Solvent extraction of alkali metals by di-ionizable nano-baskets

Article abstract of DOI:10.1080/00958972.2011.635790

The competitive solvent extractions of alkali metals by nano-baskets of di-ionizable calix[4]arenes were studied using nine scaffolds and 34 calix[4]arene derivatives. The objective of this work is to assess the effect of changing the pendant groups as well as variation of macrocycle conformation, orientation, and position of pendant moieties upon the extraction efficiency, selectivity, and pH_1/2 of calix[4]arene complexes. Alkali metal cations were extracted from aqueous solutions into chloroform by di-ionizable calix[4]arene derivatives and were measured using ion chromatography. The results revealed that alternation of aryl group in the pendant moieties, changing their orientation from cis- to trans- as well as ortho-to paraanalogues revealed no changes in the selectivity, extraction efficiency and pH _1/2 of calix[4]arene complexes. Alternation of ring conformation (cone, 1,2-alternate, and partial-cone) showed a pronounced influence upon the complexation of alkali metal cations.

Full text of DOI:10.1080/00958972.2011.635790

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Solvent extraction of alkali metals by
di-ionizable nano-baskets
Bahram Mokhtari a & Kobra Pourabdollah a
a Department of Chemical Engineering , Shahreza Branch, Islamic
Azad University , Shahreza , Iran
Published online: 14 Nov 2011.
To cite this article: Bahram Mokhtari & Kobra Pourabdollah (2011) Solvent extraction of alkali
metals by di-ionizable nano-baskets, Journal of Coordination Chemistry, 64:23, 4029-4053, DOI:
10.1080/00958972.2011.635790
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Journal of Coordination Chemistry
Vol. 64, No. 23, 10 December 2011, 4029–4053
Solvent extraction of alkali metals by
di-ionizable nano-baskets
BAHRAM MOKHTARI and KOBRA POURABDOLLAH*
Department of Chemical Engineering, Shahreza Branch, Islamic
Azad University, Shahreza, Iran
(Received 4 March 2011; in final form 14 October 2011)
The competitive solvent extractions of alkali metals by nano-baskets of di-ionizable
calix[4]arenes were studied using nine scaffolds and 34 calix[4]arene derivatives. The objective
of this work is to assess the effect of changing the pendant groups as well as variation of
macrocycle conformation, orientation, and position of pendant moieties upon the extraction
efficiency, selectivity, and pH1/2 of calix[4]arene complexes. Alkali metal cations were extracted
from aqueous solutions into chloroform by di-ionizable calix[4]arene derivatives and were
measured using ion chromatography. The results revealed that alternation of aryl group in the
pendant moieties, changing their orientation from cis- to trans- as well as ortho- to para-
analogues revealed no changes in the selectivity, extraction efficiency and pH1/2 of calix[4]arene
complexes. Alternation of ring conformation (cone, 1,2-alternate, and partial-cone) showed a
pronounced influence upon the complexation of alkali metal cations.
Keywords: Nano-basket; Solvent extraction; Calixarene; Conformation; Alkali metals
1. Introduction
Nano-baskets of calixarenes are a versatile class of macrocycles, which have been
subject to extensive research in the development of many extractants [1, 2], transporters
[3], stationary phases (using gas chromatograph, Teif Gostar Faraz Co.) [4], electrode
ionophores, and optical and electrochemical sensors [5] over the past four decades. In
the nineteenth century, Baeyer synthesized calixarenes via the reaction of formaldehyde
with p-substituted phenols in basic or acidic environment [6, 7]. However, the limited
analytical methods and instruments at that time were unable to interpret the structure
of the newly synthesized products. In the 1940s, Zinke and Ziegler discovered that the
products possessed cyclic tetrameric structures [8]. In 1975, Gutsche introduced the
presently accepted name of calixarene [9, 10]. New advances in the field of metal
extraction by calixarenes led to introducing ionizable moieties and crown ethers in their
scaffolds. The ionizable moieties not only participate in cooperative metal ion
coordination, but also eliminate the need to transfer the anions from the aqueous
phase into the organic phase by operating in a cation-exchange mode with the metal
cation [11]. Introducing the crown ether ring on the lower rims not only increases the
*Corresponding author. Email: pourabdollah@iaush.ac.ir
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2011 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2011.635790

4030
B. Mokhtari and K. Pourabdollah
cation binding ability of the calixarenic scaffold but also enhances the selectivity
through modulation of the crown ring size [12].
The small calixarenic cycles, calix[4]arene, possess a bowl-shaped conformation [13]
and those with pendent proton-ionizable groups, such as carboxylic acid [14],
phosphinoyl [15], N-(X)-sulfonyl carboxamide [16], and hydroxyamic acid [17] have
been utilized for solvent extraction of metal cations. Ionizable calixarenes are more
efficient in metal cation separation than non-ionizable analogs owing to charge
matching within the resulted complex in the organic phase. The metal cations are
transferred to the organic phase due to the production of a neutral complex. Different
complexing groups at the upper-rim of calixarenes attract with predefined selectivity,
while the lower rim moieties are usually responsible for physical properties of
calixarenes [2].
Alkyl groups larger than ethyl introduced to the lower-rim effectively fix the
calix[4]arene conformation [18]. Smirnov et al. [19] synthesized tetradiethylamideca-
lix[4]arene that exhibited excellent efficiency toward alkaline earth metals. They
reported the better binding ability of tetraamide derivatives than ester and ketone
analogs owing to their carbonyl groups (more basic), which significantly enhances the
strength of metal ion-functional group interaction. Calix[4]arene tetrathioamides are
efficient extractants for silver picrate, while they show low extraction levels for Cd2þ
,
Co2þ, Cu2þ, alkali, and alkaline earth metal picrates [20]. Calixarenes bearing
carboxylic acids were found to be much more efficient interphase carriers for alkaline
earth metals than related unfunctionalized calixarenes with phenolic groups on the
lower-rim [21]. An example of the use of a calixarene with two proton-ionizable groups
in a divalent metal ion separation is the exclusive extraction of calcium from an aqueous
solution (containing four alkaline earth metal nitrate species) at pH ¼ 5.3 into
chloroform by calix[4]arene dicarboxylic acid diamide [22].
Calixarenes are used not only for cation receptors but also for binding to anions.
In the design of neutral calixarene anion receptors, several different hydrogen bonding
groups (such as urea and thiourea) have been incorporated in upper and lower
rim frameworks. Scheerder and coworkers showed a high binding capacity for chloride
and bromide in CDCl3 with 1 : 1 stoichiometry [23]. Morzherin et al. [24] synthesized
upper-rim functionalized sulphonamide receptor. Increased polarity of N–H bonds by
electron-withdrawing SO2 group resulted in stronger hydrogen bonds with anions.
This receptor displayed remarkable selectivity for hydrogen sulfate over other anions in
CDCl3.
In solvent extraction, two immiscible liquid phases are mixed with the calixarene as
extractant in the organic phase and a stripping aqueous acidic solution is used in the
back extraction. The metal cation extracted by the calixarene ligands are analyzed
quantitatively in the aqueous phase after back extraction [25]. Different analytical
methods such as atomic absorption, inductively coupled plasma spectroscopy, UV-Vis,
and ion chromatography [26–28] are routinely used to determine the metal cation
concentrations after back extraction. The loading percentage is equal to the ratio of the
extracted amount of metal cation over the initial macrocycle concentration in the
organic phase.
In this article, the competitive solvent extractions of alkali metal cations from
aqueous solutions into chloroform by di-ionizable calix[4]arene derivatives are studied.
In nine scaffolds, 34 calix[4]arene derivatives were used to assess the effect of changing
pendant groups as well as variation of isoconformations (conformation, orientation,

Di-ionizable nano-baskets
4031
and position) upon the extraction parameters including extraction efficiency, selectivity,
and pH1/2 of complexes. The results will show the rank of the above-mentioned
variables upon the extraction parameters. Such sequential ranks will be used to predict
the extraction behavior of calixarene scaffolds before synthesis and extractions.
Moreover, using those ranks it is possible to optimize the extraction parameters by
modification of chemical structures during the synthesis steps.
2. Materials and methods
2.1. Materials and standard solutions
Sodium chloride and potassium chloride (99%) were purchased from Mallinckrodt.
Lithium chloride, rubidium chloride, and cesium chloride (99%) were obtained from
Alfa Aesar. Lithium hydroxide was purchased from Fisher Scientific, 1.0 N hydrochlo-
ric acid from J.T. Baker, chloroform from EM Science, and 2.0 N sulfuric acid from
Mallinckrodt. The chloroform was shaken with deionized water to remove the
stabilizing ethanol and stored in the dark. All of the experiments were carried out using
four derivatives of di-ionizable p-tert-calix[4]arene di-[N-(phenyl)sulfonyl carboxa-
mide], di-ionizable p-tert-calix[4]arene di-[N-(para-hydroxy phenyl)sulfonyl carboxa-
mide], di-ionizable of p-tert-calix[4]arene di-[N-(para-nitro phenyl)sulfonyl
carboxamide], and di-ionizable of p-tert-calix[4]arene di-[N-(para-methyl phenyl)sulfo-
nyl carboxamide].
2.2. Synthesis of di-ionizable calix[4]arenes
Two conformers for each four of di-ionizable cone derivatives (01–04 and 05–08), three
conformers for each four of di-ionizable 1,2-alternate derivatives (09–12, 13–16, and
17–20), and four conformers for each four of the partial-cone (21–24, 25–28, 29–31, and
32–34) conformations were synthesized as discussed before. The cis/trans symbols refer
to the direction of two di-ionizable moieties and the ortho/para depict the relative
situation of two di-ionizable moieties. Figure 1 depicts the chemical structure of two
cone conformations, three 1,2-alternate conformations, and four partial-cone
conformations of calix[4]arene derivatives.
2.3. Sample preparation
The alkali metal cations were loaded into the aqueous solutions by adding stock
solutions containing five alkali metal cations, 20.0 mmol Lꢀ1 lithium chloride solution,
and 20.0 mmol Lꢀ1 lithium hydroxide solution. The solutions of alkali metal cations
were made up as lithium, sodium, potassium, rubidium, and cesium chloride solutions
(20.0 mmol Lꢀ1 in each). The pH values of the aqueous phases were adjusted using
20.0 mmol Lꢀ1 lithium hydroxide and 0.01–1.0 mol Lꢀ1 hydrochloric acid solutions.
Extraction abilities of eight distinct dangling moieties were examined on five
conformation of calix[4]arene scaffold, in 13 solutions with pH range of 1.0–12.0. For
each macrocyclic ligand, 13 solutions for competitive solvent extraction of alkali metal

4032
B. Mokhtari and K. Pourabdollah
Figure 1. The structure of conformers investigated. R was defined as: –NHSO2phenyl; –NHSO2
(p-CH3phenyl); –NHSO2(p-OHphenyl); –NHSO2(p-NO2phenyl).
cations were prepared in 15 mL conical polypropylene centrifuge tubes. The samples
contained 2.0 mL of the aqueous phase of 10.0 mmol Lꢀ1 alkali metal cations solution
and 2.0 mL of 1.00 mmol Lꢀ1 macrocyclic ligand solution in chloroform.
2.4. Extraction procedure
The combined aqueous and organic phases were shaken for 5 min and centrifuged for
5 min. The pH of the aqueous phase was measured using a pH meter with a Corning
476,157 combination pH electrode. In the stripping step, 1.5 mL of the organic phase
was transferred to a capped conical centrifuge tube containing 3.0 mL of 0.10 mol Lꢀ1
HCl. The stripping involved 5 min of mixing and 5 min centrifuging. After that, 1.0 mL
of the aqueous phase was diluted to 10.0 mL for analysis by ion chromatography.
2.5. Ion chromatographic analysis
Determination of alkali metal cation was accomplished by Dionex DX-120 ion
chromatographs with a CS12A column, a conductivity detection and membrane
suppression. The eluent was 0.011 mol Lꢀ1 sulfuric acid after filtration through a
millipore 0.22 mm filtration membrane, while the pump flow rate at 1700 psi was about
1 mL minꢀ1. To obtain a stable baseline, the eluent was flowed through the column for
60 min and then, 2.0 mL of standard solutions were injected; they were repeated twice.

Di-ionizable nano-baskets
4033
3. Results and discussion
The results of complexation ability for the cone, the 1,2-alternate, and the partial-cone
conformations of calix[4]arene derivatives are discussed. The cone conformers in two
categories of trans-cone and cis-cone isomers are discussed first, followed by presenting
the results of three isomers of 1,2-alternate conformer including cis-1,2-alternate, ortho-
trans-1,2-alternate, para-trans-1,2-alternate. In the last section, four isoconformers of
ortho-cis partial-cone, para-cis partial-cone, ortho-trans partial-cone, and para-trans
partial-cone are considered. The identities of the dangling proton-ionizable moieties
affect the acidity of macrocycle derivatives and their ability to extract alkali metal
cations. Hence, the pH for half loading, which is defined as pH1/2, is used to measure
qualitatively the ligand acidity.
3.1. Two cone conformations
The total loadings of metal : macrocycle complexes were determined by the sum of
individual complexes toward each cation and were calculated to be about 200%, which
depict a 2 : 1 ratio of metal:macrocycle and was expected for the complexation of di-
ionizable calixarenes toward monovalent cations. The extraction characteristics of cone
isoconformers (ortho-cone and para-cone) are discussed in this section.
3.1.1. ortho-Cone isoconformers. For all four of the ortho-cone di-ionizable p-tert-
butylcalix[4]arenes 01–04, the maximum loadings were in the range of 179–197%.
In derivatives 01–04, the pH1/2 values were computed as 7.2, 7.8, 7.7, and 7.2,
respectively. The results of competitive solvent extractions by ligand derivatives 01–04
in chloroform are presented in the upper row of figure 3. Because of the selective 1 : 1
binding of Naþ with the ionizable moieties and unselective binding of other alkali
cations with those moieties, the selectivity order for calix[4]arene derivatives 01–04 at
pH ꢁ 8.0 was determined to be Rbþ, Csþ, Kþ 5 Liþ ꢂ Naþ; all maximum Naþ
loadings exceed 100%. This macrocycle presented a Naþ/Liþ selectivity of 4 under
conditions of high loading. This reveals that the binding of different alkali metal cation
species by this derivative was influenced by the pH and the identity of the dangling
proton-ionizable moieties. According to figure 2, for derivative 01, the amount of Liþ
extracted increased to its maximum loading at pH of 7.5, and then diminished as the pH
increased.
3.1.2. para-Cone isoconformers. For all four of the para-cone di-ionizable p-tert-
butylcalix[4]arenes 05–08, the maximum loadings were in the range of 197–224%.
In derivatives 05–08, the pH1/2 values were determined as 7.5, 8.0, 7.7, and 7.2,
respectively. The results of competitive solvent extractions by ligand derivatives 05–08
in chloroform are depicted in the lower row of figure 2. Owing to selective 1 : 1 binding
of Naþ with the ionizable moieties and unselective binding of other alkali cations with
those moieties, the selectivity order for calix[4]arene derivatives 05–08 at pH ꢁ 7.5 was
determined to be Kþ, Rbþ, Csþ 5 Liþ ꢂ Naþ and all maximum Naþ loadings exceed
100%. This macrocycle presented a Naþ/Liþ selectivity of 4 under conditions of high

4034
B. Mokhtari and K. Pourabdollah
Figure 2. Competitive solvent extractions of alkali metal cations by ortho-cone isoconformers 01–04 (upper
row) and para-cone isoconformers 05–08 (lower row).
loading. According to figure 2, for derivatives 05 and 08, the amount of Liþ extracted
increased to its maximum loading at pH of 8.5 and 8.0.
3.2. Three 1,2-alternate conformations
The total loading of metal : macrocycle complexes were determined to be about 230%,
which depict 2 : 1 and 3 : 1 ratios for cis- and trans-1,2-alternate conformers,
respectively. In the following, the extraction characteristics of cis-, ortho-trans, and
para-trans-1,2-alternate isoconformers are discussed.
3.2.1. cis-1,2-alternate isoconformers. The results of competitive solvent extractions
by ligand derivatives 09–12 in chloroform are presented in the upper row of figure 3.
For all four di-ionizable cis-1,2-alternate p-tert-butylcalix[4]arenes 09–12, the maximum
loadings were in the range of 150–183%. In derivatives 09–12, the pH1/2 values were
computed as 6.8, 6.8, 7.0, and 6.7, respectively. Because of the selective 1 : 1 binding of
Naþ with the ionizable moieties and unselective binding of other alkali cations with
those moieties, the selectivity order for calix[4]arene derivatives 09–12 at pH ꢁ 7.0 was
determined to be Liþ, Naþ, Csþ 5 Rbþ ꢂ Kþ and all maximum Kþ loadings
exceed 60%. This macrocycle presented a Naþ/Liþ selectivity of 2 under conditions
of high loading.
3.2.2. ortho-trans-1,2-Alternate isoconformers. For all four of the ortho-trans-1,2-
alternate di-ionizable p-tert-butylcalix[4]arenes 13–16, the maximum loadings were in
the range of 241–284%. In derivatives 13–16, the pH1/2 values were computed as 6.7,
6.7, 6.7, and 6.6, respectively. The results of competitive solvent extractions by ligand
derivatives 13–16 in chloroform are presented in the middle row of figure 3. Owing to
the unselective binding of all alkali metal cations with the moieties, the low selectivity

Di-ionizable nano-baskets
4035
Figure 3. Competitive traces for solvent extractions of alkali metal cations by 1,2-alternate isoconformers.
order for calix[4]arene derivatives 13–16 at pH ꢁ 7.5 was determined to be Liþ 5 Naþ,
Csþ 5 Kþ 5 Rbþ and all maximum Rbþ loadings exceed 80%. This macrocycle
presented a Rbþ/Kþ selectivity of 1.5 in derivative 13 under conditions of high loading.
According to figure 3, for derivatives 15 and 16, the amount of Kþ extract increased to
its maximum loading at pH of 9.0 and then diminished as the pH increased.

4036
B. Mokhtari and K. Pourabdollah
Figure 3. Continued.
3.2.3. para-trans-1,2-Alternate isoconformers. For all four of the para-trans-1,2-
alternate di-ionizable p-tert-butylcalix[4]arenes 17–20, the maximum loadings were in
the range of 240–294%. In derivatives 17–20, the pH1/2 values were computed as 7.0,
6.9, 7.0, and 6.9, respectively. The results of competitive solvent extractions by ligand

Di-ionizable nano-baskets
4037
derivatives 17–20 in chloroform are presented in the lower row of figure 3. Due to the
unselective binding of all alkali metal cations with the di-ionizable moieties, the poor
selectivity order for calix[4]arene derivatives 17–20 at pH ꢁ 8.0 was determined to be as
Liþ 5 Naþ, Csþ 5 Kþ 5 Rbþ and all maximum Rbþ loadings exceed 80%. This
macrocycle showed a Rbþ/Kþ selectivity of 1.5 for 17 under conditions of high loading.
3.3. Four partial-cone conformations
The total loading of metal : macrocycle complexes were determined to be about 90%
and 20% for cis- and trans-isomers of partial-cone conformers, respectively. This depict
a 1 : 1 ratio of metal:macrocycle and was expected for the complexation of di-ionizable
calixarenes toward monovalent cations. The extraction characteristics of partial-cone
isoconformers (cis- and trans-) are discussed in the following.
3.3.1. ortho-cis Partial-cone isoconformers. For all four of the ortho-cis partial-cone
di-ionizable p-tert-butylcalix[4]arenes 21–24, the maximum loadings were 57–115%. In
derivatives 21–24, the pH1/2 values were computed as 8.1, 7.8, 7.9, and 7.8, respectively.
The results of competitive solvent extractions by ligand derivatives 21–24 in chloroform
are presented in the first row of figure 4. The unselective binding of alkali metal cations
with the ligand shows no selectivity for calix[4]arene derivatives 21–24. All maximum
Naþ loadings exceed 25%.
3.3.2. para-cis Partial-cone isoconformers. For all four of the para-cis partial-cone di-
ionizable p-tert-butylcalix[4]arenes 25–28, the maximum loadings were in the range of
59–112%. In derivatives 25–28, the pH1/2 values were computed as 7.8, 7.5, 7.6, and 7.8,
respectively. The results of competitive solvent extractions by ligand derivatives 25–28
in chloroform are presented in the second row of figure 4. Using this macrocycle, all
maximum Naþ loadings exceed 25% and there is poor selectivity toward the cations.
3.3.3. ortho-trans Partial-cone isoconformers. The di-ionizable ortho-trans partial-
cone p-tert-butylcalix[4]-arenes with di-[N-(para-nitro phenyl)sulfonyl carboxamide]
moieties could not be synthesized. For all three of the ortho-trans partial-cone 29–31,
the maximum loadings were in the range of 17–24%. In derivatives 29–31, the pH1/2
values were computed as 8.3, 8.6, and 8.1, respectively. The results of competitive
solvent extractions by ligand derivatives 29–31 in chloroform are presented in the third
row of figure 4. These derivatives did not show any binding tendency toward Csþ and
Rbþ. Due to the selective 1 : 1 binding of Kþ with the ionizable moieties and unselective
binding of other alkali cations, the selectivity order for calix[4]arene derivatives 29–31 at
pH ꢁ 8.0 was determined to be Liþ 5 Naþ 5 Kþ and all maximum Kþ loadings exceed
12%. This macrocycle presented a Kþ/Liþ selectivity of 3, Kþ/Naþ selectivity of 2, and
Naþ/Liþ selectivity of 1.5 under conditions of high loading. This reveals that the
binding of different alkali metal cations by this derivative was influenced by the pH and
the identity of the dangling proton-ionizable moieties.

4038
B. Mokhtari and K. Pourabdollah
Figure 4. Solvent extractions of alkali metal cations by partial-cone isoconformers.

Di-ionizable nano-baskets
4039
Figure 4. Continued.
3.3.4. para-trans Partial-cone isoconformers. The third derivative with di-[N-(para-
nitro phenyl)sulfonyl carboxamide] moiety could not be synthesized. For all three of the
para-trans partial-cone di-ionizable p-tert-butylcalix[4]arenes 32–34, the maximum
loadings were 17–22%. In derivatives 32–34, the pH1/2 values were 8.6, 8.6, and 8.1,
respectively. The results of competitive solvent extractions by ligand derivatives 32–34
in chloroform are presented in the fourth row of figure 4. These derivatives did not
show any binding tendency toward Rbþ and Csþ. Owing to the selective 1 : 1 binding of
Kþ with the ionizable moieties and unselective binding of other alkali cations, the
selectivity order for calix[4]arene derivatives 32–34 at pH ꢁ 8.0 was determined to be
Liþ 5 Naþ 5 Kþ; all maximum Kþ loadings exceed 12%. This macrocycle presented
the Kþ/Liþ, Kþ/Naþ, and Naþ/Liþ selectivities of 3, 2, and 1.5 under high loading
conditions, respectively.
3.4. Analysis of variables
The effect of different substitutions in the pendant groups as well as different
isoconformations (conformation, orientation, and position) of di-ionizable calix[4]arene
derivatives on the sensitivity (extraction efficiency), selectivity, and pH1/2 values of five
alkali metal cations were determined and compared. Based upon the results, alternation
of aryl group in the pendant moieties, changing their orientation from cis- to trans- as
well as ortho- to para-analogs revealed no changes in the selectivity of macrocyclic
ligands. Besides, the cone conformers were selective to sodium cations and the 1,2-
alternate conformers showed a relative selectivity to potassium and rubidium cations.
The partial-cone conformers were selective to potassium and to one of the lithium or
sodium cations.

4040
B. Mokhtari and K. Pourabdollah
Alternation of aryl group in the pendant moieties showed no changes in the
extraction efficiency of macrocyclic ligands. The lower extraction efficiency of partial-
cone conformers than their 1,2-alternate and cone analogues demonstrated that
conformation variation had a pronounced influence upon complexation of alkali metal
cations. The 1,2-alternate conformers showed the widest range of extraction efficiency,
which was 4 and 2 times of partial-cone and cone analogues. The extraction efficiency
of cis-isomers than their trans-analogues revealed that orient variation of pendant
moieties had a pronounced influence upon the complexation of alkali metal cations.
The cis-isomers presented a middle range of extraction efficiency, while the extraction
efficiency for trans-analogs was too much high or too much low. The percent
of loading, which is related to the sensitivity of extraction method, was compared in
ortho-isomers and their para-analogues. The results depicted that the variation in
position of pendant moieties can have a pronounced influence on the extraction
efficiency of alkali metal cations. The percent of loading in ortho-isomers was equal and
lower than that of para-analogues.
Replacement of aryl group in the pendant moieties as well as changing from ortho- to
para-analogues showed no changes in the pH1/2 of the resulting complex. The lower
pH1/2 of 1,2-alternate conformers than their cone and partial-cone analogues
demonstrated that conformation variation had a pronounced influence upon the
complexation of alkali metal cations. The partial-cone conformers showed the widest
range of pH1/2 from 7.5 to 8.7, while this range in cone and 1,2-alternate conformers
were determined to be 7.7–8.0 and 6.6–7.0, respectively. The pH1/2 in cis-isomers than
their trans-analogs revealed that orient variation of pendant moieties had an influence
upon the complexation of alkali metal cations. The cis-isomers presented a middle
range of 7.0 5 pH1/2 5 8.0, while in the trans-analogs it was in pH1/2 5 7.0 or
pH1/2 4 8.0.
The selectivity of macrocycles 01–34 toward alkali metals was systematically
investigated with respect to the orientation and position of pendant moieties as well
as the functional groups on the pendant chains. Based upon the results, the cone
conformations were selective toward Naþ, while the 1,2-atlernate conformers showed
two distinct selectivities for cis- (toward Kþ) and trans- (toward Rbþ) isomers.
Likewise, the partial-cone conformers showed two selectivities for cis- (toward Naþ)
and trans- (toward Kþ) isomers.
4. Experimental
4.1. Characteristics of the reaction products
4.1.1. Synthesis of ortho-cone conformers (01–04). 5,11,17,23-Tetrakis(1,1-dimethy-
lethyl)-25,26-dihydroxy-27,28-di(1-propoxy)calix[4]arene has been synthesized by the
procedure reported here. 7.00 g (10.80 mmol) p-tert-butylcalix[4]arene was added to a
solution of DMSO (50 mL) and 40% aqueous NaOH (7.06 mL, 100.00 mmol). After
that, the mixture was warmed to 50ꢃC and 9.20 g (43.00 mmol) PrOTs was added. The
mixture was stirred for 24 h at 70ꢃC. After cooling to room temperature, the reaction
mixture was poured into a 5% aqueous HCl solution (100 mL). The crude product was
extracted with dichloromethane and the solution was dried over MgSO4. The

Di-ionizable nano-baskets
4041
dichloromethane was evaporated in vacuo and the residue was washed with MeOH to
give 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-dihydroxy-27,28-di(1-propoxy)calix[4]
arene (6.31 g, 88%) with m.p. 168–170ꢃC.
A mixture of THF (32 mL) and NaH (0.56 g, 22.19 mmol) was stirred and a solution
of THF (25 mL) and 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-dihydroxy-27,28-di(1-
propoxy)calix[4]arene (2.75 g, 3.70 mmol) was added dropwise. The solution was stirred
at room temperature under nitrogen for 3 h, and then ethyl bromoacetate (2.4 mL,
22.19 mmol) was added. The reaction mixture was refluxed for 24 h and was quenched
with 25 mL of 5% aqueous HCl. After evaporating the THF in vacuo, the residue was
allowed to cool to room temperature. The residue was washed with 5% HCl (150 mL)
and dichloromethane was used to extract 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-
bis[(ethoxycarbonyl)methoxy]-27,28-di(1-propoxy)calix[4]arene. The organic layer was
washed with water, dried over MgSO4, and evaporated in vacuo. The crude product was
recrystallized from MeOH to obtain 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-
bis[(ethoxycarbonyl)methoxy]-27,28-di(1-propoxy)calix[4]arene (2.72 g, 78%) as
white solid with m.p. 78–80ꢃC.
a
A
solution of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis[(ethoxycarbonyl)-
methoxy]-27,28-di(1-propoxy)calix[4]arene (3.54 mmol), 10% aqueous Me4NOH
(75 mL), and THF (75 mL) was refluxed for 24 h. The reaction mixture was cooled to
room temperature and was stirred with 6 N HCl (30 mL) for 2 h. After evaporating the
THF in vacuo, a white precipitate was filtered and dissolved in CH2Cl2 (75 mL). The
aqueous filtrate was extracted with CH2Cl2 (2 ꢄ 75 mL). The combined organic layers
were washed with 6 N aqueous HCl until pH ¼ 1 and dried over MgSO4. The
dichloromethane was evaporated in vacuo to give 5,11,17,23-tetrakis(1,1-dimethy-
lethyl)-25,26-bis(carboxymethoxy)-27,28-di(1-propoxy)calix[4]arene (3.40 g, 96% yield)
as a white solid with m.p. 169–171ꢃC.
4.1.1.1. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis(N-phenylsulfonyl
carbamoylmethoxy)-27,28-di(1-propoxy)calix[4]arene (01). A solution of 5,11,17,
23-tetrakis(1,1-dimethylethyl)-25,26-bis(chlorocarboxymethoxy)-27,28-di(1-propoxy)
calix[4]arene in THF (10 mL) was added to a mixture containing NaH (0.58 g,
24.0 mmol) and 9.50 mmol of phenyl sulfonamide in 100 mL THF, and the mixture was
stirred under nitrogen for 6 h at room temperature. Then 2 mL H2O was added to
decompose the excess NaH and the THF was evaporated in vacuo and 200 mL CH2Cl2
was added to the residue. The organic layer was washed with 200 mL 1N HCl and
water, and was dried over MgSO4 and was evaporated in vacuo to give the crude di-
ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2, washed
with 10% aqueous HCl and water, and dried over MgSO4. The solution was evaporated
in vacuo to give the derivative 01. Product 01 was obtained in 90% yield after
chromatography on silica gel with CH2Cl2–MeOH (80 : 1) as eluent. White solid; m.p.
1
130–142ꢃC; ꢀmax (film) (cmꢀ1): 3240 (NH), 1724 (C¼O), 1360 and 1188 (S¼O); H
NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.00–4.28 (br m, 26H), 6.22–7.32 (br
m, 8H), 7.68 (t, J ¼ 7.52, 4H), 7.82 (t, J ¼ 7.42, 2H), 7.98 (d, J ¼ 7.52, 4H), 9.32 (br s, 2H);
13C NMR (CDCl3): ꢁC 171.20, 171.00, 155.68, 153.70, 144.50, 138.12, 133.90, 132.60,
129.02, 128.20, 125.80, 72.88, 60.22, 33.88, 33.12, 33.14, 31.82, 31.04, 25.30; Anal. Calcd
C66H82N2O10S2: C, 70.30; H, 7.36; N, 2.42. Found: C, 70.20; H, 7.28; N, 2.52.

4042
B. Mokhtari and K. Pourabdollah
4.1.1.2. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis[N-(4-methylphe-
nyl)sulfonyl carbamoylmethoxy]-27,28-di(1-propoxy)calix[4]arene (02). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis(chlorocarboxymethoxy)-27,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 24.0 mmol (3.04 g)
oxalyl chloride was added and the reaction mixture was refluxed for 4 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in 10 mL THF was added to a mixture of
9.60 mmol (p-methyl)phenyl sulfonamide and 0.58 g NaH (24.0 mmol) in 100 mL THF,
and the mixture was stirred under nitrogen for 4 h at room temperature. H2O (2 mL)
was added to decompose the excess NaH. The THF was evaporated in vacuo and
200 mL CH2Cl2 was added to the residue. The organic layer was washed with 200 mL
HCl (1N) and water, dried over MgSO4, and evaporated in vacuo to give the
di-ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2,
washed with 10% aqueous HCl and water, and dried over MgSO4. The solution was
evaporated in vacuo to give product 02, which was obtained in 88% yield after
chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. White solid; m.p.
1
148–154ꢃC; ꢀmax (film) (cmꢀ1): 3254 (NH), 1720 (C¼O), 1342 and 1188 (S¼O); H
NMR (CDCl3): ꢁ 0.98 (br s, 18H), 1.24 (br s, 18H), 2.08–4.16 (br m, 32H), 6.50–7.10
(br m, 8H), 8.22 (d, J ¼ 4.76, 4H), 8.32 (d, J ¼ 4.68, 4H), 9.38 (br s, 2H); 13C NMR
(CDCl3): ꢁC 174.42, 170.62, 152.62, 150.82, 144.42,143.68, 134.26, 132.48, 129.32,
125.84, 124.66, 34.24, 33.42, 33.12, 31.28, 31.04, 25.26, 21.28; Anal. Calcd
C68H86N2O10S2 ꢅ 0.1CH2Cl2: C, 65.12; H, 7.38; N, 4.52. Found: C, 65.24; H, 7.28;
N, 4.62.
4.1.1.3. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis[N-(4-hydroxyphe-
nyl)sulfonyl carbamoylmethoxy]-27,28-di(1-propoxy)calix[4]arene (03). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis(chlorocarboxymethoxy)-27,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 24.0 mmol (3.04 g)
oxalyl chloride was added and the reaction mixture was refluxed for 5 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in 10 mL THF was added to a mixture of
9.60 mmol (4-hydroxy)phenyl sulfonamide and 0.58 g NaH (24.0 mmol) in 100 mL
THF, and the mixture was stirred under nitrogen at room temperature for 4 h. Then,
2 mL H2O was added to decompose the excess NaH. The THF was evaporated in vacuo
and 200 mL CH2Cl2 was added to the residue. The organic layer was washed with
200 mL HCl (1N) and water, dried over MgSO4, and evaporated in vacuo to give the
crude di-ionizable calix[4]arene. After purification, the product was dissolved in
CH2Cl2, washed with 10% aqueous HCl and water, and dried over MgSO4. The
solution was evaporated in vacuo to give product 03. Derivative 03 was obtained in 84%
yield after chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. White
solid; m.p. 170–176ꢃC; ꢀmax (film) (cmꢀ1): 3238 (NH), 1724 (C¼O), 1362 and 1168
1
(S¼O); H NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.08–4.04 (br m, 26H),
6.38–7.46 (br m, 8H), 7.62 (t, J ¼ 7.76, 4H), 8.02 (d, J ¼ 7.42, 4H), 8.54 (t, J ¼ 7.30, 2H),
9.44 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.38, 171.02, 155.06, 153.72, 144.18, 138.96,
133.32, 132.44, 129.20, 128.34, 125.28, 73.06, 60.08, 34.28, 33.96, 33.42, 31.14, 31.06,
22.27; Anal. Calcd C66H82N2O12S2: C, 70.66; H, 7.42; N, 2.44. Found: C, 70.28; H,
7.32; N, 2.40.

Di-ionizable nano-baskets
4043
4.1.1.4. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis[N-(4-nitrophe-
nyl)sulfonyl carbamoylmethoxy]-27,28-di(1-propoxy)calix[4]arene (04). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26-bis(chlorocarboxymethoxy)-27,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 3.04 g (24.0 mmol)
oxalyl chloride was added and the reaction mixture was refluxed for 7 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in 10 mL THF was added to a mixture of
12.20 mmol (4-nitro)phenyl sulfonamide and 28.8 mmol NaH (0.70 g) in 100 mL THF,
and the mixture was stirred under nitrogen at room temperature for 6 h. Then, 2 mL
H2O was added to decompose the excess NaH. The THF was evaporated in vacuo and
200 mL CH2Cl2 was added to the residue. The organic layer was washed with 1N HCl
(200 mL) and water, dried over MgSO4, and evaporated in vacuo to give the crude
di-ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2,
washed with 10% aqueous HCl and water, and dried over MgSO4. The solution was
evaporated in vacuo to give product 04, which was obtained in 68% yield after
chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. Yellow solid; m.p.
174–176ꢃC; ꢀmax (film) (cmꢀ1): 3232 (NH), 1704 (C¼O), 1358 and 1196 (S¼O);
1H NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.10–4.02 (br m, 26H), 6.32–7.48
(br m, 8H), 7.44 (t, J ¼ 7.08, 4H), 8.26 (d, J ¼ 7.38, 4H), 9.42 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.02, 171.24, 155.62, 153.24, 144.28, 138.82, 133.38, 132.66, 129.04,
128.48, 125.24, 73.20, 60.15, 34.40, 33.28, 33.00, 31.38, 31.10, 20.14; Anal. Calcd
C66H80N4O14S2: C, 70.16; H, 7.18; N, 4.48. Found: C, 70.26; H, 7.24; N, 4.52.
4.1.2. Synthesis of para-cone conformers (05–08). K2CO3 (82.93 g, 600 mmol) and
n-propyl p-toluensulfonate (12.85 g, 60.0 mmol) were added to the suspension of the
p-tert-butylcalix[4]arene (19.46 g, 30.0 mmol) in 200 mL of dry n-C3H7CN. The reaction
mixture was refluxed for 20 h and then another portion of n-propyl p-toluenesulfonate
(6.43 g, 30.0 mmol) was added. The mixture was heated for another 20 h. After cooling,
the reaction mixture was filtered and the solvent was evaporated in vacuo. The residue
was partitioned between 200 mL of CH2Cl2 and 200 mL of HCl (1N). The organic layer
was separated, washed with water, and evaporated in vacuo. The crude product was
purified by chromatography on silica gel column with CH2Cl2:hexanes (20 : 1) as eluent
to give 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-dihydroxy-26,28-di(1-propoxy)ca-
lix[4]arene (88%) as a white solid. The product was recrystallized from n-C3H7OH–
CH2Cl2 in 71% yield; m.p. 240–242ꢃC.
10 mmol of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-dihydroxy-26,28-di(1-pro-
poxy)calix[4]arene was added to the suspension of sodium NaH (0.96 g, 40 mmol) in
DMF (100 mL), and the mixture was stirred at room temperature. Once the evolution
of hydrogen ceased, a solution of ethyl bromoacetate (22 mmol) in DMF (10 mL) was
added over a period of 30 min. The mixture was stirred for 3 h, and another portion of
ethyl bromoacetate (10 mmol) in DMF (5 mL) was added. The reaction mixture was
stirred for another 2 h and the excess of NaH was carefully decomposed by dropwise
addition of water. The mixture was diluted with 200 mL HCl (1N) and was extracted
with CH2Cl2 (2 ꢄ 200 mL). The combined organic extracts were washed with water,
dried over MgSO4, and evaporated in vacuo. The DMF and the unreacted ethyl
bromoacetate were removed by distillation under vacuum (60ꢃC, 1 mm Hg). The
residual pale-yellow oil was purified by chromatography on silica gel with

4044
B. Mokhtari and K. Pourabdollah
hexanes:EtOAc (40 : 1) as eluent to give the final product 5,11,17,23-tetrakis(1,1-
dimethylethyl)-25,27-bis[(ethoxycarbonyl)methoxy]-26,28-di(1-propoxy)calix[4]arene in
80% yield as a white solid; m.p. 108–110ꢃC.
A
solution of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis[(ethoxycarbonyl)-
methoxy]-26,28-di(1-propoxy)calix[4]arene (5.0 mmol), THF (150 mL), and 10% aque-
ous Me4NOH (150 mL) was refluxed overnight. The reaction mixture was acidified with
HCl (10%) to pH ꢆ 1. The solvent was removed in vacuo and 200 mL CH2Cl2 was
added. The organic layer was washed with water, dried over MgSO4, and evaporated
in vacuo to give the final product 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(car-
boxymethoxy)-26,28-di(1-propoxy)calix[4]arene in 96% yield as a white solid;
m.p. 252–254ꢃC.
2.40 mmol of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(carboxymethoxy)-26,
28-di(1-propoxy)calix[4]arene was dried by benzene-azeotropic distillation. Oxalyl
chloride (3.04 g, 24.0 mmol) was added to the solution and the reaction mixture was
refluxed for 5 h under nitrogen atmosphere. The solvent was removed in vacuo to
provide the corresponding acid chloride 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-
bis(chlorocarboxymethoxy)-26,28-di(1-propoxy)calix[4]arene.
4.1.2.1. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(N-phenylsulfonyl
carbamoylmethoxy)-26,28-di(1-propoxy)calix[4]arene (05). A solution of 5,11,17,
23-tetrakis(1,1-dimethylethyl)-25,27-bis(chlorocarboxymethoxy)-26,28-di(1-propoxy)
calix[4]arene in THF (10 mL) was added to a mixture of the appropriate sulfonamide
(9.50 mmol) and NaH (0.58 g, 24.0 mmol) in THF (100 mL), and the mixture was stirred
under nitrogen at room temperature for 6 h. Then 2 mL H2O was carefully added to
decompose the excess NaH. The THF was evaporated in vacuo and CH2Cl2 (200 mL)
was added to the residue. The organic layer was washed with 200 mL HCl (1N) and
water, was dried over MgSO4, and was evaporated in vacuo to give the crude di-
ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2, washed
with 10% aqueous HCl and water, and dried over MgSO4. The solution was evaporated
in vacuo to give product 05. Derivative 05 was obtained in 86% yield after
chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. White solid; m.p.
136–140ꢃC; ꢀmax (film) (cmꢀ1): 3248 (NH), 1722 (C¼O), 1362 and 1186 (S¼O);
1H NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.04–4.22 (br m, 26H), 6.20–7.22
(br m, 8H), 7.50 (t, J ¼ 7.72, 4H), 7.59 (t, J ¼ 7.32, 2H), 8.07 (d, J ¼ 7.50, 4H), 9.48
(br s, 2H); 13C NMR (CDCl3): ꢁC 171.22, 171.02, 155.81, 153.72, 144.53, 138.15,
133.09, 132.60, 129.20, 128.02, 125.09, 72.98, 60.04, 33.96, 33.06, 33.44, 31.94, 31.02,
25.31; Anal. Calcd C66H82N2O10S2: C, 70.31; H, 7.33; N, 2.48. Found: C, 70.13; H,
7.23; N, 2.59.
4.1.2.2. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis[N-(4-methylphe-
nyl)sulfonyl carbamoylmethoxy]-26,28-di(1-propoxy)calix[4]arene (06). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(chlorocarboxymethoxy)-26,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 3.04 g (24.0 mmol)
oxalyl chloride was added and the reaction mixture was refluxed for 5 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in THF (10 mL) was added to a mixture of the
appropriate sulfonamide (9.60 mmol) and NaH (0.58 g, 24.0 mmol) in THF (100 mL),
and the mixture was stirred under nitrogen at room temperature for 5 h. Then, 2 mL

Di-ionizable nano-baskets
4045
H2O was added to decompose the excess NaH. The THF was evaporated in vacuo and
CH2Cl2 (200 mL) was added to the residue. The organic layer was washed with 1N HCl
(200 mL) and water, dried over MgSO4, and evaporated in vacuo to give the crude di-
ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2, washed
with 10% aqueous HCl and water, and dried over MgSO4. The solution was evaporated
in vacuo to give product 06. Derivative 06 was obtained in 84% yield after
chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. Yellow solid;
m.p. 144–148ꢃC; ꢀmax (film) (cmꢀ1): 3255 (NH), 1726 (C¼O), 1346 and 1180 (S¼O); 1H
NMR (CDCl3): ꢁ 0.98 (br s, 18H), 1.24 (br s, 18H), 2.06–4.20 (br m, 32H), 6.52–7.12 (br
m, 8H), 8.27 (d, J ¼ 4.80, 4H), 8.30 (d, J ¼ 4.82, 4H), 9.35 (br s, 2H); 13C NMR (CDCl3):
ꢁC 174.32, 170.82, 152.66, 150.28, 144.96,143.08, 134.52, 132.80, 129.08, 125.68, 124.02,
34.20, 33.76, 33.48, 31.46, 31.22, 25,62, 21.50; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.16; H, 7.33; N, 4.50. Found: C, 65.22; H, 7.24; N, 4.42.
4.1.2.3. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis[N-(4-hydroxyphe-
nyl)sulfonyl carbamoylmethoxy]-26,28-di(1-propoxy)calix[4]arene (07). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(chlorocarboxymethoxy)-26,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 3.04 g (24.0 mmol)
oxalyl chloride was added and the reaction mixture was refluxed for 5 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in THF (10 mL) was added to a mixture of the
appropriate sulfonamide (9.60 mmol) and NaH (0.58 g, 24.0 mmol mmol) in THF
(100 mL), and the mixture was stirred under nitrogen at room temperature for 5 h.
Then, 2 mL H2O was added to decompose the excess NaH. The THF was evaporated
in vacuo and CH2Cl2 (200 mL) was added to the residue. The organic layer was washed
with 1N HCl (200 mL) and water, dried over MgSO4, and evaporated in vacuo to give
the crude di-ionizable calix[4]arene. After purification, the product was dissolved in
CH2Cl2, washed with 10% aqueous HCl and water, and dried over MgSO4. The
solution was evaporated in vacuo to give product 07. Derivative 07 was obtained in 84%
yield after chromatography on silica gel with CH2Cl2:MeOH (80 : 1) as eluent. White
solid; m.p. 166–170ꢃC; ꢀmax (film) (cmꢀ1): 3244 (NH), 1720 (C¼O), 1360 and 1180
1
(S¼O); H NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.04–4.24 (br m, 26H),
6.30–7.42 (br m, 8H), 7.60 (t, J ¼ 7.66, 4H), 8.26 (d, J ¼ 7.40, 4H), 8.28 (t, J ¼ 7.30, 2H),
9.96 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.20, 171.04, 155.14, 153.74, 144.48, 138.12,
133.10, 132.44, 129.22, 128.32, 125.22, 73.04, 60.04, 34.00, 33.02, 33.42, 31.96, 31.04,
22.18; Anal. Calcd C66H82N2O12S2: C, 70.22; H, 7.24; N, 2.40 Found: C, 70.12;
H, 7.18; N, 2.55.
4.1.2.4. Synthesis of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis[N-(4-nitrophe-
nyl)sulfonyl carbamoylmethoxy]-26,28-di(1-propoxy)calix[4]arene (08). 2.40 mmol
of 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(chlorocarboxymethoxy)-26,28-di(1-
propoxy)calix[4]arene was dried by benzene-azeotropic distillation. 3.04 g (24.0 mmol)
oxalyl chloride was added and the reaction mixture was refluxed for 7 h under nitrogen
atmosphere. The solvent was removed in vacuo to provide the corresponding acid
chloride. A solution of the acid chloride in THF (10 mL) was added to a mixture of the
appropriate sulfonamide (12.20 mmol) and NaH (0.70 g, 28.8 mmol) in THF (100 mL),
and the mixture was stirred under nitrogen at room temperature for 7 h. Then, 2 mL
H2O was added to decompose the excess NaH. The THF was evaporated in vacuo and

4046
B. Mokhtari and K. Pourabdollah
CH2Cl2 (200 mL) was added to the residue. The organic layer was washed with 1N HCl
(200 mL) and water, dried over MgSO4, and evaporated in vacuo to give the crude di-
ionizable calix[4]arene. After purification, the product was dissolved in CH2Cl2, washed
with 10% aqueous HCl and water, and dried over MgSO4. The solution was evaporated
in vacuo to give product 08. Derivative 08 was obtained in 80% yield after
chromatography on silica gel with CH2Cl2 : MeOH (80 : 1) as eluent. Green solid;
m.p. 184–188ꢃC; ꢀmax (film) (cmꢀ1): 3244 (NH), 1720 (C¼O), 1360 and 1182 (S¼O);
1H NMR (CDCl3): ꢁ 0.96 (br s, 18H), 1.24 (br s, 18H), 2.04–4.22 (br m, 26H), 6.24–7.24
(br m, 8H), 7.52 (t, J ¼ 7.33, 4H), 8.02 (d, J ¼ 7.45, 4H), 9.24 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.08, 171.44, 155.88, 153.42, 144.34, 138.16, 133.12, 132.56, 129.22,
128.00, 125.10, 73.02, 60.08, 34.04, 33.12, 33.68, 31.88, 31.12, 20.32; Anal. Calcd
C66H80N4O14S2: C, 70.12; H, 7.14; N, 4.42. Found: C, 70.04; H, 7.20; N, 4.54.
4.1.3. Synthesis of 1,2-alternate Conformers (09–20). 5,11,17,23-Tetrakis(1,1-dimethy-
lethyl)-25,26-bis(N-X-sulfonyl
carbamoylmethoxy)-27,28-di(1-propoxy)calix[4]arene
was dissolved in 1,1,2,2-tetrachloroethane and heated to temperatures above 100ꢃC.
It was isomerized to the cis-1,2-alternate conformations until equilibrium was reached.
The X represented phenyl, p-CH3phenyl, p-OHphenyl, and p-NO2phenyl moieties. The
organic layer was washed with 200 mL 1N HCl and water, dried over MgSO4, and was
evaporated in vacuo to give the crude di-ionizable calix[4]arene. After purification, the
product was dissolved in CH2Cl2, washed with 10% aqueous HCl and water, and dried
over MgSO4. The solution was evaporated in vacuo to give the derivatives 09–20.
Products 9–12 were obtained in 15%, products 13–16 were obtained in 35%, and
products 17–20 were obtained in 50% yield after chromatography on silica gel with
CH3Cl:MeOH (60 : 1) as eluent.
4.1.3.1. Characteristics of product 09. White solid; m.p. 118–122ꢃC; ꢀmax (film)
1
(cmꢀ1): 3254 (NH), 1720 (C¼O), 1366 and 1178 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.08–4.26 (br m, 26H), 6.12–7.40 (br m, 8H), 7.62
(t, J ¼ 7.42, 4H), 7.80 (t, J ¼ 7.16, 2H), 8.04 (d, J ¼ 7.36, 4H), 9.30 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.58, 171.24, 155.34, 153.08, 144.06, 138.56 133.76, 132.08, 129.24,
128.74, 125.48, 72.42, 60.12, 33.54, 33.08, 32.96, 31.48, 31.12, 25.42; Anal. Calcd
C66H82N2O10S2: C, 70.32; H, 7.32; N, 2.16. Found: C, 70.38; H, 7.42; N, 2.28.
4.1.3.2. Characteristics of product 10. White solid; m.p. 142–146ꢃC; ꢀmax (film)
1
(cmꢀ1): 3226 (NH), 1722 (C¼O), 1332 and 1182 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.24 (br s, 18H), 2.12–4.12 (br m, 32H), 6.46–7.08 (br m, 8H), 8.24
(d, J ¼ 4.74, 4H), 8.34 (d, J ¼ 4.78, 4H), 9.36 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.24,
170.26, 152.42, 150.28, 144.36,143.34, 135.02, 132.36, 129.28, 125.72, 124.86, 34.26,
33.04, 32.92, 31.24, 31.32, 25,54, 21.86; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.34; H, 7.34; N, 4.48. Found: C, 65.30; H, 7.26; N, 4.58.
4.1.3.3. Characteristics of product 11. Yellow solid; m.p. 174–178ꢃC; ꢀmax (film)
1
(cmꢀ1): 3230 (NH), 1728 (C¼O), 1326 and 1144 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.26 (br s, 18H), 2.26–4.68 (br m, 26H), 6.52–7.18 (br m, 8H), 7.82
(t, J ¼ 7.26, 4H), 8.12 (d, J ¼ 7.52, 4H), 8.64 (t, J ¼ 7.02, 2H), 9.52 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.54, 170.98, 155.02, 153.56, 144.30, 138.78, 133.24, 132.42, 129.08,

Di-ionizable nano-baskets
4047
128.28, 125.26, 73.18, 60.16, 34.34, 33.88, 33.02, 31.18, 31.00, 22.58; Anal. Calcd
C66H82N2O12S2: C, 70.04; H, 7.28; N, 2.52. Found: C, 70.26; H, 7.16; N, 2.42.
4.1.3.4. Characteristics of product 12. White solid; m.p. 168–170ꢃC; ꢀmax (film)
1
(cmꢀ1): 3216 (NH), 1724 (C¼O), 1396 and 1168 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.18–4.32 (br m, 26H), 6.18–7.40 (br m, 8H), 7.44
(t, J ¼ 7.02, 4H), 8.26 (d, J ¼ 7.14, 4H), 9.28 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.28,
171.14, 155.26, 153.48, 144.52, 138.68, 133.58, 132.26, 129.52, 128.84, 125.50, 73.32,
60.18, 34.46, 33.02, 32.68, 31.58, 31.42, 20.50; Anal. Calcd C66H80N4O14S2: C, 70.10;
H, 7.22; N, 4.54. Found: C, 70.18; H, 7.26; N, 4.40.
4.1.3.5. Characteristics of product 13. White solid; m.p. 138–142ꢃC; ꢀmax (film)
1
(cmꢀ1): 3256 (NH), 1718 (C¼O), 1350 and 1166 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.24–4.22 (br m, 26H), 6.18–7.48 (br m, 8H), 7.56
(t, J ¼ 7.48, 4H), 7.78 (t, J ¼ 7.38, 2H), 8.02 (d, J ¼ 7.48, 4H), 9.28 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.32, 171.18, 155.54, 153.86, 144.52, 138.06, 133.58, 132.78, 129.12,
128.32, 125.54, 72.34, 60.58, 33.52, 33.08, 32.98, 31.86, 31.12, 25.58; Anal. Calcd
C66H82N2O10S2: C, 70.28; H, 7.42; N, 2.34. Found: C, 70.16; H, 7.52; N, 2.40.
4.1.3.6. Characteristics of product 14. White solid; m.p. 144–146ꢃC; ꢀmax (film)
1
(cmꢀ1): 3240 (NH), 1724 (C¼O), 1328 and 1158 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.26 (br s, 18H), 2.24–4.56 (br m, 32H), 6.08–7.52 (br m, 8H), 8.00
(d, J ¼ 4.54, 4H), 8.88 (d, J ¼ 4.02, 4H), 9.32 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.58,
170.52, 152.38, 150.04, 144.42,143.52, 134.82, 132.66, 129.72, 125.98, 124.46, 34.92,
33.88, 33.02, 31.12, 30.98, 25,38, 21.52; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.96; H, 7.20; N, 4.38. Found: C, 65.88; H, 7.32; N, 4.54.
4.1.3.7. Characteristics of product 15. White solid; m.p. 176–178ꢃC; ꢀmax (film)
1
(cmꢀ1): 3228 (NH), 1724 (C¼O), 1364 and 1158 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.28–4.32 (br m, 26H), 6.78–7.86 (br m, 8H), 7.64
(t, J ¼ 7.46, 4H), 8.12 (d, J ¼ 7.42, 4H), 8.44 (t, J ¼ 7.32, 2H), 9.64 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.48, 171.02, 155.66, 153.72, 144.12, 138.46, 133.82, 132.54, 129.22,
128.36, 125.88, 73.26, 60.12, 34.58, 33.76, 33.32, 31.04, 31.08, 22.37; Anal. Calcd
C66H82N2O12S2: C, 70.68; H, 7.32; N, 2.20. Found: C, 70.58; H, 7.22; N, 2.16.
4.1.3.8. Characteristics of product 16. White solid; m.p. 172–176ꢃC; ꢀmax (film)
1
(cmꢀ1): 3198 (NH), 1786 (C¼O), 1334 and 1156 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.12–4.12 (br m, 26H), 6.36–7.42 (br m, 8H), 7.46
(t, J ¼ 7.18, 4H), 8.16 (d, J ¼ 7.38, 4H), 9.52 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.52,
171.14, 155.52, 153.84, 144.68, 138.32, 133.08, 132.60, 129.84, 128.08, 125.28, 73.22,
60.15, 34.00, 33.26, 32.96, 31.58, 31.06, 20.76; Anal. Calcd C66H80N4O14S2: C, 70.76;
H, 7.38; N, 4.28. Found: C, 70.50; H, 7.32; N, 4.42.
4.1.3.9. Characteristics of product 17. Yellow solid; m.p. 132–136ꢃC; ꢀmax (film)
1
(cmꢀ1): 3238 (NH), 1722 (C¼O), 1348 and 1176 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.14–4.32 (br m, 26H), 6.22–7.24(br m, 8H), 7.54
(t, J ¼ 7.62, 4H), 7.56 (t, J ¼ 7.22, 2H), 8.18 (d, J ¼ 7.48, 4H), 9.58 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.42, 171.12, 155.71, 153.62, 144.63, 138.25, 133.12, 132.64, 129.32,

4048
B. Mokhtari and K. Pourabdollah
128.42, 125.98, 72.48, 60.04, 33.68, 33.22, 33.00, 31.88, 31.12, 25.48; Anal. Calcd
C66H82N2O10S2: C, 70.32; H, 7.34; N, 2.46. Found: C, 70.14; H, 7.26; N, 2.58.
4.1.3.10. Characteristics of product 18. White solid; m.p. 144–148ꢃC; ꢀmax (film)
1
(cmꢀ1): 3245 (NH), 1736 (C¼O), 1336 and 1186 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.24 (br s, 18H), 2.16–4.28 (br m, 32H), 6.58–7.16 (br m, 8H), 8.26
(d, J ¼ 4.72, 4H), 8.32 (d, J ¼ 4.72, 4H), 9.25 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.02,
170.02, 152.46, 150.48, 144.90,143.48, 134.42, 132.84, 129.00, 125.48, 124.62, 34.26,
33.96, 33.28, 31.26, 31.00, 25,02, 21.40; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.26; H, 7.35; N, 4.70. Found: C, 65.32; H, 7.34; N, 4.62.
4.1.3.11. Characteristics of product 19. Yellow solid; m.p. 168–174ꢃC; ꢀmax (film)
1
(cmꢀ1): 3234 (NH), 1722 (C¼O), 1364 and 1182 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.04–4.24 (br m, 26H), 6.30–7.32 (br m, 8H), 7.50
(t, J ¼ 7.46, 4H), 8.22 (d, J ¼ 7.42, 4H), 8.08 (t, J ¼ 7.30, 2H), 9.86 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.30, 171.24, 155.24, 153.14, 144.42, 138.52, 133.24, 132.14, 129.26,
128.22, 125.42, 73.54, 60.64, 34.02, 33.03, 33.32, 31.98, 31.14, 22.12; Anal. Calcd
C66H82N2O12S2: C, 70.20; H, 7.22; N, 2.44. Found: C, 70.22; H, 7.16; N, 2.52.
4.1.3.12. Characteristics of product 20. Green solid; m.p. 180–186ꢃC; ꢀmax (film)
1
(cmꢀ1): 3226 (NH), 1728 (C¼O), 1350 and 1186 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.26 (br s, 18H), 2.08–4.12 (br m, 26H), 6.34–7.26 (br m, 8H), 7.58
(t, J ¼ 7.43, 4H), 8.12 (d, J ¼ 7.47, 4H), 9.14 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.18,
171.44, 155.28, 153.32, 144.54, 138.12, 133.52, 132.46, 129.28, 128.50, 125.12, 73.22,
60.48, 34.14, 33.10, 33.08, 31.86, 31.32, 20.82; Anal. Calcd C66H80N4O14S2: C, 70.18;
H, 7.18; N, 4.22. Found: C, 70.14; H, 7.22; N, 4.34.
4.1.4. Synthesis of partial-cone conformers (21–34). To determine appropriate reaction
conditions for the preparation of conformationally pH restricted calix[4]arene
carboxylic acid of 25,27-dipropoxy-26,28-bis(carboxymethoxy)calix[4]arene in the
partial-cone conformation, 0.10 g of 25,27-dipropoxy-26,28-dihydroxycalix[4]arene
(0.19 mmol) was treated with methyl bromoacetate (0.70 mmol, 4,0 equivalents)
together with different bases and solvents. 4.0 equivalents of NaH and K2CO3, 5.0
equivalents of KH, and 15.0 equivalents of CS2CO3 were used. In general, sodium,
potassium, and cesium cations favor the cone, partial-cone, and 1,3-alternate
conformations, respectively, irrespective of the solvent system. Interestingly, CS2CO3
produced mostly the partial-cone isomer instead of the 1,3-alternate isomer in both
acetone and DMF solvents. This contradicts the literature prediction that CS2CO3
should favor the formation of 1,3-alternate conformational isomer. This result indicates
the effect of para substituents in controlling the conformational outcome.
On silica gel TLC, the cone and partial-cone isomers have almost the same Rf value of
0.7, but the 1,3-alternate isomer has a very low Rf value of 0.2 with EtOAc : hexane
(1 : 8) as the eluent. As a result, the partial-cone (75%) and the 1,3-alternate (25%)
isomers, formed using KH in THF, were easily separated by column chromatography,
even on a large scale. The resulted esters were hydrolyzed with 10% Me4NOH/H2O and
THF to produce 25,27-dipropoxy-26,28-bis(carboxymethoxy)calix[4]arenes in cone and
partial-cone conformers.

Di-ionizable nano-baskets
4049
4.1.4.1. Synthesis of products 21–28 (propoxy-up). To a solution of 25,27-dipropoxy-
26,28-bis(carboxymethoxy)calix[4]arene and 25,26-dipropoxy-27,28-bis(carboxy-
methoxy)calix[4]arene (1,50 g, 2.30 mmol) in benzene (50 mL), 5.0 mL of oxalyl chloride
(7.30 g, 57,5 mmol) was added. The reaction mixture was refluxed for 5 h. The benzene
and excess oxalyl chloride was evaporated in vacuo, and the crude product was dried
under high vacuum. The residue was dissolved in 30 mL THF and added into a mixture
of NaH (0.57 g, 95% dry, 23.0 mmol) and appropriate sulfonamide (6.90 mmol, 3,0
equiv) in THF (50 mL) under nitrogen at room temperature. The reaction mixture was
stirred for 15 h (except for p-nitrobenzenesulfonamide, 2 h) under nitrogen at room
temperature. The reaction was quenched with a small amount of H2O and the THF was
evaporated in vacuo. The THF layer was separated and dried under high vacuum to give
a pale yellow solid. The solid was purified by column chromatography on silica gel with
CH2Cl2, MeOH : CH2Cl2 (l : 99), and MeOH : CH2Cl2 (2 : 99) as eluents to produce a
white solid. The solid was dissolved in CH2Cl2 (100 mL) and washed with 1 N HCl
(100 mL). The organic layer was separated, washed with de-ionized H2O (100 mL), and
evaporated in vacuo to give a white solid. The solid was dissolved in small amount of
CH2Cl2 (10 mL) and hexane was added little by little (50 mL). The flask was put in the
freezer for at least 6 h. The organic solution was decanted and the oil, which was stuck
to the surface of the glassware, was washed gently with hexane. The oil was again
dissolved in CH2Cl2, which was evaporated in vacuo to produce a pale-yellow oil. The
oil became a white solid under high vacuum.
4.1.4.2. Characteristics of product 21. White solid; m.p. 112–114ꢃC; ꢀmax (film)
1
(cmꢀ1): 3200 (NH), 1710 (C¼O), 1360 and 1108 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.04–4.16 (br m, 26H), 6.10–7.46 (br m, 8H), 7.48
(t, J ¼ 7.32, 4H), 7.82 (t, J ¼ 7.14, 2H), 8.24 (d, J ¼ 7.26, 4H), 9.32 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.28, 171.54, 155.54, 153.42, 144.02, 138.92 133.48, 132.28, 129.22,
128.24, 125.38, 72.46, 60.14, 34.12, 33.48, 33.02, 31.44, 31.06, 25.52; Anal. Calcd
C66H82N2O10S2: C, 70.12; H, 7.42; N, 2.06. Found: C, 70.18; H, 7.22; N, 2.08.
4.1.4.3. Characteristics of product 22. White solid; m.p. 112–116ꢃC; ꢀmax (film)
1
(cmꢀ1): 3206 (NH), 1712 (C¼O), 1312 and 1154 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.22 (br s, 18H), 2.14–4.22 (br m, 32H), 6.36–7.18 (br m, 8H), 8.32
(d, J ¼ 4.14, 4H), 8.94 (d, J ¼ 4.58, 4H), 9.32 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.04,
170.28, 152.22, 150.18, 144.16,143.04, 135.82, 132.34, 129.26, 125.54, 124.80, 34.00,
33.34, 32.98, 31.94, 31.42, 25,04, 21.00; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.36; H, 7.30; N, 4.40. Found: C, 65.40; H, 7.28; N, 4.56
4.1.4.4. Characteristics of product 23. White solid; m.p. 114–118ꢃC; ꢀmax (film)
1
(cmꢀ1): 3252 (NH), 1758 (C¼O), 1324 and 1104 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.16–4.64 (br m, 26H), 6.32–7.98 (br m, 8H), 7.84
(t, J ¼ 7.16, 4H), 8.12 (d, J ¼ 7.32, 4H), 8.94 (t, J ¼ 7.08, 2H), 9.32 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.54, 170.88, 155.14, 153.52, 144.50, 138.58, 133.26, 132.52, 129.18,
128.26, 125.66, 73.58, 60.12, 34.36, 33.58, 33.00, 31.98, 31.08, 22.38; Anal. Calcd
C66H82N2O12S2: C, 70.44; H, 7.16; N, 2.50. Found: C, 70.36; H, 7.12; N, 2.40.
4.1.4.5. Characteristics of product 24. Yellow solid; m.p. 112–116ꢃC; ꢀmax (film)
1
(cmꢀ1): 3210 (NH), 1734 (C¼O), 1376 and 1188 (S¼O); H NMR (CDCl3): ꢁ 0.96

4050
B. Mokhtari and K. Pourabdollah
(br s, 18H), 1.22 (br s, 18H), 2.08–4.52 (br m, 26H), 6.38–7.44 (br m, 8H), 7.40
(t, J ¼ 7.82, 4H), 8.28 (d, J ¼ 7.04, 4H), 9.58 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.38,
171.12, 155.56, 153.42, 144.72, 138.58, 133.98, 132.06, 129.02, 128.78, 125.54, 73.92,
60.78, 34.48, 33.82, 32.78, 31.48, 31.54, 20.38; Anal. Calcd C66H80N4O14S2: C, 70.16;
H, 7.38; N, 4.42. Found: C, 70.08; H, 7.36; N, 4.30.
4.1.4.6. Characteristics of product 25. White solid; m.p. 112–114ꢃC; ꢀmax (film)
1
(cmꢀ1): 3208 (NH), 1716 (C¼O), 1362 and 1138 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.24–4.36 (br m, 26H), 6.18–7.58 (br m, 8H), 7.38
(t, J ¼ 7.02, 4H), 7.42 (t, J ¼ 7.24, 2H), 8.20 (d, J ¼ 7.06, 4H), 9.38 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.28, 171.54, 155.54, 153.42, 144.02, 138.92 133.48, 132.28, 129.20,
128.34, 125.34, 72.44, 60.24, 34.32, 33.44, 33.08, 31.84, 31.16, 25.12; Anal. Calcd
C66H82N2O10S2: C, 70.10; H, 7.32; N, 2.22. Found: C, 70.16; H, 7.26; N, 2.18.
4.1.4.7. Characteristics of product 26. White solid; m.p. 112–116ꢃC; ꢀmax (film)
1
(cmꢀ1): 3216 (NH), 1726 (C¼O), 1312 and 1172 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.24 (br s, 18H), 2.02–4.42 (br m, 32H), 6.56–7.28 (br m, 8H), 8.34
(d, J ¼ 4.46, 4H), 8.44 (d, J ¼ 4.58, 4H), 9.32 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.22,
170.36, 152.82, 150.78, 144.56,143.54, 135.72, 132.16, 129.78, 125.62, 124.06, 34.18,
33.84, 32.52, 31.34, 31.36, 25,54, 21.66; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.38; H, 7.26; N, 4.58. Found: C, 65.32; H, 7.36; N, 4.48.
4.1.4.8. Characteristics of product 27. White solid; m.p. 114–116ꢃC; ꢀmax (film)
1
(cmꢀ1): 3216 (NH), 1720 (C¼O), 1358 and 1164 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.06–4.50 (br m, 26H), 6.54–7.02 (br m, 8H), 7.98
(t, J ¼ 7.06, 4H), 8.18 (d, J ¼ 7.42, 4H), 8.98 (t, J ¼ 7.32, 2H), 9.02 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.52, 170.78, 155.42, 153.54, 144.34, 138.58, 133.54, 132.72, 129.14,
128.18, 125.22, 73.12, 60.56, 34.54, 33.98, 33.10, 31.94, 31.10, 22.50; Anal. Calcd
C66H82N2O12S2: C, 70.14; H, 7.38; N, 2.42. Found: C, 70.16; H, 7.36; N, 2.36.
4.1.4.9. Characteristics of product 28. Yellow solid; m.p. 114–118ꢃC; ꢀmax (film)
1
(cmꢀ1): 3218 (NH), 1734 (C¼O), 1356 and 1158 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.24 (br s, 18H), 2.08–4.42 (br m, 26H), 6.14–7.42 (br m, 8H), 7.42
(t, J ¼ 7.22, 4H), 8.22 (d, J ¼ 7.04, 4H), 9.20 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.20,
171.18, 155.86, 153.44, 144.54, 138.48, 133.78, 132.24, 129.72, 128.04, 125.80, 73.30,
60.08, 34.06, 33.92, 32.18, 31.56, 31.02, 20.58; Anal. Calcd C66H80N4O14S2: C, 70.12; H,
7.24; N, 4.50 Found: C, 70.16; H, 7.36; N, 4.48.
4.1.5. Synthesis of products 29–34 (Carbonyl-up). To a solution of 1.00 g of 25,27-
dipropoxy-26,28-bis(carboxymethoxy)calix[4]arene and 25,26-dipropoxy-27,28-bis(car-
boxymethoxy)calix[4]arene (1.53 mmol) in 30 mL benzene, 10.0 mL oxalyl chloride
(14.6 g, 122 mmol) was added. The reaction mixture was refluxed for 24 h. The benzene
and excess oxalyl chloride was evaporated in vacuo, the crude product was dried under
high vacuum. The residue was dissolved in THF (30 mL) and added to a mixture of
0.38 g NaH (95% dry, 15.3 mmol) and 0.74 g proper sulfonamide (4.59 mmol) in 50 mL
THF under nitrogen at room temperature. The reaction mixture was stirred for 15 h at
room temperature under nitrogen. The reaction was quenched with a small amount of

Di-ionizable nano-baskets
4051
H2O and the THF was evaporated in vacuo to give a white solid. The solid was purified
by column chromatography on silica gel witii CH2Cl2, EtOAc : CH2Cl2 (2 : 98), and
EtOAc : CH2Cl2 (5 : 95) as eluents to produce a white solid. The solid was dissolved in
CH2Cl2 (100 mL) and washed with 1 N HCl (100 mL). The organic layer was separated,
washed with deionized H2O (100 mL), and evaporated in vacuo to give a white solids.
4.1.5.1. Characteristics of product 29. White solid; m.p. 124–126ꢃC; ꢀmax (film)/cmꢀ1
:
1
3200 (NH), 1716 (C¼O), 1350 and 1158 (S¼O); H NMR (CDCl3): ꢁ 0.96 (br s, 18H),
1.22 (br s, 18H), 2.04–4.16 (br m, 26H), 6.10–7.42 (br m, 8H), 7.38 (t, J ¼ 7.22, 4H), 7.52
(t, J ¼ 7.22, 2H), 8.26 (d, J ¼ 7.16, 4H), 9.22 (br s, 2H); 13C NMR (CDCl3): ꢁC 171.28,
171.54, 155.54, 153.42, 144.02, 138.92 133.48, 132.28, 129.42, 128.64, 125.48, 72.56,
60.54, 34.52, 33.38, 33.08, 31.54, 31.00, 25.58; Anal. Calcd C66H82N2O10S2: C, 70.32;
H, 7.46; N, 2.16. Found: C, 70.48; H, 7.62; N, 2.18.
4.1.5.2. Characteristics of product 30. White solid; m.p. 122–126ꢃC; ꢀmax (film)
(cmꢀ1): 3220 (NH), 1702 (C¼O), 1302 and 1152 (S¼O); 1H NMR (CDCl3): ꢁ 0.98 (br–
s, 18H), 1.22 (br s, 18H), 2.02–4.32 (br m, 32H), 6.36–7.48 (br m, 8H), 8.22
(d, J ¼ 4.46, 4H), 8.24 (d, J ¼ 4.76, 4H), 9.24 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.24,
170.26, 152.42, 150.28, 144.36,143.34, 135.02, 132.36, 129.28, 125.72, 124.84, 34.46,
33.48, 32.98, 31.84, 31.02, 25,04, 21.76; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2:
C, 65.38; H, 7.36; N, 4.48. Found: C, 65.32; H, 7.46; N, 4.38.
4.1.5.3. Characteristics of product 31. White solid; m.p. 124–128ꢃC; ꢀmax (film)
1
(cmꢀ1): 3210 (NH), 1708 (C¼O), 1320 and 1104 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.06–4.60 (br m, 26H), 6.12–7.58 (br m, 8H), 7.98
(t, J ¼ 7.06, 4H), 8.22 (d, J ¼ 7.02, 4H), 8.68 (t, J ¼ 7.12, 2H), 9.72 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.24, 170.96, 155.32, 153.26, 144.50, 138.58, 133.54, 132.02, 129.18,
128.84, 125.96, 73.10, 60.26, 34.48, 33.58, 33.00, 31.10, 30.96, 22.48; Anal. Calcd
C66H82N2O12S2: C, 70.14; H, 7.22; N, 2.32. Found: C, 70.16; H, 7.26; N, 2.22.
4.1.5.4. Characteristics of product 32. White solid; m.p. 122–124ꢃC; ꢀmax (film)
1
(cmꢀ1): 3216 (NH), 1752 (C¼O), 1368 and 1122 (S¼O); H NMR (CDCl3): ꢁ 0.96
(br s, 18H), 1.22 (br s, 18H), 2.24–4.56 (br m, 26H), 6.18–7.56 (br m, 8H), 7.28
(t, J ¼ 7.02, 4H), 7.92 (t, J ¼ 7.04, 2H), 8.34 (d, J ¼ 7.16, 4H), 9.34 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.18, 171.48, 155.84, 153.08, 144.36, 138.62 133.08, 132.22, 129.12,
128.32, 125.08, 72.24, 60.04, 34.10, 33.40, 33.00, 31.04, 31.00, 25.32; Anal. Calcd
C66H82N2O10S2: C, 70.42; H, 7.32; N, 2.16. Found: C, 70.38; H, 7.20; N, 2.18.
4.1.5.5. Characteristics of product 33. White solid; m.p. 122–126ꢃC; ꢀmax (film)
1
(cmꢀ1): 3228 (NH), 1782 (C¼O), 1302 and 1142 (S¼O); H NMR (CDCl3): ꢁ 0.98
(br s, 18H), 1.22 (br s, 18H), 2.02–4.08 (br m, 32H), 6.56–7.18 (br m, 8H), 8.14
(d, J ¼ 4.14, 4H), 8.54 (d, J ¼ 4.58, 4H), 9.12 (br s, 2H); 13C NMR (CDCl3): ꢁC 174.14,
170.56, 152.52, 150.48, 144.34,143.38, 135.08, 132.86, 129.98, 125.92, 124.96, 34.56,
33.54, 32.98, 31.98, 31.04, 25,38, 21.46; Anal. Calcd C68H86N2O10S2 ꢅ 0.1 CH2Cl2: C,
65.24; H, 7.30; N, 4.40. Found: C, 65.32; H, 7.24; N, 4.28.
4.1.5.6. Characteristics of product 34. White solid; m.p. 124–126ꢃC; ꢀmax (film)
1
(cmꢀ1): 3220 (NH), 1722 (C¼O), 1322 and 1124 (S¼O); H NMR (CDCl3): ꢁ 0.96

4052
B. Mokhtari and K. Pourabdollah
(br s, 18H), 1.24 (br s, 18H), 2.16–4.88 (br m, 26H), 6.58–7.08 (br m, 8H), 7.42
(t, J ¼ 7.26, 4H), 8.02 (d, J ¼ 7.82, 4H), 8.64 (t, J ¼ 7.32, 2H), 9.82 (br s, 2H); 13C NMR
(CDCl3): ꢁC 171.54, 170.98, 155.02, 153.56, 144.32, 138.38, 133.54, 132.52, 129.58,
128.24, 125.56, 73.58, 60.18, 34.84, 34.28, 33.92, 31.98, 31.50, 22.58; Anal. Calcd
C66H82N2O12S2: C, 70.14; H, 7.08; N, 2.50. Found: C, 70.28; H, 7.06; N, 2.40.
5. Conclusions
Alternation of aryl group in the pendant moieties was ineffective, while changing their
orientation (cis- and trans-) and position (ortho- and para-) as well as the scaffold
conformation (cone, 1,2-alternate, partial-cone) analogs presented a pronounced effect
on the efficiency of extractions. Changing the scaffold conformation affected the
selectivity of extractions, while alternation of aryl groups, changing their orientation
and position showed no effect. Replacement of aryl groups and changing the moiety’s
position showed no changes in the pH1/2 of extractions, while variations of
conformations and the orientation of pendant moieties have pronounced effect on
the pH1/2 of extractions.
Acknowledgments
This work was supported by Islamic Azad University (Shahreza Branch) and Iran
Nanotechnology Initiative Council.
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