New redox anion receptors based on calix[4]pyrrole bearing ferrocene amide

Article abstract of DOI:10.1016/j.tet.2008.07.035

Two redox anion receptors based on calix[4]pyrrole and ferrocene have been synthesized. The electrochemical investigation revealed that these compounds can be response to the anions with different shifts of Fc/Fc⁺ couple. With the ¹H

Full text of DOI:10.1016/j.tet.2008.07.035

Tetrahedron 64 (2008) 9244–9252
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
New redox anion receptors based on calix[4]pyrrole bearing ferrocene amide
,
Wenzhi Yang a, Zhenming Yin a b, Chun-Hua Wang a, Chengyun Huang a, Jiaqi He a, Xiaoqing Zhu a,
,
Jin-Pei Cheng a
*
a Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, NanKai University, Tianjin 300071, China
b College of Chemistry and Life Science, Tianjin Normal University, Tianjin 300387, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two redox anion receptors based on calix[4]pyrrole and ferrocene have been synthesized. The electro-
chemical investigation revealed that these compounds can be response to the anions with different shifts
of Fc/Fcþ couple. With the 1H NMR titration study, the selectivity to Fꢀ and AcOꢀ ions in CD3CN solution
was confirmed. The conformations of the mono-aromatic meso-substituted calix[4]pyrroles, which were
the synthetical intermediate of the ferrocene based receptors, and their anion complexes in the solid
state have also been studied by single X-ray crystallography, and the rationality of the crystal confor-
mations was proved by theoretical study.
Received 4 February 2008
Received in revised form 8 July 2008
Accepted 11 July 2008
Available online 16 July 2008
Keywords:
Anion recognition
Calix[4]pyrrole
Crystal structure
Redox receptor
Theoretical calculation
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
3-aminophenylcalix[4]pyrrole 3 as the substrate to construct three
anion receptors. The unique character of these compounds was that
The research on anion recognition has attracted rapidly growing
attention recently due to the important roles of anions in many
scientific areas such as chemistry, biology, therapeutics, ecology,
pharmacology, and in industries.1,2 As the significance of qualitative
and quantitativeinformationon anion recognition has becomemore
and more visible, lots of interesting anion-hosting molecules were
developed and their binding properties were more vigorously
studied.1,2 Among the anion receptors reported in the literature,
calixpyrroles shouldbe of particularinterestsincetheyshowed good
binding capability both in the solution and in the solid phase.3,4
However, unlike simple calixpyrroles, the synthesis of their
derivatives often turned out to be not so straightforward. For ex-
ample, the synthesis of the important meso-substituted series in
the calixpyrrole family, which showed higher affinity to anions
and had versatile reporter groups, was reported only in limited
cases.5–16 Furthermore, their binding behaviors were even less in-
vestigated. In these work, some meso-hook derivates of cal-
ix[4]pyrrole have been synthesized and characterized13–16 while
the mono-meso aromatic-substituted calix[4]pyrrole attracted
more attention because of the cooperation ability of the aromatic
group to the anions binding progress. In the research of second
generation calixpyrrole,5 Sessler and co-workers employed
they supported additional binding sites that could dramatically
increase the binding capability to anions. These receptors could be
treated as the analogs of lariat crown esters, whose recognition
mechanism for ions was also the cooperation of the original ion
receptor and the additional binding sites.
In the present work, a new type of redox anion receptors based
on calix[4]pyrrole and ferrocene has been synthesized and char-
acterized. The electrochemical investigation revealed that these
compounds can respond to the anions with the different shifts of
Fc/Fcþ couple and the selectivity to Fꢀ and AcOꢀ ions in CD3CN
solution was confirmed with the 1H NMR titration study. The
conformations of the mono nitrobenzene-substituted cal-
ix[4]pyrroles and their anion complexes in the solid state have also
been studied by X-ray single crystal diffraction, and the rationality
of the crystal conformations was proved by theoretical study.
2. Result and discussion
2.1. Synthesis
The nitrobenzene-substituted calix[4]pyrroles 5 and 6 were
prepared by the co-condensation of nitroacetophenone 7 (or 8),
pentan-3-one, and pyrrole in the presence of BF3$Et2O (Scheme 1).
Then, 5 and 6 were reduced to the corresponding amine derivates 3
and 4 by hydrazine hydrate under the catalysis of Pd/C. The ferro-
cenoyl chloride was obtained conveniently when triphosgene was
* Corresponding author.
E-mail address: chengjp@nankai.edu.cn (J.-P. Cheng).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.07.035

W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
9245
O
R1
R1
Cl
O
R2
R2
Fe
NH HN
NH HN
NH
BF3 Et2O
+
+
O
pyridine
N
H
NH
HN
HN
R1
R2
O
7: R1=NO2, R2=H
8: R1=H, R2=NO2
5: R1=NO2 , R2=H
6: R1=H, R2=NO2
NH
Fe
1: R1=
,
R2=H
NH2NH2 Pd/C
3: R1=NH2 , R2=H
4: R1=H, R2=NH2
O
NH
Fe
2: R1=H, R2=
Scheme 1. The synthetic route of receptor 1 and 2.
reacted with ferrocene carboxylic acid in methylene dichloride at
room temperature in the presence of triethylamine and DMAP.17
The reaction between aminobenzene-substituted calix[4]pyrrole 3
(or 4) and ferrocenoyl chloride in CH2Cl2 in the presence of pyridine
gave the receptor 1 (or 2) successfully.
For 1, with the addition of the fluoride, the signals of the pyrrole
NHs disappeared until the new signals appeared at 12.3 ppm,
which represented the formation of the stable complexes. Mean-
while, the upfield shifts of the signal of C2 and C4 protons of re-
ceptor
1
were observed dramatically. The addition of
Compound 3 was an important intermediate compound and has
been used in the synthesis of functional calixpyrrole. It was pre-
pared in two steps from Cbz-protected 3-aminoacetophenone,
pentan-3-one, and pyrrole in the presence of BF3$Et2O and fol-
lowed by deprotonation of the initial product by catalytic hydro-
genation5 or 40% aqueous KOH in MeOH.18 Herein, the synthetic
route was shortened from three steps (including the preparation of
Cbz-protected 3-aminoacetophenone) to two relatively simple
steps with quite high total yield.
dihydrogenphosphate caused the same changes in the spectra,
except for the disappearance of the amide NH and the attractive
shifts of C6 proton and ferrocene protons when the anion was
1
1+F
1+Cl
1+Br
1+H2PO4
O
O
1+AcO
1+HSO4
HN
HN
2
Fe
2
6
5
3
Fe
HN
NH
NH HN
NH
6
4
5
NH HN
HN
2
1
800
600
400
E (mV) vs Fc/Fc+
200
0
-200
2.2. Electrochemical study
2
F
Cl
Br
H2PO4
AcO
HSO4
The electrochemical properties of the anion receptors 1 and 2
were investigated by cyclic voltammetry (CV) and square-wave
voltammetry (SWV) in CH3CN (Fig. 1). The receptor was firstly
scanned between þ300 and ꢀ100 mV (vs Fc/Fcþ), and a reversible
Fc/Fcþ wave was observed. While the cyclovoltammogram was
scanned between þ800 and ꢀ100 mV, a further oxidation wave
appeared, which could be attributed to the calixpyrrole redox-ac-
tivated center. The Fc/Fcþ redox potentials of the receptors are
summarized in Table 1. The fluoride induced the greatest cathodic
shift of the Fc/Fcþ couple around the halide, which was accompa-
nied by chloride and bromide in turn. Among the complex anions,
similar with the former literature,10 the dihydrogenphosphate
caused the largest cathodic shift, which was larger than the acetate
and even larger than the halide. Additionally, the hydrogen sulfate
caused a little anodic shift.
800
600
400
E (mv) vs Fc/Fc+
200
0
-200
2.3. 1H NMR titration study
The 1H NMR titrations were also employed to study the binding
properties of the receptors 1 and 2 in CD3CN (Fig. 2).
Figure 1. Cyclic voltammograms of 1 (top) and 2 (bottom) recorded in CH3CN (0.1 mol/l
n-Bu4NF6 electrolyte).

9246
W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
Table 1
receptors, which are summarized in Table 1. It is clear that the
Binding and electrochemical properties of compounds 1 and 2
binding constants of receptors 1 and 2 were higher than the octa-
methylcalix[4]pyrrole even in acetonitrile. On the other hand, the
polarized solvent may hamper the aggregations of the hosts for the
formation of intermolecular hydrogen bond and let the receptor to
bind the anions more efficiently. Compared with the mono-
substituted analogs, 1 and 2 also showed larger binding affinities to
the anions, which could be attributed to the relatively smaller
meso-substituted group (ethyl vs cyclohexanyl, phenyl vs ferro-
cene) and much efficient cooperation of the phenyl group, which
was more close to the calix[4]pyrrole moiety. The constants also
showed that the receptors have a selective recognition toward Fꢀ
and AcOꢀ. It is inconsistent with the electrochemical investigation.
Same phenomena were also observed by Gale.10,23 It may due to
that H2POꢀ4 can interact more with ferrocene group and phenyl
group whereas less interaction for Fꢀ and AcOꢀ (Fig. 2).
Aniona
Receptor 1
Receptor 2
Ka
E1/2 (mV)c
D
E (mV)c Ka
E1/2 (mV)c
D
E (mV)c
b
b
No anion N/A
196
80
N/A
116
32
N/A
192
N/A
80
32
ꢀ4
132
80
ꢀ8
Fꢀ
>100,000
>100,000 112
5300 160
150 196
1900
>100,000 112
ND 200
Clꢀ
3600 164
80 200
770 54
Brꢀ
ꢀ4
H2POꢀ4
142
76
60
CH3COOꢀ >100,000 120
HSOꢀ4
ND
208
ꢀ12
a
Used in the form of their (n-Bu4N)þ salts.
b
Association constants for anion binding, recorded in CD3CN, errors<20%, de-
termined from ) [ppm] pyrrole -CH since the signal of pyrrole N-H became
obscure during the titration.
D(
d
b
c
Determined in CH3CN containing 0.1 mol/L n-Bu4NPF6 as the supporting elec-
trolyte. Solutions of 1/2 were 1ꢁ10ꢀ3 mol/L and potentials were determined with
reference to Fc/Fcþ. E1/2 values obtained from SWVs.
added. It revealed that the binding of receptors to the dihy-
drogenphosphate was profound and the multi-site binding, hy-
drogen bonds from calixpyrrole NH, amide NH, and ferrocene C–H,
was dominated. The acetate also caused significant changes in
the 1H NMR of the receptor 1 and the whole process seemed like
the binding process of the fluoride, which has been announced
in the former publications.18,19 Unlike the dihydrogenphosphate,
the amide NH didn’t disappeared at all, which indicated that the
calix[4]pyrrole was the main binding site. A clear doublet peak at
10.8 ppm suggested that the formation of the receptor–acetate
complex was very stable, which maybe attributed to the relative
small radius (oxygen vs chloride) and simple geometry (acetate vs
dihydrogenphosphate).
With the addition of the chloride, similar phenomenon was
observed as the fluoride titration except for the smaller shifts of all
protons. These can be attributed to the larger radius of the anions
that do not fit in the cavity of the calix[4]pyrrole and the relatively
lower charge density that weaken the hydrogen bond. The bromide
and the hydrogen sulfate caused only little changes in the spectra.
The non-linear fitting of the titration results with the
WinEQNMR program20 afforded associated constants of the
2.4. Single crystal study
In order to explain the binding behavior more exactly, the single
crystals of the receptors and their anions complexes were obtained
(Table 3). In fact the crystals of 5 and 6 and the complexes were
obtained to illustrate the binding mode of the complexes because of
the difficulty to acquire the single crystals of the receptors 1 and 2
and their complexes with anions.
The 1H NMR titration experiments of the substrates 5 and 6
were not realized due to their poor solubility in CD3CN at room
temperature. Fortunately, the same experiments were succeeded in
CDCl3 and DMSO, and the same phenomena, which in accord to 1
and 2 during the titrations that the aromatic C–Hs shifted upfield
on the addition of the anions, were observed.
The suitable single crystal of 5 was obtained from hot CH3CN
solution of 5, while the single crystals of 6 were also obtained by
the similar process in hot CH3CN and hot acetone. All three single
crystals adopted distorted 1,3-alternative conformations (Figs. 3–
5), which were the common cases of the unsubstituted-cal-
ix[4]pyrroles21 and even the mono-aromatic meso-substituted
calix[4]pyrrole in Gale’s work.10 In all three crystals, the phenyl
Figure 2. 1H NMR spectra of compound 1 in CD3CN solution on addition of 1 equiv of tetrabutylammonium anions.

W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
9247
Figure 3. Top view (left) and side view (right) of the X-ray structure of 5.
Figure 4. Top view (left) and side view (right) of the X-ray structure of 6 (in CH3CN).
Figure 5. Top view (left) and side view (right) of the X-ray structure of 6 (in acetone).
groups were almost parallel to the calix[4]pyrrole plants, which
were like the widespread samples in the four-aromatic meso-
substituted calix[4]pyrroles24–26 and the di-aromatic meso-
substituted calix[4]pyrroles.25 On the other hand, in some cases of
di-aromatic meso-substituted calix[4]pyrroles,26 the aromatic
groups were sometimes vertical to the calix[4]pyrrole plant due to
the favor in the thermal dramatics.
The single crystals of 5$Fꢀ and 6$Fꢀ were obtained by the dif-
fusion of n-hexane to the CH2Cl2 solutions of 5–(n-Bu)4NF and 6–
(n-Bu)4NF. The two single crystals adopted cone conformations
(Figs. 6 and 7), which were the common cases of the almost cal-
ix[4]pyrroles–anion complexes3,4 and some uncomplexed four-
aromatic meso-substituted calix[4]pyrroles.8,22,24 There were two
kinds of complexes in the crystal of 6$Fꢀ, which showed a little

9248
W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
Figure 6. Top view (left) and side view (right) of the X-ray structure of 5$Fꢀ complex ((n-Bu)4Nþ counter-ions were omitted for clarity).
Figure 7. Two types of complexes (top view (left) and side view (right)) of the X-ray structure of 6$Fꢀ complex ((n-Bu)4Nþ counter-ions were omitted for clarity).
difference in the orientation of the meso ethyl group. However, after
investigated in detail, the most attractive features of these crystals
were the strange conformations of the phenyl group in the com-
plexes. It is unexpected to find that similar to the free hosts 5/6 the
aromatic groups were parallel to the calix[4]pyrrole plant, showing
some differences to our former work.26 Further observation
showed that the average pyrrole N–H/F distance of 6 (2.766 Å)
was much shorter than that of 5 (2.788 Å) (Table 2), which illus-
trated that the binding ability of 6 to the anions was higher than 5.
2.5. Theoretical calculation
In order to explain the strange conformations of the receptors
and the complexes, the theoretical investigations were applied by

W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
9249
Table 2
Advantage mass spectrometer. All other commercially available
reagents were used without further purification.
Intermolecular and direct host–guests hydrogen bond parameters for crystals in this
study
D–H/A
d (Å) (H/A)
q
(ꢂ) (D–H/A)
d (Å) (D/A)
4.2. Synthesis of receptors
5$Fꢀ
6$Fꢀ
N1–H1/F1
N2–H2/F1
N3–H3/F1
N4–H4/F1
1.912
1.915
1.987
1.903
170.98
171.12
153.41
173.61
2.785
2.788
2.801
2.779
4.2.1. Compound 5
3-Nitroacetophenone 7 (1.656 g, 10 mmol), pyrrole (2.7 ml,
40 mmol), and penton-3-one (3.17 ml, 30 mmol) were dissolved in
a mixture of methanol and dichloromenthane (160 ml, 1:1 v/v),
borontrifluoride–etherate (2.58 ml, 20 mmol) was added to the
solution, and the mixture was stirred at room temperature for 60 h.
The reaction mixture was washed with saturated aqueous NaHCO3
and brine, and dried over MgSO4. The large amount of solvent was
moved and the residue was purified by column chromatography
over silica gel (eluant: petrol ester/ethyl acetate¼30:1) to give 5
N1–H1/F1
N2–H2/F1
N3–H3/F1
N4–H4/F1
N7–H7/F2
N8–H8/F2
N9–H9/F2
N10–H10/F2
1.874
1.953
1.893
1.887
1.899
1.984
1.921
1.895
172.59
159.60
172.33
167.20
173.30
151.70
172.30
166.25
2.749a
2.794a
2.767a
2.752a
2.775
2.790
2.796
2.758
a
(1.104 g, 17.8%) as a yellow powder. 1H NMR (300 MHz, CDCl3)
d:
xꢀ1/2, –yþ1/2, z].
8.06 (1H, d, J¼7.8 Hz, phenyl C–H), 7.78 (1H, t, phenyl C–H), 7.49–
7.46 (1H, m, phenyl C–H), 7.40 (1H, t, phenyl C–H), 7.17 (2H, s,
pyrrole N–H), 6.95 (2H, s, pyrrole N–H), 5.95–5.91 (6H, m, pyrrole
C–H), 5.63–5.59 (2H, m, pyrrole C–H), 1.91 (3H, s, –CH3), 1.87–1.73
(12H, m, –CH2–), 0.71–0.59 (18H, m, –CH3); 13C NMR (300 MHz,
using semi-empirical method in gas phase. We also constructed the
phenyl-horizontal conformation of compounds 5 and 6 and the
complexes by rotating the phenyl plant for 90ꢂ and ꢀ90ꢂ. All the
single crystals and the constructed conformations were optimiza-
CDCl3) d: 149.8, 148.0, 137.2, 136.1, 135.5, 135.0, 133.5, 128.3, 122.4,
tion at the B3LYP/3-21G
*
level of theory, and the single-point en-
level of theory. The
121.6, 106.3, 105.9, 105.1, 104.9, 44.6, 43.0, 29.0, 28.9, 28.5, 28.4, 8.1,
7.9, HRMS (ESI) calcd for C39H50N5O2: 620.3959 ([MþH]þ), found:
620.3962 ([MþH]þ).
ergy was calculated at the B3LYP/6-31G
*
stabilization energies were calculated as the difference in the en-
ergy between the sum of the receptor and the free fluoride and the
complex.
4.2.2. Compound 6
According to our calculated results, the following observations
can be made (1) for free hosts, the phenyl-horizontal conformations
were the only theoretical optimized results from different initial
conformations we constructed, which agree well with our crystal
structure. (2) Concerning the complexes, the phenyl-horizontal
style was also more favorable than the phenyl-vertical style
according to the energy comparison (Fig. 8). For compounds 6, 5
(nitro-exo), and 5 (nitro-endo), the phenyl-horizontal style is more
stable than phenyl-vertical style by about 1.4, 0.0, and 5.0 kcal/mol
in the gas phase, respectively. All these energy changes were small
so that the phenyl group may rotate freely. (3) The associate energy
of compound 6 (166.3 kcal/mol) was much higher than compound
5 (121.3 kcal/mol), which agrees well with the 1H NMR titration
observations of compound 1/2. These can be attributed to the large
volume of the nitro group, which results in the deviation of the
pyrrole N–H and the phenyl group to the anions.
4-Nitroacetophenone 7 (1.656 g, 10 mmol), pyrrole (2.7 ml,
40 mmol), and penton-3-one (3.17 ml, 30 mmol) were reacted in
accord with the procedure used for the synthesis of 5 and gave 6
(1.035 g,16.6%) as ayellowpowder.1HNMR (300 MHz, CDCl3)
d: 8.07
(2H, d, J¼9 Hz, phenyl C–H), 7.20–7.17 (4H, m, phenyl C–H and pyr-
role N–H), 6.94 (2H, s, pyrrole N–H), 5.94–5.91 (6H, m, pyrrole C–H),
5.64–5.63 (2H, m, pyrrole C–H),1.89 (3H, s, –CH3),1.86–1.75 (12H, m,
–CH2–), 0.68–0.61 (18H, m, –CH3); 13C NMR (300 MHz, CDCl3)
d:
155.0,146.5,137.0,136.1,135.4,134.9,128.3,122.8,106.3,105.8,105.1,
104.9, 44.9, 43.0, 29.1, 28.9, 28.6, 28.5, 8.1, 8.0; HRMS (ESI) calcd for
C
39H48N5O2: 618.3813 ([MꢀH]ꢀ), found: 618.3822 ([MꢀH]ꢀ).
4.2.3. Compound 3
To the suspension of 5 (0.620 g, 1 mmol) and Pd/C (5%, 0.200 g)
in ethanol (40 ml) was added NH2NH2$H2O (80%, 2.0 ml), and the
mixture was allowed to heat under reflux for 2 h. Pd/C was re-
moved by the filtration of the reaction mixture while cooling. The
filtrate was evaporated to dryness in vacuo. The residue was
redissolved in CH2Cl2, dried over Na2SO4, and evaporated to dry-
ness. The white solid was purified by column chromatography over
silica gel (eluant: dichloromethane/ethyl acetate¼50:1) to give 3
3. Conclusion
In summary, two redox anion receptors based on calix[4]pyrrole
and ferrocene have been synthesized. The electrochemical in-
vestigation revealed that these compounds can respond to the
anions with the different shifts of Fc/Fcþ couple. With the 1H NMR
titration study, the selectivity to Fꢀ and AcOꢀ ions in CD3CN solu-
tion was confirmed.27–32 The conformations of the mono-aromatic
meso-substituted calix[4]pyrroles and their anion complexes in the
solid state have been studied, and the rationality of the crystal
conformations was proved by theoretical study.
(0.469 g, 79.6%) as a white powder. 1H NMR (400 MHz, CDCl3)
d:
7.15 (2H, s, pyrrole N–H), 7.04 (1H, t, phenyl C–H), 6.96 (2H, s,
pyrrole N–H), 6.68–6.66 (1H, m, phenyl C–H), 6.54 (1H, d, J¼6.8 Hz,
phenyl C–H), 6.45 (1H, s, phenyl C–H), 5.90 (6H, s, pyrrole C–H),
5.67 (2H, s, pyrrole C–H), 1.83 (3H, s, –CH3), 1.81–1.74 (12H, m,
–CH2–), 0.66–0.57 (18H, m, –CH3); ESI-MS([MþH]þ): 590.58.
4.2.4. Compound 4
Compound
6 (0.620 g, 1 mmol), Pd/C (5%, 0.200 g), and
4. Experimental
4.1. General
NH2NH2$H2O (80%, 2.0 ml) were reacted in accord with the pro-
cedure used for the synthesis of 3 (eluant: dichloromethane) and
gave 4 (0.504 g, 85.5%) as a white powder. 1H NMR (300 MHz,
CDCl3) d: 7.17 (2H, s, pyrrole N–H), 7.00 (2H, s, pyrrole N–H), 6.81
1H NMR spectra were recorded in CDCl3, CD3CN, and DMSO,
with TMS as an internal standard, on a Varian Mercury Vx300
spectrometer and an Oxford AS400 MHz spectrometer. High reso-
lution mass spectra were recorded on an IonSpec QFT-ESI 7.0 T
mass spectrometer. Mass spectra were recorded on a Finnigan LCQ
(2H, d, J¼8.4 Hz, phenyl C–H), 6.55 (2H, d, J¼8.4 Hz, phenyl C–H),
5.91–5.90 (6H, m, pyrrole C–H), 5.67 (2H, s, pyrrole C–H), 3.53 (2H,
br s, –NH2), 1.87–1.45 (15H, m, –CH3 and –CH2-),0.66–0.60 (18H, m,
–CH3); 13C NMR (300 MHz, CDCl3)
d
: 144.6, 137.8, 137.1, 136.1, 135.9,
135.8, 128.2, 114.4, 105.6, 105.4, 104.9, 43.9, 43.0, 29.2, 29.0, 28.8,

9250
W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
Figure 8. Calculated structure and the energy differences for the 5$Fꢀ and 6$Fꢀ models.
28.7, 8.1, 8.0; HRMS (ESI) calcd for C39H50N5: 618.3813 ([MꢀH]ꢀ),
found: 618.3822 ([MꢀH]ꢀ).
ferrocenoyl chloride (0.287 g, 1.16 mmol) was added dropwise. The
reaction mixture was stirred for 24 h at room temperature and
washed with 40% citric acid, dried over MgSO4, and evaporated to
dryness in vacuo. The residue was purified by column chromato-
graphy over silica gel (eluant: dichloromethane) to give 1 (0.353 g,
4.2.5. Compound 1
A solution of 3 (0.701 g, 1.19 mmol) and pyridine (1.0 ml) in
dichloromethane (20 ml) was cooled in an ice-water bath and
38.1%) as an orange solid. 1H NMR (300 MHz, CD3CN)
d: 8.06 (1H, s,

W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
9251
Table 3
X-ray crystallographic data for 5, 6 (in CH3CN), 6 (in acetone), 5$Fꢀ, and 6$Fꢀ
5
6 (in CH3CN)
6 (in acetone)
5$Fꢀ
6$Fꢀ
CCDC number
Empirical form
Formula weight
Crystal system
Space group
a (Å)
675246
675245
C41H54N6O2
662.89
Triclinic
Pꢀ1
675247
C45H61N5O4
735.99
Triclinic
Pꢀ1
675249
C55H88FN6O3.50
908.31
Monoclinic
P121/n1
12.068(6)
22.243(11)
19.911(10)
90
97.485(6)
90
5300(5)
4
675248
C39H49N5O2
C112H174Cl4F2N12O4
1932.43
Orthorhombic
Pna21
619.83
Monoclinic
P121/c1
12.525(3)
10.634(5)
13.231(7)
14.940(8)
103.196(10)
108.839(9)
96.503(10)
1896.6(16)
2
9.5670(15)
14.600(2)
16.960(3)
75.150(18)
78.31(2)
72.980(16)
2168.6(6)
2
39.100(16)
11.358(5)
25.469(11)
90
90
90
b (Å)
c (Å)
16.783(3)
19.490(6)
90
123.14(2)
90
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
V (Å3)
3430.5(15)
4
11311(8)
4
Z
Dcalcd (g/cm3)
1.200
0.075
1.157
0.072
1.127
0.072
1.138
0.073
1.135
0.162
m
(mmꢀ1
)
Total reflections
Unique reflections
31,606
8141
9858
6650
15,882
7319
39,637
9351
68,050
19,656
R1/wR2 [I>2
R1/wR2 (all data)
GoF on F2
s
(I)]
0.0624/0.1628
0.0713/0.1707
1.089
0.0626/0.1379
0.2382/0.2100
0.921
0.1231/0.2468
0.1778/0.2783
1.203
0.1471/0.2889
0.1775/0.3055
1.261
0.0898/0.1792
0.1122/0.1921
1.132
amide N–H), 7.60 (2H, s, pyrrole N–H), 7.56–7.53 (1H, m, phenyl C–
H), 7.35 (2H, br s, pyrrole N–H), 7.30 (1H, t, phenyl C–H), 7.19 (1H, t,
phenyl C–H), 6.63 (1H, d, J¼7.8 Hz, phenyl C–H), 5.88–5.82 (6H, m,
pyrrole C–H), 5.75 (2H, t, pyrrole C–H), 4.81 (2H, t, Fc C–H), 4.42
(2H, t, Fc C–H), 4.21 (5H, s, Fc C–H), 1.87–1.81 (15H, m, –CH3 and
25 ꢂC as described previously. n-Bu4NPF6 (0.1 mol/L) was employed
as the supporting electrolyte. A standard three-electrode cell con-
sists of a glassy carbon disk as working electrode, a platinum wire
as counter electrode, and 0.01 mol/L AgNO3/Ag (in 0.1 mol/L
n-Bu4NPF6– MeCN) as reference electrode. The ferrocenium/ferro-
cene redox couple was taken as the internal standard. The re-
producibility of the potentials was smaller than 10 mV. All sample
solutions were 1ꢁ10ꢀ4 mol/L, while the anions (5 equiv) were
added to the corresponding receptors.
–CH2–), 0.68–0.55 (18H, m, –CH3); 13C NMR (300 MHz, CD3CN)
d:
168.036, 148.895, 138.060, 136.856, 135.968, 135.906, 135.521,
127.548, 122.402, 119.801, 118.464, 104.729, 104.238, 104.177,
70.391, 69.335, 68.143, 44.302, 42.373, 42.312, 27.857, 27.690,
27.530, 26.725, 26.535, 7.199; HRMS (ESI) calcd for C50H58FeN5O:
800.3997 ([MꢀH]ꢀ), found: 800.3985 ([MꢀH]ꢀ).
4.5. DFT calculation
4.2.6. Compound 2
All theoretical calculations were carried out using the Gaussian
0332 packages mounted on NKStar supercomputer. All the single
crystals and the constructed conformations were optimization at
Compound 4 (0.834 g, 1.41 mmol), pyridine (1.0 ml), and ferro-
cenoyl chloride (0.301 g,1.22 mmol) were reacted in accord with the
procedure used for the synthesis of 1 (eluant: chloroform/ethyl
acetate¼20:1) and gave 2 (0.669 g, 59.0%) as an orange solid.1H NMR
the B3LYP/3-21G
*
level of theory, and the single-point energy were
level of theory. The stabilization
calculated at the B3LYP/6-31G
*
(300 MHz, CD3CN) d: 8.11 (1H, s, amide N–H), 7.61 (2H, m, pyrrole N–
energies were calculated as the difference in the energy between
the sum of the receptor and the free fluoride and the complex.
H), 7.50 (2H, d, J¼8.7 Hz, phenyl C–H), 7.32 (2H, br s, phenyl N–H),
6.92 (2H, d, J¼8.7 Hz, phenyl C–H), 5.87–5.82 (6H, m, pyrrole C–H),
5.71 (2H, t, pyrrole C–H), 4.85 (2H, t, Fc C–H), 4.42 (2H, t, Fc C–H), 4.22
(5H, s, Fc C–H),1.97–1.83 (15H, m, –CH3 and –CH2–), 0.67–0.56 (18H,
4.6. X-ray crystallography
m, –CH3); 13C NMR (400 MHz, CD3CN)
d: 168.656, 144.097, 137.363,
The diffraction data were measured on a BRUKER SMART 1000
136.688,136.377,136.121,127.898,127.770,119.796,105.185,104.752,
104.682, 104.591, 70.928, 69.843, 68.677, 44.433, 42.872, 42.762,
28.427, 28.173, 28.067, 27.074, 26.846, 7.600; HRMS (ESI) calcd for
CCD diffractometer with Mo K
a
radiation (
l¼0.71073 Å) by
u scan
mode. All data were corrected by semi-empirical method using
SADABS program. The program SAINT33 was used for integration of
the diffraction profiles. The structure was solved by the direct
methods using SHELXS program of the SHELXL-97 package and
refined with SHELXL.34 The final refinement was performed by full
matrix least-squares methods with anisotropic thermal parameters
for all non-hydrogen atoms of F2. The hydrogen atoms of the
compounds were placed in the geometrically calculated positions.
All hydrogen atoms were included in the final refinement in the
riding model approximation with displacement parameters de-
rived from the parent atoms to which they were bonded. Crystal-
lographic data and refinement parameters of the five crystals are
summarized in Table 3.
C
50H58FeN5O: 800.3997 ([MꢀH]ꢀ), found: 800.4007 ([MꢀH]ꢀ).
4.3. 1H NMR titration experimental
The 1H NMR spectra were recorded on a Varian Mercury Vx300
and Oxford AS400 instrument. In a typical anion titration experi-
ment, aliquots of an anion (tetrabutylammonium fluoride, chloride,
bromide, dihydrogenphosphate, acetate, or hydrogen sulfate,
0.25 mol/L CD3CN solutions) were added to a 0.5 mL 5 mmol/L
solution of receptor; 17 aliquots were added corresponding to 0, 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0 and
5.0 equiv of anion. The chemical shift of the pyrrole b-CH on the
receptor was monitored as it moved upfield upon addition of anion.
Acknowledgements
4.4. Electrochemical studies
This project was supported by the Major State Basic Research
Development Program of China (Grant no. G2007CB808000). We
also thank the computational support of Nankai University ISC and
All electrochemical experiments were carried out using a BAS-
100 W electrochemical apparatus in dry acetonitrile solution at

9252
W. Yang et al. / Tetrahedron 64 (2008) 9244–9252
22. Anzenbacher, P., Jr.; Jursı´kova´, K.; Lynch, V. M.; Gale, P. A.; Sessler, J. L. J. Am.
Chem. Soc. 1999, 121, 11020–11021.
23. Szyman´ ska, I.; Radecka, H.; Radecki, J.; Gale, P. A.; Warriner, C. N. J. Electroanal.
the technical support of the Center for Theoretical and Computa-
tional Chemistry, College of Chemistry of Nankai University.
Chem. 2006, 591, 223–228.
24. Woods, C. J.; Camiolo, S.; Light, M. E.; Coles, S. J.; Hursthouse, M. B.; King, M. A.;
Gale, P. A.; Essex, J. W. J. Am. Chem. Soc. 2002, 124, 8644–8652.
References and notes
`
25. Bruno, G.; Cafeo, G.; Kohnke, F. H.; Nicolo, F. Tetrahedron 2007, 63, 10003–
10010.
1. Binachi, A.; Bowman-James, K.; Garcia-Espana, E. Supramolecular Chemistry of
Anion [M]; Wiley-VCH: New York, NY, 1997.
26. Yang, W.; Yin, Z.; Li, Z.; He, J. and Cheng, J.-P. Unpublished.
27. Wang, T.; Bai, Y.; Ma, L.; Yan, X.-P. Org. Biomol. Chem. 2008, 6, 1751–1755.
28. Wang, Y.-H.; Lin, H.; Lin, H.-K. Chin. J. Chem. 2007, 25, 1430–1433.
29. Zhang, Y.-M.; Ren, H.-X.; Zhou, Y.-Q.; Luo, R.; Xu, W.-X.; Wei, T.-B. Turkish
J. Chem. 2007, 31, 327–334.
2. Beer, P. D.; Gale, P. A. Angew. Chem., Int. Ed. 2001, 40, 486–516.
3. Gale, P. A.; Sessler, J. L.; Kra´l, V. Chem. Commun. 1998, 1–8.
4. Gale, P. A.; Anzenbacher, P., Jr.; Sessler, J. L. Coord. Chem. Rev. 2003, 240, 191–221.
5. Anzenbacher, P., Jr.;Jursikova, K.;Sessler, J. L. J. Am. Chem. Soc. 2000,122, 9350–9351.
6. Song, M.-Y.; Na, H.-K.; Kim, E.-Y.; Lee, S.-J.; Kim, K. I.; Baek, E.-M.; Kim, H.-S.; An,
D. K.; Lee, C.-H. Tetrahedron Lett. 2004, 45, 299–301.
30. Han, F.; Bao, Y.; Yang, Z.; Fyles, M. T.; Zhao, J.; Peng, X.; Fan, J.; Wu, Y.; Sun, S.
Chem. Eur. J. 2007, 13, 2880–2892.
31. Shi, D.-Q.; Wang, H.-Y.; Li, X.-Y.; Yang, F.; Shi, J.-W.; Wang, X.-S. Chin. J. Chem.
2007, 25, 973–976.
7. Camiolo, S.; Gale, P. A. Chem. Commun. 2000, 1129–1130.
8. Bonomo, L.; Solari, E.; Toraman, G.; Scopelliti, R.; Latronico, M.; Floriani, C.
Chem. Commun. 1999, 2413–2414.
9. Turner, B.; Botoshansky, M.; Eichen, Y. Angew. Chem., Int. Ed.1998, 37, 2475–2478.
10. Gale, P. A.; Hursthouse, M. B.; Light, M. E.; Sessler, J. L.; Warriner, C. N.; Zim-
merman, R. S. Tetrahedron Lett. 2001, 42, 6759–6762.
11. Turner, B.; Shterenberg, A.; Kapon, M.; Suwinska, K.; Eichen, Y. Chem. Commun.
2002, 404–405.
12. Harmjanz, M.; Gill, H. S.; Scott, M. J. J. Org. Chem. 2001, 66, 5374–5383.
13. Sessler, J. L.; Andrievsky, A.; Gale, P. A.; Lynch, V. Angew. Chem., Int. Ed. 1996, 35,
2782–2785.
14. Sessler, J. L.; Gebauer, A.; Gale, P. A. Gazz. Chim. Ital. 1997, 127, 723–726.
15. Sessler, J. L.; Gale, P. A.; Genge, J. W. Chem.dEur. J. 1998, 4, 1095–1099.
16. Gale, P. A.; Bleasdale, E. R.; Chen, G. Z. Supramol. Chem. 2001, 13, 557–563.
17. Wang, Q.; Huang, R. J. Organomet. Chem. 2000, 604, 287–289.
18. Saki, N.; Akkaya, E. U. J. Inclusion Phenom. Macrocyclic Chem. 2005, 53, 269–273.
19. Sessler, J. L.; An, D.; Cho, W.-S.; Lynch, V. J. Am. Chem. Soc. 2003, 125, 13646–
13647.
32. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.;
Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.;
Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.;
Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.;
Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao,
O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A.
J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G.
A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.;
Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Fores-
man, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.;
Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P.
M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian
03, Revision C.01; Gaussian: Wallingford, CT, 2004.
33. Bruker AXS. SAINT Software Reference Manual; Bruker: Madison, WI, 1998.
34. Sheldrick, G. M. SHELXTL NT, Program for Solution and Refinement of Crystal
Structures, version 5.1; University of Go¨ttingen: Go¨ttingen, Germary, 1997.
20. Hynes, M. J. J. Chem. Soc., Dalton Trans. 1993, 311–312.
21. Gale, P. A.; Sessler, J. L.; Kra´l, V.; Lynch, V. J. Am. Chem. Soc. 1996, 118, 5140–5141.