Novel triphenylamine appended 1,3-alternate-calix[4]arenes: Synthesis and characterization

Article abstract of DOI:10.1080/00397911.2012.659830

In the present study, two novel calix[4]arene receptors containing triphenylamine units in 1,3-alternate conformation have been synthesized and characterized in detail. First, the 25,27-dipropoxy-26,28-bis[(3-aminopropyl) oxy]-calix[4]arene 4 and 25,26,27

Full text of DOI:10.1080/00397911.2012.659830

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Novel Triphenylamine Appended 1,3-
Alternate-Calix[4]arenes: Synthesis and
Characterization
Serkan Erdemir a & Mustafa Yilmaz a
a Department of Chemistry, Selcuk University, Konya, Turkey
Accepted author version posted online: 10 Aug 2012.Version of
record first published: 06 Mar 2013.
To cite this article: Serkan Erdemir & Mustafa Yilmaz (2013): Novel Triphenylamine Appended 1,3-
Alternate-Calix[4]arenes: Synthesis and Characterization, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 43:12, 1668-1675
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Synthetic Communications1, 43: 1668–1675, 2013
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2012.659830
NOVEL TRIPHENYLAMINE APPENDED 1,3-
ALTERNATE-CALIX[4]ARENES: SYNTHESIS
AND CHARACTERIZATION
Serkan Erdemir and Mustafa Yilmaz
Department of Chemistry, Selcuk University, Konya, Turkey
GRAPHICAL ABSTRACT
Abstract In the present study, two novel calix[4]arene receptors containing triphenylamine
units in 1,3-alternate conformation have been synthesized and characterized in detail. First,
the 25,27-dipropoxy-26,28-bis[(3-aminopropyl)oxy]-calix[4]arene 4 and 25,26,27,28-
tetra[(3-aminopropyl)oxy]-calix[4]arene 7 were prepared by using convenient reagents.
Then, these amino derivatives of calix[4]arene were converted to Schiff base derivatives
appended to triphenylamine of calix[4]arene (5 and 8) using 4-formyltriphenylamine via
condensation. The 1,3-alternate conformation of the synthesized calix[4]arenes was deter-
mined by 1H and 13C NMR analyses. Also, their structures have been characterized by
using 1H and 13C NMR, infrared, and elemental analyses.
Supplemental materials are available for this article. Go to the publisher’s online edition
of Synthetic Communications1 to view the free supplemental file.
Keywords Calix[4]arene; characterization; Schiff base; synthesis; triphenylamine
INTRODUCTION
Calixarenes (Fig. 1) is one of the most important macrocyclic host molecules in
supramolecular chemistry,[1,2] together with crown ethers[3] and cyclodextrins.[4]
Received January 4, 2012.
Address correspondence to Serkan Erdemir, Selcuk University, Department of Chemistry, Konya
42031, Turkey. E-mail: serdemir82@gmail.com
1668

TRIPHENYLAMINE-APPENDED CALIX[4]ARENES
1669
Figure 1. The general molecular structures of calix[n]arenes. (Figure is provided in color online.)
They are prepared by the base-catalyzed reaction of formaldehyde with phenol
derivatives. Calixarenes have generated considerable interest as useful building
blocks for the synthesis of hosts for cations, anions, and neutral molecules. During
the past two decades, they have attracted much attention as receptors in supramol-
ecular chemistry. The increasing interest in these compounds is stimulated by the
simple large-scale synthesis of calixarenes, and the different ways in which they
can be selectively functionalized at the narrow (phenolic groups) or at the wide
rim (aromatic nuclei). One of the most important features of these compounds is
their diversity. Calixarenes find applications as selective binders and carriers, as ana-
lytical sensors, as catalysts, and as model structures for biomimetic studies.[5–8]
Considerable studies have been made on organic light-emitting diodes (OLEDs)
for potential applications in next-generation full-color displays as a promising alterna-
tive to the conventional liquid-crystal displays.[9–12] Among the various kinds of
OLED materials, triarylamine derivatives have been widely investigated for almost
two decades because these compounds have showed excellent thermal and electro-
chemical stability, electron-donating ability, and optoelectronic properties,[13–17] and
they are standard hole-transport materials.[18–22] Considerable effort in synthetic
chemistry, in particular by Shirota and coworkers, has led to the development of many
classes of triphenylamine-based compounds as hole-transporting or electrolumines-
cent materials.[23,24] To our knowledge, most triphenylamine derivatives are con-
nected by the N–C single bond and obtained either through palladium-catalyzed
cross-coupling reactions requiring expensive and extremely air-sensitive palladium
catalysts or through copper-catalyzed Ullmann condensations usually involving
high temperatures and prolonged reaction times.[25–28] Few papers about tripheny-
lamine derivatives connected by the C–C double bond have been published.[29,30]
Recently, the synthesis of different compounds containing triphenylamine and their
luminescent characteristics have been reported, whereas the calixarene derivatives
bearing triphenylamine have not been synthesized until now. We think that they
could be interesting as organic light-emitting diodes (OLEDs). Therefore we report
the synthesis and characterization of the new triphenylamine-bearing calix[4]arene
derivatives in the present study.

1670
S. ERDEMIR AND M. YILMAZ
Scheme 1. Synthesis of 4-formyltriphenylamine.
RESULTS AND DISCUSSION
The main focuses of this work are the synthesis and characterization of new 1,3-
alternate-calix[4]arene receptors bearing triphenylamine. To achieve the desired goal,
first we have synthesized 4-formyltriphenylamine using phosphorus oxychloride and
dimethylformamide (DMF) according to the literature procedure[31] (Scheme 1). Two
novel calix[4]arene Schiff base derivatives containing triphenylamine groups were
synthesized by using 25,27-dipropoxy-26,28-bis[(3-aminopropyl)oxy]calix[4]arene 4
or 25,26,27,28-tetra[(3-aminopropyl)oxy]-calix[4]arene 7 and 4-formyltriphenylamine
as the precursor. The synthetic routes for these Schiff bases are shown in Scheme 2
and 3. Calix[4]arene 1, 25,27-bis[(3-phthalimidopropyl)oxy]-calix[4]arene 2, 25,27-
Scheme 2. Schematic representation of synthesis of 1,3-alternate-25,27-Bis[(3-iminotriphenylaminepropy-
l)oxy]-26,28-dipropoxy calix[4]arene 5.

TRIPHENYLAMINE-APPENDED CALIX[4]ARENES
1671
Scheme 3. Schematic representation of the synthesis of 1,3-alternate-25,26,27,28-tetra[(3-iminotriphenyla-
minepropyl)oxy]-calix[4]arene 8.
dipropoxy-26,28-bis[(3-phthalimidopropyl)oxy]-calix[4]arene 3, and 25,27-dipropoxy-
26,28-bis[(3-aminopropyl)oxy]-calix[4]arene 4 were synthesized according to the
reported literature procedures.[6,32] Compound 4 was refluxed with 4-formyltripheny-
lamine and a catalytic amount of triethylamine in CHCl3–methanol to give the corre-
sponding Schiff base derivative of calix[4]arene 5 in 80% yield. Scheme 3 shows the
pathway for the synthesis of 1,3-alternate-25,26,27,28-tetra[(3-iminotriphenylamine-
propyl)oxy]-calix[4]arene 8. To obtain 25,26,27,28-tetra[(3-phthalimidopropyl)oxy]-
calix[4]arene 6 in a 65% yield, 25,27-bis[(3-phthalimidopropyl)oxy]-calix[4]arene 2
was reacted with N-(3-bromopropyl)phthalimide in the presence of Cs2CO3. Subse-
quently, the phthalimido groups in compound 6 were removed with hydrazine hydrate
in ethanol to give 25,26,27,28-tetra[(3-aminopropyl)oxy]-calix[4]arene 7 in a 90%
yield. Then, 25,26,27,28-tetra[(3-iminotriphenylaminepropyl)oxy]-calix[4]arene 8 was
obtained by reacting compound 7 with 4-formyltriphenylamine and a catalytic
amount of triethylamine in CHCl3–methanol.
The structures of the synthesized compounds were characterized by a combination
1
of Fourier-transform infrared (FTIR), H NMR, 13C NMR, and elemental analyses.
=
The formation of 5 and 8 was confirmed by the appearance of imine protons (CH N)
at 8.18 and 8.13 ppm in 1H NMR spectra, respectively (see the Supporting Information,
available online). The synthesis of Schiff base derivatives of calix[4]arene (5 and 8) was
=
also confirmed by the appearance of the characteristic HC N bands at about 1641 and

1672
S. ERDEMIR AND M. YILMAZ
1640 cmꢀ1 and by the disappearance of the NH2 band at 3368 and 3369 cmꢀ1 in their
FTIR spectra, respectively. The 13C NMR spectra of compound 5 and 8 show the
=
appearance of carbon signals at 160.26 and 160.44 ppm belonging to C N groups of
Schiff base, respectively (see the Supporting Information, available online).
The conformational characteristics of the synthesized calix[4]arenes were
conveniently estimated by the splitting pattern of the ArCH2Ar methylene protons
in the 1H and 13C NMR spectra. 1H and 13C NMR spectra showed that 5 and 8 have
a 1,3-alternate conformation. The 1,3-alternate conformation of 5 and 8 was confirmed
by the carbon absorption of the bridging methylene groups (ArCH2Ar) of the calix[4]-
arene present at 36.68 and 37.31 ppm in the 13C NMR and the singlet around 3.66 and
3.71 ppm in the 1H NMR for the corresponding methylene hydrogens,[33] respectively.
To summarize, we have designed and synthesized two novel calix[4]arene
receptors, 5 and 8, which have two and four triphenylamine units at a narrow rim
of the calix[4]arene moiety. The availability as OLED material of the prepared
new receptors will be investigated soon.
EXPERIMENTAL
Melting points were determined on an Electrothermal 9100 apparatus in
1
a sealed capillary and are uncorrected. H and 13C NMR spectra were recorded at
room temperature on a Varian 400-MHz spectrometer in CDCl3. FTIR spectra were
obtained on a Perkin-Elmer Spectrum 100 FTIR spectrometer. Elemental analyses
were performed using a Leco CHNS-932 analyzer. Analytical thin-layer chromato-
graphy (TLC) was performed using Merck prepared plates (silica gel 60 F254 on
aluminum). All reactions, unless otherwise noted, were conducted under a nitrogen
atmosphere. All starting materials and reagents used were of standard analytical
grade from Fluka, Merck, and Aldrich and used without further purification.
1,3-Alternate-25,27-bis[(3-iminotriphenylaminepropyl)oxy]-26,28-
dipropoxy-calix[4]arene 5
1,3-Alternate-25,27-Bis[(3-aminopropyl)oxy]-26,28-dipropoxy-calix[4]arene
4
(1.0 g, 1.61 mmol) in CHCl3 (30 mL) was added to a stirred solution of 4-formyltri-
phenylamine (0.92 g, 3.38 mmol) and triethylamine (1 mL, excess) in methanol
(20 mL), and the mixture was stirred for 24 h under nitrogen. After evaporation of
the solvent, the solid residue was washed with cool methanol twice to remove
unreacted 4-formyltripꢀh1enylamine and dried in vacuum. Yield 80%; mp 209–
1
213 ꢁC; FTIR; 1641 cm (HC N); H NMR (400 MHz, CDCl3): d (ppm) 0.88 (t,
=
6H, J ¼ 7.4 Hz, CH2CH3), 1.57 (h, 4H, J ¼ 7.4 Hz, OCH2CH2CH3), 1.95 (p, 4H,
J ¼ 7.0 Hz, OCH2CH2CH2N), 3.49 (t, 4H, J ¼ 7.2 Hz, CH2CH2N), 3.59 (2 ꢂ t, 8H,
J ¼ 6.8 Hz and J ¼ 7.0 Hz, OCH2CH2CH2N and OCH2CH2CH3), 3.66 (s, 8H,
ArCH2Ar), 6.68–6.72 (m, 4H, ArH), 7.01 (d, 4H, J ¼ 7.4 Hz, ArH), 7.04–7.07 (m,
12H, ArH), 7.10–7.13 (m, 8H, ArH), 7.59 (d, 4H, J ¼ 8.0 Hz), 8.18 (s, 2H, CHN).
13C NMR (100 MHz, CDCl3): d (ppm) 160.26, 156.52, 149.95, 147.20, 133.72,
129.93, 129.77, 129.72, 129.36, 129.00, 125.08, 123.58, 122.16, 121.66, 121.61, 73.31,
69.79, 58.38, 36.68, 31.74, 23.36, 10.40. Calculated for C78H76N4O4: C, 82.65%; H,
6.76%; N, 4.94%. Found: C, 82.72%; H, 6.81%; N, 5.01%.

TRIPHENYLAMINE-APPENDED CALIX[4]ARENES
1673
1,3-Alternate-25,26,27,28-tetra[(3-phthalimidopropyl)oxy]-
calix[4]arene 6
A
solution of 25,27-bis[(3-phthalimidopropyl)oxy]calix[4]arene
2
(1.0 g,
1.25 mmol), Cs2CO3 (1.6 g, 4.9 mmol), and N-(3-bromopropyl)phthalimide (2.0 g,
7.5 mmol) in dry MeCN (100 mL) was refluxed for 3 days. Then, the solvent was
removed under reduced pressure. Subsequently, the residue was dissolved in CH2Cl2
(70 mL) and washed with 1 N NH4Cl (3 ꢂ 50 mL) and water (2 ꢂ 50 mL). The organic
phase was separated, dried with MgSO4, and evaporated to afford a solid, which was
crystallized from MeOH to give 6 as a pure white powder. Yield 65%; mp 255–257 ꢁC;
1
FTIR; 1694 cmꢀ1 (C O); H NMR (400 MHz, CDCl3): d (ppm) 7.79–7.65 (m, 16H,
=
PhH), 6.98 (d, 8H, J ¼ 7.4 Hz, ArH), 6.82 (t, 4H, J ¼ 7.4 Hz, ArH), 3.72 (s, 8H,
ArCH2Ar), 3.52 (t, 8H, J ¼ 7.2 Hz, NCH2), 3.45 (t, 8H, J ¼ 7.4 Hz, OCH2), 1.59 (p,
8H, J ¼ 7.2 Hz, OCH2CH2CH2N); 13C NMR (100 MHz, CDCl3): d (ppm) 168.3,
156.6, 134.0, 133.9, 132.4, 129.6, 123.2, 122.9, 68.4, 38.0, 35.4, 29.0. Calculated for
C72H60N4O12: C, 73.71%; H, 5.15%; N, 4.78%. Found: C, 73.76%; H, 5.21%; N, 4.83%.
1,3-Alternate-25,26,27,28-tetra[(3-aminopropyl)oxy]-calix[4]arene 7
25,26,27,28-Tetra[(3-phthalimidopropyl)oxy]-calix[4]arene 6 (1.0 g, 0.85 mmol)
and NH2NH2 ꢃ H2O (0.83 g, 17 mmol) were solved in ethanol (50 mL), and this
mixture was refluxed at 110–120 ꢁC for 16 h. Then, the solvent was removed under
reduced pressure. The residue was dissolved in CH2Cl2 (30 mL) and washed with a
solution of NH4OH (pH 9) (3 ꢂ 15 mL). The organic phase was separated, dried with
MgSO4, and evaporated to afford 7 as a pure solid. Yield 90%; mp 179–181 ꢁC;
FTIR: 3369 cmꢀ1 (NH2); 1H NMR (400 MHz, CDCl3): d (ppm) 7.05 (d, 8H,
J ¼ 7.8 Hz, ArH), 6.80 (t, 4H, J ¼ 7.4 Hz, ArH), 3.74 (s, 8H, ArCH2Ar), 3.62 (t,
8H, J ¼ 6.8 Hz, NCH2), 2.64 (t, 8H, J ¼ 6.8 Hz, OCH2), 1.61 (p, 8H, J ¼ 6.8 Hz,
OCH2CH2CH2N). 13C NMR (100 MHz, CDCl3): d (ppm) 156.6, 133.8, 129.8,
123.7, 68.4, 39.9, 37.9, 34.1. Calculated for C40H52N4O4: C, 73.59%; H, 8.03%; N,
8.58%. Found: C, 73.62%; H, 8.11%; N, 8.61%.
1,3-Alternate-25,26,27,28-tetra[(3-iminotriphenylaminepropyl)oxy]-
calix[4]arene 8
A solution of 4-formyltriphenylamine (1.33 g, 6.20 mmol) and triethylamine
(1 mL, excess) in methanol (20 mL) was added to a solution of 25,26,27,28-tetra[(3-
aminopropyl)oxy]-calix[4]arene 7 (1.0 g, 1.53 mmol) in CH2Cl2 (30 mL). The mixture
was refluxed for 24 h under nitrogen. After evaporation of the solvent, the solid resi-
due was washed with cool methanol twice to remove unreacted 4-formyltriphenyla-
ꢀ1
mine and dried in vacuum. Yield 75%; mp 180–184 ꢁC; FTIR: 1640 cm (HC N);
=
1H NMR (400 MHz, CDCl3): d (ppm) 1.86 (p, 8H, J ¼ 6.6 Hz, CH2CH2CH2), 3.54 (t,
8H, J ¼ 6.6 Hz, NCH2), 3.66 (t, 8H, J ¼ 6.6 Hz, OCH2), 3.71 (s, 8H, ArCH2Ar), 6.72
(t, 4H, J ¼ 7.2 Hz, ArH), 7.03–7.12 (m, 40H, ArH), 7.24–7.28 (m, 16H, ArH), 7.57 (d,
8H, J ¼ 8.4 Hz), 8.13 (s, 4H, CHN); 13C NMR (100 MHz, CDCl3): d (ppm) 160.44,
156.83, 150.17, 147.44, 134.04, 130.17, 130.00, 129.94, 129.60, 129.22, 126.53, 125.31,

1674
S. ERDEMIR AND M. YILMAZ
123.81, 122.39, 119.57, 69.69, 58.57, 37.31, 31.83. Calculated for C116H104N8O4: C,
83.22%; H, 6.26%; N, 6.69%. Found: C, 83.31%; H, 6.34%; N, 6.76%.
ACKNOWLEDGMENT
We thank the Scientific Research Projects Foundation of Selcuk University for
financial support of this work.
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