Anion receptors based on ureidocalix[4]arenes immobilised in the partial cone conformation

Article abstract of DOI:10.1039/c2nj40724h

A novel method enabling the synthesis of receptors based on the calix[4]arenes immobilized in the partial cone conformation is reported. The application of a protection/deprotection strategy using nosyl groups enables the regioselective introduction of functional groups (NO₂ and NH ₂) into the upper rim of calix[4]arenes, leading finally to the substitution pattern so far inaccessible to calixarene chemistry. The introduction of two ureido functions at the para positions of the partial cone conformer yields a novel type of receptor which can bind anions even in a highly competitive solvent (DMSO). This revealed that the partial cone conformation, so far rather ignored in supramolecular chemistry, can be also very useful in design of novel anion receptors.

Full text of DOI:10.1039/c2nj40724h

NJC
View Article Online
View Journal | View Issue
PAPER
Anion receptors based on ureidocalix[4]arenes
immobilised in the partial cone conformation†
Cite this: NewJ.Chem., 2013,
37, 220
a
a
b
c
d
ˇ
ˇ
ˇ´
´
ˇ´
´
´ ˇ
´
Oldrich Hudecek, Jan Budka, Hana Dvorakova, Petra Curınova, Ivana Cısarova
a
´
and Pavel Lhotak*
A novel method enabling the synthesis of receptors based on the calix[4]arenes immobilized in the
partial cone conformation is reported. The application of a protection/deprotection strategy using nosyl
groups enables the regioselective introduction of functional groups (NO2 and NH2) into the upper rim
of calix[4]arenes, leading finally to the substitution pattern so far inaccessible to calixarene chemistry.
The introduction of two ureido functions at the para positions of the partial cone conformer yields a
novel type of receptor which can bind anions even in a highly competitive solvent (DMSO). This
revealed that the partial cone conformation, so far rather ignored in supramolecular chemistry, can be
also very useful in design of novel anion receptors.
Received (in Victoria, Australia)
14th August 2012,
Accepted 2nd October 2012
DOI: 10.1039/c2nj40724h
www.rsc.org/njc
hydrogen bonds from amide, sulfonamide, urea or thiourea
moieties5 which can effectively interact with anions, especially
Introduction
The importance of anions in various biological systems is well
recognised. Hence, the study of the complexation of anionic
species plays an important role in contemporary supramolecular
chemistry as witnessed by many review articles1 and books2
published recently. Given the importance of anions in chemistry,
medicine, environmental pollution or industrial processes,
much effort has been focused on the design of anion binding
ligands, receptors and sensors.3
if they are suitably preorganised. From this point of view,
calix[4]arenes6 offer many possibilities due to their tuneable
3D shapes of the molecule leading to four different conforma-
tions (cone, partial cone, 1,3-alternate, and 1,2-alternate) (Fig. 1).
This makes calix[4]arenes ideal candidates for the role of
molecular scaffolds in the design of novel receptors allowing
the elaborated introduction of various functional groups into
precisely defined mutual positions.
Not surprisingly, the main strategy for anion recognition
relies on the application of positively charged species like
polyammonium, guanidinium, or quaternary ammonium
salts,4 which can bind anions mainly via electrostatic inter-
actions. On the other hand, neutral organic receptors for anion
recognition via hydrogen bonding interactions are especially
useful in the design. These receptors can use highly directional
Many neutral calixarene-based ligands for anion recognition
have been reported in the literature so far.7,8 We have previously
focused on a series of arylamide- or arylureido-substituted
calix[4]arenes9 which can be used for anion recognition in
solution. The systematic study of ureidocalix[4]arenes revealed
that bis(phenylureido)-calix[4]arene immobilised in the cone
conformation10 can bind benzoate with surprisingly high selec-
tivity. On the other hand, receptors in the 1,3-alternate confor-
mation bearing four ureido functions bind anions with a
negative allosteric effect11 where only one site of the molecule
is capable of forming a complex. Interestingly, albeit there are
many references for the cone or 1,3-alternate conformations,
there is almost no precedence9d,12 of using anion receptors in
the remaining two conformations – partial cone or 1,2-alternate.
While the 1,2-alternate is scarcely used because of the lack of
general synthetic methods leading to this conformation, preparation
of the partial cone isomers is relatively easy. The problem lies in the
wrong mutual positions of nitro groups used as the starting point for
subsequent derivatization. Usually we start with distally disubstituted
calix[4]arenes (Scheme 1, path a), where subsequent nitration and
a Department of Organic Chemistry, Institute of Chemical Technology Prague (ICT),
Technicka 5, 166 28 Prague 6, Czech Republic. E-mail: lhotakp@vscht.cz;
Fax: +420 220444288; Tel: +420 220445055
b Laboratory of NMR Spectroscopy, Institute of Chemical Technology Prague (ICT),
Technicka 5, 166 28 Prague 6, Czech Republic
c Institute of Chemical Process Fundamentals, v.v.i., Academy of Sciences of the
´
Czech Republic, Rozvojova 135, 165 02 Prague 6, Czech Republic
d Department of Inorganic Chemistry, Charles University, Hlavova 8,
128 43 Prague 2, Czech Republic
† Electronic supplementary information (ESI) available: 1H NMR, 13C NMR,
COSY, HMBC, HMQC and NOE spectra of compound 4, including complete
structure assignment of this compound. CCDC 894549. For ESI and
crystallographic data in CIF or other electronic format see DOI: 10.1039/
c2nj40724h
c
220 New J. Chem., 2013, 37, 220--227
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013

View Article Online
Paper
NJC
synthetic strategy is based on a direct nitration or ipso-nitration
of the corresponding nosyl-substituted derivatives 1b–3b. As
the reactivity of alkoxy substituted aromatic rings is higher
compared to that of aromatic units bearing nosyl groups, one
can selectively introduce nitro groups at the para positions of
alkylated aromatic subunits. The whole strategy consists of
three basic steps: (i) lower-rim protection (introduction of a
nosyl moiety) leading to the formation of compounds 1b–3b,
(ii) nitration or ipso-nitration (depending on the upper rim
substitution) to form 1c–3c, and (iii) deprotection of the nosyl
group by an alkaline hydrolysis to yield 1–3. This procedure
straightforwardly (overall yield for the transformation of 1a to 1
is 75%) leads to the substitution pattern (Scheme 1) which is
so far inaccessible to calix[4]arene chemistry and which is
complementary to the commonly used isomers (Scheme 2).
The isomers 1–3 were then used for the formation of the
partial cone conformers. The alkylation with propyl iodide using
Cs2CO3 as a base led always to the mixture of the partial cone
and cone isomers in approximately 95 : 5 ratio. Unfortunately,
these mixtures could not be separated by column chromato-
graphy either on silica gel or on alumina. On the other hand, a
simple precipitation from CH2Cl2–MeOH system gave pure
partial cone isomers 4–6 in medium yields (E40%).
Fig. 1 Four basic conformations of calix[4]arene: (a) cone, (b) partial cone,
(c) 1,2-alternate and (d) 1,3-alternate.
The conformation of 4–6 was confirmed using 1H NMR
spectroscopy. The partial cone conformer can be imaginary
bisected into two halves – one having the cone-like arrangement
with the syn orientation of the aromatic units, and the second
one possessing the 1,3-alternate-like features (anti oriented
phenolic rings). Both halves retained their typical splitting
pattern and signal multiplicity known from 1H NMR spectra
of common conformers. Thus, dinitro derivative 4 (Fig. 2)
showed one doublet at 3.12 ppm for equatorial CH bond of
the bridging CH2 moiety, and another doublet at 4.06 ppm for
the axial CH bond, both with typical geminal interaction
constants (J = 13.8 Hz). On the other hand, signals of bridging
units in the 1,3-alternate-like part of the molecule possess
almost identical chemical shifts (E3.72 ppm). While the propyl
group in the 1,3-alternate-like half of the molecule exhibits
typical shifts (Fig. 2), the analogous signals of the opposite
propyl group in the cone-like part are distinctly shifted towards
the stronger field (upfield shift). This indicates that protons
Ha–Hc are located close to the distal inverted aromatic unit
which leads to substantial shielding of all aliphatic signals due
to the magnetic anisotropy of the aromatic system (for total
structure assignment see ESI†).
Scheme 1 Two different substitution patterns in dinitro substituted partial cone
calix[4]arenes: (a) common nitration followed by alkylation and (b) nitration
using nosyl protection/deprotection method followed by alkylation.
final alkylation of dinitro intermediate A leads to substitution pattern
PC1. Unfortunately, this partial cone conformer bears nitro groups on
the opposite sites of the cavity which is not suitable for the design of
receptors. Recently we have reported a straightforward regioselective
synthesis13 enabling the preparation of dinitro isomers B with the
nitro groups on the unsubstituted aromatic rings (Scheme 1, path b).
Here we report on the synthesis of novel type of anion receptors
based on the calix[4]arenes immobilized in the partial cone confor-
mation possessing a PC2 substitution pattern. These isomers have
been so far inaccessible to calixarene chemistry and represent
structures which are complementary to commonly used calixarene-
based receptors (compare PC1 and PC2 in Scheme 1).
Thus, the comparison of the corresponding chemical shifts
(Fig. 2) clearly shows the substantial upfield shift (approx.
0.60 ppm) for all protons (compare 3.84 (Ha0)/3.25 (Ha) ppm
for –OCH2– moiety, or 1.15 (Hc0)/0.69 (Hc) ppm for terminal CH3
group). Similar features and trends can be observed in all newly
prepared derivatives 4–14 possessing the partial cone conformation
(for complete structure assignment of compound 4, see ESI†).
The final unambiguous structural evidence for compound 5
was obtained by X-ray crystallographic analysis of monocrystals
Results and discussion
The regioselective introduction of nitro groups into the calix- grown from the methanol–CH2Cl2 mixture. The molecule
arene skeleton was recently described by our group.13 The adopts a partial cone conformation (Fig. 3) where the aromatic
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013
New J. Chem., 2013, 37, 220--227 221

View Article Online
NJC
Paper
Scheme 2 Synthesis of calixarene-based receptors in the partial cone conformation.
is almost ideally perpendicular (89.06(8)1) to the main plane formed
by the four carbon bridging atoms. The remaining anti-oriented
aromatic unit is noticeably tilted from the cavity with the interplanar
angle = 151.10(8)1 (with the main plane). Interestingly, both nitro
groups are slightly turned out from the ideal coplanar arrangement
with attached aromatic units by 10.1(3)1 and 15.9(3)1.
Nitro derivatives 4–6 were then smoothly reduced with
SnCl2ꢀ2H2O in refluxing ethanol to give amino derivatives 7, 8
and 9 in 95, 97, and 98% yields, respectively. Target receptors
10–14 were obtained by the reaction of amines 7–9 with appro-
priate isocyanates (phenyl, p-trifluoromethylphenyl or p-nitro-
phenyl) in dichloromethane at room temperature and they were
isolated in 63–78% yields (for 10–13) and 31% yield (for 14).
The complexation ability of ligands 10–13 was studied by
standard 1H NMR titration experiments using an increasing
concentration of appropriate anions to obtain different calixarene :
anion ratios (1 : 0.3–10). To avoid possible unwanted interactions of
receptors with counter-cations all anions studied were used in the
form of tetrabutylammonium salts. In the beginning, the 1H NMR
titration experiments were performed in the mixed solvent (CDCl3/
CD3CN = 4 : 1, v/v) to ensure the solubility of both organic and
inorganic parts. Under these conditions, the addition of anions to
the receptor led to the remarkable down-field shifts of ureido NH
signals thus indicating the complexation phenomenon under fast
exchange conditions. Very high complexation induced chemical
shifts (CIS) were observed for chloride and bromide (43 ppm).
Unfortunately, the binding constants were too high (K c 104) to be
reliably measured by the NMR technique.14
Fig. 2 Typical features of the 1H NMR spectra of derivative 4 (CDCl3, 298 K, 300 MHz).
Fig. 3 X-Ray structure of derivative 5.
Based on these preliminary results, we decided to change
the solvent system for more polar DMSO-d6. Despite the usage
of this highly competitive solvent towards hydrogen bonding
units bearing NO2 groups are pointing towards each other into
the cavity, and the third aromatic unit with the syn orientation
c
222 New J. Chem., 2013, 37, 220--227
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013

View Article Online
Paper
NJC
Table 1 Binding constants of receptors 10–13 towards selected anions (1H NMR
titration, 300 MHz, DMSO-d6, 298 K)
K/Mꢁ1
10
11
12
13
Anion
Clꢁ
870 ꢂ 200
1540 ꢂ 370c
450 ꢂ 50
60 ꢂ 10
800 ꢂ 180
Brꢁ
120 ꢂ 40
920 ꢂ 100
30 ꢂ 6
210 ꢂ 80
175 ꢂ 40
Iꢁ
a
a
AcOꢁ
BzOꢁ
CNꢁ
6400 ꢂ 560
2250 ꢂ 300 13 000 ꢂ 3000 2700 ꢂ 650
2750 ꢂ 390 16 500 ꢂ 3500 16 000 ꢂ 2800 6200 ꢂ 1200
50 ꢂ 13
120 ꢂ 20
8 ꢂ 2
730 ꢂ 120
380 ꢂ 70
12 ꢂ 3
240 ꢂ 50
28 ꢂ 7
680 ꢂ 150
7 ꢂ 2
ꢁ
a
NO3
DMSO-d6
b
11 ꢂ 1
a
Too small changes in chemical shifts upon addition of anions.
Titration experiments were carried out in pure CDCl3.
The complexation constant for the cone analogue of receptor 11
b
c
Fig. 4 binding isotherm of receptor 12 with a chloride anion (1H NMR titration,
(measured for the comparison): KCl = 173 ꢂ 24 Mꢁ1
.
300 MHz, 298 K, DMSO-d6).
for 12 and KAc = 2250 Mꢁ1 for 11. This leads to selectivity factor
(KBz/KAc) 1.23 for 12 and 7.33 for 11. The only exception is
represented by the unsubstituted receptor 10 showing higher
selectivity for acetate (KBz = 2750 Mꢁ1, KAc = 6400 Mꢁ1).
interactions, reasonable CIS values for NH protons were
observed for all anions measured. Thus, CIS value for the
11/AcOꢁ system was 1.50 ppm and similar values were obtained
for all receptors with benzoate and acetate, while other anions
usually showed lower values (compare CIS = 0.65 for the 11/Clꢁ
system). The binding constants were determined from the CIS
values of NH protons, Fig. 4 shows a typical binding isotherm
constructed for 12/Clꢁ system. All titration curves (with excep-
tion of receptor 14 bearing three ureido moieties) best fit with
the formation of 1 : 1 complexes (calix/anion), the stoichiometry
was also proved by the independent Job plot analysis15 for
selected anions (Fig. 5). The calculated binding constants are
summarised in Table 1.
All ureido or amidic receptors for anions are known to
operate via the hydrogen bonds between the N–H moiety and
negatively charged species (N–Hꢀ ꢀ ꢀAꢁ). Albeit DMSO is known
as a highly competitive solvent towards HB interactions, the
binding constants of receptors 10–13 are surprisingly high. In
all cases, the carboxylates possess the highest binding con-
stants, with selectivity for benzoate over acetate (for 11–13).
Thus, both receptors 11 and 12 bearing electron withdrawing
substituents (NO2 and CF3) possess almost the same complexa-
tion ability towards benzoate (KBz E 16 000 Mꢁ1), while the
complexation of acetate is reasonably different KAc = 13 000 Mꢁ1
As follows from Table 1, the binding site created by two
preorganised ureido functions can bind also other anions
possessing various geometries. Thus, a linear cyanide anion is
efficiently bound by 11 (KCN = 730 Mꢁ1) or by 13 (KCN = 680 Mꢁ1).
The binding constants for spherical halides are inversely related
to their basicity as can be documented by the results for
compound 11: KCl = 1540 Mꢁ1, KBr = 920 Mꢁ1, and KI = 30 Mꢁ1
.
Receptor 14 bearing threeꢁureido functions on the upper rim
was inefficient towards NO3 and CNꢁ anions. On the other
hand, halogens or carboxylates showed rather complicated
behaviour which did not correspond to the formation of com-
plexes possessing 1 : 1 stoichiometry. We have also studied
the interaction of receptors with solvent used – DMSO. The
1H NMR titrations of receptors 10–13 with DMSO-d6 was carried
out in CDCl3 and the corresponding complexation constants
are shown in Table 1. As the K values are very small (o12 Mꢁ1),
these interactions were neglected in experiments carried out
using DMSO-d6 as solvent.
Conclusions
A novel method enabling the synthesis of receptors based on
the calix[4]arenes immobilized in the partial cone conformation
is reported. The application of a protection/deprotection strat-
egy using nosyl groups enables the regioselective introduction
of functional groups (NO2 and NH2) into the upper rim of
calix[4]arenes, leading finally to the substitution pattern so far
inaccessible to calixarene chemistry, and structurally comple-
mentary to commonly used calixarene-based receptors The
introduction of two ureido functions at the para positions of
calix[4]arenes immobilised in the partial cone conformation
gave a novel type of receptor used successfully for the com-
plexation of anions.18 Albeit based on the hydrogen-bonding
interactions, these receptors can bind anions even in a highly
competitive solvent like DMSO. The complexation study
revealed that the partial cone conformation, so far rather
Fig. 5 Job plot for system 13/Clꢁ in DMSO-d6 (1H NMR titration, 300 MHz, 298 K).
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013
New J. Chem., 2013, 37, 220--227 223

View Article Online
NJC
Paper
ignored in supramolecular chemistry, can be very useful in precipitated by addition of 50 ml of methanol. The precipitate
design of novel anion receptors.
was filtered off, dissolved in 2 ml of CH2Cl2, and then the whole
procedure was repeated two more times, the third precipitate
was air dried to give 0.23 g of product 4 as a white powder in
40% yield, mp: 197–198 1C. 1H NMR (300 MHz, CDCl3, 298 K) d:
7.87 (2H, d, J = 2.9 Hz, ArH), 7.23 (2H, d, J = 7.6 Hz, ArH), 7.17
Experimental
Materials and instrumentations
All chemicals were purchased from commercial sources and (2H, d, J=7.6 Hz, ArH), 7.09 (2H, d, J = 2.9 Hz, ArH), 7.02 (1H, t,
used without further purification. Solvents were dried and J = 7.5 Hz, ArH), 6.92 (1H, t, J = 7.5 Hz, ArH), 4.06 (2H, d, J = 13.8
distilled using conventional methods. Melting points were Hz, ArCH2Ar ax), 3.86–3.59 (10H, m, 3 ꢃ OCH2 + 2 ꢃ ArCH2Ar),
measured on a Heiztisch Mikroskop-Polytherm A (Wagner & 3.29–3.21 (2H, m, OCH2), 3.12 (2H, d, J = 14.1 Hz, ArCH2Ar eq),
Munz, Germany). NMR spectra were performed on Varian 2.14–2.06 (2H, m, OCH2CH2), 1.95–1.83 (4H, m, OCH2CH2),
Gemini 300 (1H: 300 MHz, 13C: 75 MHz) and on Bruker Avance 1.29–1.21 (2H, m, OCH2CH2), 1.17–1.08 (9H, m, CH3), 0.69 (3H,
DRX 500 (1H: 500 MHz, 13C: 125 MHz) spectrometers. Deuter- t, J = 7.6 Hz, CH3). 13C{1H} NMR (75 MHz, CDCl3, 298 K): d
ated solvents used are indicated in each case. Chemical shifts 161.1, 157.4, 156.5, 142.3, 136.1, 135.5, 133.3, 133.2, 131.0,
(d) are expressed in ppm and are referred to the TMS as an 130.0, 125.1, 123.8, 122.6, 76.9, 75.8, 75.5, 35.7, 30.9, 24.1,
internal standard; coupling constants (J) are in Hz. The signal 24.0, 22.5, 11.0, 10.9, 9.4; TOF HRMS (ESI+): calcd for
assignment was supported by H–1H COSY, H–13C HMQC or [C40H46N2O8 + Na]+: 705.3146. Found: m/z (rel. int%) 705.3146
1
1
1H–13C HMBC 2D NMR and 1D H–DPFGSE NOE experiments (100) [M + Na]+. For complete structure assignment using
1
using the standard pulse sequences provided by Bruker. The various NMR techniques, see ESI.†
mass analyses were performed using ESI technique on a Q-TOF
5,17-Di-tert-butyl-11,23-dinitro-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone, syn-dinitro) 5
(Micromass) spectrometer. Elemental analyses were done on
Perkin-Elmer 240, Elementar vario EL (Elementar, Germany) or
Mitsubishi TOX-100 instruments. All samples were dried in the A general procedure was applied to 11,23-di-tert-butyl-5,17-
desiccator over P2O5 under vacuum (1 Torr) at 80 1C for 8 hours. dinitro-26,28-dipropoxycalix[4]arene-25,27-diol 2 (1.00 g, 1.41 mmol),
The IR spectra were measured on an FT-IR spectrometer Nicolet Cs2CO3 (1.83 g, 5.62 mmol) and 1-iodopropane (0.82 ml, 8.41 mmol).
740 or Bruker IFS66 spectrometers equipped with a heatable The residue after evaporation was dissolved in 2 ml of CH2Cl2, then
Golden Gate Diamante ATR-Unit (SPECAC) in KBr. 100 Scans for 40 ml of methanol was added and the resulting solution was stored
one spectrum were co-added at a spectral resolution of 4 cmꢁ1
.
at 0 1C overnight. The crystals formed were filtered off, quickly
The courses of the reactions were monitored by TLC using TLC washed with cold methanol and air dried to give 0.50 g of product 5
aluminum sheets with Silica gel 60 F254 (Merck). The column as a yellowish powder in 45% yield, mp: 237–240 1C. 1H NMR (300
chromatography was performed using Silica gel 60 (Merck).
MHz, CDCl3, 298 K) d: 7.86 (2H, d, J = 2.9 Hz, ArH), 7.21 (2H, s, ArH),
7.15–7.13 (4H, m, ArH), 4.09 (2H, d, J = 13.5 Hz, ArCH2Ar ax), 3.80–
3.57 (10H, m, 3 ꢃ OCH2 + 2 ꢃ ArCH2Ar), 3.33–3.27 (2H, m, OCH2),
Synthesis
All intermediates 1a–1c, 2a–2c, 3a–3c and 1–3 were prepared 3.10 (2H, d, J = 13.8 Hz, ArCH2Ar eq), 2.06–1.98 (2H, m, OCH2CH2),
according to the recently published procedures.13
1.96–1.84 (4H, m, OCH2CH2), 1.41–1.32 (20H, m, OCH2CH2 + 2 ꢃ
But), 1.12–1.05 (9H, m, CH3), 0.65 (3H, t, J = 7.5 Hz, CH3). 13C{1H}
NMR (75 MHz, CDCl3, 296 K) d: 161.3, 155.2, 153.4, 146.5, 144.5,
142.2, 135.4, 135.4, 133.5, 132.2, 127.7, 126.6, 125.3, 123.9, 76.9,
General procedure: synthesis of 25,26,27,28-tetrapropoxy
derivatives 4–7 in the partial cone conformation
The corresponding calix[4]arene derivatives 1–3 were dissolved 74.9, 74.8, 36.5, 34.5, 34.3, 31.8, 31.5, 24.1, 23.8, 21.6, 11.0, 10.8, 9.9;
in anhydrous acetone (200 ml for 1 g), then powdered Cs2CO3 TOF HRMS (ESI+): calcd for [C48H62N2O8 + Na]+: 817.4398. Found:
(2 equiv. for each hydroxyl group) and 1-iodopropane (3 equiv. m/z (rel. int. %) 817.4397 (100) [M + Na]+.
for each hydroxyl group) were added. The mixture was heated to
5-tert-Butyl-11,17,23-trinitro-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone) 6
reflux for 3 days (monitored by TLC), and the solvent was
removed under reduced pressure. The residue was acidified
with 1 M hydrochloric acid and extracted twice with CH2Cl2. A general procedure was applied to 5-tert-butyl-11,17,23-tri-
The combined organic layers were washed with water, then nitro-26,27,28-tripropoxycalix[4]arene-25-ol 3 (0.80 g, 1.08 mmol),
with brine and dried over MgSO4. Organic solvent was evapo- Cs2CO3 (0.70 g, 2.15 mmol) and 1-iodopropane (0.30 ml,
rated to dryness. The further purification is described below for 3.08 mmol). The residue after evaporation was dissolved in
each particular derivative.
2 ml of CH2Cl2, then 40 ml of methanol was added and the
resulting solution was stored at 0 1C overnight. The crystals
formed were filtered off, quickly washed with cold methanol and
5,17-Dinitro-25,26,27,28-tetrapropoxycalix[4]arene
(partial cone, syn-dinitro) 4
air dried to give 0.30 g of product 6 as a white powder in
1
A
general procedure was applied to 5,17-dinitro-26,28- 35% yield, mp: 222–224 1C. H NMR (300 MHz, CDCl3, 298 K)
dipropoxycalix[4]arene-25,27-diol 1 (0.50 g, 0.84 mmol), Cs2CO3 d: 8.11 (2H, s, ArH), 7.92 (2H, d, J = 2.6 Hz, ArH), 7.24 (2H, s, ArH),
(1.09 g, 3.35 mmol) and 1-iodopropane (0.5 ml, 5.13 mmol). The 7.12 (2H, d, J = 2.6 Hz, ArH), 4.16 (2H, d, J = 13.8 Hz, ArCH2Ar
residue after evaporation was dissolved in 2 ml of CH2Cl2 and ax), 3.85–3.58 (10H, m, 3 ꢃ OCH2 + 2 ꢃ ArCH2Ar), 3.44–3.39
c
224 New J. Chem., 2013, 37, 220--227
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013

View Article Online
Paper
NJC
(2H, m, OCH2), 3.28 (2H, d, J = 14.1 Hz, ArCH2Ar eq), 2.09–1.86 5,11,17-Triamino-23-tert-butyl-25,26,27,28-
(6H, m, OCH2CH2), 1.37–1.30 (11H, m, OCH2CH2 + But), 1.13– tetrapropoxycalix[4]arene (partial cone) 9
1.06 (9H, m, CH3), 0.67 (3H, t, J = 7.5 Hz, CH3). 13C{1H} NMR
A general procedure was applied to trinitro derivative 6 (0.25 g,
0.32 mmol), SnCl2ꢀ2H2O (1.08 g, 4.79 mmol). The product 9 was
isolated as a dark brown powder (0.22 g) in 98% yield, mp: 124–
(75 MHz, CDCl3, 296 K) d: 161.7, 161.3, 155.05, 144.7, 143.0,
142.4, 137.4, 134.0, 133.6, 132.0, 127.8, 126.0, 125.2, 123.4, 77.2,
75.2, 75.0, 36.4, 34.3, 31.8, 31.2, 24.0, 23.9, 21.8, 11.0, 10.7, 10.0;
TOF HRMS (ESI+): calcd for [C44H53N3O10 + Na]+: 806.3623.
Found: m/z (rel. int. %) 806.3627 (100) [M + Na]+.
1
126 1C. H NMR (300 MHz, CDCl3, 296 K) d: 7.16 (2H, s, ArH),
6.44 (2H, s, ArH), 6.41 (2H, d, J = 2.9 Hz, ArH), 5.79 (2H, d, J = 2.6
Hz, ArH), 3.99 (2H, d, J = 12.9 Hz, ArCH2Ar ax), 3.72–3.42 (10H,
m, 3 ꢃ OCH2 + 2 ꢃ ArCH2Ar), 3.30–3.25 (2H, m, OCH2), 2.83
(2H, d, J = 12.9 Hz, ArCH2Ar eq), 1.89–1.77 (6H, m, OCH2CH2),
1.37–1.32 (11H, m, OCH2CH2 + But), 1.08–0.98 (9H, m, CH3),
0.63 (3H, t, J = 7.5 Hz, CH3). 13C{1H} NMR (75 MHz, CDCl3, 298
K) d: 155.5, 149.7, 149.6, 143.4, 140.5, 140.0, 137.9, 133.9, 133.1,
133.0, 127.3, 118.3, 116.2, 116.0, 76.5, 74.9, 73.9, 36.9, 31.9,
31.2, 29.9, 24.3, 24.0, 21.5, 11.1, 10.8, 10.0; TOF HRMS (ESI+):
calcd for [C44H59N3O4 + H]+: 694.4578. Found: m/z (rel. int. %)
694.4582 (100) [M + H]+.
General procedure: reduction of nitro derivatives 4–6
The corresponding nitro derivatives 4–6 were dispersed in
ethanol (10 ml for 100 mg) and SnCl2ꢀ2H2O (5 equiv. for each
nitro group) was added. The mixture was heated to reflux
overnight and then poured into 1 M NH3 (aq.). Resulting
suspension was repeatedly extracted with CH2Cl2, combined
organic layers were washed with water, then with brine and
dried over MgSO4. Organic solvent was removed under reduced
pressure to give the pure products 7–9.
General procedure: synthesis of calixarene-based receptors
10–14
5,17-Diamino-25,26,27,28-tetrapropoxycalix[4]arene
(partial cone, syn-diamino) 7
The amino derivatives 7–9 were dissolved in anhydrous CH2Cl2
(30 ml for 0.100 g) under the atmosphere of dry nitrogen. The
corresponding isocyanate (2.50 equiv. for each amino group)
was added and the mixture was stirred overnight at room
temperature. The reaction was quenched by the addition of
methanol, then organic solvents were removed under reduced
pressure and the residue was purified. The purification method
is described below for each particular ligand.
A general procedure was applied to dinitro derivative 4 (0.43 g,
0.63 mmol), SnCl2ꢀ2H2O (1.42 g, 6.30 mmol). The product 7
was isolated as a brown powder (0.37 g) in 95% yield, mp:
176–179 1C. 1H NMR (300 MHz, CDCl3, 298 K) d: 7.20 (2H, d, J =
7.6 Hz, ArH), 7.05 (2H, d J = 7.3 Hz, ArH), 6.87 (1H, t, J = 7.0 Hz,
ArH), 6.83 (1H, t, J = 7.5 Hz, ArH), 6.45 (2H, d, J = 2.6 Hz, ArH),
5.61 (2H, d, J = 2.6 Hz, ArH), 4.04 (2H, d, J = 13.5 Hz, ArCH2Ar
ax), 3.75–3.45 (10H, m, 3 ꢃ OCH2 + 2 ꢃ ArCH2Ar), 3.29–3.23
(2H, m, OCH2), 2.96 (2H, d, J = 13.5 Hz, ArCH2Ar eq), 2.00–1.93
(2H, m, OCH2CH2), 1.89–1.77 (4H, m, OCH2CH2), 1.42–1.34
(2H, m, OCH2CH2), 1.14–1.07 (9H, m, 3 ꢃ CH3), 0.68 (3H, t, J =
7.6 Hz, CH3). 13C{1H} NMR (75 MHz, CDCl3, 296 K) d: 157.7,
149.5, 140.3, 137.4, 134.3, 134.1, 132.9, 130.5, 129.1, 122.0, 121.9,
118.1, 116.1, 76.4, 75.6, 74.8, 35.9, 31.0, 24.6, 24.0, 22.6, 11.2,
11.1, 9.6; TOF HRMS (ESI+): calcd for [C40H50N2O4 + H]+:
623.3843. Found: m/z (rel. int. %) 623.3847 (100) [M + H]+.
5,17-Bis[N0-(phenyl)ureido]-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone) 10
A general procedure was applied to amino derivative 7 (0.15 g,
0.24 mmol) and phenyl isocyanate (143 mg, 0.13 ml,
1.20 mmol). The product 10 was isolated by column chromato-
graphy (30 g of Al2O3, eluent CH2Cl2/MeOH = 50 : 1, then
CH2Cl2/MeOH = 1 : 1, RF = 0.11) as a white powder (0.14 g) in
66% yield, mp: 163–166 1C. 1H NMR (300 MHz, DMSO-d6,
298 K) d: 8.36 (2H, s, NH), 8.05 (2H, s, NH), 7.32 (4H, d, J =
7.9 Hz, ArH), 7.22–7.12 (8H, m, ArH), 7.06 (2H, d, J = 2.1 Hz,
ArH), 6.91–6.82 (4H, m, ArH), 6.47 (2H, d, J = 2.3 Hz, ArH), 4.00
5,17-Diamino-11,23-di-tert-butyl-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone, syn-diamino) 8
A general procedure was applied to dinitro derivative 5 (0.30 g,
0.38 mmol), SnCl2ꢀ2H2O (0.85 g, 3.77 mmol). The product 8
was isolated as a brown powder (0.27 g) in 97% yield, mp:
(2H, d, J = 12.6 Hz, ArCH2Ar ax), 3.76–3.57 (8H, m, OCH2
+
ArCH2Ar), 3.44–3.30 (4H, m, OCH2), 3.08 (2H, d, J = 13.5 Hz,
ArCH2Ar eq), 1.80–1.64 (6H, m, OCH2CH2), 1.43–1.23 (2H, m,
OCH2CH2), 1.03 (6H, t, J = 7.3 Hz, CH3), 0.74 (3H, t, J = 7.2 Hz,
CH3), 0.66 (3H, t, J = 7.6 Hz, CH3). 13C NMR (75 MHz, CDCl3, 296
K) d: 157.4, 154.2, 153.4, 139.0, 137.0, 135.3, 133.8, 133.5, 131.0,
130.5, 129.5, 129.1, 124.0, 123.2, 122.7, 122.6, 122.2, 119.6, 76.4,
75.6, 35.5, 31.0, 24.4, 24.0, 22.6, 11.2, 10.9, 9.5; TOF HRMS
(ESI+): calcd for [C54H60N4O6 + Na]+: 883.4405. Found: m/z
(rel. int. %) 883.4402 (100) [M + Na]+.
1
104–105 1C. H NMR (300 MHz, CDCl3, 298 K) d: 7.17 (2H, s,
ArH), 7.01 (2H, s, ArH), 6.42 (2H, d, J = 2.6 Hz, ArH), 5.70 (2H, d,
J = 2.9 Hz, ArH), 4.07 (2H, d, J = 13.2 Hz, ArCH2Ar ax), 3.75–3.63
(2H, m, OCH2), 3.58 (4H, d, J = 4.7 Hz, ArCH2Ar), 3.52–3.44 (2H,
m, OCH2), 3.36–3.30 (4H, m, OCH2), 2.94 (2H, d, J = 13.5 Hz,
ArCH2Ar eq), 1.89–1.75 (6H, m, OCH2CH2), 1.41–1.32 (20H, m,
OCH2CH2 + 2 ꢃ But), 1.12–1.02 (6H, m, CH3), 0.91 (3H, t, J = 7.5
Hz, CH3), 0.63 (3H, t, J = 7.6 Hz, CH3). 13C{1H} NMR (75 MHz,
CDCl3, 296 K) d: 155.4, 154.2, 149.9, 144.7, 143.5, 140.0, 136.4,
134.3, 133.3, 133.1, 127.4, 125.8, 118.3, 116.2, 76.5, 74.7, 73.9,
37.0, 36.5, 34.3, 34.2, 31.9, 24.2, 24.0, 21.6, 11.2, 10.6, 9.9; TOF
5,17-Bis[N0-(4-nitrophenyl)ureido]-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone) 11
HRMS (ESI+): calcd for [C48H66N2O4 + H]+: 735.5095. Found: A general procedure was applied to amino derivative 7 (0.10 g,
m/z (rel. int. %) 735.5095 (100) [M + H]+.
0.16 mmol) and 4-nitrophenyl isocyanate (97% purity, 136 mg,
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013
New J. Chem., 2013, 37, 220--227 225

View Article Online
NJC
Paper
0.80 mmol). The product 11 was isolated by column chromato- (2H, d, J = 2.3 Hz, ArH), 7.20 (2H, s, ArH), 7.15 (2H, s, ArH), 6.58
graphy (30 g of Al2O3, eluent CH2Cl2/MeOH = 160 : 1, RF = 0.14) (2H, d, J = 2.6 Hz, ArH), 4.04 (2H, d, J = 12.3 Hz, ArCH2Ar ax),
as a red powder (0.12 g) in 78% yield, mp: 227–230 1C. 1H NMR 3.78–3.60 (6H, m, OCH2 + ArCH2Ar), 3.46–3.32 (4H, m, OCH2),
(300 MHz, DMSO-d6, 298 K) d: 8.97 (2H, s, NH), 8.10 (2H, s, NH), 3.10 (2H, d, J = 12.9 Hz, ArCH2Ar eq), 2.95 (2H, t, J = 7.5 Hz,
8.01 (4H, d, J = 9.4 Hz, ArH), 7.43 (4H, d, J = 9.4 Hz, ArH), 7.19– OCH2), 1.83–1.72 (4H, m, OCH2CH2), 1.50–1.31 (22H, m,
7.13 (6H, m, ArH), 6.91 (1H, t, J = 7.5 Hz, ArH), 6.84 (1H, t, J = 7.5 OCH2CH2 + 2 ꢃ But), 0.99 (6H, t, J = 7.5 Hz, CH3), 0.63 (3H, t,
Hz, ArH), 6.37 (2H, d, J = 2.6 Hz, ArH), 3.99 (2H, d, J = 12.9 Hz, J = 7.5 Hz, CH3), 0.54 (3H, t, J = 7.3 Hz, CH3). 13C{1H} NMR (75
ArCH2Ar ax), 3.77–3.58 (6H, m, OCH2 + ArCH2Ar), 3.51–3.39 MHz, DMSO-d6, 298 K) d: 154.9, 153.8, 151.7, 146.7, 144.9,
(4H, m, OCH2), 3.26 (2H, t, J = 8.2 Hz, OCH2), 3.08 (2H, d, J = 142.8, 140.8, 135.2, 133.3, 133.2, 133.0, 132.5, 127.5, 125.8,
13.2 Hz, ArCH2Ar eq), 1.85–1.72 (6H, m, OCH2CH2), 1.40–1.32 125.2, 120.2, 118.6, 117.2, 76.0, 74.8, 72.3, 37.8, 34.0, 33.8,
(2H, m, OCH2CH2), 1.05 (6H, t, J = 7.3 Hz, CH3), 0.87 (3H, t, 31.7, 31.7, 30.6, 30.0, 23.2, 22.8, 20.6, 10.9,9.6; TOF HRMS
J = 7.3 Hz, CH3), 0.66 (3H, t, J = 7.5 Hz, CH3). 13C{1H} NMR (ESI+): calcd for [C62H74N6O10 + Na]+: 1085.5359. Found: m/z
(75 MHz, DMSO-d6, 298 K) d: 157.4, 156.6, 151.6, 151.3, 146.7, (rel. int. %) 1085.5354 (100) [M + Na]+.
140.6, 136.5, 133.6, 133.2, 132.4, 130.6, 129.1, 125.1, 122.7,
121.3, 120.4, 118.4, 117.1, 75.9, 75.1, 73.8, 36.2, 30.1, 23.4,
5-tert-Butyl-11,17,23-tris[N0-(4-nitrophenyl)ureido]-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone) 14
23.4, 21.4, 11.0, 10.4, 9.4; TOF HRMS (ESI+): calcd for
[C54H58N6O10 + Na]+: 973.4107. Found: m/z (rel. int. %) A general procedure was applied to amino derivative 9 (0.10 g,
973.4101 (100) [M + Na]+. EA found (%) C, 68.14; H, 6.12; N, 0.14 mmol) and 4-nitrophenyl isocyanate (97% purity, 183 mg,
8.83 (C54H58N6O10 requires C 68.20; H 6.15; N 8.84).
1.08 mmol). The product 14 was isolated by column chromato-
graphy (30 g of Al2O3, eluent CH2Cl2/MeOH = 160 : 1, then
CH2Cl2/MeOH = 1 : 1, RF = 0.15) as a yellow powder (0.04 g) in
5,17-Bis{N0-[(4-trifluoromethyl)phenyl]ureido}-25,26,27,28-
tetrapropoxycalix[4]arene (partial cone) 12
1
31% yield, mp: 232–235 1C. H NMR (300 MHz, DMSO-d6, 298
A general procedure was applied to amino derivative 7 (0.10 g, K) d: 9.36 (1H, s, NH), 9.00 (2H, s, NH), 8.78 (1H, s, NH), 8.25
0.16 mmol) and 4-(trifluoromethyl)phenyl isocyanate (150 mg, (2H, s, NH), 8.20 (2H, d, J = 9.1 Hz, ArH), 8.10 (4H, d, J = 9.1 Hz,
0.11 ml, 0.80 mmol). The first purification was used to remove ArH), 7.72 (2H, d, J = 9.1 Hz, ArH), 7.49 (4H, d, J = 9.1 Hz, ArH),
the majority of carbamate by column chromatography (50 g of 7.27 (2H, s, ArH), 7.20 (2H, s, ArH), 7.18 (2H, d, J = 2.6 Hz, ArH),
Al2O3, eluent pure CH2Cl2 – carbamate fractions; second eluent 6.53 (2H, d, J = 2.3 Hz, ArH), 4.03 (2H, d, J = 12.9 Hz, ArCH2Ar
pure MeOH – calix[4]arene fractions). The product 12 was ax), 3.77–3.60 (6H, m, OCH2 + ArCH2Ar), 3.46–3.32 (6H, m,
finally isolated by preparative GPC (isocratic elution of CHCl3, OCH2), 3.06 (2H, d, J = 12.9 Hz, ArCH2Ar eq), 1.85–1.73
column PLgel 10 mm, 100 Å, 600 ꢃ 25 mm, fl. rate 5 ml minꢁ1
,
(4H, m, OCH2CH2), 1.70–1.62 (2H, m, OCH2CH2), 1.46–1.36
detector UV 254 nm) as a white powder (0.10 g) in 63% yield, (11H, m, OCH2CH2 + But) 1.02 (6H, t, J = 7.5 Hz, CH3), 0.77 (3H,
1
mp: 197–199 1C. H NMR (300 MHz, DMSO-d6, 298 K) d: 8.68 t, J = 7.3 Hz, CH3), 0.64 (3H, t, J = 7.5 Hz, CH3). 13C NMR (75
(2H, s, NH), 8.05 (2H, s, NH), 7.47 (8H, brs, ArH), 7.20–7.12 (6H, MHz, DMSO-d6, 298 K) d: 155.6, 152.7, 152.2, 152.1, 152.0,
m, ArH), 6.93–6.82 (2H, m, ArH), 6.41 (2H, s, ArH), 4.00 (2H, d, 147.3, 147.2, 143.2, 141.5, 141.2, 137.1, 134.1, 133.4, 133.3,
J = 12.9 Hz, ArCH2Ar ax), 3.75–3.58 (8H, m, OCH2 + ArCH2Ar), 133.2, 132.8, 125.9, 125.7, 121.2, 119.8, 119.0, 118.0, 117.6,
3.43–3.24 (4H, m, OCH2), 3.08 (2H, d, J = 12.9 Hz, ArCH2Ar eq), 76.5, 75.2, 73.4, 37.7, 34.4, 32.1, 31.0, 23.9, 23.6, 21.2, 11.4,
1.81–1.74 (6H, m, OCH2CH2), 1.41–1.33 (2H, m, OCH2CH2), 1.04 10.7, 10.2; TOF HRMS (ESI+): calcd for [C65H71N9O13 + Na]+:
(6H, t, J = 7.0 Hz, CH3), 0.82 (3H, t, J = 7.3 Hz, CH3), 0.66 (3H, t, 1208.5064. Found: m/z (rel. int. %) 1208.5073 (100) [M + Na]+.
J = 7.0 Hz, CH3). 19F NMR (282 MHz, DMSO-d6, 296 K) d: ꢁ60.49
(6F, s, CF3). 13C{1H} NMR (75 MHz, CDCl3, 296 K) d: 157.4,
Crystallographic measurements
156.99, 153.6, 153.5, 141.9, 136.7, 135.5, 133.5, 133.4, 130.3,
Crystallographic data for C48H62N2O8 (5). Mr = 795.00,
130.1, 129.3, 126.2 (q, J = 3.8 Hz), 124.7 (q, J = 32.0 Hz), 124.0 monoclinic system, space group P21/c, a = 13.7360 (4) Å, b =
(q, J = 271.0 Hz), 123.6, 122.4, 122.1, 118.5, 76.3, 75.4, 75.2, 35.1, 17.1360 (5) Å, c = 23.2760 (3) Å, b = 123.9930 (14)1, Z = 4, V =
30.3, 24.2, 23.8, 22.5, 10.9, 10.8, 9.3; TOF HRMS (ESI+): calcd for 4542.4 (2) Å3, Dx = 1.162 Mg mꢁ3, crystal dimensions 0.4 ꢃ 0.4 ꢃ
[C56H58F6N4O6 + Na]+: 1019.4159. Found: m/z (rel. int. %) 0.4 mm. Data were collected on a Nonius KappaCCD diffracto-
1019.4153 (100) [M + Na]+.
meter by monochromatized MoKa radiation (l = 0.71073 Å) at
150(2) K. An absorption was neglected (m = 0.08 mmꢁ1) a 47 233
total of measured reflections (ymax = 27.51), from which 10 398
were unique (Rint = 0.033) and 6859 observed (I 4 2s(I)). The
5,17-Di-tert-butyl-11,23-bis[N0-(4-nitrophenyl)ureido]-
25,26,27,28-tetrapropoxycalix[4]arene (partial cone) 13
A general procedure was applied to amino derivative 8 (0.10 g, structure was solved by direct methods16 and refined by full-
0.14 mmol) and 4-nitrophenyl isocyanate (97% purity, 115 mg, matrix least squares based on F2 (SHELXL97).17 The hydrogen
0.68 mmol). The product 13 was isolated by column chromato- atoms were fixed into idealised positions (riding model) and
graphy (30 g of Al2O3, eluent CH2Cl2/MeOH = 160 : 1, RF = 0.15) assigned temperature factors either Hiso(H) = 1.2 Ueq(pivot
as a red powder (0.10 g) in 75% yield, mp: 248–250 1C. 1H NMR atom) or Hiso(H) = 1.5 Ueq(pivot atom) for –CH3. The refinement
(300 MHz, DMSO-d6, 286 K) d: 9.09 (2H, s, NH), 8.30 (2H, s, NH), converged (D/smax = 0.001) to R = 0.061 for observed reflections
8.09 (4H, d, J = 9.4 Hz, ArH), 7.54 (4H, d, J = 9.1 Hz, ArH), 7.22 and wR(F2) = 0.196, GOF = 1.00 for 533 parameters and all
c
226 New J. Chem., 2013, 37, 220--227
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013

View Article Online
Paper
NJC
7 For review on calixarene-based receptors for anions, see:
(a) E. A. Shokova and V. V. Kovalev, Russ. J. Org. Chem., 2009,
45, 1275–1314; (b) S. E. Matthews and P. D. Beer, Supramol.
Chem., 2005, 17, 411–435; (c) P. Lhotak, Top. Curr. Chem.,
2005, 255, 65–95.
10 398 reflections. The final difference map displayed no peaks
of chemical significance (Drmax = 0.68, Drmin ꢁ0.49 e Åꢁ3). The
displacement parameters of atoms of tert-butyl groups are
wittnesing disorder of these moieties, however the attempt to
split positions of these atoms did not improve the model.
8 For some recent examples on anion recognition using
neutral calixarenes, see: (a) E. K. Bullough, C. A. Kilner,
M. A. Little and C. E. Willans, Org. Biomol. Chem., 2012, 10,
2824–2829; (b) A. J. McConnell, C. J. Serpell and P. D. Beer,
New J. Chem., 2012, 36, 102–112; (c) E. Quinlan,
S. E. Matthews and T. Gunnlaugsson, J. Org. Chem., 2007,
72, 7497–7503; (d) E. Metay, M. C. Duclos, S. Pellet-Rostaing,
M. Lemaire, J. Schulz, R. Kannappan, C. Bucher, E. Saint-
Aman and C. Chaix, Eur. J. Org. Chem., 2008, 4304–4312.
9 (a) K. Flidrova, M. Tkadlecova, K. Lang and P. Lhotak, Dyes
Pigm., 2012, 92, 668–673; (b) K. Flidrova, M. Tkadlecova,
Acknowledgements
This research was supported by the Czech Science Foundation
(No. 203/09/0691), and by the Grant Agency of the Academy of
Sciences of the Czech Republic (No. IAAX08240901).
References
1 (a) P. A. Gale, Chem. Commun., 2008, 4525–4540; (b) R. Vilar, Eur.
J. Inorg. Chem., 2008, 357–367; (c) I. Ravikumar and P. Ghosh,
Chem. Soc. Rev., 2012, 41, 3077–3098; (d) M. Wenzel, J. R.
Hiscock and P. A. Gale, Chem. Soc. Rev., 2012, 41, 480–520;
(e) P. A. Gale, Chem. Commun., 2011, 47, 82–86; ( f ) P. S. Dieng
and C. Sirlin, Int. J. Mol. Sci., 2010, 11, 3334–3348.
´
K. Lang and P. Lhotak, Tetrahedron Lett., 2012, 53, 678–680;
´
(c) J. Kroupa, I. Stibor, M. Pojarova, M. Tkadlecova and
P. Lhotak, Tetrahedron, 2008, 64, 10075–10079;
(d) P. Curinova, I. Stibor, J. Budka, J. Sykora, K. Lang and
P. Lhotak, New J. Chem., 2009, 33, 612–619; (e) A. Krajewska,
P. Lhotak and H. Radecka, Sensors, 2007, 7, 1655–1666.
2 (a) Anion Coordination Chemistry, ed. K. Bowman-James,
A. Bianchi and E. Garcia-Espana, Wiley-VCH Verlag, 2012;
(b) Anion Recognition in Supramolecular Chemistry, in 10 I. Stibor, J. Budka, V. Michlova, M. Tkadlecova, M. Pojarova,
´
Topics in Heterocyclic Chemistry, ed. P. A. Gale and
W. Dehaen, Springer Verlag, 2010, vol. 24; (c) J. L. Sessler,
P. Curinova and P. Lhotak, New J. Chem., 2008, 32,
1597–1607.
P. A. Gale and W. S. Cho, Anion Receptor Chemistry, The Royal 11 J. Budka, P. Lhotak, V. Michlova and I. Stibor, Tetrahedron
Society of Chemistry, Cambridge, 2006; (d) Recognition of Lett., 2001, 42, 1583–1586.
Anions, in Structure and Bonding, ed. R. Vilar, Springer Verlag, 12 M. Kumar, A. Dhir and V. Bhalla, Chem. Commun., 2010, 46,
2008, vol. 129; (e) Anion Sensing, Topics in Current Chemistry,
ed. I. Stibor, Springer, Berlin, 2005, vol. 255.
3 (a) H. T. Ngo, X. Liu and K. A. Jolliffe, Chem. Soc. Rev., 2012,
41, 4928–4965; (b) X. Wu, Microchim. Acta, 2012, 176, 23–47;
(c) S. Kubik, Chem. Soc. Rev., 2010, 39, 3648–3663.
6744–6746.
´
13 (a) O. Hudecek, P. Curinova, J. Budka and P. Lhotak, Tetra-
hedron, 2011, 67, 5213–5218; (b) O. Hudecek, J. Budka,
V. Eigner and P. Lhotak, Tetrahedron, 2012, 68, 4187–4193.
14 P. Thordarson, Chem. Soc. Rev., 2011, 40, 1305–1323.
4 (a) J. M. Llinares, D. Powell and K. Bowman-James, Coord. 15 Z. D. Hill and P. MacCarthy, J. Chem. Educ., 1986, 63,
Chem. Rev., 2003, 240, 57–75; (b) C. Rether and C. Schmuck, 162–167.
Eur. J. Org. Chem., 2011, 1459–1466; (c) M. P. Coles, Chem. 16 A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi,
Commun., 2009, 3659–3676.
5 (a) V. Amendola, L. Fabbrizzi and L. Mosca, Chem. Soc. Rev.,
M. C. Burla, G. Polidori and M. Camalli, J. Appl. Crystallogr.,
1994, 27, 435.
2010, 39, 3889–3915; (b) P. Dydio, D. Lichosyt and J. Jurczak, 17 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr.,
Chem. Soc. Rev., 2011, 40, 2971–2985; (c) M. O. Odago, 2008, 64, 112–122.
A. E. Hoffman, R. L. Carpenter, D. C. T. Tse, S.-S. Sun and 18 As suggested by one of the referees we have carried out the
A. J. Lees, Inorg. Chim. Acta, 2011, 374, 558–565.
additional complexation study using the cone analogue of
receptor 11 to directly compare the complexation abilities of
both conformers. As one can see from ESI† (page 14), the
complexation of Clꢁ occurred with a 1 : 1 stoichiometry (Job
plot) and the corresponding complexation constant is 173 ꢂ
24 Mꢁ1 which is much lower than that of the partial cone
derivative 11 (1540 ꢂ 370). This indicates that the partial
cone conformation can be much better choice than the cone
conformers used so far in the design of novel anion
receptors.
6 For books on calixarenes, see:(a) C. D. Gutsche, Calixarenes:
An introduction, The Royal Society of Chemistry, Thomas
Graham House, Cambridge, 2nd edn 2008; (b) Calixarenes in
the Nanoworld, ed. J. Vicens, J. Harrowfield and L. Backlouti,
Springer, Dordrecht, 2007; (c) Calixarenes 2001, ed. Z. Asfari,
¨
V. Bohmer, J. Harrowfield and J. Vicens, Kluwer Academic
Publishers, Dordrecht, 2001; (d) L. Mandolini and
R. Ungaro, Calixarenes in Action, Imperial College Press,
London, 2000.
c
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2013
New J. Chem., 2013, 37, 220--227 227