Synthesis of triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties and its complexation with paraquat derivatives: Li+-ion-controlled binding and release of the guests in the complexes

Article abstract of DOI:10.1021/jo3000755

A new triptycene-derived macrotricyclic host containing two dibenzo-[18]-crown-6 moieties was synthesized and shown to form 1:1 complexes with paraquat derivatives in solution, in which the guests all thread the central cavity of the host. However, it was

Full text of DOI:10.1021/jo3000755

Article
pubs.acs.org/joc
Synthesis of Triptycene-Derived Macrotricyclic Host Containing Two
Dibenzo-[18]-crown-6 Moieties and Its Complexation with Paraquat
Derivatives: Li+-Ion-Controlled Binding and Release of the Guests in
the Complexes
Ying Han,†,‡ Hai-Yan Lu,‡ Qian-Shou Zong,† Jia-Bin Guo,† and Chuan-Feng Chen*,†
†Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of
Chemistry, Chinese Academy of Sciences, Beijing 100190, China
‡Graduate University of Chinese Academy of Sciences, Beijing 100049, China
S
* Supporting Information
ABSTRACT: A new triptycene-derived macrotricyclic host
containing two dibenzo-[18]-crown-6 moieties was synthe-
sized and shown to form 1:1 complexes with paraquat
derivatives in solution, in which the guests all thread the
central cavity of the host. However, it was interestingly found
that, depending on the paraquat derivatives with different
functional groups, the host can form stable 1:1 or 1:2
complexes in different complexation modes in the solid state,
which is significantly different from those of the macrotricyclic
host containing two dibenzo-[24]-crown-8 moieties. The
formation of the complexes was also proved by the ESI MS
and electrochemical experiments. Moreover, it was found that
the binding and release of the guests in the complexes could be easily controlled by the addition and removal of lithium ions.
triptycene-derived macrotricyclic host 1b containing two
dibenzo-18-crown-6 moieties13 (Figure 1) and its complexation
with different functional paraquat derivatives in solution and in
the solid state, which shows significantly different complexation
modes with those ones between 1a and the paraquat
derivatives. Moreover, Li+-ion-controlled binding and release
of the guests in the complexes is also described.
INTRODUCTION
■
Since Pedersen first reported1 the cation-complexing properties
of the crown ethers, host−guest chemistry2 has been a topic of
great interest during the past decades. One particular interest in
this research area came from the complexation between
paraquat derivatives and bisarylene crown ethers reported by
Stoddart and his co-workers in 1987,3 which have resulted in a
variety of interlocked supramolecular assemblies,4 such as
pseudorotaxanes, rotaxanes, and catenanes. Consequently,
paraquat derivatives have become some of the most common
guests, and crown ethers,5 cryptands,6 cylindrical macrotricyclic
polyethers,7 cucurbit[n]uril,8 calix[6]arene derivatives,9 and
other macrocycles10 have been utilized as the hosts for
formation of the host−guest complexes with specific structures
and properties.
RESULTS AND DISCUSSION
■
Synthesis of Host 1b. According to the same method as
described previously,12a host 1b was synthesized via three steps
starting from triptycene derivative 11. As shown in Scheme 1,
reaction of 11 and 2-(2-hydroxyethoxy)ethyl 4-methylbenze-
nesulfonate in the presence of K2CO3, followed by reaction
with p-toluenesufonyl chloride, gave triptycene derivative 12 as
a yellow oil in 50% total yield for the two steps. Compound 12
was then reacted with 11 under a high dilution condition in the
presence of K2CO3 to give 1b in 22% yield. The structure of 1b
was confirmed by 1H NMR, 13C NMR, MALDI-TOF MS, and
elemental analysis.
In host−guest chemistry, macrocyclic hosts have undoubt-
edly played key roles in constructing different kinds of
complexes, and the development of novel macrocyclic hosts
with the capability of binding substrate species strongly and
selectively is also a permanent and challenging topic in this
research area.11 Recently, we reported a novel triptycene-
derived cylindrical macrotricyclic host containing two dibenzo-
[24]-crown-8 lateral cavities12a (1a) and found that host 1a
showed guest-dependent complexation with different functional
paraquat derivatives, which resulted in formation of a series of
stable complexes with specific structures in both solution and
the solid state.12b In this paper, we report the synthesis of a new
Complexation Between Host 1b and Paraquat
Derivatives in Solution. Complexation between host 1b
and the paraquat derivatives 2−10 was first studied in solution
1
by the H NMR spectroscopic method. When we mixed the
Received: January 11, 2012
Published: February 9, 2012
© 2012 American Chemical Society
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Figure 1. Chemical structures and proton designations of the hosts 1a and 1b, and the guests 2−10.
Scheme 1. Synthesis of Host 1b
Figure 2. Partial 1H NMR spectra (300 MHz, CD3CN/CDCl3 = 2:3, v/v, 295 K) of (a) free guest 2, (b) 1b and 1.0 equiv of 2, and (c) free host 1b.
[1b]0 = 4.0 mM.
host 1b (4.0 mM) and 1.0 equiv of 2 in 2:3 (v/v) CD3CN/
CDCl3, a deep orange solution formed immediately because of
charge transfer between the electron-rich aromatic rings of the
host and the electron-poor pyridinium rings of the guest. As
0.21 ppm) due to the shielding effect of aromatic rings in 1b,
and H1 and Ha proton signals also shifted upfield. The H
1
NMR spectroscopic titrations further afforded a quantitative
estimate for the complexation between host 1b and guest 2 by
monitoring the changes of the chemical shift of the proton H1
of 2. The results showed that a 1:1 complex between 1b and 2
was formed by a mole ratio plot. Accordingly, the apparent
association constant Ka,exp was calculated to be 4.0( 0.1) × 102
M−1 by the Scatchard plot.14,15 Previously, we found that the
triptycene-derived macrotricyclic host containing two dibenzo-
1
shown in Figure 2, the H NMR spectrum of a 1:1 mixture of
1b and 2 showed only one set of different signals from those of
the separated host and guest, which suggested that a new
complex 1b·2 was formed, and the complexation between 1b
and 2 was a fast exchange process. Especially, it was found that
the proton Hb of the paraquat ring showed a upfield shift (Δδ =
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Figure 3. Partial 1H NMR spectra (300 MHz, CD3CN/CDCl3 = 2:3, v/v, 295 K) of (a) free host 1b, (b) 1b and 1.0 equiv of 6, and (c) free guest 6.
[1b]0 = 4.0 mM.
[24]-crown-8 moieties (1a) could also form a 1:1 stable
complex with the paraquat 2, but the complexation between
host 1a and 2 was a slow exchange process. Especially, the
methyl groups in 2 are all positioned at the two lateral crown-8
the results are summarized in Table 1. It was found that the
association constant of 1:1 complex 1b·10 is the biggest among
Table 1. Summary of the Stoichiometries and Association
Constants of the Complexes
1
cavities of the host 1a, which was proved by the H−1H
NOESY spectrum.12a However, in the case of complex 1b·2, its
ROESY 2D NMR spectrum showed no intermolecular cross-
signals for the methyl proton Hc and the crown ether protons
in host 1b,14 which implied that the paraquat 2 might thread
the central cavity of the host 1b to form a 1:1 complex. This
different complexation mode might be attributed to the smaller
cavity of 1b than that of the macrocycle 1a.
a
complex
stoichiometry (H/G)
Ka [M−1
]
1b·2
1b·3
1b·4
1b·5
1b·6
1b·7
1b·8
1b·9
1b·10
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
4.0( 0.1) × 102
2.0( 0.1) × 102
9.0( 0.1) × 102
3.0( 0.1) × 102
4.0( 0.1) × 102
4.0( 0.1) × 102
2.0( 0.1) × 102
3.0( 0.1) × 102
1.4( 0.1) × 103
Similarly, we found that the complexation between host 1b
and guest 6 was also a fast exchange process. Correspondingly,
the proton Hb of the paraquat ring showed an upfield shift (Δδ
= 0.22 ppm) due to the shielding effect of aromatic rings in 1b,
while H1 and Ha proton signals also shifted upfield (Figure 3).
Moreover, the stoichiometry of the complex was determined to
be 1:1 by a mole ratio plot, and the association constant Ka for
the complex was calculated to be 4.0( 0.1) × 102 M−1 by the
Scatchard plot. The 2D ROESY spectral experiment14 of
complex 1b·6 was further carried out to investigate the
complexation between the host and the guest. The results
showed that the cross-peaks between proton Ha in the
bipyridinium ring of 6 and the protons in crown ether units
of 1b were found, which suggested that the guest could thread
the central cavity of host 1b to form a 1:1 complex. This result
is similar to the complexation between 2 and 1b, but different
from that case between 6 and 1a in which two guests of 6 were
included in the central cavity of the host 1a to form a 1:2
complex.12b Formation of a 1:1, not a 1:2, complex between 1b
and 6 is also attributed to the small cavity of 1b.
a
From the 1H NMR titration experiments in CD3CN/CDCl3 (2:3, v/
v).
those of the tested complexes, which might be due to
significant intermolecular interactions between the host and
the anthracyl groups in the guest.
Complexation Between Host 1b and Paraquat
Derivatives in the Solid State. By vapor diffusion of
diisopropyl ether into a solution of 1b and 3 in CH3CN and
CHCl3 (2:3, v/v), we obtained a rodlike single crystal suitable
for X-ray diffraction analysis. The crystal structure showed that
the host 1b formed 1:2 complex 1b·32 with two guests of 3
(Figure 4), in which one bipyridinium guest (A) threaded
symmetrically through the central cavity of the host, while
another bipyridinium guest (B) was located at a pseudo cavity
formed by the crown rings of two adjacent macrocycles of 1b.
The two bipyridinium guests in the complex are almost vertical.
This complexation mode of complex 1b·32 in the solid state is
different from that in solution, and also obviously different from
that of the host 1a with the N-alkyl substituted paraquats, in
which the two N-alkyl groups in the guest were threaded out
from the two lateral crown-8 cavities of the host to form a 1:1
complex.
We also tested the complexation between host 1b and other
paraquat derivatives with different functional groups in solution
by NMR spectroscopy. The results showed that, similar to the
complexation modes between host 1b and 2, and 1b and 6, the
guests 3−5 and 7−10 could all thread the central cavity of host
1b to form 1:1 complexes. Moreover, the association constants
for the complexes were all calculated by the Scatchard plot, and
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Figure 4. Top view (a) and side view (b) of the crystal structure of complex 1b·32. Blue lines denote the noncovalent interactions between the host
and the guests. The C−H···O hydrogen bond distances (Å): i = 2.53, j = 2.51, k = 2.65, l = 2.49, m = 2.39, n = 2.50, o = 2.65, p = 2.23, q = 2.46, r =
2.40, s = 2.50, t = 2.39. (c) Packing of complex 1b·32 viewed along the a axis. Solvent molecules, PF6− counterions, and hydrogen atoms not involved
in the noncovalent interactions were omitted for clarity.
As shown in Figure 4a, it was found that the guests A and B
were distorted by the dihedral angles between the pyridinium
rings of 9.74° and 8.82°, respectively. For the guest A, there
existed multiple C−H···O hydrogen bonding interactions
between the protons of the bipyridinium ring and ether oxygen
atoms of the host with the distances of 2.38 Å for a, 2.45 Å for
b, 2.46 Å for c, and 2.47 Å for d, and also the π−π stacking
interaction between the paraquat ring and one aromatic ring of
the triptycene skeleton with the distance of 3.28 Å (e). For the
guest B positioned at the pseudo cavity formed by the crown
ether rings of the two adjacent macrocycles of 1b, besides the
multiple C−H···O hydrogen bonding interactions between the
protons of the bipyridinium ring and ether oxygen atoms of the
adjacent macrocycles, there also existed multiple CH···π
interactions between the methylene protons of the crown
ethers and the bipyridinium ring with the distances of 2.82 Å
for f, 2.83 Å for g, 2.82 Å for h, 2.88 Å for u, 2.75 Å for v, and
2.85 Å for w, respectively. These multiple noncovalent
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Figure 5. (a) The crystal structure of complex 1b·62. Blue lines denote the noncovalent interactions between the host and the guests. (b) Packing of
the complex 1b·62 viewed along the a axis. Solvent molecules, PF6 counterions, and hydrogen atoms not involved in the noncovalent interactions
were omitted for clarity.
interactions between the host and the guest play an important
role in the stability of complex 1b·32. Moreover, it was also
found that complex 1b·32 can self-assemble into a linear
supramolecular array, which further results in a 2D layer viewed
along the a axis and a 3D microporous network (Figure 4c).
Similarly, we obtained the single crystals suitable for X-ray
diffraction analysis from the CH3CN/CHCl3 mixture solution
of 1b and 6. As shown in Figure 5a, it was found that the host
1b also formed 1:2 complex 1b·62 with two guests of 6 in the
solid state, in which one bipyridinium guest (A) threaded
through the central cavity of the host, while another
bipyridinium guest (B) was located at a pseudo cavity formed
by two adjacent triptycene moieties. The two bipyridinium
guests in complex 1b·62 are at the same position. Formation of
1:2 complex 1b·62 in the solid state was not consistent with the
1:1 complex in solution, and also obviously different from the
complex formed by the host 1a with the guest 6, in which the
two guests of 6 threaded the central cavity of host 1a to form
1:2 complex 1a·62 in both solution and the solid state.
Moreover, the complexation mode of complex 1b·62 is different
from that of 1b·32, which might be due to the repulsion
between the hydroxyl groups of the guest 6 and the oxygen
atoms of the crown ethers. These results suggested that a small
structural change in the host or the guest could result in the
formation of a complex with a different structure and a different
complexation mode, which might provide a new opportunity to
develop supramolecular systems with specific structures and
properties.
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For the guest A in the cavity of the host, the dihedral angle
between the two pyridinium rings is 8.32°. There existed
multiple π−π stacking interactions between the bipyridinium
ring and one aromatic ring of the triptycene skeleton with the
distances of 3.36 (i), and 3.29 Å (j), respectively. Moreover, C−
H···O hydrogen bonds (2.61 Å for a, 2.68 Å for b, and 2.54 Å
for c) between the protons of the paraquat ring and ether
oxygen atoms of the host were also observed. For the guest B
outside the cavity of the host, there also existed the π−π
stacking interactions (3.28 Å for k and 3.33 Å for l) between the
bipyridinium ring and the aromatic rings of the triptycene
moieties, and CH···π interactions (2.80 Å for e, 2.86 Å for f,
2.89 Å for j, and 2.88 Å for h) between the protons of the
bipyridinium ring and the aromatic rings of the triptycene
mioeties. By virtue of a pair of C−H···π (dC−H···π, 2.78 Å)
interactions between the protons of the crown ether moiety
and the aromatic ring of the adjacent triptycene, the complex
1b·62 could further form a 2D gridlike viewed along the a axis
(Figure 5b), in which there was one guest in each grid while the
bipyridinium ring outside the cavity of the host connected the
two adjacent hosts.
small “pseudo cavity” formed by the adjacent triptycene
moieties that could not include the guest 8 with big terminal
groups. There existed π−π stacking interactions between the
paraquat ring and one aromatic ring of the triptycene skeleton
with the distances of 3.38 Å (c) and 3.36 Å (e), respectively.
Moreover, there existed C−H···O hydrogen bonding inter-
actions between the protons of the paraquat ring and ether
oxygen atoms of the host with the distances of 2.30 Å for a,
2.62 Å for b, and 2.29 Å for d, respectively. These multiple
noncovalent interactions between the host and the guest also
played an important role in the stability of the complex. In
addition, 1·8 could also self-assemble into a linear supra-
molecular array by virtue of a pair of C−H···π (dC−H···π, 2.78 Å)
interactions between the protons of the crown ether moiety
and the aromatic ring of the adjacent triptycene, which further
resulted in a 2D layer viewed along the a axis.
ESI MS Studies on Formation of the Complexes. The
electrospray ionization (ESI) mass spectrometry was also used
to characterize the complexes between host 1b and the guests.
Consequently, the strongest peak at m/z 579.6 for [1b·2-
2PF6]2+ was found by using the solution of 1b and 2 in 3:2 (v/
v) chloroform and acetonitrile, which provided another
evidence for formation of a 1:1 stable complex between host
1b and the paraquat derivative 2. Similarly, formation of the 1:1
complexes between host 1b and the paraquat derivatives 3−10
was also evidenced by the ESI mass spectra, in which the strong
peaks at m/z 607.9, 605.8, 618.0, 609.7, 616.8, 624.0, 648.1, and
756.0 for [1b·3-2PF6]2+, [1b·4-2PF6]2+, [1b·5-2PF6]2+, [1b·6-
2PF6]2+, [1b·7-2PF6]2+, [1b·8-2PF6]2+, [1b·9-2PF6]2+, and
[1b·10-2PF6]2+, respectively, were all observed.14
By vapor diffusion of diisopropyl ether into a CH3CN/
CHCl3 (2:3, v/v) mixture solution, we also obtained the single
crystals of complex 1b·8 suitable for X-ray diffraction analysis.
As shown in Figure 6, the guest 8 threaded symmetrically the
Electrochemical Studies on Formation of the Com-
plexes. Since the paraquat derivatives are organic redox-active
molecules, their electrochemical behaviors in the absence and
presence of host 1b were also studied. As shown in Figure 7,
Figure 7. CV curves for a solution of [10-2PF6]2+ (1 × 10−3 M) in
CH3CN/CHCl3 (2:3, v/v) with (NBu4)PF6 (0.1 M) as the supporting
electrolyte in the absence (black line, a) and the presence (red line, b)
of 1b (3.0 × 10−3 M). Working electrode: Pt. Scan rate: 0.1 V s−1.
Figure 6. (a) Top view and (b) side view of the crystal structure of
complex 1b·8. Blue lines denote the noncovalent interactions between
the host and the guests. (c) Packing of the complex 1b·8 viewed along
the a axis. Solvent molecules, PF6 counterions, and hydrogen atoms
not involved in the noncovalent interactions were omitted for clarity.
the [10-2PF6]2+ showed two reversible one-electron reduction
processes16 corresponding to the successive reduction of the
4,4′-bipyridinium core with the half-wave potential values [E1/2
= (Epa + Epc)/2] at −0.589 and −1.050 V vs Ag/AgNO3,
respectively.17 Upon the addition of 1b to the CH3CN and
CHCl3 (2:3, v/v) solution of 10, both the cathodic and the
anodic peaks of the first one-electron reduction process
significantly moved to the more negative values while the
peaks corresponding to the second one-electron reduction
process slightly moved to the more negative values. These
central cavity of the host 1b to form 1:1 complex 1b·8. The two
β-methoxyethyl groups in 8 were located outside the cavity and
nearly vertical with the pyridinium rings, which resulted in a
“Z”-like structure of the guest. The complexation mode of
complex 1b·8 in the solid state is different from those between
the host 1b and the guests 3 and 6, which might be due to the
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Figure 8. Partial 1H NMR spectra (300 MHz, CD3CN/CDCl3 = 1:1, v/v, 295 K) of (a) free guest 6, (b) 1b and 1.0 equiv of 6, (c) to the solution of
(b) was added 4.0 equiv of LiClO4, and (d) to the solution of (c) was added 6.0 equiv of 12-crown-4. [1b]0 = 3.0 mM.
observations suggested that the stable host−guest complex
formed, and formation of the complex was caused by a charge-
transfer interaction and the complex might dissociate upon two
one-electron reductions of the bipyridinium ring. Under the
same conditions as above, it was found that, upon the addition
of host 1b to the solution of guests 2−9, both the cathodic and
the anodic peaks corresponding to the first and the second one-
electron reduction processes of the bipyridinium core all moved
to the more negative values,14 but they are smaller than those in
the cases of guest 10. The results implied that, compared with
guest 10, the guests 2−9 showed the smaller complexation, but
similar complexation mode with the host 1b, which are
CONCLUSION
■
In conclusion, we have synthesized a new triptycene-derived
macrotricyclic host containing two dibenzo-[18]-crown-6
moieties and proved that paraquat derivatives with different
functional groups can all thread the cavity of the host to form
1:1 stable complexes in solution. Interestingly, it was found that
the host could form 1:2 complexes with propyl and
hydroxyethyl substituted paraquat derivatives in different
complexation modes, while the host formed a 1:1 complex
with a methoxyethyl substituted paraquat derivative in the solid
state. The formation of these complexes was also proved by the
ESI MS and electrochemical experiments. Furthermore, it was
found that the binding and release of the guests in the
complexes could be easily controlled by the addition and
removal of Li+ ions. The results presented here suggested that a
small structural change in the host or the guest could result in
the formation of the complex with different structures and
different complexation modes. Consequently, it will provide us
with a new opportunity to develop supramolecular systems with
specific structures and properties, which is underway in our
laboratory.
1
consistent with the results of H NMR experiments.
Li+-Ion-Controlled Binding and Release of the Guests
in the Complexes. The host containing two dibenzo-18-
crown-6 moieties could form a complex with cations, such as
lithium ions, and the consequent complexation of cations
would introduce extra electrostatic repellent force to the
cationic organic guest molecules and dissociate the previously
formed host−guest complex. Moreover, it was known that 12-
crown-4 is a strong sequestering agent18 for lithium ions. Thus,
a series of 1H NMR experiments were carried out for
investigating the ion-controlled binding and release of the
guest molecules in the complexes. As shown in Figure 8,
spectrum c, when 4.0 equiv of LiClO4 was added into the
solution of complex 1b·6, the proton signals of the complex
disappeared, while the proton signals of the deprotonated guest
6 and 1b were observed. These observations suggested that
decomplexation of the complex occurred due to the complex-
ation of the crown cavities with lithium ions. However, when
6.0 equiv of 12-crown-4 ether was added into the above system,
it was found that the proton signals of complex 1b·6 recovered
(Figure 8, spectrum d), which suggested that complex 1b·6
formed again. Thus, the ion-controlled binding and release of
guest 6 in the complex could be easily performed by adding and
removing the lithium ions. Similarly, Li+-ion-controlled binding
and releasing of guest 3 in complex 1b·3 was also found.14
EXPERIMENTAL SECTION
■
The guests 2−1012b,19,20 and compound 1112a were prepared
according to the published procedures.
Compound 12. To a stirred solution of 11 (2.2 g, 6.3 mmol) and
2-(2-hydroxyethoxy)ethyl 4-methylbenzenesulfonate (7.5 g, 28.8
mmol) in dried CH3CN (120 mL) was added K2CO3 (7.9 g, 57.2
mmol). The reaction mixture was stirred at reflux for 30 h, cooled to
room temperature, and then filtered. The filtrate was concentrated
under reduced pressure. The residue was dissolved in dried CH2Cl2
(100 mL), and TsCl (6.5 g, 34.0 mmol), Et3N (6 mL, 43.2 mmol), and
DMAP (0.2 g, 1.66 mmol) were added. The reaction mixture was
stirred at refluxed temperature for 12 h. The solution was washed with
H2O and dried over anhydrous sodium sulfate. Evaporation of the
solvent, followed by column chromatography (SiO2: 100:1 CH2Cl2/
1
MeOH), gave 12 (4.2 g, 50%) as a pale yellow sticky oil. H NMR
(300 MHz, CDCl3) δ 2.27 (s, 18H), 3.61−3.64 (m, 16H), 3.92−3.95
(m, 8H), 4.04−4.08 (m, 8H), 6.87 (s, 4H), 6.90−6.94 (m, 2H), 7.15−
7.18 (m, 8H), 7.21−7.24 (m, 2H), 7.66−7.68 (m, 8H); 13C NMR (75
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MHz, CDCl3) δ 12.8, 20.5, 46.9, 67.8, 68.3, 68.8, 69.0, 108.9, 119.0,
123.6, 126.9, 128.8, 131.9, 141.6, 143.7, 144.8, 147.7; MALDI-TOF
MS m/z 1314.7 (M+). Anal. Calcd for C66H74O20S4·H2O: C, 59.44; H,
5.74. Found: C, 59.33; H, 5.75.
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(8) For recent examples of cucurbit[n]uril/paraquat complexes, see:
(a) Zhang, Z.-J.; Zhang, Y.-M.; Liu, Y. J. Org. Chem. 2011, 76, 4682−
4685. (b) Jiang, W.; Wang, Q.; Linder, I.; Klautzsch, F.; Schalley, C. A.
Chem.Eur. J. 2011, 17, 2344−2348. (c) Huang, W. H.; Zavalij, P. Y.;
Isaacs, L. Org. Lett. 2008, 10, 2577−2580. (d) Ling, Y. H.; Mague, J.
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(9) For recent examples of calixarenes/paraquat complexes, see:
(a) Zhang, J.; Guo, D. S.; Liu, Y. Chin. J. Chem. 2010, 28, 1575−1579.
(b) Garcia-Sosa, I.; Ramirez, F. J. Mex. Chem. Soc. 2010, 54, 143−152.
(c) Pierro, T.; Gaeta, C.; Troisi, F.; Neri, P. Tetrahedron Lett. 2009, 50,
350−353. (d) Guo, D. S.; Wang, L. H.; Liu, Y. J. Org. Chem. 2007, 72,
7775−7778. (e) Lu, L.-G.; Li, G.-K.; Peng, X.-X.; Chen, C.-F.; Huang,
Z.-T. Tetrahedron Lett. 2006, 47, 6021−6025.
Compound 1b. A suspension of potassium carbonate (492 mg,
3.56 mmol) in anhydrous DMF (50 mL) under an argon atmosphere
was stirred and then heated to 100 °C. To the mixture was added
dropwise a solution of 11 (154 mg, 0.445 mmol) and 12 (585 mg,
0.445 mmol) in anhydrous DMF (50 mL) over 12 h. The reaction
mixture was stirred at 110 °C for another 3 days. After cooling down
to ambient temperature, the mixture was filtered and washed with
DMF. The filtrate was concentrated under reduced pressure, and the
residue was dissolved in CHCl3 (100 mL) and washed with H2O. The
organic layer was dried over anhydrous sodium sulfate. After removal
of the solvent, the resulting oil was subjected to successive column
chromatography (SiO2: 50:1 CH2Cl2/MeOH) to yield 1b (103 mg,
1
22%) as a white solid. mp > 300 °C. H NMR (300 MHz, CD3CN/
CDCl3 = 2:3, v/v) δ 2.25 (s, 12H), 3.73−3.86 (m, 16H), 4.02−4.06
(m, 8H), 4.17−4.22 (m, 8H), 6.81 (s, 8H), 6.96−6.99 (m, 4H), 7.26−
7.28 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 13.7, 47.8, 69.5, 69.9,
107.5, 119.9, 124.6, 141.8, 145.0, 148.6; MALDI-TOF MS m/z 973.6
(M+). Anal. Calcd for C60H60O12·CH2Cl2: C, 69.25; H, 5.91. Found:
C, 69.53; H, 6.23.
ASSOCIATED CONTENT
■
S
* Supporting Information
1
Copies of H and 13C NMR spectra for new compounds,
1H−1H COSY spectra and ROESY spectra for the complexes,
determination of the association constants, ESI-MS for the
complexes, and X-ray crystallographic files (CIF) for the
complexes 1b·32, 1b·62, and 1b·8. This material is available free
of charge via the Internet at http://pubs.acs.org.
(10) (a) Olsen, J. C.; Fahrenbach, A. C.; Trabolsi, A.; Friedman, D.
C.; Dey, S. K.; Gothard, C. M.; Shveyd, A. K.; Gasa, T. B.; Spruell, J.
M.; Olson, M. A.; Wang, C.; Jacquot de Rouville, H. P.; Botros, Y. Y.;
Stoddart, J. F. Org. Biomol. Chem. 2011, 9, 7126−7133. (b) Hmadeh,
M. A.; Fahrenbach, C.; Basu, S.; Trabolsi, A.; Benítez, D.; Li, H.;
Albrecht−Gary, A. M.; Elhabiri, M.; Stoddart, J. F. Chem.Eur. J.
2011, 17, 6076−6087. (c) Boyle, M. M.; Forgan, R. S.; Friedman, D.
C.; Gassensmith, J. J.; Stoddart, J. F.; Sauvage, J. Chem. Commun. 2011,
47, 11870−11872. (d) Hu, S.-Z.; Chen, C.-F. Chem.Eur. J. 2011, 17,
5424−5431. (e) Cao, J.; Lu, H.-Y.; You, X.-J.; Zheng, Q.-Y.; Chen, C.-
F. Org. Lett. 2009, 11, 4446−4449.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: cchen@iccas.ac.cn.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
(11) (a) Steed, J. W.; Atwood, J. L. Supramolecular Chemistry, 2nd
ed.; John Wiley & Sons: Chichester, U.K., 2009. (b) Schrader, T.,
Hamilton, A. D., Eds. Functional Synthetic Receptors; Wiley-VCH
Verlag GmbH & Co. KGaA: Weinheim, Germany, 2005.
We thank the National Natural Science Foundation of China
(91127009, 20972162) and the National Basic Research
Program (2011CB932501) for financial support.
(12) (a) Zong, Q.-S.; Chen, C.-F. Org. Lett. 2006, 8, 211−214.
(b) Zhao, J.-M.; Zong, Q.-S.; Han, T.; Xiang, J.-F.; Chen, C.-F. J. Org.
Chem. 2008, 73, 6800−6806.
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