A highly copper selective chromogenic calix[4]arene derivative

Article abstract of DOI:10.1039/c0nj00396d

In this article, copper selective complexation behavior of 5,11,17,23-tetrakis[(N,N-dicyclohexylamino)methyl]-25,26,27,28- tetrahydroxycalix[4]arene (4) has been explored. Besides this, the binding ability of 4 toward different metal ions such as Cd²⁺, Co ²⁺, Cu²⁺, Hg²⁺, Ni²⁺, Pb ²⁺ and Zn²⁺ has been investigated by UV-visible and fluorescence spectroscopies. The chromoionophore 4 shows pronounced selectivity for Cu²⁺ even in the presence of other metal ions. The results reveal that Cu²⁺ forms 11 host-guest complex with 4. The FT-IR spectroscopic method has also been applied for further confirmation of complex formation between 4 and Cu²⁺ and found to be satisfactory.

Full text of DOI:10.1039/c0nj00396d

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PAPER
www.rsc.org/njc | New Journal of Chemistry
A highly copper selective chromogenic calix[4]arene derivative
Mansoor Ahmed Qazi, Imdadullah Qureshi and Shahabuddin Memon*
Received (in Victoria, Australia) 25th May 2010, Accepted 7th July 2010
DOI: 10.1039/c0nj00396d
In this article, copper selective complexation behavior of 5,11,17,23-tetrakis[(N,N-
dicyclohexylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4) has been explored. Besides
this, the binding ability of 4 toward different metal ions such as Cd2+, Co2+, Cu2+, Hg2+, Ni2+
Pb2+ and Zn2+ has been investigated by UV-visible and fluorescence spectroscopies.
The chromoionophore 4 shows pronounced selectivity for Cu2+ even in the presence of other
metal ions. The results reveal that Cu2+ forms 1 : 1 host–guest complex with 4. The FT-IR
spectroscopic method has also been applied for further confirmation of complex formation
between 4 and Cu2+ and found to be satisfactory.
,
metal complexes and solvatochromic effect of 5,11,17,23-tetra-
kis[(N,N-dicyclohexylamino)methyl]-25,26,27,28-tetrahydroxy-
calix[4]-arene (4) using UV-visible, fluorescence and FT-IR
techniques.
Introduction
In the recent years, the development of robust chromo-
ionophoric receptors or optical chemical sensors remains an
important venture for the recognition of heavy metals via ionic
or molecular interactions because of their applications in areas
of biological, environmental and chemical systems.1–8 Among
the heavy metals copper is an essential element that is very
important for creatures however, its excessive or inadequate
uptake causes several health hazards.9–12 Therefore, it is very
important and meaningful to develop better methods to detect
copper in the environment and biological systems.
Result and discussions
The p-tert-butylcalix[4]arene 2 as well as its derivatives 3 and 4
illustrated in Scheme 1 were prepared by methods described
previously.27–29 The characterization of the compounds for the
confirmation of their structure and purity was made by
various techniques such as melting point, TLC, IR, and
elemental analysis.
Although various intriguing aspects of complexation of
alkali and alkaline earth metal ions were disclosed by studying
the absorption behavior of chromophoric groups.13,14 Never-
theless, there are relatively few reports on the design of sensors
for heavy metal ions.15 Because, unlike alkali and alkaline
earth metals, heavy metals do not differ too much in size,
and possess similar chemistry. However, they can establish
coordinative interactions of very different energies, which can
be used for discriminative purposes, especially for fluorescent
sensing.
Solvatochromic effect
It is a general perception in solvatochromic study that ground
state is less polar than the excited state for almost all molecules.
Therefore, a polar solvent will tend to stabilize the excited
state more than the ground state. If a red shift (bathochromic
effect) is observed in the absorption spectrum with an increase
in the polarity of solvent, it is termed as ‘‘positive solvato-
chromism’’ and vice versa is true for less polar solvents.30
Spectral investigations of ligand 4 were evaluated in various
solvents (Fig. 1) like acetone (ACO), acetonitrile (ACN),
chloroform (CF), dichloromethane (DCM), tetrahydrofuran
(THF), methanol (MeOH), dimethylformamide (DMF) and
dimethylsulfoxide (DMSO). UV-visible spectroscopic data, i.e.
In this regard, calixarenes have received considerable attention
because of their potential for the synthesis of highly efficient
and selective receptors.16–18 Several fluorescent chemosensors
based on calixarenes have been synthesized and show highly
specific recognition, especially towards alkali metal cations.
However, the generation of fluorescent sensors for heavy
metals is of increasing importance in calixarene chemistry.
Consequently, many excellent studies of Cu2+ sensing by
synthesized colorimetric/fluorescent probes have been reported
and investigated for selective complexation of metal ions,19–26
which reveal that the sensing ability and selectivity depends
upon the nature of substituents, size and conformation of
calix[4]arene molecule.
l
are given in Table 1.
max, and molar extinction coefficient (e in L molÀ1 cmÀ1) both
Compound 4 shows red shifts in its absorption maxima
(B12 nm range) in DMF and DMSO with respect to CF or
DCM. These red shifts can be attributed to the p - p* and
n - p* transitions arising from solvent polarity differences.
The color of 4 and changes in the absorption spectrum
(Fig. 1 and 2) in different solvents suggest its potential as a
probe for these solvents.
In view of the above studies and our previous experience,3
herein we report an investigation regarding synthesis of
Other low polarity solvents like CF, DCM and THF
show hypsochromic shifts with a new absorption peak
(with reference to DMF and DMSO). From these observations,
it may be concluded that probably there is no significant change
in the stability of the excited state in the aforementioned
National Center of Excellence in Analytical Chemistry,
University of Sindh, Jamshoro 76080, Pakistan.
E-mail: shahabuddinmemon@yahoo.com; Fax: 0092 (22) 2771560;
Tel: 0092 (22) 2772065
c
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Scheme 1 Reaction pathway for the synthesis of ligand: (a) HCHO/NaOH, (b) phenol – AlCl3/(dry) toluene, (c) dicyclohexylamine–
HCHO/acetic acid : THF.
Fig.
2
Naked eye color changes of 4 in DMF and DMSO
(4.3 Â 10À5 M).
bearing nitrogen atom, and it interacts with less polar solvents.
That’s why it gives blue shifting (i.e. negative solvato-
chromism) in less polar solvents like CF, DCM, and THF
with well defined absorption bands B1 and B2 in the regions of
240 and 270–280 nm through p - p* and n - p* transitions,
respectively.
Fig. 1 UV-visible spectral data of ligand 4 in different solvents
(4.3 Â 10À5 M).
solvents. Moreover, 4 is devoid of groups such as carboxylic or
ester groups and possesses moderately intermediate nature
Table 1 UV-visible spectroscopic data (l/nm and e/L molÀ1 cmÀ1) of 4 in selected solvent system and the effect of acid and base on it
Absorption coefficient (LÀ1 molÀ1 cmÀ1) at specific l
B1 (e)
B2 (e)
Medium
DCM
18 605 (240 nm)
23 256 (246 nm)
11 628 (240 nm)
19 302 (240 nm)
16 279 (243 nm)
18 605 (240 nm)
17 442 (240 nm)
53 488 (246 nm)
22 093 (240 nm)
—
23 256 (275 nm), 20 930s (281 nm)
23 256 (275 nm), 24 884s (287 nm)
20 930 (275 nm), 18 605s (281 nm)
20 930 (276 nm), 19 070s (282 nm)
23 256 (276 nm), 20 930s (282 nm)
18 605 (276 nm), 18 605s (282 nm)
18 605 (275 nm), 18 605s (281 nm)
13 953 (283 nm), 9302s (287 nm)
16 279 (275 nm), 16279s (281 nm)
42 325 (287 nm), 13 953s (309 nm)
32 558 (287 nm), 11 628s (309 nm)
27 674 (287 nm), 9302s (309 nm)
35 581 (283 nm), 4651s (310 nm)
34 651 (283 nm), 11 628s (310 nm)
30 232 (287 nm), 4651s (310 nm)
DCM + piperidine
DCM + acetic acid
CF
CF + piperidine
CF + acetic acid
THF
THF + piperidine
THF + acetic acid
DMF
DMF + piperidine
DMF + acetic acid
DMSO
—
—
—
—
DMSO + piperidine
DMSO + acetic acid
—
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Many attempts have been made to observe the solvato-
chromic behavior of 4 in MEOH, THF, ACO and ACN even
at low concentration; but due to aggregation and too much
noise in the spectra, all of them have been discarded. Thus,
DCM was preferred for absorption as well as fluorescence
studies since it gives maximum number of absorption bands
within standard absorption limits and shows no aggregation as
compared with DMF or DMSO.
In pursuit of acid and base influence on the equilibrium state
of 4, acetic acid and piperidine were added in its various
solvent systems. UV-visible spectra showed that except in
THF, no significant change in the spectra was observed when
a small amount of piperidine was added to the solutions of
4 in CF, DCM, DMSO and DMF separately. Addition of
piperidine in THF caused a dramatic effect (Fig. 3a–e) where
appreciable enhancement along with red shifting was observed
in both bands (B1 and B2) at 240 and 275 nm (along with
shoulder at 281 nm), which shifted to 246 and 283 nm,
respectively. Absorption peaks at the longest wavelength
indicate that the compound may exist in a dissociated
form in DMF and DMSO due to deprotonation of phenolic
hydrogens. However, the addition of acid (i.e. acetic acid) did
not cause a significant effect. The changes in the molar
Effect of acid and base in different solvent systems
A change in the nature of medium in which the compound is
dissolved may cause significant effect on its spectral behavior,
because interactions between solute and solvent are disturbed
and thus, the shapes of bands and their positions are changed.
Fig. 3 UV-visible spectral data of 4 (4.3 Â 10À5 M) before and after the addition of piperidine and acetic acid in (a) DCM, (b) CF, (c) THF,
(d) DMSO, (e) DMF.
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extinction co-efficient values of respective absorption bands in
different solvents are given in Table 1.
Stability of 4 in selected solvent
After solvent selection, stability determination of compound
in a particular solvent is an important parameter, which tells
whether the compound used in complexation studies in that
solvent is stable or not even after a long time. Therefore, the
UV-visible absorption spectra of 4 in DCM were immediately
obtained after continuous UV irradiation with the passage of
0, 20, 40, 60, 80, 100, 120 and 140 minutes.31 The results
confirm the stability of 4 in DCM as there was no change
appearing in the spectra with the passage of time (Fig. 4).
Fig. 5 %Extraction of the selected metal picrates. Aqueous phase,
[metal picrate] = 2.5 Â 10À5 M; organic phase, dichloromethane,
[4] = 1 Â 10À3 M at 25 1C for 1 h.
Complexation studies
In this work, we have chosen a calix[4]arene derived Mannich
base for synthesis and complexation study because of ease of
its synthesis, possessing a borderline nitrogen donor atom with
macrocyclic effect that may prove to be a promising candidate
for the formation of stable complexes with soft/borderline
metal cations such as Cu2+, Hg2+ and Pb2+ etc.32
Table 2 Comparative %extraction efficiency of 2 and 4 with selected
metal picrates
Extracted metal picrates (%)
Thus, different titration experiments were carried out in
order to determine whether 4 can form complexes with these
metals and consequently different parameters were checked to
evaluate its selectivity.
Cd2+ Cu2+ Co2+ Ni2+ Pb2+ Hg2+ Zn2+
Ligand
2a
4
9.4
20
9.9
80
7.9
30
6.3
24
o1
15.5
40
—
43
15
a
Ref. 35.
Liquid–liquid extraction study
of 4. This is in accordance with our previous work.33,34 This
characteristic enhances the utility of 4 in various fields such as
food/environmental chemistry, membrane technology, ion
selective electrodes technology and phase-transfer reactions.
Liquid–liquid extraction experiments were performed to evaluate
the extraction ability of ligand 4 in transferring heavy metals,
such as Cd2+, Co2+, Cu2+, Hg2+, Ni2+, Pb2+ and Zn2+
,
from aqueous into organic phase, i.e. DCM. From the data
given in Fig. 5 (Table 2), it has been observed that 4 shows
greater affinity toward Cu2+ among the metal cations used in
the experiments as compared to the parent compound 2. The
extraction ability of 4 toward the metal cations is in the order
UV-visible study
The solvatochromic behavior of 4 suggested DCM as a solvent
of preferable choice however, attempts have been made to use
DCM with a series of different solvents such as methanol,
ethanol and isopropanol. Since most of the metal nitrate salts
were insoluble in DCM therefore, DCM–MeOH as a binary
solvent system was found to be appropriate and selected for
complexation studies.
Cu2+ 4 Zn2+ 4 Hg2+ 4 Co2+ 4 Ni2+ 4 Cd2+ 4 Pb2+
.
The increased extraction of Cu2+ with 4 may be due to the
presence of borderline nature of both Cu2+ and the binding
sites (i.e. nitrogen containing functionalities). Moreover, the
enhanced extraction may reflect the arrangement of binding
sites according to the geometry of Cu2+, i.e. square planar; as
well as the compatibility between the cavity size and ionic radii
Preliminary measurements were made to checkout the
complexation behavior of
4 in DCM–MeOH solution
(4.3 Â 10À5 M) for selected metal ions such as Cd2+, Co2+
,
Cu2+, Hg2+, Ni2+, Pb2+ and Zn2+. The UV-visible spectra
of free ligand 4 show a strong band at 230–240 nm which is
attributed to p - p* and another band at 270–290 nm due to
n - p* transition (Fig. 6). Generally, the bands of complexes
are shifted to shorter or longer wavelengths than that of the
free ligand, but the high intensity of the bands after complexa-
tion is also an indication of the complex formation. However,
the addition of each metal cation (5 equiv.) in ligand 4 causes
enhancement in the intensity of the previous bands as shown
in Fig. 6. The electronic spectra of the complexes observed at
230–240 and 270–290 nm could be assigned to nitrogen–metal
charge transfer absorption.36 Upon complexation with metal
ions, 4 showed high specificity toward Cu2+ because considerable
enhancement in the absorptions of bands has been observed as
Fig. 4 Time dependent UV-visible absorption spectra of 4 in DCM
(4.3 Â 10À5 M) upon irradiation of UV light.
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Fig. 8 Job’s plot of 4 and Cu2+. The concentration of 4 and
Cu2+ was kept fixed, i.e. 4.3 Â 10À5 M. The absorbance was measured
at 275 nm.
Fig. 6 UV-visible response of 4 (4.3 Â 10À5 M) before and after
titration with selected metal ions (5 eq.).
Fig. 7 UV-visible titration spectra of 4 (4.3 Â 10À5 M) upon addition
Fig.
9 Time-dependent UV-visible absorption spectra of
of various equivalents of Cu2+
.
4–Cu2+ complex (4.3 Â 10À5 M) in DCM–MeOH upon irradiation
of UV light; (inset) graph showed stability of 4 with respect to
time.
compared with free ligand 4 or other ions including Hg2+ and
Zn2+. The results imply that 4 is highly selective for Cu2+
.
In an attempt to have further insight into the chromogenic
behavior of 4, the absorption profile as a function of metal
ion concentration was obtained followed by increase in the
intensity of absorbance with respect to increased Cu2+ ion
concentration (Fig. 7).
Interference study of competing ions
Selectivity of 4 toward Cu2+ in the presence of co-existing ions
was determined by the competition experiments carried out in
the presence of Cu2+ (5 eq.) mixed with Cd2+, Co2+, Hg2+
,
Ni2+, Pb2+ and Zn2+ (5 eq. each) separately as shown in
For the determination of stoichiometric ratio between the
Fig. 10. It was observed that metal ions such as Cd2+, Co2+
,
ligand and metal ion, the Job’s plot experiment was conducted
by varying the concentration of both ligand 4 and Cu2+
Ni2+, Pb2+ do not interfere with the absorption enhanced
.
Fig. 13 shows typical Job’s plots of ligand–metal com-
plexation. For 4–Cu2+ complex, measured at 275 nm, the
maximum value of the mole fractions was found as 0.5, which
refers to ligand–metal ratio of 1 : 1 in the complex as shown in
Fig. 8.
Response time and the stability of complex in DCM–MeOH
Response time measurement of chromoionophores/chemosensors
based on macrocyclic compounds is an intense area of study.
However, it has been aimed to investigate the response time
and stability of 4–Cu2+ complex. The results reveal that 4
responds very fast and when titrated with Cu(NO3)2Á3H2O, a
significant enhancement in absorption of a band in the region
of 270–280 nm occurs very rapidly within 1 min and remains
stable up to a long time (Fig. 9), i.e. remains the same even
after three days.
Fig. 10 Interference study of Cu2+-complex of 4 with selected metal
ions (5 eq.) in DCM–MeOH.
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spectra of 4–Cu2+ complex except Hg2+ and Zn2+, which
show a little interference.
Fluorescence study
The fluorescence response of 4 toward various cations is
illustrated in Fig. 11–13. In cationic fluorescence sensing, upon
addition of 5 eq. of each cation, despite the border line nature
of Co2+, Zn2+ and Ni2+, a little response has been observed
with 4 as compared to Cu2+, which causes a dramatic
quenching in fluorescence intensity, i.e. considerable reduction
in the emission intensity from 886 to 458 a.u. at 308 nm.
Such
a significant difference in fluorescence intensity
between Cu2+ and other metal ions indicates that not only
the binding sites of 4 are more suitable for Cu2+ than for other
Fig. 14 Interference study of Cu2+-complex of 4 with selected metal
ions (5 eq.) in DCM–MeOH using fluorescence spectroscopy.
metal ions but there are other factors that are also responsible
for the selective complexation as discussed earlier. This may be
attributed to stronger complex formation with the metal ion in
preference over others, following Irving–Williams order of
stability.37 Moreover, paramagnetic character and borderline
nature of both ligand and metal ion may also impart the
selectivity of 4 toward Cu2+ ions.
Fluorescence spectroscopic study of interfering ions also
supports the results obtained in the UV-visible spectra as there
was no shifting (bathochromic or hypsochromic shift),
quenching or enhancement in the fluorescence spectra of
4–Cu2+ complex after the addition of metals and gave
approximately similar results (Fig. 14).
Fig. 11 Excitation and emission spectra of 4 (4.3 Â 10À5 M).
Regarding another complexation possibility between the
phenolic OH functionalities of host and the metal ions, it
may be presumed that the metal may be able to interact with
the phenolic moieties at lower rim of calix[4]arene38,39 but due
to intramolecular hydrogen bonding of lower rim, metal
ion may not be accommodated within this region of lower
cavity of calix[4]arene. Nonetheless, all the UV-visible and
fluorescence spectra suggest that 4 may be used as a potential
Cu2+ selective chromoionophore. Thus, according to the
Jobs’ plot analysis as discussed above, it has been revealed
that Cu2+ forms 1 : 1 metal–ligand complex with 4. The
proposed mechanism for metal–ligand interaction is shown
in Fig. 15.
Fig. 12 Fluorescence spectra of 4 (4.3 Â 10À5 M) in DCM–MeOH
solution before and after adding nitrate salt of selected metal ions
(5 eq.).
Fig. 13 Fluorescence spectra of 4 (4.3 Â 10À5 M) in DCM–MeOH
solution before and after adding nitrate salt of Cu2+ (5 eq.).
Fig. 15 Proposed interaction between compound 4 and Cu2+
.
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for recording IR spectra using KBr pellets in a wide spectral
range, i.e. 4000–400 cmÀ1. Elemental analyses were performed
using a CHNS instrument model Flash EA 1112 elemental
analyzer. UV-visible spectral studies of 4 (Scheme 1) and its
metal complexes were performed on a Perkin Elmer Lambda-
35 UV-visible double beam spectrophotometer using standard
1.00 cm quartz cells. Analytical TLC was performed on pre-
coated silica gel plates (SiO2, Merck PF254). All the reagents
and solvents were of analytical grade and used without further
purification.
Synthesis of 4
The required starting materials p-tert-butylcalix[4]arene (2),
calix[4]arene (3) and tetraamine derivative (4) were prepared
by published procedures.31–33
Fig. 16 Comparative FT-IR spectra for (a) compound 4, and
(b) Cu2+-complex of 4.
Synthesis of metal complexes with 4
FT-IR study
For FT-IR experiments, 4 with a nitrate salt of Cu2+ and KBr
were mixed and then ground to powder form in an agate
mortar. The resulting mixture was kept in an oven at 115 1C
for 1 h and then pressed to form pellets.40
FT-IR spectroscopic technique also provides strong
evidence of complexation of 4 with Cu2+. FT-IR spectrum
showed characteristic bands of this ligand (KBr/cmÀ1) at
3180 [n(OÁ Á ÁH) intermolecular hydrogen bond], 2938 n(CH2),
2872 d(CH2), 1379 n(C–N). Coordination of the Cu2+ ion was
readily evidenced in the FT-IR spectrum of the complexes.
Fig. 16 clearly gives the stronger evidence for complexation as
shifting in various frequencies of specific functional groups
occurred as a result of introduction of Cu2+ into receptor
cavity. For example, marked changes appeared in the region of
1370–1450 cmÀ1, where considerable decrease in the intensity
of band at 1448 cmÀ1 and appearance of a new sharp band at
1388 cmÀ1 for n((C–N)–Cu2+) complexation indicates the
involvement of N donor atom of secondary amine in the
binding process with Cu2+. This clearly indicates the forma-
tion of 4–Cu2+ complex. Other prominent bands at 3180 and
2872 are also shifted to 3190 and 2861 cmÀ1, respectively,
which give informative sign for changes in the geometry of 4
after complexation.
Analytical procedure
Solvent extraction. Picrate extraction experiments were
performed following Pedersen’s procedure.41 A 20 mL mixture
of aqueous picrate solution (2.5 Â 10À5 M) and 4 in CH2Cl2
(1 Â 10À3 M) in 1 : 1 ratio were vigorously agitated in a
stoppered glass tube with a mechanical shaker for 2 min then
magnetically stirred in a thermostated water-bath at 25 1C for
1 h, and finally left standing for an additional 30 min. The
concentration of picrate ion remaining in the aqueous phase
was then determined through UV-visible spectrophotometry
as previously described.42
The transition metal picrates were prepared by stepwise
addition of a 1 Â 10À2 M of metal nitrate solution to a
2.5 Â 10À5 M aqueous picric acid solution and shaken at 25 1C
for 1 h.
Conclusions
Stoichiometric ratio of the metal and ligand in the complex.
Job’s method43 (continual variation method) was used to
determine the stoichiometric ratio between 4 and Cu2+ for
their complexation in a binary solvent i.e., DCM–MeOH. The
solutions were prepared by mixing equimolar concentration
(4.3 Â 10À5 M) of both components in different ratios varying
from 1 : 9 to 9 : 1. Then the absorbance was measured at
275 nm.
In the present work, the chromogenic potential of 4 was found
with high specificity toward Cu2+ among a series of selected
metal ions that attributed to the changes in intensities of the
spectral lines observed in UV-visible and fluorescence spectra
of Cu2+–4 complex. It is also confirmed by FTIR spectral
analysis. Moreover, the design of 4 that comprises four donor
nitrogen atoms as binding sites seems to be an ideal geometry
in terms of size, arrangement and accommodation of Cu2+. It
infers the importance of pre-organization in designing the
ligand. From the results, it may be concluded that the study
General procedure for fluorescence study. Stock solutions of
(1.00 mM) 4 and metal nitrate salts were prepared in DCM
and MeOH, respectively. Test solutions were prepared by
placing 50 mL of 4 into a cuvette, adding appropriate aliquot
(5 eq.) of each metal stock, and diluting the solution up to
3.5 mL with DCM. Same equivalents (5 eq.) were taken for
the interference study of co-existing ions in a solution con-
taining 4–Cu2+complex. For all measurements, excitation
was 260 nm; excitation and emission slit widths were both
5 nm each.
may be treated as a test for the detection of Cu2+
.
Experimental section
General experimental information
Melting points were determined on a Gallenkamp (UK)
apparatus in a sealed capillary tube and are uncorrected.
Thermo Nicollet AVATAR 5700 FTIR spectrometer was used
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19 R. Kamer, Angew. Chem., Int. Ed., 1998, 37, 772.
¨
20 P. Ghosh, P. K. Bharadwaj, S. Mandal and G. Sanjib, J. Am.
Chem. Soc., 1996, 118, 1553.
21 Y. Zheng, J. Orbulescu, X. Ji, F. M. Andreopoulos, S. M. Pham
and R. M. Leblanc, J. Am. Chem. Soc., 2003, 125, 2680.
22 M. Royzen, Z. Dai and J. W. Canary, J. Am. Chem. Soc., 2005,
127, 1612.
Acknowledgements
We thank the National Centre of Excellence in Analytical
Chemistry, University of Sindh, Jamshoro/Pakistan, for the
financial support of this work.
23 J. P. Sumner, N. M. Westerberg, A. K. Stoddard, T. K. Hurst,
M. Cramer, R. B. Thompson, C. A. Fierke and R. Kopelman,
Biosens. Bioelectron., 2006, 21, 1302.
24 H. Yang, Z.-Q. Liu, Z.-G. Zhou, E.-X. Shi, F.-Y. Li, Y.-K. Du,
T. Yi and C.-H. Huang, Tetrahedron Lett., 2006, 47, 2911.
25 M. Yilmaz, S. Memon, M. Tabacki and R. A. Bartsch, Design of
Polymer Appended Calixarenes Ion Carriers: New Frontiers in
Polymer Research, Nova Science Publisher, Hauppauge, New
York, 2006.
26 H. Deligoz and E. Erdem, Solvent Extr. Ion Exch., 1997, 15, 811.
¨
27 C. D. Gutsche, M. Iqbal and D. Stewart, J. Org. Chem., 1986, 51,
742.
28 C. D. Gutsche and L.-G. Lin, Tetrahedron, 1986, 42, 1633.
29 C. D. Gutsche and K. C. Nam, J. Am. Chem. Soc., 1988, 110, 6153.
30 U. Harikrishnan and S. K. Menon, Dyes Pigm., 2008, 77, 462.
31 Z. Liang, Z. Liu and Y. Gao, Spectrochim. Acta, Part A, 2007, 68,
1231.
References
1 Z. C. Xu, X. H. Qian and J. N. Cui, Org. Lett., 2005, 7, 3029.
2 L. H. Feng and Z. B. Chen, Sens. Actuators, B, 2007, 120, 665.
3 M. A. Qazi, I. Qureshi and S. Memon, J. Mol. Struct, 2010, 975,
69.
4 M. D. Barkovskaya, D. M. Roundhill, S. Memon, M. I. Bhanger
and M. Yilmaz, Pak. J. Anal. Environ. Chem., 2007, 8, 1.
5 V. Amendola, L. Fabbrizzi, F. Forti, M. Licchelli, C. Mangano,
P. Pallavicini, A. Poggi, D. Sacchi and A. Taglieti, Coord. Chem.
Rev., 2006, 250, 273.
6 L. Pu, Chem. Rev., 2004, 104, 1687.
7 G. W. Gokel, W. M. Leevy and M. E. Weber, Chem. Rev., 2004,
104, 2723.
8 X. Y. Fang, L. U. Feng, X. U. Z. Chao, C. T. Yu and Q. X. Hong,
Sci. China, Ser. B: Chem., 2009, 52, 771.
9 D. J. Waggoner, T. B. Bartnikas and J. D. Gitlin, Neurobiol. Dis.,
1999, 6, 221.
10 C. Vulpe, B. Evinson, S. Whitney, S. Packman and J. Gitschier,
Nat. Genet., 1993, 3, 7.
11 J. F. B. Mercer, Trends Mol. Med., 2001, 7, 64.
12 D. R. Brown and H. Kozlowski, Dalton Trans., 2004, 1907.
13 Y. Inoue and G. W. Gokel, Cation Binding by Macrocycles:
Complexation of Cationic Species by Crown Ethers, M. Dekker,
New York, 1990.
14 A. P. De Silva, H. Q. N. Gunaratne, T. Gunnlaugsson, A. J. M.
Huxley, C. P. McCoy, J. T. Rademacher and T. E. Rice, Chem.
Rev., 1997, 97, 1515.
32 Verlagder Zeitschrift fur Naturforschung, Tubingen! http//www.
znaturforsch.com.
¨
¨
33 S. Memon and M. Yilmaz, J. Mol. Struct., 2001, 595, 101.
34 S. Memon and M. Yilmaz, Sep. Sci. Technol., 2001, 36, 473.
35 S. Memon and M. Yilmaz, React. Funct. Polymers, 2000, 44, 227.
36 S. B. Maamar, N. Jadambaa, F. Vocanson, F. Meganem, C. Felix
and I. Dumazet-Bonnamour, Supramol. Chem., 2009, 21, 450.
37 H. Irving and R. J. P. Williams, Nature, 1948, 162, 746.
38 T. L. Kao, C. C. Wang, Y. T. Pan, Y. J. Shiao, J. Y. Yen,
C. M. Shu, G. H. Lee, S. M. Peng and W. S. Chaung, J. Org.
Chem., 2005, 70, 2912.
39 T. C. Kram and I. S. Lurie, Forensic Sci. Int., 1992, 55, 131.
40 S. F. Lim, Y.-M. Zheng, S.-W. Zou and J. P. Chen, Environ. Sci.
Technol., 2008, 42, 2551.
41 C. J. Pedersen, Ionic complexes of macrocyclic polyethers, Fed.
Proc., 1968, 27, 1305.
15 Q. L. Ma, H. M. Ma, Z. H. Wang, M. H. Su, H. Z. Xiao and
S. C. Liang, Chem. Lett., 2001, 100.
16 C. D. Gutsche, in Calixarenes Revisited, Monographs in Supra-
molecular Chemistry, ed. J. F. Stoddart, RSC, Cambridge, 1998.
17 V. Bohmer and J. Vicens, Calixarenes: A Versatile Class of
Macrocyclic Compounds, Kluwer Academic Publishers, Dordrecht,
1991.
42 H. Deligoz and M. Yilmaz, Solvent Extr. Ion. Exch., 1995, 13, 19.
¨
43 D. C. Harris, Quantitative Chemical Analysis, W. H. Freeman and
Co., New York, 4th edn, 1995.
18 V. Bohmer, Angew. Chem., Int. Ed. Engl., 1995, 34, 713.
c
2586 New J. Chem., 2010, 34, 2579–2586 This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010