Thiacalix[4]arene derivatives containing multiple aromatic groups: High efficient extractants for organic dyes

Article abstract of DOI:10.1007/s12039-015-0911-1

Click reaction of alkynylthiacalix[4]arene with ethyl 2-azidoacetate, followed by ammonolysis with hydrazine hydrate and Schiff-base condensation with benzaldehyde or salicyic aldehyde, afforded two novel thiacalix[4]arene derivatives containing multiple aromatic groups in yields of 86% and 90%. Their complexation properties for four organic dyes were investigated by liquid-liquid extraction experiments, complexation UV-Vis spectra and mass spectrum. The highest extraction percentage was 97% for Neutral red. The UV-Vis spectra and ESI-MS spectrum indicated the 1:1 complexes in DMSO solution. The association constants were as high as 1 ～ 8×10⁴ M^-1. These complexation experiments showed that thiacalix[4]arene receptors possess excellent complexation capabilities for dyes. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s12039-015-0911-1

J. Chem. Sci. Vol. 127, No. 8, August 2015, pp. 1383–1388. ꢀc Indian Academy of Sciences.
DOI 10.1007/s12039-015-0911-1
Thiacalix[4]arene derivatives containing multiple aromatic groups:
High efficient extractants for organic dyes
a
a
a
a
a,b,∗
CHUANG YANG , ZUSHENG WANG , HONGYU GUO , ZIYU JIAO and FAFU YANG
a
College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou 350007, P. R. China
Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, P. R. China
b
e-mail: yangfafu@fjnu.edu.cn
MS received 26 January 2015; revised 14 April 2015; accepted 29 April 2015
Abstract. Click reaction of alkynylthiacalix[4]arene with ethyl 2-azidoacetate, followed by ammonolysis
with hydrazine hydrate and Schiff-base condensation with benzaldehyde or salicyic aldehyde, afforded two
novel thiacalix[4]arene derivatives containing multiple aromatic groups in yields of 86% and 90%. Their com-
plexation properties for four organic dyes were investigated by liquid-liquid extraction experiments, complex-
ation UV-Vis spectra and mass spectrum. The highest extraction percentage was 97% for Neutral red. The UV-
Vis spectra and ESI-MS spectrum indicated the 1:1 complexes in DMSO solution. The association constants
4
−1
were as high as 1∼ 8×10 M . These complexation experiments showed that thiacalix[4]arene receptors
possess excellent complexation capabilities for dyes.
Keywords. Thiacalix[4]arene; aromatic; synthesis; complexation; dye.
1
. Introduction
cavity is a disadvantage for binding dyes, the calix[4]a-
rene derivatives with aromatic conjugate groups could
bind dyes effectively based on the new cavities con-
structed by calixarene skeleton and aromatic groups.
Moreover, the π-π action between aromatic groups and
dyes were usually the important factors in complexa-
tion. Lately, we prepared several thiacalix[4]arene
derivatives with triazole rings by click chemistry and
studied their excellent complexation abilities for dyes
Dyes are important chemicals for textiles, papers, lea-
ther, etc. However, the application of dyes also brought
about serious pollution in these industries.1 In order to
remove the dyes from waste water, many conventional
treatment processes have been developed, such as pre-
cipitation, extraction, adsorption, membrane filtration,
photodegradation, etc.3 Among them, liquid-liquid
extraction is seen as an effective method due to its ad-
vantages of selective separation and recovery of dyes
from the effluent mixtures. Normally, the extractants or
carriers play the decisive roles in liquid-liquid extrac-
tion. Recently, supramolecular chemistry has been con-
sidered as a good way to search for molecular structures,
which could be modified by introducing various func-
tional groups to construct a suitable binding site for
,2
–7
22
based on π-π interaction. In this paper, this thiacalix
4]arene triazole derivatives were further modified by
[
introducing new aromatic conjugate groups to construct
novel π-cavity for binding dyes. The complexation
results suggested that they possess better complexation
abilities for dyes than the precursor compounds, as
expected.
8
–10
dyestuff.
Calixarenes are considered as the third ge-
neration supramolecules after crown ether and cyclod-
extrin. They possess tunable 3D-shaped cavities with
2
. Experimental
versatile complexation abilities.11,12 Lately, some cali- 2.1 Instruments and reagents
xarene derivatives exhibited good extraction abilities
for dyes. A series of calixarene-based derivatives and Melting points were tested on WRS-3 micro melting
1
polymers were reported as effective dye receptors by point instrument. H NMR spectra were recorded in
13–15
16,17
18
Yilmaz,
Memnon
and Diao. Our group also CDCl
3
on a Bruker-ARX 400 instrument, using TMS
described a series of calixarene derivatives with excel- as reference. ESI-MS spectra were obtained from
lent dye complexation abilities.1
9–22
These literature DECAX-30000 LCQ Deca XP mass spectrometer. Ele-
suggested that, although the small size of calix[4]arene mental analyses were performed at Vario EL III Ele-
mental Analyzer. IR spectra were recorded on a Thermo
Nicolet AVATAR 5700 FTIR spectrometer using KBr
∗
For correspondence
1383

1384
Chuang Yang et al.
pellet. The UV-Vis measurements were performed on concentration of dye remaining in the aqueous phase
Varian UV-Vis spectrometer. Dyes were purchased was subsequently determined by UV-Vis analyses.
from Acros Organics, China. All solvents were purified Blank experiments showed that dye extraction was less
by standard procedures. Compounds 1, 2 and 3 were than 2% in the absence of extractant. The percent
prepared according to the literature method.2 Com- extraction (E%) was calculated as: E% = 100 (A −
3
o
pound 4 was synthesized according to the procedure in A)/A where A and A are initial and final concentra-
o.
o
22
reference.
tions of the dye before and after the extraction, respec-
tively. Each experiment was repeated thrice. The dye
concentration in the receiving phase was reported as
the mean of the determination and the relative standard
2
.2 The procedure for syntheses of compound 5a
Under N atmosphere, the mixture of compound 4 (0.4 deviation from the mean was less than 5%.
2
g, 0.3 mmol) and benzaldehyde (0.2 mL, 1.9 mmol)
was stirred and refluxed in 15 mL of MeOH-CHCl3
2
.5 UV-Vis spectral studies of complexation
(3:2, v/v). TLC analysis revealed that compound 4 dis-
experiments
appeared in 6 h. After cooling, the solvent was removed
under reduced pressure. The residue was treated with
All UV-Vis experiments were performed in DMSO
solution by adding aliquots of stock solution of the
respective dyes. The stoichiometry of the complexes
was determined by the Job method of continuous vari-
ations. The association constants were calculated by
Benesi-Hilderbrand formula with linear curve fitting
10 mL of MeOH and white precipitation appeared. The
precipitate was filtrated and dried under vacuum. Com-
pound 5a was obtained as white solid in yield of 86%.
◦
1
5
(
a: M.p. 252∼254 C. H NMR (400 MHz, CDCl )δ:
3
ppm) 1.04 (s, 36H, CH ), 4.97 (s, 8H, NCH ), 5.66 (s,
3 2
8
H, OCH ), 7.42∼8.31 (m, 36H, CH and ArH), 11.85
24,25
2
procedure.
+
(
s, 4H, NH). ESI-MS m/z(%): 1684.9(M , 100). Anal.
Calcd. for C H N O S : C 62.69, H 5.50, N 16.61;
88
92 20
8 4
found C 62.61, H 5.45, N 16.56.
.3 The procedure for syntheses of compound 5b
Under N atmosphere, the mixture of compound 4 (0.4 g,
3. Results and Discussion
3.1 Synthesis and characterization
2
The synthetic route was illustrated in scheme 1. As per
22
2
our report on click reaction, thiacalix[4]arene deriva-
0
.3 mmol) and salicylaldehyde (0.2 mL, 2.0 mmol)
was stirred and refluxed in 20 mL of MeOH-CHCl3
1:1, v/v). TLC analysis revealed that compound 4 dis-
tive 3 was prepared by treating alkynylthiacalix[4]arene
2
with compound 1 in yield of 70%. Then, by reacting
(
compound 3 with hydrazine hydrate, the thiacalix[4]
arene hydrazide derivative 4 was obtained in yield of
appeared in 5 h. After cooling, the solvent was distilled
under reduced pressure and 10 mL of MeOH was added
to give white precipitation. Then the precipitate was
filtered and dried under vacuum. Compound 5b was
8
6%. Finally, by Schiff-base condensation of compound
4
with benzaldehyde or salicyic aldehyde, two novel
thiacalix[4]arene derivatives 5a and 5b containing mul-
obtained as white solid in yield of 90%. 5b: M.p. tiple aromatic groups were synthesized after simple
◦
1
2
69–272 C. H NMR (400 MHz, CDCl )δ: (ppm) 1.02 recrystallization. The yields of compounds 5a and 5b
s, 36H, CH ), 5.00 (s, 8H, NCH ), 5.65 (s, 8H, OCH ), were as high as 86% and 90%, respectively.
The structures of the new compounds 5a and 5b were
1.77 (s, 4H, NH). ESI-MS m/z(%): 1749.4(M 100). confirmed by elemental analyses, IR, ESI-MS and H
3
(
3
2
2
6
1
.89∼8.47 (m, 32H, CH and ArH), 10.06 (s, 4H, OH),
+
1
Anal. Calcd. for C H N O S : C 60.39, H 5.30, NMR spectra. Their IR spectra showed correspon-
88
92 20 12 4
N 16.01; found C 60.33, H 5.34, N 16.04.
ding adsorption peaks of Schiff-base groups (C=N) at
620 cm approximately. The corresponding molecular
peaks in their ESI-MS spectra were observed at 1684.9
−1
1
2.4 Extraction of dyes
+
+
1
(
M ) and 1747.4(MH ), respectively. In the H NMR
22
According to the reported method, 10 mL of 2.0 × spectra, one singlet for the tert-butyl groups supported
−
5
1
1
0 M aqueous solution of dye and 10 mL of 1.0 × the cone conformations of compounds 5a and 5b.
−3
0 M solution of receptor in CH Cl were vigorously
2
2
agitated in a stoppered glass tube with a mechanical
3
.2 Complexation studies for dyes
shaker for 2 min. Then the mixture was stirred magneti-
◦
cally in a thermostated water-bath at 25 C for 1 h, and As can be seen that compounds 5a and 5b possess mul-
was finally left standing for an additional 30 min. The tiple aromatic triazole rings and phenyl groups, which

Novel thiacalix[4]arene receptors for dyes
1385
O
O
NaN3
DMF
Cl
N3
O
O
1
O
N
O
N
N
OH
O
O
*
S
Br
*
S
1
*
S
*
*
*
K CO
4
2
3
4
CuI
4
2
3
NH NH
2
2
CH HC
CH
R
HC
N
R
R
N
N
N
NHNH2 NHNH2
O
R
R
NHNH2
O
NH
NH
NH
O
NHNH2
O
O
O
N
O
NH
N
N
N
N
O
N
N
N
N
N
CHO
N
N
N
N
N
N
N
O
N
N
N
N
N
N
N
O
O
O
O
O
O
O
4
5
5
a: R = H
b: R = OH
Scheme 1. The synthetic route of title compound.
could construct novel π-cavity with thiacalix[4]arene extraction abilities for the tested dyes. Their extraction
skeleton, resulting in excellent complexation abilities percentages were higher than that of their precursor
for dyes potentially. Thus, four common dyes with large compound 4. The extraction percentage of compound
π-conjugate system including Orange G (OG), Neutral 5b for Neutral red was as high as 97%. By compar-
red (NR), Methylene blue (MB) and Brilliant ponceau ing with the structures of compounds 5a, 5b and 4,
(
BP), were used as representative dyes for the complex- the excellent extraction percentages of compounds 5a
ation studies of compounds 5a and 5b. Their structures and 5b could be attributed to the introduction of Schiff-
are shown in figure 1. base aromatic groups, which enhance the π-π action
The two phase extraction experiments (H O/CH Cl ) between receptors and guests. On the other hand, the
2
2
2
were preliminarily applied to investigate the complex- extraction percentages of compounds 5a and 5b were
ation abilities of compounds 5a and 5b towards four similar, although compound 5b showed a little higher
dyes. The extraction results are summarized in table 1. extraction percentage than that of compound 5a.
The control experiments without host showed that dye
Furthermore, the complexation behaviors of recep-
extractions were less than 2%. One can see that, as tors 5a and 5b for dyes were studied by UV-Vis spectral
expected, compounds 5a and 5b exhibit excellent titration. The respective UV-Vis spectra of compounds
H3C
H3C
H2N
N
HO
N
N
N
H C
3
N
N
SO Na
3
N
HN
NaO S
S
3
OH
NaO S
N+ CH3
Cl-
3
N+ CH3
Cl-
H C
NaO S
3
3
H C
SO3Na
Orange G (OG)
3
Neutral red (NR)
Methylene blue (MB)
Brilliant ponceau 5R (BP)
Figure 1. The structures of four dyes in complexation studies.

1386
Chuang Yang et al.
Table 1. Extraction percentages of three dyes with com- 5a and 5b, four dyes, and compounds 5a and 5b with
pounds 4, 5a and 5b*.
−5
four dyes at various concentrations (up to 2.0×10 M)
were studied. Figures 2 and 3 exhibit the representative
UV-Vis spectra of complexation of compound 5a with
MB. In figure 2, absorption wavelength of MB at 660
nm shifted to 666 nm after complexation. Moreover, the
absorbance at 294 nm increased but the absorbance at
Compound
OG
NR
MB
BP
4
91
95
96
1.3
82
94
97
1.5
79
93
95
1.4
86
91
92
1.9
5
a
5b
None
6
65 nm decreased distinctly after complexation. These
*
The pH=7 in aqueous solution were adjusted by HAc or
results certainly supported the existence of intermolec-
ular complexation action between compound 5a and
MB. In figure 3, the maximal absorbance at 294 nm
increased gradually in non-proportional manner with
the increase of concentration of MB, also indicating
the interaction between host and guest. Based on
the absorbance at maximal absorption wavelength, the
association constants and correlation coefficients were
calculated by Benesi-Hildebrand equation, which was
usually used to study the complexation behaviors of
ammonia. The extraction data of compound 4 are cited from
reference.
22
1
1
0
0
0
0
0
.2
.0
.8
.6
.4
.2
.0
MB
compound 5a
MB + compound 5a (1:1)
24,25
host-guest.
and (2):
The calculation follow equations (1)
1
1
1
=
+
(1)
n
ꢀ
A
K ꢀε [H] [G]
ꢀε [H]
s
H + nG → H · nG
(2)
300
400
500
600
700
Wavelength / nm
Where H is host, G is guest, n is the ratio of com-
plexation. [H] and [G] are the concentrations of host
Figure 2. The UV spectra of compound 5a (1×10 3M),
−
and guest, respectively. K is association constant; ꢀε
−
5
−3
s
MB (1×10 M), and 5a (1×10 M) in the presence of MB
−5
is difference in molar absorption coefficients. ꢀA is the
(
1×10 M) in DMSO.
1
1
1
1
0
0
0
0
0
.6
.4
.2
.0
.8
.6
.4
.2
.0
1
6
4
2
0
1
1
1
2
.0mL
8
6
4
2
0
0
mL
0
1
2
3
4
5
1
/ [G]
300
400
500
600
700
800
Wavelength/nm
Figure 3. The UV spectra of compound 5a (1×10 3M) in the presence of
−
MB in DMSO. The concentrations of MB were from the bottom 0.0, 0.2, 0.4,
−
5
0
.6, 0.8, 1.0, 2.0 (×10 M). Inset: Plot of 1/(A-Ao)vs 1/[G], where [G] was
5
−1
the concentration of dye. The unit of 1/[G] is 10 M
.

Novel thiacalix[4]arene receptors for dyes
1387
Table 2. Association constants (Ks) and correlation coef- with benzaldehyde and salicyic aldehyde. The yields
2
ficients (R ) for the complexation of 5a and 5b with three
dyes.
were as high as 86% and 90%, respectively. Their com-
plexation abilities for dyes were studied by liquid-liquid
5a R2
−1
5b R2
−1
extraction experiments, UV-Vis spectra and mass spec-
trum. The extraction percentages were over 90%, which
were higher than that of the precursor compound. The
UV-Vis spectra indicated formation of 1:1 complexes
between host and guest. The association constants are
dyes
n
Ks (M
)
n
Ks (M
)
4
3
3
3
4
4
4
3
OG
MB
NR
BP
1
1
1
1
0.9989 1.585×10
0.9981 7.549×10
0.9978 5.239×10
0.9947 1.328×10
1
1
1
1
0.9982 8.40×10
0.9985 3.69×10
0.9891 7.66×10
0.9878 9.71×10
4
−1
1
∼ 8×10 M . The ESI-MS spectrum of complex of
5b with Neutral red also implied the formation of 1:1
complex in DMSO. All these experiments supported
that thiacalix[4]arene derivatives 5a and 5b contain-
ing multiple aromatic groups are excellent receptors for
binding organic dyes.
change of absorbance at maximal absorption wave-
length.
The results of association constants (K ) and corre-
s
2
lation coefficients (R ) are summarized in table 2. It
could be seen that the correlation coefficients (R ) were
2
Supplementary Information
near 1 when the values of the ratio of complexation (n)
were set as 1. These results suggested the stoichiomet- The electronic supporting information, including the
ric ratio of 1:1 for host-guest complexes of compounds characteristic data of new compounds and the complex-
5
a and 5b with dyes. On the other hand, the asso- ation UV-Vis spectra for dyes are available at www.ias.
ciation constants of compounds 5a and 5b with dyes ac.in/chemsci.
4
−1
were as high as 1∼8×10 M . Moreover, compound
5b possessed higher association constants than that of Acknowledgements
compound 5a, indicating that the hydroxyl groups in
compound 5b were favorable for dye complexation
based on hydrogen bonding action. All these data
implied the strong complexation action between hosts
and guests, which were in agreement with the results of
extraction experiments.
The ESI-MS spectrum of compound 5b with excess
Neutral red (mol ratio = 1:4) was studied to investi-
gate the complexation behavior in DMSO. The ESI-MS
spectrum showed two strong peaks clearly (figure S13
in SI). One peak at 1748.6 was for compound 5b and
another one at 2001.7 was for the complex of compound
Financial support from the National Natural Science
Foundation of China (No: 21406036), Fujian Natu-
ral Science Foundation of China (No. 2014J01034),
Project of Fujian provincial department of edu-
cation(JA11044) and the Program for Innovative
Research Team in Science and Technology in Fujian
Province University and Program for Excellent young
researchers in University of Fujian Province (JA10056)
are greatly acknowledged.
References
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excess Neutral red was added, only 1:1 complexation
peak appeared and the relative abundance attained 100.
This result suggested that strong intermolecular action
between host and guest, which is also in accordance
with the result of 1:1 complexation of UV-Vis spectra.
In a word, all the complexation experiments supported
that compounds 5a and 5b have excellent complexation
abilities for dyes and prefer to 1:1 complexes in DMSO
solution.
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