).
The reaction was monitored in a similar way; by IR spectroscopy
Polymer 8 is insoluble in hydrocarbons or chlorinated solvents,
but soluble in dipolar aprotic solvents, such as NMP or DMSO,
consistent with the presence of significant interchain hydrogen
bonding. Polymer 8 was characterized by NMR, IR and GPC before
chemical modification in our previous work [27]; although in this
work, 8 exhibits a higher Mw of 27,220 and a PD of 1.6.
using the band at 2140 cm 1. The polymers 10a-10j were obtained
−
with conversions of about 70%. We attribute the signal at 6.34–
6
.67 ppm to the protons on the pyrrole ring.
2
.2. Polymer reactions
2
.3. Polymer properties
Examples in the literature have reported modification of
The GPC and thermal analysis data of polymers 9a-9j and 10a-
diacetylene-containing polymers with amines and hydrogen sul-
10j are shown in Table 1. The new polymers 9a-9j are soluble in
3

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Scheme 5. Reactions between polymer 6 and amines.
Fig. 2. 1H NMR spectrum of 9a (300 MHz, CDCl3).
Fig. 3. 13 C NMR spectrum of 9a (75 MHz, CDCl3).
ple 9e and Mw of 2130–8770 and polydispersity of 1.31–1.81 for
the remaining polymers obtained.
chlorinated solvents and show TGA onset decomposition temper-
atures at 136–260 °C. GPC analysis exhibited Mw = 12,350 and
PD = 1.66 for polymer 9b; Mw = 19,900 and PD = 3.44 for sam-
New polymers 10a-10j showed a TGA onset decomposition tem-
perature at 205–270 °C. Polymers 10a-10j are insoluble in hydro-
Scheme 6. Chemical modification of polymer 8.
4

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Table 1
tra for the polymers 9 and 10 are shown in Fig. 5; in all cases,
Characterization of the polymers obtained.
Polymer Mw PD Td (onset, °C)
5050 1.39 137
the spectra present a defined vibrational structure, whose bands
∗
can be assigned to different π-π transitions. The characteristic
bands show an intense electromagnetic absorption that is visible,
with the maximum of lower energy absorption in the range of
high energy between 315 and 360 nm, corresponding to the violet
zone of the spectrum. Table 2 summarizes the wavelengths corre-
sponding to the different vibronic peaks that relate to each optical
absorption.
9
a
9
b
12,350
2650
2130
19,900
8770
2630
4060
4600
4260
1810
2750
1890
2460
5500
12,570
8730
2760
5860
9240
1.66
1.81
1.31
3.44
1.39
1.71
1.70
1.26
1.26
1.12
1.34
1.18
1.56
1.83
2.47
1.86
1.07
1.72
2.06
228
251
260
224
230
222
231
236
136
229
230
205
248
215
270
270
225
231
249
9
9
9
9
9
9
9
9
1
1
1
1
1
1
1
1
1
1
c
d
e
f
g
h
Control of the band gap of the organic semiconductors has been
at the center of the synthesis of functional π-conjugated systems
i
j
[
41]. Within the field of conjugated semiconductor polymers, the
0a
0b
0c
0d
0e
0f
0g
0h
0i
0j
low or moderate band gap polymers are particularly interesting
because of their high capacity for sunlight absorption (visible and
near infrared), their high intrinsic conductivity in neutral state and
their transparency in doped state [9, 41]. These properties have
provoked great interest in band gap polymers for their applica-
tion in photovoltaic devices, transistors with field effect or elec-
trochromic devices [41, 42]. In order to evaluate the optical gap
in the diphenyl-pyrrole based polymers, the analysis of the UV–
Vis spectra was performed to obtain the absorption coefficient (α)
and photon energy (hν) and later to obtain the optical band gap,
using Tauc’s method. This method consists of the extrapolation of
the linear stretch of the skirt of the lower energy band of the
carbons or chlorinated solvents, and soluble in THF and DMSO. GPC
data showed Mw of 9240 and polydispersity of 2.06 for the sample
2
1
0j; Mw of 12,570 and polydispersity of 2.47 for the polymer 10f
(αhv) , up to the cutoff point with the abscissa axis, correspond-
and Mw of 1810–8730 and polydispersity of 1.07–1.86 for the other
polymers obtained. Chemical modification was carried out under
mild conditions, severely limiting chain scission.
ing to the energy of the photon (hν). Frequency (ν) is the inverse
of the wavelength, and the absorption coefficient (α) is obtained
from the absorbance data, while h is Planck’s constant. Figs. 6 and
7 present Tauc’s graphs for the various polymers. Notably, the op-
tical gap is the energy necessary for the photons to be absorbed
and an exciton is formed (hollow-electron pair linked by means of
a coulombic interaction) inside the material [43]. Table 2 presents
the band gap values for each of the polymers 9 and 10 in wafer
structure. Concerning polymer 9, the band gap values are in a
range 2.0–2.9 eV, although these values do not correspond to a low
band gap, they fall within the range of organic semiconductors. The
reason why these materials showed band gaps in the semiconduc-
tor range refers to their high electronic delocalization within the
aromatic rings, their different aromatic structures and the presence
of the electronegative oxygen in the chain. Similarly, substituents
play an important role in defining the band gap value of polymers.
The polymer that has as substituents, two –NO2 groups in the po-
sitions 3,5 of the substituted aromatic ring (9i) has a band gap of
2.04, and this can be attributed to the strong inductive effect of
the substituents. When the positions of the –NO2 groups change
to 2,4, the band gap value rises to 2.39 eV (9j), which may be be-
cause the inductive effect is not as strong as in the previous case.
This increase in band gap value is also observed when the sub-
stituents –NO2 and –CF3 are in positions 2,4, as in the case of the
polymer 9e (2.60 eV) and the sample 9f (2.87 eV). However, when
the substituents –CF3 y –NO2 are in the positions 3,4 respectively
(9g), the inductive effect is greater than the previous cases, result-
ing in a lower band gap value: 2.41 eV. The polymer 9a, whose
only substituent is the -F group in the para position, presents the
second-best band gap value (2.18 eV). However, when the -F group
changes to CF3 (9d), the band gap value increases (2.4), showing
that the inductive effect of the -F group is greater than that of the
CF3 group in these materials. Similarly, when there is another sub-
stituent in meta position, apart from the -F group in para position,
as is the case of the –CN (9c) group or –CF3 (9b) group, these in-
crease their band gap values to 2.45 and 2.52 eV, respectively. Fi-
nally, when the material presents the substituents –CF3 y –COOH
in the positions 3,5 (9 h), the inductive effect decreases, resulting
in one of the highest band gap values (2.68 eV).
Therefore, we opine that the apparent decrease in molecular
weights can be mostly explained by increasing polymer chain flex-
ibility because of the modification of the diacetylenic units that
results in a decrease in the hydrodynamic radii of the macro-
molecules. Likewise, the introduction of side groups may also re-
duce hydrodynamic radii, as apparent in the case of comb-like
polymers. Both these factors indicate that the molecular weights
of the pyrrole-based polymers, measured by GPC, reduce in com-
parison with those of their diacetylenic precursors.
As is common in materials of this type, most of the previously
synthetized π-conjugated polymers, do not withstand high tem-
peratures; nor are they soluble in a considerable number of sol-
vents (see Table 1). These two characteristics hinder the use of
polymers in thin film shape, which is the structure normally used
for the manufacture of devices [1, 7–9, 35, 36]. To solve this prob-
lem and in contrast to the works reported on the use of polymers
in films [1, 7-9, 35, 36], we propose the use of the diphenyl-pyrrole
based polymers, in wafer form. Polymer wafers are manufactured
by mechanical means that are less damaging to the molecular
structure of the polymer than the chemical or thermal methods
used in the manufacture of films. Polymer wafers were manufac-
tured by simple compaction of the polymer powder into a cylin-
drical mold. In order to analyze the structure of the material, an
XRD was carried out, until reaching the spectra shown in Fig. 4. In
the patterns obtained by XRD of the polymers 9a-9i and 10a-10i,
evidently most of these are amorphous; however, polymers 9a, 9b,
9d, 9f, 9g, 9h and 10 d manifest a number of reflections, corre-
sponding to a crystalline phase.
Considering an application such as a semiconductor of a de-
termined polymer in an electronic device, where absorption is
the principle on which its function is based, knowledge of the
electroscopic properties of this material is of great importance.
The information related to these properties enables it to be ap-
propriately incorporated in a certain type of device. It also en-
sures that in combination with the rest of the material compo-
nents of the device, it contributes to enhancing yield. Obtaining
the UV–Vis spectra for previously synthetized polymers will enable
evaluating their structure-property relationship. The UV–Vis spec-
Considering polymers 10, the range for band gap values falls
between 1.35 – 2.8 eV; these values are specific to semiconduc-
5

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Fig. 4. XRD patterns of polymers 9 and 10 in wafers.
Fig. 5. Absorption UV–vis spectra of the polymers 9 and 10 in wafer form.
tor materials. In the case of this type of material, notably the poly-
mer 10e presents a low band gap. This polymer has as substituents,
the –NO2 group and –CF3 group in positions 2,4 respectively. How-
ever, when there is an exchange in the positions of the substituents
case of the sample 10j (2.57 eV), which has the –NO2 groups in
positions 2,4. This occurs in a similar way with the compound 10i,
which presents two –NO2 groups but in different positions (3,5)
to the polymer 10j, as this also provokes a decrease in the band
gap value (2.38 eV). Among materials, which do not have the –
NO2 group as substituent, it is the polymer 10d, which manifests
the –CF3 group in the para position and exhibits a 2.2 eV band
gap. When the substituent is replaced by the -F group (10a), there
is an increase in the band gap value (2.34 eV), an opposite case to
the first polymer modified. However, by having the -F group and
(
10f), the highest band gap value results (2.80 eV), indicating that
the inductive effect of the –NO2 group in these materials is not
outstanding. When the positions of –CF3 and NO2 substituents are
different, 3,4 respectively, as in the case of the polymer 10 g, it is
possible to decrease the band gap to 2.63 eV. Besides, when there
are two -NO2 groups, the band gap value also decreases, as in the
6

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Table 2
Electronic transitions of the polymers 9 and 10 in wafer form.
Sample
Bandgap (eV)
2.18
λ (nm)
Sample
Bandgap (eV)
2.34
λ (nm)
Identification
Pyrrole
9
9
9
9
9
a
b
c
352
10a
345
319
346
318
350
325
350
320
350
335
320
353
334
322
352
336
320
348
320
351
331
319
351
337
323
3
23
343
26
350
21
342
22
357
Substituted aromatic ring
Pyrrole
2.52
2.45
2.40
2.60
10b
10c
10d
10e
2.43
2.22
2.23
1.35
3
Substituted aromatic ring
Pyrrole
3
Substituted aromatic ring
Pyrrole
d
e
3
Substituted aromatic ring
Pyrrole
3
3
31
20
-NO2 group
Substituted aromatic ring
Pyrrole
9
9
f
2.87
2.41
357
10f
2.80
2.63
3
3
36
22
-NO2 group
Substituted aromatic ring
Pyrrole
g
353
10g
3
3
34
20
-NO2 group
Substituted aromatic ring
Pyrrole
9
9
h
i
2.68
2.04
348
21
353
10h
10i
2.41
2.38
3
Substituted aromatic ring
Pyrrole
3
3
32
23
-NO2 group
Substituted aromatic ring
Pyrrole
9
j
2.39
355
10j
2.57
3
3
37
27
-NO2 group
Substituted aromatic ring
one more substituent in the meta position, the band gap value may
decrease or increase, as is the case of the sample 10c (2.22 eV),
which is also part of the -CN group, or the polymer 10b (2.43 eV),
which is part of the –CF3 group. Finally, there is the compound
10 h, which has the –CF3 group and the –COOH group in positions
3,5 and exhibits a 2.41 eV band gap.
From the previous results, it is apparent that the band gap ob-
tained for all the synthesized polymers depends mainly on the
substituents found in their structure. This causes modulation of
the band gap, by modifying the position and type of substituent.
In contrast, the amorphous or crystalline morphology is not a de-
termining factor for achieving a low band gap. Another impor-
tant aspect to emphasize is the fact that the band gap was ob-
tained for wafers, which allow these polymers with moderate de-
composition temperature, to be used in devices, without the need
to manufacture them in the form of thin films. The synthetized
diphenyl-pyrrole based polymers present a series of characteris-
tics that make them suitable materials for their incorporation in
optoelectronic devices such as organic diodes (OLEDs) and organic
transistors (OFETs).
3. Experimental part
3
.1. Materials and instruments
All chemicals were provided by the Aldrich Chemical Company
and used as received. FT-IR spectra were recorded, using a Thermo
Scientific, Nicolet 6700 spectrophotometer with an ATR attachment
Smart Orbit. 1H and 13C NMR spectra for all compounds were
recorded using a Bruker, Avance 300 MHz and Bruker, Avance III
HD 400 MHz spectrometers. Chemical shifts were reported in ppm,
scaled relative to TMS. Thermal gravimetric analyses (TGA) were
−1
carried out, using TA Instruments, Q5000IR under a 25 mL min
air flux, at a heating rate of 10 °C min 1. Differential Scanning
−
Calorimetry (DSC) was accomplished using TA Instruments, Q2000
under a N2 atmosphere, at a scan rate of 10 °C min 1. High Pres-
sure Size Exclusion Chromatography Analysis was carried out on a
Waters, Alliance 2695 Separations Module, columns (Styragel, HR
−
Fig. 6. Tauc’s graphs for wafer-shaped polymers 9.
4
E and Styragel, HR 5E), detector (Waters 2414) and Empower 3
7

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
CDCl ): δ 4.78 (s, 2H, –OCH ), 6.98 (m, 2H, H-Ar), 7.04 (t, 1H, H-
3
2
Ar), 7.33 (m, 2H, H-Ar). 13C NMR (100 MHz, CDCl ): δ 56.20, 71.04,
3
7
4.70, 114.90, 121.78, 129.55, 157.43.
.3. Synthesis of polymers
6) Copper (I) chloride (0.03 g, 0.3 mmol) was added to a solu-
3
(
tion of 2 (1 g, 3.28 mmol) in dioxane and a few drops of N,N,N’,N’-
tetramethylethylenediamine (TMEDA). The reaction mixture was
stirred in an atmosphere of oxygen, at 70 °C for 3 h and then
poured into methanol. The resulting white film was filtered off,
washed with methanol and dried in a vacuum. The polymer yield
was quantitative. 1H NMR (300 MHz, CDCl ): δ 1.62 (s, 6H, -CH ),
3
3
4
.69 (s, 4H, –OCH ), 6.82 (d, 4H, -C H ), 7.13 (d, 4H, -C H ). 13C
2 6 4 6 4
NMR (75 MHz, CDCl ): δ 31.00, 41.81, 56.26, 70.99, 74.82, 114.23,
3
127.83, 144.09, 155.34.
(
8) Polymer synthesis was carried out in a single-necked 20 mL
flask, equipped with a magnetic stirrer in an ice bath. To a mix-
ture of 5 (2.098 g, 0.8 mmol) and (1.353 g, 9.2 mmol) of isatin
7
were added dichloromethane (4 mL), trifluoroacetone (6 mL),
methanesulfonic acid (6 mL) and trifluoromethansulfonic acid
1 mL).The reaction mixture was stirred for 3 h and then poured
into methanol. The resulting pure white fibrous polymer was fil-
tered off, washed with methanol and then dried in a vacuum. 1
NMR (300 MHz, DMSO–d ): δ 4.85 (s, 4H, –OCH ), 6.91 (m, 6H, H-
(
H
6
2
o in 8, H-5, H-6 in isatin ring), 7.10 (m, 4H, H-m in 8), 7.18 (m, 2H,
H-7, H-8 isatin ring), 10.41 (s, 1H, N–H). 13C NMR (75 MHz, DMSO–
d6): δ 55.74, 60.45, 69.73, 75.73, 109.60, 114.41, 121.44, 125.43,
127.73, 128.76, 133.19, 134.72, 140.96, 155.81, 178.04.
3
.4. Polymer reactions with amines: general procedure
Copper (I) chloride (0.03 g, 0.33 mmol) was added to a stirred
solution of 6 (0.5 g, 1.65 mmol) in dimethylformamide (10 mL) and
the corresponding amine (3.3 mmol) in an atmosphere of nitrogen,
for 48 h at a temperature of 110 °C; then the solution was diluted
with excess acidified water. The precipitate was collected by filtra-
tion, to be dried at room temperature.
Fig. 7. Tauc’s graphs for wafer shaped polymers 10.
Software. THF was employed as eluent at 35 °C and flux speed of
(
9a) 1H NMR (300 MHz, CDCl ): δ 1.60 (s, 6H, -CH ), 4.69
−
1
3
3
1
.0 mL min after calibration with polystyrene standards.
(
(
s, 2H, –OCH ), 6.38 (s, 1H, H-pyrrole), 7.01 (m, 12H). 13C NMR
2
75 MHz, CDCl ): δ 31.00, 41.75, 71.00, 110.82 (C-pyrrole), 114.23,
3
3
.2. Synthesis of precursor compounds
114.70, 115.82, 127.83, 130.70, 133.05, 144.09, 155.31, 156.13.
(
9b) 1H NMR (300 MHz, CDCl ): δ 1.62 (s, 6H, -CH ), 4.69
3
3
(
2) 2,2-Bis(4-(prop–2-ynyloxy)phenyl)propane. The procedure
(s, 2H, –OCH ), 6.39 (s, 1H, H-pyrrole), 6.95 (m, 11H). 13C NMR
2
was similar to that described in the literature. Yield: 90%. M.p.:
(75 MHz, CDCl ): δ 31.01, 41.82, 71.00, 111.37 (C-pyrrole), 114.24,
3
8
0 °C (m.p.: 80 °C [44]).
4) 1-(Prop-2-ynyloxy) benzene. Potassium carbonate (17.6 g,
.12 mol) was added to a solution of phenol (10.0 g, 0.10 mol)
114.73, 127.83, 130.91, 144.10, 155.33.
(
(9c) 1H NMR (300 MHz CDCl ): δ 1.61 (s, 6H, -CH ), 4.87 (s, 2H,
3
3
0
–OCH ), 6.41 (s, 1H, H-pyrrole), 6.95 (m, 11H). 13C NMR (75 MHz,
2
in dry acetone, stirred for one hour at room temperature; subse-
quently adding (19.0 g, 0.155 mol) of propargyl bromide. The re-
sulting mixture was stirred at 50 °C for 22 h. The residue was
treated with water, extracted with ethyl acetate and dried over
anhydrous magnesium sulfate. We purified the product by vac-
uum distillation to obtain colorless oil. Yield: 90%, b.p.: 65–68 °C
CDCl ): δ 30.50, 41.30, 70.01, 110.81 (C-pyrrole), 112.79, 114.15,
116.73, 119.07, 127.66, 131.13, 141.43, 143.91, 155.38, 156.07.
3
(9d) 1H NMR (300 MHz, CDCl ): δ 1.61 (s, 6H, -CH ), 4.70
3
3
(s, 2H, –OCH ), 6.41 (s, 1H, H-pyrrole), 6.93 (m, 12H). 13C NMR
2
(75 MHz, CDCl ): δ 30.98, 41.70, 70.96, 111.92 (C-pyrrole), 114.21,
3
126.57, 127.79, 128.30, 144.09, 144.29, 155.27.
at 5 mm Hg [45, 46], IR (cm ): 3295, 2124. 1H NMR (400 MHz,
−
1
(9e) 1H NMR (300 MHz, CDCl ): δ 1.62 (s, 6H, -CH ), 4.71
3
3
CDCl ): δ 2.64 (t, 1H, -CCH), 4.77 (d, 2H, –OCH ), 7.13 (m, 3H, H-
(s, 2H, –OCH ), 6.38 (s, 1H, H-pyrrole), 6.94 (m, 11H). 13C NMR
3
2
2
Ar), 7.44 (m, 2H, H-Ar). 13C NMR (100 MHz, CDCl ): δ 55.8, 77.4,
(75 MHz, CDCl ): δ 30.93, 41.67, 70.90, 110.59 (C-pyrrole), 114.15,
3
3
7
8.9, 115.1, 121.7, 129.7, 157.7.
5) 1-(6-Phenoxyhexa-2,4-diynyloxy)benzene [47, 48]. To a so-
lution of 4 (2.64 g, 20 mmol) in isopropanol, we added copper (I)
chloride (0.4 g, 4 mmol) and N, N, N, N- tetramethylethylendiamine
127.72, 127.83, 144.02, 155.22.
(
(9f) 1H NMR (300 MHz, CDCl ): δ 1.63 (s, 6H, -CH ), 4.70
3
3
(s, 2H, –OCH ), 6.75 (s, 1H, H-pyrrole), 7.03 (m, 11). 13C NMR
2
(75 MHz, CDCl ): δ 31.01, 41.81, 56.25, 71.00, 108.91 (C-pyrrole),
´
3
´
(TMEDA), 0.1 mL (0.077 g, 0.6 mmol). The mixture was left stirring
114.22, 127.83, 144.10, 155.32.
for 3 h under a stream of oxygen, and the resulting solution added
to acidified water. The product was separated by filtration, dried in
a vacuum; then purified by recrystallization from hexane. A white
solid was obtained: m.p.: 82 °C. Yield: 90%. 1H NMR (400 MHz,
(9 g) 1H NMR (400 MHz, CDCl ): δ 1.62 (s, 6H, -CH ), 4.71 (s,
3
3
2H, –OCH ), 6.71 (s, 1H, H-pyrrole), 6.93 (m, 9H), 7.95 (d, 2H). 13C
2
NMR (100 MHz, CDCl ): δ 31.00, 41.74, 70.99, 112.86 (C-pyrrole),
3
114.21, 127.83, 128.83, 144.11, 155.29.
8

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
(s, 1H, N–H). 13C NMR (100 MHz, DMSO–d ): δ 61.23, 70.43, 110.48
(C-pyrrole), 115.06, 115.54, 120.24, 122.41, 123.86, 126.34, 128.69,
129.19, 129.78, 133.92, 135.47, 141.72, 150.28, 156.46, 178.92.
(
9 h) 1H NMR (300 MHz, CDCl ): δ 1.62 (s, 6H, -CH ), 4.69
3 3
6
(
(
s, 4H, –OCH ), 6.35 (s, 2H, H-pyrrole), 6.98 (m, 11H). 13C NMR
2
75 MHz, CDCl ): δ 30.92, 41.72, 70.90, 110.89 (C-pyrrole), 114.15,
3
1
19.29, 127.73, 131.54, 144.00, 155.23.
(
9i) 1H NMR (400 MHz, CDCl ): δ 1.61 (s, 6H, -CH ), 4.75 (s,
3.5. Characterization of wafer-shaped polymers
3
3
2
H, –OCH ), 6.53 (s, 1H, H-pyrrole), 6.91 (m, 8H), 8.03 (s, 2H), 8.90
2
(
(
s, 1H). 13C NMR (100 MHz, CDCl ): δ 30.39, 41.33, 69.99, 110.18
C-pyrrole), 114.16, 127.67, 144.13, 155.40.
We used a Unicam spectrophotometer, model UV300, in the
wavelength range of 200–1100 nm, to measure the optical proper-
ties of the UV–vis spectroscopy of the polymers. The optical band
gap values of polymers were calculated from the absorption coef-
ficient and photon energy. The X-ray diffraction analysis was un-
dertaken using the θ−2θ technique, applying Bragg-Brentano Ge-
ometry with a Bruker, D8 Avance diffractometer and working with
CuK-α (λ=0.15405 nm) radiation.
3
(
9j) 1H NMR (400 MHz, CDCl ): δ 1.64 (s, 6H, -CH ), 4.73 (s, 2H,
3
3
–
OCH ), 6.68 (s, 1H, H-pyrrole), 6.98 (m, 11H). 13C NMR (100 MHz,
2
CDCl ): δ 31.00, 41.81, 70.99, 107.95 (C-pyrrole), 114.23, 127.84,
29.84, 144.11, 148.23, 155.32.
3
1
A mixture of 8 (0.1 g, 0.25 mmol), copper (I) chloride (0.005 g,
0
.05 mmol) and the corresponding amine (0.5 mmol), in DMF
(
10 mL) was maintained at 110 °C for 48 h, while stirring in an
atmosphere of nitrogen; then the solution was diluted with excess
acidified water. The precipitate was filtered off and then dried at
room temperature.
4. Conclusions
In this work, we synthesized 20 novel polymers containing pyr-
role fragments with electron-withdrawing groups, as new poten-
tial organic materials with semiconductor behavior, following the
Reisch-Schulte procedure. These new diphenyl-pyrrole based poly-
mers were fully characterized by NMR, IR and thermal analysis.
The molecular weights of the polymers were also determined. The
chemical reactions on the part of the diacetylene group can be em-
ployed to modify polydiacetylenes, resulting in very different poly-
mers. Likewise, the reactions of diacetylene groups with aromatic
amines to produce N-diaryl-pyrrole fragments in the presence of
copper (I) chloride as a catalyst proceed under mild conditions,
helping curtail unwanted side-effects.
(
10a) 1H NMR (300 MHz, DMSO–d ): δ 4.90 (s, 4H, –OCH ),
6
2
.34 (s, 1H, H-pyrrole), 7.04 (m, 16H), 10.65 (s, 1H, N–H). 13C NMR
6
(
75 MHz, DMSO–d ): δ 60.68, 69.91, 109.86 (C-pyrrole), 114.46,
15.04, 121.79, 124.92, 125.80, 128.01, 132.11, 133.79, 135.29, 141.19,
6
1
1
56.33, 178.69.
10b) 1H NMR (300 MHz, DMSO–d ): δ 4.91 (s, 4H, –OCH ),
(
6
2
.39 (s, 1H, H-pyrrole), 6.95 (m, 15H), 10.66 (s, 1H, N–H). 13C NMR
6
(
75 MHz, DMSO–d ): δ 60.71, 69.91, 109.86 (C-pyrrole), 114.55,
6
1
15.03, 121.79, 125.81, 128.19, 129.13, 132.15, 133.41, 134.96, 141.20,
1
55.95, 178.41.
10c) 1H NMR (300 MHz, DMSO–d ): δ 4.91 (s, 4H, –OCH ) 6.37
6 2
(
s, 1H, H-pyrrole), 6.96 (m, 15H), 10.65 (m, 1H, N–H). 13C NMR
(
(
The optical band gap of polymers was obtained using Tauc’s
method, revealing values in a range of 2.0–2.9 eV for the polymers
9a-9j and of 1.35–2.8 eV for the polymers 10a-10j.
75 MHz, DMSO–d ): δ 60.71, 69.92, 109.90 (C-pyrrole), 114.48,
15.06, 121.84, 125.85, 128.06, 129.16, 132.15, 133.81, 135.31, 141.22,
6
1
1
56.36, 178.72.
10d) 1H NMR (300 MHz, DMSO–d ): δ 4.92 (s, 4H, –OCH ),
All polymers present semiconductor behavior. Importantly, their
band gap can be modulated by modifying the position and type of
the substituent. These polymers exhibit moderate decomposition
temperatures and can be used in optoelectronic devices in wafer
form, without the need to manufacture thin films.
(
6
2
.40 (s, 1H, H-pyrrole), 7.04 (m, 16H), 10.63 (s, 1H, N–H). 13C NMR
6
(
75 MHz, DMSO–d ): δ 60.66, 69.88, 109.81 (C-pyrrole), 114.51,
6
115.00, 121.76, 125.80, 126.20, 128.98, 132.09, 133.76, 135.26,
1
41.17, 156.29, 178.65.
(
10e) 1H NMR (300 MHz, DMSO–d ): δ 4.91 (s, 4H, –OCH ),
Declaration of Competing Interest
6
2
.67 (s, 1H, H-pyrrole), 7.04 (m, 15H), 10.72 (s, 1H, N–H). 13C NMR
6
(
75 MHz, DMSO–d ): δ 61.16, 70.36, 110.44 (C-pyrrole), 114.98,
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
6
1
15.49, 120.97, 122.38, 123.91, 123.97, 126.29, 129.59, 131.54,
33.85, 135.41, 141.66, 148.58, 156.38, 178.86.
10f) 1H NMR (300 MHz, DMSO–d ): δ 4.91 (s, 4H, –OCH ), 6.67
1
(
6
2
(
(
(
s, 1H, H-pyrrole), 7.03 (m, 12H), 7.82 (m, 1H), 8.16 (m, 2H), 10.72
CRediT authorship contribution statement
s, 1H, N–H). 13C NMR (75 MHz, DMSO–d ): δ 60.75, 76.04, 110.02
6
C-pyrrole), 114.57, 115.07, 116.47, 121.96, 123.80, 125.89, 128.24,
Olivia Monroy: Investigation, Methodology, Validation.
Lioudmila Fomina: Investigation, Writing – original draft, Visual-
ization, Funding acquisition. María-Elena Sánchez-Vergara: Con-
ceptualization, Methodology, Formal analysis. Giovanna Angélica
Vázquez-Hernández: Methodology, Validation, Visualization.
Larissa Alexandrova: Investigation, Supervision, Funding acquisi-
tion. Ruben Gaviño: Formal analysis, Data curation. Lev Rumsh:
Conceptualization, Methodology, Visualization. Mikhail G. Zolo-
tukhin: Investigation, Writing – review & editing, Formal analysis.
Roberto Salcedo: Conceptualization, Software, Writing – review &
editing.
1
28.80, 129.18, 133.44, 135.00, 141.24, 151.78, 155.96, 178.46.
10 g) 1H NMR (300 MHz, DMSO–d ): δ 10.69 (s, 1H, N–H), 8.00
(
6
(
d, 2H), 7.02 (m, 13H), 6.67 (s, 1H, H-pyrrole), 4.91 (s, 4H, –OCH ).
2
13C NMR (75 MHz, DMSO): δ 60.70, 69.92, 109.97 (C-pyrrole),
114.43, 114.54, 121.89, 125.83, 128.17, 129.12, 129.61, 133.40, 134.95,
141.20, 155.94, 178.40.
(
10 h) 1H NMR (300 MHz, DMSO–d ): δ 4.91 (s, 4H, –OCH ),
6
2
.55 (s, 1H, H-pyrrole), 6.98 (m, 15H), 10.62 (s, 1H, N–H). 13C
6
NMR (75 MHz, DMSO–d ): δ 61.18, 70.41, 110.35 (C-pyrrole), 111.78,
6
1
14.90, 114.96, 115.52, 122.28, 126.30, 128.50, 129.51, 129.62,
32.61, 134.29, 135.79, 141.70, 151.06, 156.83, 179.18.
10i) 1H NMR (400 MHz, DMSO–d ): δ 4.90 (s, 4H, –OCH ), 6.52
1
(
Acknowledgments
6
2
(
s, 1H, H-pyrrole), 7.01 (m, 12H), 7.74 (d, 2H), 7.89 (t, 1H), 10.69 (s,
H, N–H). 13C NMR (100 MHz, DMSO–d ): δ 61.22, 70.43, 104.21,
1
The authors are grateful to G. Cedillo Valverde and M. Á.
Canseco Martinez for their assistance with Nuclear Magnetic Res-
onance and IR analyses, respectively, to S. López Morales for GPC
measurements and to K. E. Reyes Morales for thermal analyses. The
authors wish to express their gratitude to M. T. Vázquez Mejia, O.L.
Jiménez Alvarez for technical help and to A. López Vivas and A.
6
1
10.48 (C-pyrrole), 112.88, 115.06, 122.41, 126.34, 128.69, 129.30,
29.53, 132.63, 133.93, 135.47, 141.72, 151.63, 156.46, 178.92.
10j) 1H NMR (400 MHz, DMSO–d ): δ 4.90 (s, 4H, –OCH ), 6.67
1
(
6
2
(
s, 1H, H-pyrrole), 7.04 (m, 12H), 8.16 (m, 2H), 8.79 (d, 1H), 10.70
9

O. Monroy, L. Fomina, M.-E. Sánchez-Vergara et al.
Journal of Molecular Structure 1245 (2021) 131012
Pompa for computer support. O. Monroy is grateful for the schol-
arship from CONACyT. We also wish to acknowledge financial sup-
port from CONACYT, Mexico (Grants 151842 and 251693) and from
DGAPA-UNAM (PAPIIT IN 105314–3, 203517, 103920 and IG100420).
M.E. Sánchez-Vergara would also like to thank Anahuac Univer-
sity, Mexico for their financial support; Project number NNAIA-
SEVM16070616.
[22] Edder C, P.B. Armstrong, K.B. Prado, J.M. Frechet, Benzothiadiazole- and
Pyrrole-based polymers bearing thermally cleavable solubilizing groups as pre-
cursors for low bandgap polymers, Chem. Commun. 18 (2006) 1965–1967,
doi:10.1039/B601296P.
ꢀ
[23] S. Fomine, T. Ogawa, Diacetylene-Containing Polymers III. Poly(m,m -
ꢀ
butadiynylenesuccindianilide) and Poly(m,m -butadiynylene sebacodianilide):
novel materials for preparation of transparent Polydiacetylene containing
films, Polym. J. 26 (1994) 93–97, doi:10.1295/polymj.26.93.
[24] S. Fomine, I. Posada, T. Ogawa, Diacetylene-containing polymers, 8. Syn-
thesis and characterization of novel high molecular weight diacetylene-
containing poly(ester-co-urethanes), Macromol. Chem. Phys. 196 (1995) 3723–
3732, doi:10.1002/macp.1995.021961124.
References
[25] S. Fomine, C. Sánchez, R. Gaviño, T. Ogawa, Diacetylene-Containing Poly-
mers IX. Halogenation of some Diacetylene-containing Polyesters, Polym. J. 28
[
[
[
1] C. Zhang, P. Chen, W. Hu, Organic light-emitting transistors: materials, device
(
1996) 249–255, doi:10.1295/polymj.28.249.
configurations, and operations, Small 12 (2016) 1252–1294, doi:10.1002/smll.
ꢀ
[
26] S. Fomine, L. Fomina, T. Ogawa, Charge transfer complexes between 4,4 -
disubstituted diphenyldiacetylenes: experimental and theoretical study, J. Mol.
Struct. Theochem. 540 (2001) 123–130, doi:10.1016/S0166-1280(00)00712-0.
201502546.
2] M. Bendikov, F. Wudl, D.F., Perepichka, tetrathiafulvalenes, oligoacenenes, and
their buckminsterfullerene derivatives: the brick and mortar of organic elec-
tronics, Chem. Rev. 104 (2004) 4891–4946, doi:10.1021/cr030666m.
3] R. Blanco Bazaco, Diseño, Síntesis y Estudio de polímeros conjugados fun-
cionalizados Ph.D. Thesis, Facultad de Ciencias Químicas, Universidad Com-
plutense de Madrid, Madrid, Spain, 2010.
[
27] G. Huerta, L. Fomina, L. Rumsh, M.G. Zolotukhin, New polymers with N-
phenyl pyrrole fragments obtained by chemical modifications of diacety-
lene containing-polymers, Polym. Bull. 57 (2006) 433–443, doi:10.1007/
s00289-006-0576-5.
ꢀ
ꢀ
[28] J. Reisch, K.E. Schulte, Pyrrol-derivate aus Diacetylenen, Angew. Chemie 73
1961) 241–241, doi:10.1002/ange.19610730708.
[
4] F. Wudl, R.C. Haddon, E.T. Zellers, F.B. Branwell, 3,4:3 ,4 -Bibenzo[b]thiophene,
J. Org. Chem. 44 (1979) 2491–2493, doi:10.1021/jo01328a034.
(
[29] K.E. Schulte, J. Reisch, H. Walker, Dipyrrole und Porphin aus Acetylen-
verbindungen, Arch. Pharm. (Weinheim) 299 (1966) 1–7, doi:10.1002/ardp.
[
5] C. Bulumulla, R. Gunawardhana, P.L. Gamage, J.T. Miller, R.N. Kularatne,
M.C. Biewer, M.C. Stefan, Pyrrole-containing semiconducting materials: synthe-
sis and applications in organic photovoltaics and organic field-effect transis-
tors, ACS Appl. Mater. Interfaces 12 (2020) 32209–32232, doi:10.1021/acsami.
19662990102.
[
30] K.E. Schulte, J. Reisch, H. Walker, Eine neue Pyrrolsynthese aus Butadiin-
Derivaten, Chem. Ber. 98 (1965) 98–103, doi:10.1002/cber.19650980111.
0c07161.
[
31] J. Sołoducho, J. Doskocz, J. Cabaj, S. Roszak, Practical synthesis of bis-
substituted tetrazines with two pendant 2-pyrrolyl or 2-thienyl groups, precur-
sors of new conjugated polymers, Tetrahedron 59 (2003) 4761–4766, doi:10.
[
6] N.T. Thi Truong, L. Tan Nguyen, H.L. Thi Mai, B. Kim Doan, D. Hung Tran,
K. Tung Truong, V. Quoc Nguyen, L.-T.T. Nguyen, M. Ha Hoang, T. Van Pham,
V. Mau Nguyen, T. Minh Huynh, T.C. Duc Doan, H. Tran Nguyen, Phenothiazine
derivatives, diketopyrrolopyrrole-based conjugated polymers: synthesis, opti-
cal and organic field effect transistor properties, J. Polym. Res. 27 (2020) 223,
doi:10.1007/s10965-020-02199-x.
1
016/S0040-4020(03)00709-9.
32] J. Sołoducho, New route to the synthesis of the indolo[7,6-g]indole
“bis(pyrrolo)naphthalene”) system starting from 1,5-dihydroxynaphthalene,
[
(
Tetrahedron Lett. 40 (1999) 2429–2430, doi:10.1016/S0040-4039(99)00121-5.
33] T.A. Skotheim, R.L. Elsenbaumer, J.R. Reynolds (Eds.), Handbook of Conducting
Polymers, Marcel Dekker, Inc., New York, 1998.
34] M.E. Sánchez Vergara, I.F. Islas Bernal, M. Rivera, A. Ortiz Rebollo, J.R. Al-
varez Bada, Formation and characterization of thin films from phthalocyanine
complexes: an electrosynthesis study using the atomic-force microscope, Thin
Solid Films 515 (2007) 5374–5380, doi:10.1016/j.tsf.2007.01.033.
[
7] A.J. Heeger, Semiconducting polymers: the third generation, Chem. Soc. Rev.
[
[
39 (2010) 2354–2371, doi:10.1039/B914956M.
[
8] B. Kang, H.N. Kim, S. C., S.K. Kwon, K. Cho, Y.-.H. Kim, π-Extended thiazole-
containing polymer semiconductor for balanced charge-carrier mobilities,
Macromol. Rapid Commun. (2021) 2000741, doi:10.1002/marc.202000741.
9] M.C. Scharber, N.S. Sariciftci, Low Band gap conjugated semiconducting poly-
mers, Adv. Mater. Technol. (2021) 2000857, doi:10.1002/admt.202000857.
[
[
35] M.E. Sánchez, M. Rivera, A. Ortiz-Rebollo, A. Moreno, J.R. Álvarez-Bada, Sub-
strate influence on the morphological and conductive properties of modified
iron-phthalocyanine thin films, J. Mater. Sci.: Mater. Electron. 21 (2010) 822–
[
10] K.A. Vishnumurthy, A.V. Kesavan, S.K. Swathi, P.C. Ramamurthy, Low band
gap thienothiophene-diketopyrrolopyrole copolymers with V2O5 as hole trans-
port layer for photovoltaic application, Opt. Mater. (Amst.) 109 (2020) 110303,
doi:10.1016/j.optmat.2020.110303.
826, doi:10.1007/s10854-009-0001-6.
[36] M.-.F. Grenier-Loustalot, Thermal polymerization of arylacetylenes: spectro-
scopic and thermal studies, High Perform. Polym. 6 (1994) 347–383, doi:10.
[
11] A.L. Djoumessi Yonkeu, M.M. Ndipingwi, C. Ikpo, K. Nwambaekwe, S. Yus-
suf, H. Tesfay, E. Iwuoha, Photoluminescence quenching of a novel electrocon-
ductive Poly(propylene thiophenoimine)-co-Poly(ethylenedioxy thiophene) star
copolymer, Polymers (Basel) 12 (2020) 2894, doi:10.3390/polym12122894.
1
088/0954-0083/6/4/005.
37] S. Dirlikov, Z. Chen, D. Wang, Poly(dipropargyl terephthalate):
for thermosetting fibres, Polymer (Guildf) 34 (1993) 705–707, doi:10.1016/
032-3861(93)90351-A.
[
a
candidate
[
[
[
[
[
[
[
12] W.C. Oh, K.N. Fatema, Y. Liu, C.H. Jung, S. Sagadevan, Md M.R. Ud, D. Biswas,
0
Polypyrrole-bonded quaternary semiconductor LiCuMo2O11 -graphene
[
[
[
38] H.M. Colquhoun, M.G. Zolotukhin, L.M. Khalilov, U.M. Dzhemilev, Superelec-
nanocomposite for a narrow band gap energy effect and its gas-sensing per-
formance, ACS Omega 5 (2020) 17337–17346, doi:10.1021/acsomega.0c01699.
13] L. Fomina, G.Z. Galán, M. Bizarro, J.G. Sánchez, I.P. Zaragoza, R. Salcedo, Semi-
conductor behavior of 2,5-aromatic disubstituted pyrroles, viewed from an ex-
perimental and theoretical perspective, Mater. Chem. Phys. 124 (2010) 257–
trophiles in aromatic polymer chemistry, Macromolecules 34 (2001) 1122–
1124, doi:10.1021/ma001579o.
39] D.R. Rutherford, J.K. Stille, Poly(ethynylene-2,5-thiophenediylethynylenes). Pro-
cessable, reactive polymers that thermally cross-link, Macromolecules 21
(1988) 3530–3532, doi:10.1021/ma00190a035.
263, doi:10.1016/j.matchemphys.2010.06.028.
40] W. Bracke, Aromatization of polydiethynylbenzene, J. Polym. Sci. Part A-1
Polym. Chem. 10 (1972) 975–981, doi:10.1002/pol.1972.150100402.
14] L. Fomina, C. León, M. Bizarro, A. Baeza, V. Gómez-Vidales, L.E. Sansores, R. Sal-
cedo, TTF derivative of 2,5-aromatic disubstituted pyrrole, synthesis and elec-
tronic study, J. Mol. Struct. 1108 (2016) 370–377, doi:10.1016/j.molstruc.2015.
[41] J. Roncali, Molecular engineering of the band gap of π-conjugated systems:
facing technological applications, Macromol. Rapid. Commun. 28 (2007) 1761–
12.010.
1775, doi:10.1002/marc.200700345.
15] B. Derkowska-Zielinska, E. Gondek, M. Pokladko-Kowar, A. Kaczmarek-
Kedziera, A. Kysil, G. Lakshminarayana, O. Krupka, Photovoltaic cells with vari-
ous azo dyes as components of the active layer, Solar Energy 203 (2020) 19–24,
doi:10.1016/j.solener.2020.04.022.
[
42] M.M. Wienk, M.G.R. Turbiez, M.P. Struijk, M. Fonrodona, R.A.J. Janssen, Low-
band gap poly(di-2-thienylthienopyrazine):fullerene solar cells, Appl. Phys.
Lett. 88 (2006) 153511, doi:10.1063/1.2195897.
[43] J.I. Pankove, Optical Processes in Semiconductors, Dover Publications Inc., 1976
ISBN 10: 0486602753 ISBN 13: 9780486602752.
16] T. Han, X. Feng, B. Tong, J. Shi, L. Chen, J. Zhi, Y. Dong,
A novel “turn-
on” fluorescent chemosensor for the selective detection of Al3+ based on
[
44] C.P. McArdle, M.C. Jennings, J.J. Vittal, R.J. Puddephatt, Self-assembly of
rings, catenanes, and doubly braided catenane containing gold (I): the
hinge-group effect in diacetylide ligands, Chem. - A Eur. J. 7 (2001) 3572
aggregation-induced emission, Chem. Commun. 48 (2012) 416–418, doi:10.
a
1039/C1CC15681K.
17] T. Han, X. Feng, J. Shi, B. Tong, Y. Dong, J.W.Y. Lam, Y. Dong, B.Z. Tang, DMF-
induced emission of an aryl-substituted pyrrole derivative: a solid thermo-
responsive material to detect temperature in a specific range, J. Mater. Chem.
C. 1 (2013) 7534, doi:10.1039/c3tc31573h.
1
0.1002/1521-3765(20010817)7:16<3572::AID−-CHEM3572>3.0.CO;2-C.
[
45] M.T.W. Hearn, Carbon-13 chemical shifts of some propargyl alcohol derivatives,
Tetrahedron 32 (1976) 115–120, doi:10.1016/0040-4020(76)80030-0.
46] F.-.T. Luo, S.-.L. Ko, L. Liu, H. Chen, Stereoselective synthesis of (Z)-
a-Phenoxymethylene-g-butyrolactone and Its Sulfur Analogues from 2-
Propynyloxy- or 2-Propynylthiobenzene, Heterocycles 53 (2000) 2055–2066,
doi:10.3987/COM-00-8964.
[
18] Kou C.T, Liou T.R., Characterization of metal-oxide-semiconductor field-effect
transistor (MOSFET) for Polypyrrole and Poly (N-Alkylpyrrole)s prepared by
electrochemical synthesis, Synth. Met. 82 (3) (1996) 167–173, doi:10.1016/
S0379-6779(96)03773-3.
[
47] A. Sharifi, M. Mirzaei, M.R. Naimi-Jamal, Copper-catalysed oxidative homo-
coupling of terminal acetylenes on alumina assisted by microwave irradiation,
J. Chem. Res. 2002 (2002) 628–630, doi:10.3184/030823402103171050.
[
19] G.A. Cordell, 2-Halopyrroles. Synthesis and chemistry, J. Org. Chem. 40 (22)
1975) 3161–3169, doi:10.1021/jo00910a001.
(
[
20] H.M. Gilow, D.E. Burton, Bromination and chlorination of pyrrole and some
reactive 1-substituted pyrroles, J. Org. Chem. 46 (11) (1981) 2221–2225, doi:10.
[48] F. Toda, Y. Tokumaru, Oxidative coupling reaction of acetylene compounds in
the Solid State, Chem. Lett. 19 (1990) 987–990, doi:10.1246/cl.1990.987.
1021/jo00324a005.
[
21] M. De Rosa, G. Cabrera Nieto, Effect of halogen on the reaction of 1-
Methylpyrrole with N-Haloimides, Tetrahedron Lett. 29 (20) (1988) 2405–2408,
doi:10.1016/S0040-4039(00)87893-4.
10