Synthesis and properties of alkyl chain substituted naphthalenetetracarboxylic monoanhydride monoimides and unsymmetrically substituted naphthalene derivatives

Article abstract of DOI:10.14233/ajchem.2016.20111

1,4,5,8-Naphthalenedianhydride is converted to N-(2-ethylhexyl)-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (2a) and N-(2-hydroxyethyl)-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (2c) through the potassium salt prepared from

Full text of DOI:10.14233/ajchem.2016.20111

Asian Journal of Chemistry; Vol. 28, No. 12 (2016), 2755-2758
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2016.20111
Synthesis and Properties of Alkyl Chain Substituted Naphthalenetetracarboxylic
Monoanhydride Monoimides and Unsymmetrically Substituted Naphthalene Derivatives
1,*
2
3
BANU KOZ , SERAFETTIN DEMIC and SIDDIK ICLI
1Department of Energy Systems Engineering, Faculty of Engineering, Karamanoglu Mehmetbey University, Karaman, Turkey
2Department of Material Science and Engineering, Faculty of Engineering, Izmir Katip Çelebi University, Izmir, Turkey
3Solar Energy Institute, Ege University, Izmir, Turkey
*Corresponding author: Tel: +90 338 2262000/5051; E-mail: banukoz@kmu.edu.tr
Received: 30 May 2016;
Accepted: 22 July 2016;
Published online: 1 September 2016;
AJC-18075
1,4,5,8-Naphthalenedianhydride is converted to N-(2-ethylhexyl)-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (2a)
and N-(2-hydroxyethyl)-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (2c) through the potassium salt prepared from a
reaction with potassium hydroxide. N-Dodecyl-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (2b) was prepared by the
condensation reaction of 1,4,5,8-naphthalenedianhydride with dodecylamine. Naphthalene-1,4-N-(2-ethylhexyl)-imide-N-ethyl-1H-
benzo[d]imidazol-5-carboxylate and naphthalene-1,4-N-dodecyl-imide-N-ethyl-1H-benzo[d]imidazol-5-carboxylate were prepared by
the condensation reaction of N-alkyl-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide (alkyl = 2-ethylhexyl and dodecyl)
with ethyl 3,4-diaminobenzoate. Molecular structures and electrochemical properties of all naphthalene derivatives were determined.
Their thermal properties were also studied by thermal gravimetric analysis.
Keywords: Condensation reaction, Monopotassium salt, Monoanhydride monoimides.
In this present paper, the synthesis of monoimides and
unsymmetrically naphthalene derivatives having an alkyl chain
are described (Scheme-I). The thermal stabilities and electro-
chemical properties of these derivatives are also reported.
INTRODUCTION
Since the photovoltaics are clean energy sources and
reduces the dependency on fossil fuels, public and private sectors’
interest on this technology are highly appreciated [1,2]. Using
of thin films of organic dyes with conjugated π-electron system
increases in recent years like organic light-emitting diodes
(OLED) and solar cells [3-11]. Due to their high thermal and
chemical stabilities and excellent photoconductive properties,
the organic pigments or dyes are attracted much attention [12-15].
Previously prepared 1,4,5,8-naphthalenedianhydride was
converted to N-(2-ethylhexyl)-1,4,5,8-naphthalenetetracar-
boxylic monoanhydride monoimide (2a) and N-(2-hydroxyethyl)-
1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide
(2c) through the condensation reaction in the presence of pota-
ssium salt (PathA) (Scheme-I) by the application of previously
published procedure [16]. N-dodecyl-1,4,5,8-naphthalene-
tetracarboxylic monoanhydride monoimide (2b) was obtained
by another procedure in which it was the condensation of
1,4,5,8-naphthalenedianhydride with dodecylamine (Path B)
(Scheme-I) [17]. Unsymmetrically naphthalene derivatives
(3a-b) were obtained by the condensation of the N-alkyl-
EXPERIMENTAL
1,4,5,8-Naphthalenedianhydride, 2-ethylhexylamine, 2-
aminoethanol, zinc acetate, quinoline, sodium carbonate,
hydrochloric acid (36-38 %), ortho-phosphoric acid, potassium
hydroxide, acetic acid (glacial), potassium carbonate, sodium
perchlorate, ammonium solution (25%) were obtained Fluka
and Merck and used as supplied. All organic solvents (chloro-
form, ethanol, acetonitrile, dimethyl formamide, dimethyl
sulfoxide) were of spectrophotometric grade.
Synthesis of naphthalene-1,4,5,8-tetracarboxylic acide
monoanhydride monopotassium carboxylate (1) [16]:
1,4,5,8-Naphthalenedianhydride (7.6 mmol), 35 mL ratio of
5 % potassium hydroxide were under stirring heated to 90 °C.
12.5 mL ratio of 10 % ortho-phosphoric acid was then added
dropwise to the reaction mixture.After further stirring at 90 °C,
the precipate was filtered, washed thourougly with water and
dried overnight in vacuum dessicator.
1,4,5,8-naphthalenetetracarboxylic
monoimide (2a-b) with ethyl 3,4-diaminobenzoate.
monoanhydride
Synthesis of N-(2-ethylhexyl)-1,4,5,8-naphthalene-
tetracarboxylic monoanhydride monoimide (2a) [16]: Naphtha-

2756 Koz et al.
Asian J. Chem.
Scheme-I: Synthetic routes of N-alkyl-1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimides (2a-c) and unsymmetrical naphthalene
derivatives (3a-b)
lene-1,4,5,8-tetracarboxylic acide monoanhydride mono-
potassium carboxylate (2.2 mmol), 2-ethylhexylamine (11
mmol) and 40 mL of water was stirred at 0-5 °C for 3 h, heated
at 90 °C for 1 h with stirring and then 12.5 mL ratio of 25 %
aqueous solution of potassium carbonate was added. Reaction
mixture was acidified by the addition of 5 % hydrochloric acid
solution and the resulting precipate was filtered, washed with
water to remove residual amine, dried overnight in vacuum
dessicator. Molecular structure was monitored by means of
at 90 °C for 2 h with stirring and then 12.5 mL ratio of 25 %
aqueous solution of potassium carbonate was added. Reaction
mixture was acidified by the addition of 5 % hydrochloric
acid solution and the resulting precipate was filtered, washed
with water to remove residual amine and finally dried overnight
in vacuum dessicator. Molecular structure was identified by
1
1
means of H NMR, 13C NMR. H NMR spectra (400 MHz,
ppm in DMSO): 8.52 (d, 2H), 8.17 (d, 2H), 4.14 (t, 2H), 3.62
13
(t, 2H), 2.45 (s, OH); C NMR (100 MHz, ppm in DMSO):
1
FT-IR, H NMR, 13C NMR. FT-IR (KBr, νmax, cm-1): 1791,
169.19 (C=O), 163.66 (C=O), 137.48, 130.71, 129.87, 129.30,
126.17, 125.36, 58.44, 42.85.
1763, 1708 (C=O), 1669 (imide), 1080 (C-O); 1H NMR (400
MHz, CDCl3): 8.72 (s, 4H), 4.12 (t, 2H), 1.93 (m, 1H), 1.34
(m, 8H), 0.89 (m, 6H); 13C NMR (100 MHz, CDCl3): 162.80,
159.05, 133.35, 131.47, 129.09, 128.13, 127.11, 123.02, 45.05,
38.16, 30.91, 28.80, 24.25, 23.22, 14.24, 10.78.
Synthesis of ethyl 3,4-diaminobenzoate [18]: Dry H2SO4
(3 mL) treated over dry ethanol (30 mL) until the weight increased
10 % and 3,4-diaminobenzoic acid (1 g) was added into this
acid mixture and the mixture was heated under reflux with
stirring for 20 h [19]. To this mixture deionized water (30 mL)
was added, and then the dark brown solution was neutralized
by Na2CO3. The precipate was filtered, recrystallized from water
and dried under vacuum overnight. Molecular structure was
analyzed by means of FT-IR, 1H NMR, 13C NMR. FT-IR (KBr,
Synthesis of N-dodecyl-1,4,5,8-naphthalenetetra-
carboxylic monoanhydride monoimide (2b) [17]: 1,4,5,8-
Naphthalenedianhydride (7.46 mmol) was dissolved in 20 mL
of dry DMF and heated to reflux under argon. Dodecylamine
(4 mmol) diluted in 10 mL of dry DMF was then added
dropwise to the refluxing solution over the period of 1 h. After
refluxing the whole solution for 8 h, the mixture was added
into cold diethylether. The precipate was filtered, washed with
diethylether, then chloroform and dried overnight in vacuum
dessicator. Molecular structure was characterized by FT-IR,
1H NMR, 13C NMR. FT-IR (KBr, νmax, cm-1): 1789, 1770, 1709
ν
max, cm-1): 1735 (C=O), 1H NMR (400 MHz, ppm in CDCl3):
7.46 (m, 2H), 6.67 (d, 1H), 4.30 (m, 2H), 3.54 (broad s, 4H),
1.35 (t, 3H); 13C NMR (100 MHz, ppm in CDCl3): 167.09
(C=O), 140.53 (C–NH2),133.32 (C–NH2), 123.47, 121.78,
118.59, 115.14, 60.57, 14.62.
Synthesis of naphthalene-1,4-N-(2-ethylhexyl)-imide-
N-ethyl-1H-benzo[d]imidazol-5-carboxylate (3a): N-(2-
Ethylhexyl)-1,4,5,8-naftalenetetracarboxylic monoanhydride
monoimide (0.181 mmol), ethyl 3,4-diaminobenzoate (0.362
mmol), zinc acetate (0.0543 mmol) was dissolved in 25 mL of
quinoline. The temperature was gradually increased to 200 °C.
The mixture was kept at this temperature for 7 h under nitrogen
atmosphere. The warm solution poured slowly into 2 molar
ratio of 30 mL HCl. The precipate was filtered and washed
thoroughly 10 % Na2CO3. Product dried under vacuum over a
night at 100 °C. Molecular structure was characterized by
means of 1H NMR. 1H NMR (400 MHz, ppm in CDCl3): 9.1
1
(C=O), 1659, 1080 (imide). H NMR (400 MHz, ppm in
CDCl3): 8.74 (s, 4H), 4.19 (t, 2H), 1.72 (m, 2H), 1.36 (m,
18H), 0.87 (m, 3H); 13C NMR (100 MHz, ppm in CDCl3):
162.41 (C=O) , 159.04 (C=O) 133.34, 131.41, 128.17, 123.04,
41.44, 32.12, 29.82, 29.78, 29.72, 29.54, 29.50, 28.24, 27.27,
22.88, 14.30.
Synthesis of N-(2-Hydroxyethyl)-1,4,5,8-naphthalene-
tetracarboxylic monoanhydride monoimide (2c) [16]:
Naphthalene-1,4,5,8-tetracarboxylic acid monoanhydride
monopotassium carboxylate (2.2 mmol), 2-aminoethanol (11
mmol) and 40 mL of water was stirred at 0-5 °C for 3 h, heated

Vol. 28, No. 12 (2016)
Synthesis of Alkyl Chain Substituted Naphthalene Derivatives 2757
4.0
3.0
2.0
1.0
0
(s, 1H), 8.9 (m, 1H), 8.8 (m, 1H), 8.5 (s, 1H), 8.5 (d, 1H), 8.2
(d, 1H), 7.9 (d, 1H), 4.5 (m, 2H), 4.1 (m, 2H), 1.9 (m, 1H), 1.4
(m, 9H), 0.9 (m, 6H).
Synthesis of naphthalene-1,4-N-dodecyl-imide-N-
ethyl-1H-benzo[d]imidazol-5-carboxylate (3b): N-Dodecyl-
1,4,5,8-naphthalenetetracarboxylic monoanhydride monoimide
(0.181 mmol), ethyl 3,4-diaminobenzoate (0.362 mmol), zinc
acetate (0.0543 mmol) was dissolved in 25 mL of quinoline.
The temperature was gradually increased to 200 °C. The mixture
was kept at this temperature for 7 h under nitrogen. The warm
solution poured slowly into 2 molar ratio of 30 mL HCl. The
precipate was filtered and washed thoroughly by 10% Na2CO3.
The product was dried under vacuum overnight at 100 °C.
Molecular structure was characterized by means of 1H NMR.
1H NMR (400 MHz, ppm in CDCl3): 8.74 (s, 4H), 4.19 (t,
2H), 1.72 (m, 2H), 1.36 (m, 18H), 0.87 (m, 3H); 13C NMR
(100 MHz, ppm in CDCl3): 162.41 (C=O) , 159.04 (C=O)
133.34, 131.41, 128.17, 123.04, 41.44, 32.12, 29.82, 29.78,
29.72, 29.54, 29.50, 28.24, 27.27, 22.88, 14.30.
Cyclic voltammetry measurements: Cyclic voltammetry
(CV) measurements were carried out in DMSO by using a 3-
electrode cell with a polished 2 mm glassy carbon as the
working electrode, Pt wire as the counter electrode and Ag/
AgCl as the reference electrode; the solution was 10–3 M in
electroactive material and 0.2 M supporting electrolyte, sodium
perchlorate; the instrument was Metrohm 746 VA Trace
Analyser; ferrocene was the internal reference electrode
NaClO4 dissolved in DMSO under nitrogen gas protection at
a scan rate of 100 mV/s at 25 °C.All solutions were purged with
nitrogen for at least 10 min before starting the measurements.
-1.0
-2.0
-3.0
-4.0
-5.0
-6.0
1.0
0.8
0.4
0
-0.4
-0.8
-1.2
-1.6
Potential (V)
Fig. 1. Cyclic voltammogram of naphthalene-1,4-N-(2-ethylhexyl)-imide-
N-ethyl-1H-benzo[d]imidazol-5-carboxylate (3a) (in DMSO,
supporting electrolyte 0.2 M sodium perchlorate, scan rate 100
mV s–1) at 25 °C
1,4-N-(2-ethylhexyl)-imide-N-ethyl-1H-benzo[d]imidazol-5-
carboxylate displays two cathodic peaks (at -0.44 and -0.80
V) and two anodic peaks (at -0.36 V and -0.73 V) and two
reversible steps of reductions (at -0.40 V and -0.77 V) with
respect to Ag/AgCl in DMSO corresponding to the first and
second electron processes . The reduction potential with respect
to ferrocene is -0.87 and -1.24 V and the corresponding LUMO
energy leves is calculated as -3.93 eV. These results are
comparable with those obtained by Uzun et al. [22] for 1,4,5,8-
naphthalenediimide derivatives in chloroform solution and the
reported LUMO value was -3.91 eV.
RESULTS AND DISCUSSION
Thermal stability of synthesized naphthalene derivatives:
Naphthalene diimides have long been known to be thermal
and photostable compounds [23]. Thermal stability of synthe-
sized naphthalene derivatives was determined by means of
thermal gravimetric (TGA) measurements. Their TGA thermo-
grams are shown in Figs. 2 and 3. All TGA curves show multi-
step weight loss. The highest and the lowest decomposition
temperature were shown by 3b and 2c, respectively. The initial
weight loss of 5.5 % (up to 225 °C) for 2c corresponds to the
degradation of hydroxyl group and 72 % (up to 510 °C) for
2b corresponds to the degradation of alkyl group attached
Electrochemistry of synthesized naphthalene derivatives:
Cyclic voltammetry is a valuable tool to study reversible redox
behaviour, electrochemical stability and to get information
about LUMO energy values of the material under investigation.
Measured potentials and the calculated LUMO values are summa-
rized in Table-1. The LUMO energy values were calculated based
on the value of 4.8 eV for ferrocene (Fc) with respect to zero
vacuum level [20,21].All of synthesized naphthalene derivatives
exhibited two cathodic peaks and two anodic peaks in solution.
For example, the cyclic voltammogram (Fig. 1) of naphthalene-
TABLE-1
CYCLIC VOLTAMMETRY DATA AND LUMO ENERGY VALUE OF N-ALKYL-1,4,5,8-NAPHTHALENETETRACARBOXYLIC
MONOANHYDRIDE MONOIMIDE [ALKYL = ETHYLHEXYL (2a), DODECYL (2b), ETHANOL (2c)] AND UNSYMMETRICAL
NAPHTHALENE DERIVATIVES [(3a), (3b)] IN DMSO. [E1/2/(V) vs. Fc = (E1/2/V vs. Ag/AgCl) – (EFc/V vs. Ag/AgCl)]
E1/2 (V) vs.
Ag/AgCl
EFc (V) vs.
Ag/AgCl
Compounds
Epc (V)
Epa (V)
E1/2 (V) vs. Fc
LUMO (eV)
-3.96
-0.40
-0.80
-0.41
-0.79
-0.40
-0.91
-0.44
-0.80
-0.44
-0.78
-0.34
-0.74
-0.34
-0.73
-0.34
-0.70
-0.36
-0.73
-0.34
-0.71
-0.37
-0.77
-0.37
-0.76
-0.37
-0.81
-0.40
-0.77
-0.39
-0.74
0.468
0.468
0.468
0.468
0.476
0.476
0.466
0.466
0.476
0.476
-0.83
-1.23
-0.83
-1.22
-0.84
-1.28
-0.87
-1.24
-0.87
-1.22
2a
2b
2c
3a
3b
-3.45
-3.95
-3.93
-3.93
(Supporting electrolyte, 0.2 M sodium perchlorate, Scan rate 100 mV s–1, [2a] = [2b] = [2c] = [3a] = [3b] = 1 × 10–3 M).

2758 Koz et al.
Asian J. Chem.
100
90
80
70
60
50
40
30
20
10
Synthesized naphthalene derivatives have thermal stability
between 150-310 °C. Therefore, these naphthalene derivatives
can be used in the fabrication of solar cells. The LUMO energy
levels were determined by electrochemical analysis. The pro-
perties of synthesized naphthalene derivatives make them
useful for application in optical and electronic materials.
2c
ACKNOWLEDGEMENTS
2b
2a
The authors thank Ege University Research Fund Office
for financial support.
0
50 100
200
300
400
500
600
700
800
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41 % weight loss (up to 550 °C) for 3b corresponds to the degra-
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Conclusion
A novel unsymmetrical naphthalene derivatives were
synthesized from N-alkyl-1,4,5,8-naphthalene tetracarboxylic
monoanhydride monoimide. Since the naphthalene derivatives
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