Synthesis, Characterization, Electrical Conductivity and Fluorescence Properties of Polyimine Bearing Phenylacetylene Units

Article abstract of DOI:10.1007/s10895-016-1842-z

In this study, a Schiff base was synthesized by the condensation reaction of 4-bromobenzaldehyde and 4-aminophenol. Then, phenylacetylene substituted Schiff base monomer (IPA) was obtained by HBr elimination reaction of IPA with phenylacetylene through So

Full text of DOI:10.1007/s10895-016-1842-z

J Fluoresc
DOI 10.1007/s10895-016-1842-z
ORIGINAL ARTICLE
Synthesis, Characterization, Electrical Conductivity
and Fluorescence Properties of Polyimine Bearing
Phenylacetylene Units
Dilek Şenol1 & Feyza Kolcu1,2 & İsmet Kaya1
Received: 28 December 2015 /Accepted: 30 May 2016
#
Springer Science+Business Media New York 2016
Abstract In this study, a Schiff base was synthesized by the
condensation reaction of 4-bromobenzaldehyde and 4-
aminophenol. Then, phenylacetylene substituted Schiff base
monomer (IPA) was obtained by HBr elimination reaction of
IPA with phenylacetylene through Sonogashira reaction. IPA
was polymerized via chemical oxidative polycondensation re-
action. FT-IR and NMR measurements were used for the
structural analyses of the synthesized substances.
Fluorescence and UV–Vis analyses were carried out for opti-
cal characterization. Electrochemical characteristics, electrical
conductivities and thermal properties were determined using
cyclic voltammetry (CV), four-point probe conductometer,
TG-DTA and DSC methods. The main purpose of the present
study was to investigate the effects of phenylacetylene bearing
units on the properties of conjugated aromatic polyimines.
The spectral analysis signified a green light emission behavior
when irradiated at different wavelengths. Combined with fluo-
rescent behavior and good thermal stability, the electrical con-
ductivity was found to be very crucial for π-conjugated
polymer.
Introduction
Conducting polymers have already been found widespread
use in many, mainly optical and electronic applications such
as batteries, displays, plastic wires, optical signal processing,
information storage, solar energy conversion, etc. Scientific
interest in monosubstituted polyacetylenes, the first synthe-
sized conducting polymers, e.g., poly(ethynylbenzene), as π-
conjugated polymers have been rapidly growing for many
years and recently focused on the many interesting physico-
chemical characteristics and novel properties, in particular on
conductivity [1, 2], ferromagnetism [3], oxygen permeability
[4, 5], humidity sensor [6, 7], nonlinear optical (NLO) mate-
rials [8, 9], electroluminescence (EL) materials [10], and so
on. Taking this into consideration, imine polymers synthe-
sized in the presence of phenyl acetylene group was targeted
to increase the conductivity [11, 12]. Sonogashira reaction is
the commonly used method in producing conjugated materials
with their potential use in photonic devices. Phenylacetylene
oligomers and polymers have semi-conductivity features due
to the presence of intense conjugation. The applications of
these kinds of materials are used for polarizers, nonlinear optic
liquid crystal displays, luminous diodes, thin films, sensors
and explosive detection. In addition, they are used in mainly
aerospace industry, machine production and rocket techniques
because of their resistance to high temperatures. With a view
to investigating potential polymers for the aforementioned
properties of polyacetylene, a macromolecule with a Nobel
Prize, in this study, it is aimed to increase the conductivity in
the presence of phenylacetylene group along the imine poly-
mer chain. In addition, water solubility of the synthesized
polymer makes it possible to be used in medicine, cosmetic,
paint and food industry. Poly(imine)s interact with electron
acceptor gases such as iodine with its electron donor feature
of its group, leading to the formation of polaron structure thus,
.
.
Keywords Imine polymers Synthesis and characterization
.
Thermal Fluorescence properties
* Dilek Şenol
dilek_dilek1734@hotmail.com
* İsmet Kaya
kayaismet@hotmail.com
1
Faculty of Sciences and Arts, Department of Chemistry, Polymer
Synthesis and Analysis Laboratory, Çanakkale Onsekiz Mart
University, 17020 Çanakkale, Turkey
2
Lapseki Vocational School, Department of Chemistry and Chemical
Processing Technologies, Çanakkale Onsekiz Mart University,
Çanakkale, Turkey

J Fluoresc
increasing the conductivity of the polymer. By linking acety-
lene group to the polymer, the conductivity of the polymer is
expected to increase. In addition, electrochemical band gap
and optical band gap are calculated by determining the
HOMO-LUMO values by cyclic voltammetry (CV) and
UV–Vis measurements, respectively.
polymeric product was dried in a vacuum drying-oven at
80 °C for 1 day (Scheme 1). The combinations of the
phenylene (C-C) and oxyphenylene (C-O-C) units formed
polymer are given in Scheme 2.
IPA: 1H-NMR (DMSO-d6): δ ppm, 9.49 (s, 1H, -OH), 8.54
(s, 1H, –CH = N), 7.77 (d, 2H, Ar-Hc), 7.64 (d, 2H, Ar-Hf),
7.56 (d, 2H, Ar-Hg), 7.41–7.37 (t, 3H, Ar- Hı, Ar-Hj), 7.13 (d,
2H, Ar-He), 6.72 (d, 2H, Ar-Hb). IPA: 13C-NMR (DMSO-
d6): δ ppm, 157.05 (C1-H), 156.38 (C5-H), 142.00 (C6-H),
132.92 (C8-H), 132.29 (C12-H), 130.54 (C13,C14-H),
129.44 (C4,C11-H), 124.75(C9-H), 123.15(C7-H), 120.92
(C3-H), 116.23 (C2-H), 90.10 (C10-H).
Experimental
Materials
1
4-bromo benzaldehyde (4BB), 4-aminophenol (4AP), phenyl
acetylene (PA), Pd catalysis, cuprous iodide (CuI),
triethylamine, tetrabutylammoniumhexafluorophosphate
( T B A P F 6 ) , N , N - d i m e t h y l f o r m a m i d e ( D M F ) ,
tetrahydrofurane (THF), dimethylsulfoxide (DMSO), metha-
nol, ethanol, acetonitrile (AN), ethyl acetate, diethyl ether,
KOH, HCl were supplied by Merck Chemical Co.
(Germany) and they were used as received. 30 % aqueous
solution of sodium hypochlorite (NaOCl) was supplied by
Paksoy Chemical Co. (Turkey).
PIPA: H-NMR (DMSO-d6): δ ppm, 9.30 (s, 1H, -OH),
8.33 (s, 1H, –CH = N), 7.74 (d, 2H, Ar-Hc), 7.62–7.61 (d, 4H,
Ar-Hf, Ar-Hg), 7.51–7.50 (d, 3H, Ar- Hı, Ar-Hj), 7.36 (d, 2H,
Ar-He), 6.76 (d, 2H, Ar-Hb). PIPA: 13C-NMR (DMSO-d6): δ
ppm, 159.82 (C1-H), 158.66 (C5-H), 156.00 (C-O-C new
peak), 151.73(C6-H), 139.31 (C9-H), 138.94 (C = C new
peak), 133.65 (C10-H), 131.36 (C12-H)129.28(C2-H),
128.82(C3-H,C13-H,C14-H), 127.32(C4-H, C8-H, C15-H),
124.20 (C11-H), 122.15 (C7-H), 119.96 (C-O-C new peak).
Characterization Techniques
4-((4-(phenylethynyl)benzylidene)amino)phenol
Monomer and its Polymer Synthesis
The solubility tests were done in different solvents by using
1 mg sample and 1 ml solvent at 25 °C. The infrared and
ultraviolet–visible spectra were measured by PerkinElmer
FT-IR Spectrum one and Analytikjena Specord 210 Plus, re-
spectively. The FT-IR spectra were recorded using universal
ATR sampling accessory (4000–550 cm−1). 1H and 13C-NMR
spectra (Bruker AC FT-NMR spectrometer operating at 400
and 100.6 MHz, respectively) were also recorded by using
deuterated DMSO-d6 and D2O as solvent at 25 °C. X-ray
diffractograms were recorded by a PANalytical empyrean
model X-ray diffractometer instrument with CuKα radiation
at a wavelength of 1.54 A0 over a 2θ range from 50 to 900
with the scan speed of 40 min−1. Scanning electron micro-
scope (SEM) analysis of polymer was obtained by a Jeol
JSM-7100 F instrument. The tetramethylsilane was used as
internal standard. Thermal data were obtained by using a
Perkin Elmer Diamond Thermal Analysis system. TG-DTA
measurements were made between 25 and 900 °C (in N2, rate
10 °C min−1). DSC analyses were carried out between 25 and
450 °C (in N2, rate 10 °C min−1) by using Perkin Elmer Pyris
Sapphire DSC.
Schiff base was synthesized by a condensation reaction of
equimols of 4-bromobenzaldehyde and 4-aminophenol solved
in ethanol and placed into a 100 mL one-necked round bottom
flask fitted with a condenser, a thermometer and a magnetic
stirrer. The main reaction was maintained for 5 h under reflux
at room temperature. The substance was crystallized in aceto-
nitrile and its solvent was evaporated. Coupling was per-
formed by using THF as the solvent, piperidine as a strong
base, CuI as a co-catalyzer and Pd(PPh)3)4 as a catalyzer ac-
cording to Sonogashira reaction in which phenyl acetylene
compound was attached to the synthesized Schiff base.
Obtained imine-phenylacetylene was put into a 250 mL
three-necked round bottom flask and 30 mL distilled water
was added. The reaction flask was placed onto the magnetic
stirrer with condenser and thermometer. Schiff base was
solved by adding KOH (0.1 mol) in the reaction medium.
The reaction temperature was increased to 80 °C and 1 mL
of 30 % NaOCl solution was added to the environment as the
oxidizing agent at regular intervals within 20 min. Reaction
mixture became dark brown after adding oxidizing agent. The
reaction was maintained for 6 h by stirring with magnetic
stirrer. After the reaction, a piece of dark brown solution was
transferred into 100 mL beaker and equimolar of 0.1 M HCl
solution to KOH used was added to neutralize but, no precip-
itation was observed. Since there was no precipitated polymer
after neutralization, the solvent was just vaporized to get the
polymeric product as the potassium salt. Dark colored
Optical and Electrochemical Properties
Ultraviolet–visible (UV–Vis) spectra were measured by
Perkin Elmer Lambda 25. The absorption spectra were record-
ed by using DMSO at 25 °C. The optical band gaps (Eg) were
calculated from their absorption edges.

J Fluoresc
Scheme 1 Synthesis procedures
of IPA and PIPA
Cyclic voltammetry (CV) measurements were carried out
with a CHI 660 C Electrochemical Analyzer (CH Instruments,
Texas, USA) at a potential scan rate of 20 mV/s. All the ex-
periments were performed in a dry box filled with argon at
room temperature. The electrochemical potential of Ag was
calibrated with respect to the ferrocene/ferrocenium (Fc/Fc+)
couple. The half-wave potential (E1/2) of (Fc/Fc+) was mea-
sured in acetonitrile solution of 0.1 M tetrabutylammonium
Scheme 2 The combinations of
the phenylene (C-C) and
oxyphenylene (C-O-C) units

J Fluoresc
hexafluorophosphate (TBAPF6) and was 0.39 V with respect
to Ag wire. The voltammetric measurements were carried out
in acetonitrile for the Schiff bases and acetonitrile/DMSO
mixture (v/sv:5/1) for the polymers.
formation of imine (-HC = N) was proved by the appearance
of a peak at 1619 cm−1 as a result of a condensation reaction
between aldehyde and amine in the spectrum of Schiff base
monomer due to the loss of characteristic peaks of aldehyde
and amine (Fig. 1c). Then, the -CH peak for acetylene group at
3290 cm−1 was not observed in Fig. 1e when phenyl acetylene
was added to the synthesized Schiff base (Fig. 1d). The ab-
sorption bands for imine (C = N) at 1619 cm−1 and acetylene
(C ≡ C) at 2260 cm−1 were observed due to the Schiff base
monomer structure containing acetylene group (IPA). As seen
in Fig. 1f, broadening in the peaks and observation of the
absorption bands for the imine and acetylene groups were
the indications of a polymer (PIPA) formation.
Electrical Properties
Conductivities of the synthesized materials were measured on
a Keithley 2400 Electrometer. The pellets were pressed on a
hydraulic press developing up to 1687.2 kg/cm2. Iodine dop-
ing was carried out by exposing the pellets to iodine vapour at
atmospheric pressure and room temperature in a desiccator.
The measurements were carried out per 24 h [11, 12].
1H-NMR and 13C-NMR spectrum of the monomer and the
polymer were taken at DMSO-d6, D2O, respectively. The
structures and the chemical shifts of 1H-NMR and 13C-NMR
for the monomer (IPA) and its polymer (PIPA) are given in
Figs. 2 and 3. 1H-NMR spectrum of IPA monomer gave sharp
proton signals as expected. The hydroxyl, azomethine and
aromatic proton signals were observed in 9.49, 8.54 and
Fluorescence Measurements
A Shimadzu RF-5301PC spectrofluorophotometer was used
in fluorescence measurements. Emission and excitation spec-
tra of the synthesized Schiff base and its polymer were obtain-
ed in DMF. Measurements were made in a wide concentration
range between 3.125 and 100 mg/L to determine the optimal
fluorescence concentrations. Slit width in all measurements
was 5 nm.
1
7.77–6.71 ppm, respectively [13]. In H-NMR spectrum of
polymer, an increase in the number of the peaks and an en-
largement of the peaks were observed. This enlargement was
due to the presence of the repeated monomer units with dif-
ferent chemical environments. The observation of a decrease
in the intensity and broad peak of hydroxyl group for the
polymer indicated that polymerization went through C-O-C
coupling. According to the 13C-NMR spectrum of the mono-
mer and polymer, it was observed that the hydroxyl (C-OH)
and acetylene (C ≡ C) peaks at 157.05 and 90.02 ppm shifted
to 159.82 and 89.00 ppm, respectively. The oxyphenylene (C-
O-C) carbon and phenylene (C-C) carbon signals formed due
to the imine-acetylene formation were observed at 119.96 and
138.94 ppm, respectively [14]. Since the oxygen atom of hy-
droxyl group and C2 atom at ortho positon possessed the
highest propensity in the HOMO level as seen in Fig. 4, the
polymer formation was expected via C-O-C and C-C cou-
plings, respectively.
Computational Method
The electron distribution along the polymer chain for the
HOMO-LUMO levels were calculated by using PM3 semi
empirical method implemented in Chem Office 2004 version.
Results and Discussion
Solubility of the Compounds
Schiff base polymer containing phenyl acetylene unit was
completely soluble in water while it was partially soluble in
polar solvents like DMSO and DMF. It was observed that
Schiff base was dissolved in all polar solvents.
Optical and Electrochemical Properties
Spectral Analyses of the Synthesized Compounds
According to the UV–Vis spectra of monomer and polymer as
seen in Fig. 5, three sharp and one shoulder bands were
displayed with λmax values of 290, 308, 330 and 352 nm,
respectively. Peak sharpness observed in monomer became
broader as a result of the polymer formation, and the forma-
tion of a new peak observed at 464 nm for the n → π* transi-
tion in polymer indicated the increase in conjugation along the
polymer chain. λonset values of the monomer and the polymer
were found to be 405 and 450 nm, respectively. Eg values
were given in Table 1 as a result of the calculations using
the formula of 1242/ λonset. [15]. Eg value of polymer was
found to be lower than that of the monomer which was an
Structures of the synthesized monomer and polymer were ex-
plained by FT-IR, UV–Vis, 1HNMR and 13CNMR analyses.
Spectra were taken by using Fourier Transform Infrared (FT-
IR) Spectrometer (Perkin Elmer FT-IR Spectrum one, with
ATR sampling accessory). Characteristic carbonyl peak at
1687 cm−1 for 4-bromobenzaldehyde in Fig. 1a, and hydroxyl
(-OH) peak at 3341–3282 cm−1 and double branch peaks at-
tributed to amine group at 3310 cm−1 for 4-aminophenol in
Fig. 1b were observed. As a result of Schiff base formation,
the loss of amine and hydroxyl protons could be observed as a
result of the formation of a broad peak in that area. The

J Fluoresc
Fig. 1 FT-IR spectra of 4-
bromobenzaldehyde (a) 4-
aminophenol (b), Schiff base (c),
phenyl acetylene (d), Schiff base
containing acetylene group (e),
imine polymer containing acety-
lene group (f)
Fig. 2 1H-NMR (a) and 13C-
NMR (b) spectra of IPA

J Fluoresc
Fig. 3 1H-NMR (a) and 13C-
NMR (b) spectra of PIPA
indication of increasing conjugation along the polymer chain
[16].
positive region for both monomer and polymer in the spec-
trum, the peaks regarding to the reduction of imine (-HC = N)
nitrogen by being protonated were observed in negative re-
gion. CVs of the synthesized compounds were taken by using
glassy carbon electrode (GCE). The voltammetric measure-
ments were carried out in acetonitrile solution of 0.1 M
Electrochemical properties of the synthesized Schiff base
monomer and its polymer were examined by using cyclic
voltammetry (CV) technique and the oxidation-reduction
peak potentials of potential-current voltammograms for the
monomer and its polymer are given in Fig. 6a. While oxida-
tion peak was observed for the hydroxyl group (OH) in
Fig. 4 Graphical representation of the HOMO and LUMO orbitals,
together with the optimized molecular structure of PIPA
Fig. 5 Absorption spectra of the IPA (a) and PIPA (b)

J Fluoresc
Table 1 Electronic structure
parameters of the synthesized
compounds
Compounds
Eox (V)
ERed (V)
aHOMO (eV)
bLUMO (eV)
cE’g (eV)
dEg (eV)
IPA
1.61
1.32
−1.52
−1.22
−6.00
−5.71
−2.87
−3.17
3.13
2.54
3.06
2.26
PIPA
a Highest occupied molecular orbital
b Lowest unoccupied molecular orbital
c Electrochemical band gap
d Optical band gap
tetrabutylammonium hexafluorophosphate (TBAPF6) and
water/TBAPF6 mixture (v/v:1/3) for the monomer and poly-
mer, respectively. Electrochemical data of the monomer and
its polymer are given in Table 1. The HOMO-LUMO energy
levels and electrochemical band gaps (E'g) were figured out
from the oxidation and reduction peak potentials [17]. The
calculations were made by using the following equations
[18, 19]:
E’g ¼ ELUMO−EHOMO
ð3Þ
To determine the oxidation and reduction potentials in volt-
ammograms of the monomer and the polymer, the first deriv-
ative of voltammograms were plotted as a function of the
potential. Examination of the first derivative of the CV for
the compounds proved that one oxidation peak at 1.61 V and
one reduction peak at −1.52 V for the monomer, and one
oxidation peak at 1.32 V and one reduction peak at −1.22 V
for the polymer were reached (Fig. 6b). Additionally, the cal-
culated electrochemical band gaps agreed with the optical
band gap values; as a result of the polyconjugated structure,
the polymer had lower band gap than that of the Schiff base.
EHOMO ¼ −ð4:39 þ EoxÞ
ð1Þ
ð2Þ
ELUMO ¼ −ð4:39 þ Ered
Þ
Fluorescence Characteristics
Fluorescence spectrum of Schiff base-phenyl acetylene and its
corresponding polymer are given in Figs. 7 and 8. Slit with
was set to be 5 nm in all fluorescence measurements. As seen
in Fig. 7, the polymer turned into green while the color of its
monomer was unchanged when looked under UV lamp with a
wavelength at 366 nm by dissolving both monomer and poly-
mer in aqueous solution of KOH. When polymer were excited
with a light of 366 nm the maximum emission wavelength
Fig. 7 Emission spectra of daylight of IPA (a) and PIPA (b) A] under UV
lamp of IPA (a) and PIPA (b) B] Slit width: λEx 5 nm, λEm 5 nm;
concentration of the compounds: 0.01 mg/ mL
Fig. 6 Cyclic voltammograms of the IPA (a) and PIPA (b)

J Fluoresc
Table 2 Fluorescence spectral data of the synthesized compounds with
optimum concentrations in THF solvent
Compounds
λEx
410
430
450
IPA
Imax(Em)
λmax(Em)
Imax(Em)
λmax(Em)
260
468
374
500
213
491
203
502
119
497
52
PIPA
507
λEx Excitation wavelength for emission, λmax(Em) Maximum emission
wavelength, Imax(Em) Maximum emission intensity
14 % in the UV (366 nm) and visible area (410 nm),
respectively [20, 21].
Electrical Conductivities
The current–voltage plotted regarding to the solid state con-
ductivity values measured for the synthesized polymer at ni-
trogen atmosphere and the results are given in Fig. 9. The
measurements for the polymer were carried out in pure form
Fig. 8 Emission spectra of IPA (a) and PIPA (b) at different wavelengths,
Slit width: λEx 5 nm, λEm 5 nm; concentration of the compounds:
0.01 mg/ mL
was found to be 500 nm with an intensity of 197, and that
fluorescence intensity was observed to be zero for the mono-
mer. Stoke shift and FWHM values of the polymer were found
to be 134 and 78 nm, respectively. As seen in Fig. 8, when
both monomer and polymer were stimulated with a visible
wavelength, both of them had fluorescence intensity, but poly-
mer (Fig. 8b) had a higher level than that of the monomer
(Fig. 8a). As seen in Fig. 8, fluorescence intensities of both
monomer and polymer decreased as the wavelength increased.
The wavelength and the intensity related to the maximum
emissions are given in Table 2. When excited at 410
and 430 nm, the monomer emitted blue and green fluo-
rescence light with an emission intensity of 260 and
213, respectively. The polymer emitted green light at
500 and 502 nm with an emission intensity of 374
and 203 when excited with 410 and 450 nm. The poly-
mer emitted green light when excited with an excitation
wavelength of 366 nm under UV light. The fluorescence
quantum yields of polymer were calculated to be 9 and
Fig. 9 Current–voltage graph before doped (a) after 24 h doped (b) of
PIPA

J Fluoresc
Table 3 Thermal degradation values of the synthesized compounds
then, the polymer were exposed to iodine vapor in a desicca-
tor, and the change in their conductivities versus time was
measured at specific time intervals (2 h, 5 h, 10 h, 24 h, vs.)
by doping. There was no observable change in current values
by changing the applied voltage before and after PIPA was
doped, resulting in having a direct proportion between voltage
and current as an evidence of ohmic resistance. Consequently,
conductivity values were calculated to be 5.26 × 10−6 and
5.27 × 10−6 S cm−1 before and after iodine doping, respectively
[22, 23].
Compounds
aTon
IPA
PIPA
185
190
bWmax.
T
249, 339
234
179, 216
753
20 % weight Loss
50 % weight Loss
% char at 1000 °C
DTA (exo/endo)
480
869
34
52
–/–
–/–
DSC [cTg (°C) / dΔCp (J/g)]
–/–
174/0.638
In doping process, electron donor amine nitrogen and
electron acceptor iodine were coordinated and the for-
mation of radical cation (polaron) structure in polymer
chain (on amine nitrogen) was enabled. Electron vacan-
cy formed due to the polaron formation facilitated elec-
tron flow resulting in an increase in electrical conduc-
tivity. High electron intensity allowed the polymer to
coordinate with iodine and consequently, electron flow
increased at a higher level was obtained. Delocalization
of π–conjugation was achieved through a combination
of imine and acetylene functional groups in the polymer
structure.
a The onset temperature
b Maximum weight temperature
c Glass Transition Temperature
d Change of specific heat during glass transition
were obtained to be 185 and 190 °C, respectively. IPA
and PIPA lost 20 % of their initial weights at 234 and
753 °C; and the temperatures corresponding to 50 %
weight losses were observed at 480 and 869 °C for
IPA and PIPA, respectively. Additionally, the char %
amounts at 1000 °C listed in Table 3, indicating that
the maximum value of 52 % was obtained for PIPA
which was highly thermostable. TG results revealed that
Thermal Analysis
Thermal decomposition steps of IPA and PIPA are given
in Fig. 10. Thermal analysis curves to determine T20,
T50, Ton temperatures and the number of decomposition
steps, the exothermic and endothermic peaks for the
monomer and polymer as well as the glass transition
temperature (Tg) of polymer are given in Table 3.
According to Table 3, initial decomposition temperature
of the monomer was found to be higher than that of the
polymer due to the formation of C-O etheric bond dur-
ing the OP reaction (C-O-C coupling). Initial degrada-
tion temperatures (Ton) of the monomer and its polymer
Fig. 10 TG curves of IPA (a) and PIPA (b)
Fig. 11 XRD patterns of IPA (a) and PIPA (b)

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Table 4 X-RD parameters of
monomer and polymer
Compounds
Peak pos. [°2Th]
β (B obs. [°2Th])
Cos θ
Crystallite size [nm]
Five major peaks of
the monomers
18.016
19.342
22.802
25.313
26.691
28.705
32.134
40.881
50.545
0.128
0.128
0.154
0.179
0.154
0.128
0.128
0.154
0.154
0.95
0.94
0.92
0.90
0.89
0.87
0.85
0.76
0.64
11.43
11.55
9.81
8.62
10.14
12.48
12.77
11.87
14.10
Five major peaks of
the polymer
the polymer with a long conjugated π–band increased
the delocalization of π electrons, leading to a higher
resistance against temperature. Glass transition
temperature (Tg) of the synthesized polymer was found
to be lower than glass initial decomposition temperature
(Ton) as expected.
Fig. 12 SEM photographs 10 μm and 1 μm of IPA (a–b) 10 μm and 1 μm of PIPA (c–d)

J Fluoresc
X-Ray Diffraction (X-RD)
References
Figure 11 shows the X-RD patterns of imine-phenyl
acetylene and its polymer. A decrease in the crystallinity
rate was observed from 33 to 19 % for the Schiff base
monomer and the polymer, respectively. The reason
could be attributed to the loss of peaks between 2θ
values of 10 and 30, when Fig. 11 was analyzed.
Using the diffraction data, the mean crystallite sizes of
the monomer and the polymer, D, were determined ac-
cording to the Scherer equation D = (0.9λ) / (β.cosθ),
where λ was X-ray wavelength (1.5406 Å), θ was
Bragg diffraction angle, and β was the full width at half
maximum of the diffraction peak) [24, 25]. The average
crystallite sizes of the monomer and the polymer are
given in Table 4. The calculated D values gave infor-
mation about the types of crystal structure and the in-
terlayer distance.
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Morphological Characterization
Surface morphological analyses for imine-phenylacetylene
(IPA) and its polymer (PIPA) are given in Fig. 12. For
IPA, nonhomogeneous flat structured particles were ob-
served as it got closer to the surface. For PIPA, the parti-
cles were seen to be more corrugated and interlocked ho-
mogeneous structures.
Conclusion
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acetylenic and imine functional groups in the structure.
The monomer and polymer were spectroscopically char-
acterized. The synthesized imine-phenyl acetylene poly-
mer was found to be fluorescent due to the imine por-
tion of the molecule dominating the electronic transi-
tions and some contribution from the aryl acetylene
moiety. Low level electronic structure calculations on
models of these compounds also showed that the π-
electrons in the combined imine/acetylene systems were
delocalized over both functional groups. Consequently,
the increase in the conductivity of the substance gave a
possible usage as the semi-conductive polymer in elec-
tronic, opto-electronic and photovoltaic applications. TG
results revealed that the polymer with a heat resistant
property was successfully synthesized.
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Acknowledgments The authors thank Çanakkale Onsekiz Mart
University scientific research project commission for support with the
project number (Project Nu.: FBA-2015-490).

J Fluoresc
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