A controllable chiral molecular machine: Movement on molecular level

Article abstract of DOI:10.1002/smll.201200670

With the view to develop new chiral molecular switches, a new pH-controlled bistable chiral [3]rotaxane with a binaphthalene as chiral moiety is synthesized and characterized. The movement of the macrocycle DB24C8 along the thread tunes the dihedral angle between the two naphthalene rings and supplies tunable circular dichroism output signals.

Full text of DOI:10.1002/smll.201200670

Molecular Switches
A Controllable Chiral Molecular Machine: Movement
on Molecular Level
Wenlong Yang, Yongjun Li,* Jianhong Zhang, Nan Chen, Songhua Chen,
Huibiao Liu, and Yuliang Li*
W ith the view to develop new chiral molecular switches, a new pH-controlled
bistable chiral [3]rotaxane with a binaphthalene as chiral moiety is synthesized and
characterized. The movement of the macrocycle DB24C8 along the thread tunes
the dihedral angle between the two naphthalene rings and supplies tunable circular
dichroism output signals.
angles of binaphthalene molecules can be modulated through
1. Introduction
introducing tunable units into two naphthalene groups. Sev-
In the past decade, great effort has been devoted to the
eral binaphthalene chiral molecular switches which contained
synthesis of rotaxanes and catenanes.[1] The rapid develop-
ment of this new area of chemistry has promoted the under-
standing of the concepts of design and strategies of synthesis
and offered golden opportunities to explore the beautiful
chemistry to design novel supramolecular systems for appli-
cations on molecular smart devices.[2] The alteration of rela-
tive positions of the interlocked components constitutes a
basic kind of mechanical switch, capable of varying physical
properties of the molecular rotaxane such as conductivity,[3]
circular dichroism (CD),[4] absorption and fluorescence,[5]
even aggregate structures.[6]
Binaphthalene molecules are widely used as chiral lig-
ands in asymmetric synthesis[7] and as fluorescent sensors
for chiral species[8] because of its chiral properties. In recent
years, they have also been used as building blocks for chiral
molecular switches.[9] This is because of the strong circular
dichroism signals shown from axially chiral binaphthalene
molecules which serve as the detectable output signals,[10]
and the intensity of circular dichroism signals is dependent
on the dihedral angles of binaphthalene rings.[11] The dihedral
some redox or photochromic groups have been reported.[9,12]
As the movement of the macrocycle can impose different
steric hindrances, it is possible to modulate the CD spectrum
of binaphthalene by external signals when two [2]rotaxanes
units are separately linked to the two naphthalene rings of
binaphthalene. It should be mentioned that a few exam-
ples of chiral molecular switches based on binaphthalene
and photochromic[9b,d,f] or redox active units[9a] have been
described. However, the use of a binaphthalene in a rotaxane
as a chiral moiety and modulation of the CD speactra of
binaphthalene through the movement of the macrocycle
have never been described so far. Here we report a chiral
[3]rotaxane 3 and a pH-controlled bistable chiral [3]rotaxane
4, which uses a chiral binaphthalene group as the public
stopper.
2. Results and Discussion
As shown in Scheme 1, the [3]rotaxane 3 was synthesized
through CuI-catalyzed 1,3-dipolar cycloaddition reactions
of organic azides and terminal alkynes which emerged as a
powerful and appealing synthetic tool for the construction of
rotaxanes and catenanes.[13] A dilute half equimolar amount
of 2 was added dropwise to a dilute mixture containing an
equimolar amount of compound 1, DB24C8, and catalyst
[Cu(MeCN)4]PF6 in dichloromethane at room tempera-
ture. The mixture was stirred for 48 h at room temperature,
[3]rotaxane 3 was obtained in 56% yield. The MALDI-TOF
spectrum of 3 gave sharp peak at m/z 2508.3 [M–H–2PF6]+
W. Yang, Dr. Y. Li, J. Zhang, N. Chen, S. Chen,
Dr. H. Liu, Prof. Y. Li
CAS Key Laboratory of Organic Solids
Beijing National Laboratory for Molecular Sciences
Institute of Chemistry
Chinese Academy of Sciences
Beijing 100190, P. R. China
E-mail: ylli@iccas.ac.cn; liyj@iccas.ac.cn
DOI: 10.1002/smll.201200670
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DOI: 10.1002/smll.201200670
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W. Yang et al.
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and the other still sit on the –NH– station
(Scheme2b). This may be due to the spa-
tial limitation of two N-methyltriazolium
stations.[5h] However, when more DIEA
(up to 50 equivalents) was added to the
solution of 4, the two DB24C8 could move
toward the N-methyltriazolium station
(Scheme 2c).
This phenomenon was clearly observed
1
from the H NMR spectral titration of 4
with DIEA (Figure 1). When 1 equiva-
lent of DIEA was added to the solution
of 4, the peaks for the N-methyltriazolium
C–H protons Hi and Hi’ are splitted into
two peaks, one of which was evidently
shifted downfield due to the C–H…O
hydrogen-bond interaction (Figure 1b).
When 5 equivalents of DIEA was added,
the integral ratio of Hi and Hi’ is nearly
1:1, which indicated that one DB24C8
moved to the N-methyltriazolium station
and the other still sit on the –NH– sta-
tion (Figure 1d). When 50 equivalents of
DIEA was continuously added, the peak
for the N-methyltriazolium proton Hi was
almost disappeared, and the signals for
the protons adjacent to the triazole rings
exhibit a substantial upfield shift (Hg: δ =
0.28 and Hh: 0.26 ppm), which could be
attributed to the aromatic shielding effect
by DB24C8. All these changes indicated
that the two DB24C8 both moved to the
N-methyltriazolium stations (Figure 1i).
Furthermore, upon addition of trifluoro-
acetic acid (TFA) to the deprotonated
[3]rotaxane 4, the signal for the N-methyl-
triazolium C-H proton Hi shifted upfield to
δ = 7.8 ppm, suggesting that the DB24C8
returned to the original –NH2+– recogni-
Scheme 1. Synthesis of the chiral [3]rotaxane and thread.
(see the Supporting Information, SI), which revealed the tion site (Figure 1j). The signal changes of the protons Hi, Hg,
feature of an interlocked molecule. Regioselective methyla- and Hh indicated that the pH-controlled switching process is
tion of the [3]rotaxane 3 was carried out in iodomethane at reversible.
40 °C overnight to afford the bistable [3]rotaxane 4 by anion
The UV-vis absorption spectrum of [3]rotaxane 4 exhib-
exchange in 85% yield. As shown in Figure S1 (SI), there is ited a blue-shift of 4.0 nm as compared with [3]rotaxane 3
an obvious downfield shift for Hs (Δδ = 0.56 ppm) and Ht (Figure 2a), indicating that there was the weak interaction
(Δδ = 0.33 ppm) in 4 relative to Hs and Ht in the thread 6 (see between N-methyltriazolium and naphthalene units. The
SI). On the other hand, the chemical shifts of Hg, Hh, Hp, and two strong Cotton effects (negative one at ∼239 nm, posi-
1
Hk are almost unchanged. The results indicated that DB24C8 tive one at ∼227 nm), which are characteristic of the Bb
in 4 mostly reside around the secondary dialkylanilinium transition of the naphthalene chromophore, were revealed
position.[14]
in CD spectra of 3 (shot dash green curve, Figure 2b).[17]
Diisopropylethylamine (DIEA) is strong enough to depro- However, compared with 3, [3]rotaxane 4 showed a strong
tonate the NH2+ center.[15] The crown ethers can move toward negative Cotton effect at about 235 nm and a very weak
the N-methyltriazolium station upon addition of DIEA to the positive Cotton effect at about 221 nm (solid blue curve,
[3]rotaxane 4 (Scheme 2) because of the strong interaction Figure 2b), which was in accordance with the shifted
between the electron-rich crown ethers ring and the electron- absorbance spectra. The CD signal intensity of [3]rotaxane
deficient N-methyltriazolium station.[14,16] The deprotonation 4 was weaker than that of 3, which could be attributed to
of the [3]rotaxane 4 was carried out in acetone with a large the Coulombic repulsion between two N-methyltriazolium
excess of DIEA. After removal of the excess DIEA,[14a,5h] rings that would lead to a larger dihedral angle of binaph-
only one DB24C8 moved to the N-methyltriazolium station thalene rings in 4. This result was further confirmed by
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DOI: 10.1002/smll.201200670
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A Controllable Chiral Molecular Machine: Movement on Molecular Level
As the DB24C8 could move toward
and away from the naphthalene stopper,
which could tune the space between the
two N-methyltriazolium stations and then
change the dihedral angle of binaphtha-
lene rings, it could be expected that the
dihedral angle of the binaphthalene ring
in 4a should be larger than that in 4b
(with one DB24C8 unit) and that in 4c
(with two DB24C8 units reside around
the N-methyltriazolium station) (Scheme
2). Therefore, the CD signal of 4a should
be weaker than that of 4b and 4c,[11]
namely, the CD spectra of 4 may be tuned
upon the addition of base. The difference
between 4a and 4b in terms of CD signal
may be small since only one DB24C8 unit
moved toward the N-methyltriazolium
station which could not lead to the evi-
dent spatial changes of the two N-methyl-
triazolium moieties. To our surprise, these
expectations did not agree well with the
experimental observation as illustrated
by Figure 3, where the CD spectra of
4 in the presence of different amounts
of DIEA are displayed. Upon the addi-
tion of DIEA (5 equiv) to the solution
Scheme 2. Movement process of 4 under acid/base stimuli.
1
1
the H NMR spectral study. The H NMR signals for the of 4 (5.0 × 10−6 m in acetonitrile), the intensity of the CD
protons (Hg and Hh) adjacent to the binaphthalene in 4 signals at about 235 nm did not decrease but increased
were splitted obviously as compared with those signals in 3 (about 10%) (solid black curve, Figure 2b), which could be
(Figure 3). In [3]rotaxane 4, the steric hindrance exerted by attributed to the interaction between one DB24C8 with one
two DB24C8 along the threads opened the binaphthalene N-methyltriazolium station that weakened the Coulombic
rings in compound 6, and reduce the intensity of the Cotton repulsion between the two N-methyltriazolium rings and led
effect at 235 nm.[18]
to smaller dihedral angle of binaphthalene ring of 4. The CD
signal intensity increased more (about
30%) after the addition of 50 equivalents
of DIEA (solid red curve, Figure 2b).
However, for the thread 6, no CD spectral
change was found when DIEA was added
(short dot curves, Figure 2b). Therefore,
the CD signal of the [3]rotaxane 4 could
be modulated by the movement of the
macrocyle, and the Coulombic repul-
sion between two N-methyltriazolium
rings can lead to larger dihedral angle of
binaphthalene ring than the steric hin-
drance exerted by the two DB24C8 which
both located around the N-methyltriazo-
lium stations.
3. Conclusion
In summary, we have presented
a
novel chiral [3]rotaxane incorporating
binaphthalene as chiral moieties. In this
system, the movement of the macro-
cycle DB24C8 along the thread driven
by pH influenced the dihedral angle
Figure 1. 1H NMR spectra of 4 (1.5 mM) in CD3CN at 298 K upon titrational addition of DIEA:
a) 0, b) 1, c) 3, d) 5, e) 10, f) 20, g) 30, h) 40, and i) 50 equivalents; j) further addition of 55
equivalents of TFA.
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W. Yang et al.
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4. Experimental Section
Compound 9: A solution of the compound 7 (3.93 g, 10 mmol)
and 8 (2.22 g, 10 mmol) in toluene (100 mL) was heated under
reflux overnight by using a Dean-Stark apparatus. The solvent was
removed under reduced pressure after the reaction was cooled to
room temperature. The residue was dissolved in tetrahydrofuran
(THF; 50 mL), then NaBH4 (0.4 g, 10.5 mmol) was added cautiously
at 0 °C. The mixture was stirred at room temperature for a further
4 h. Water was added to quench the excess NaBH4. The solvent
was evaporated off, and the residue was extracted with CH2Cl2.
The combined organic layers were dried over Na2SO4, filtered, and
concentrated in vacuo. The crude product was purified by chroma-
tography (SiO2: CH2Cl2/MeOH, 20:1) to afford 9 as stick oil (5 g,
85%). 1H NMR (CD3CN, 400 MHz, δ): 7.27–7.18 (m, 14H), 7.14 (m,
8H), 6.81 (d, J = 8.6 Hz, 2H), 6.72 (d, J = 8.9 Hz, 2H), 4.31 (s, 2H),
3.87 (t, J = 12.1, 6.3 Hz, 4H), 3.47 (m, 2H), 3.27 (m, 2H), 1.95–
1.81 (m, 2H), 1.79–1.66 (m, 2H), 1.43 (m, 6H); 13C NMR (CD3CN,
100 MHz, δ): 159.3, 157.8, 148.2, 139.8, 132.8, 131.7, 129.8,
128.5, 126.8, 115.3, 114.3, 80.1, 68.7, 65.21, 62.5, 33.5, 29.9,
28.6, 27.9, 26.5, 26.4; Anal. calcd for C41H45NO3: C 82.10, H 7.56,
N 2.34; found: C 81.99, H 7.53, N 2.31.
Compound 10: A solution of di-tert-butyl dicarbonate (1.31 g,
6 mmol) in dry CH2Cl2 (10 mL) was added under argon at 0 °C to a
solution of 9 (3 g, 5 mmol) and triethylamine (1 mL) in dry CH2Cl2
(30 mL). The reaction mixture was stirred at room temperature for
24 h. The solvent was removed in vacuo and the residue was dis-
solved with CH2Cl2 (60 mL) and water (40 mL). The aqueous layer
was extracted with CH2Cl2 (3 × 50 mL). The combined organic
extracts were washed with water (25 mL), dried (MgSO4), filtered
and evaporated in vacuo. The crude product was purified by chro-
Figure 2. a) UV–vis absorption specta of [3]rotaxane 3 and 4; b) CD
spectra of [3]rotaxane 3 (dash curve), [3]rotaxane 4 (solid curve), thread
6 (dot curve) before and after addition of DIEA in CH3CN (5.0 × 10−6 M,
298 K).
between the two naphthalene rings, thus modulated the matography (SiO2: CH2Cl2/MeOH, 60:1) to afford 10 as stick oil
CD signals. [3]Rotaxane 4 showed a weak Cotton effect (3.1 g, 88%). 1H NMR (400 MHz, CDCl3, δ): 7.26–7.05 (m, 20H),
when DB24C8 located at the secondary N-alkylanilinium 6.82 (d, J = 8.5 Hz, 2H), 6.73 (d, J = 8.7 Hz, 2H), 4.38 (m, 2H), 4.13
position; the intensities of the CD signals increased when (t, J = 6.6 Hz, 2H), 3.91 (t, J = 6.3 Hz, 4H), 3.33 (m, 2H), 1.94 (m,
DB24C8 moved to the N-methyltriazolium station upon 2H), 1.72 (m, 4H), 1.55–1.35 (m, 15H); 13C NMR (100 MHz, CDCl3,
addition of DIEA. The incorporation of one chiral unit in δ): 158.3, 156.7, 155.9, 155.4, 147.1, 138.9, 132.1, 131.1, 130.3,
the molecular shuttle as a bulk stopper has promoted the 129.2, 127.4, 125.8, 114.4, 113.1, 79.6, 67.8, 67.7, 64.3, 53.4,
understanding of the concepts of design and strategies of 29.1, 28.6, 28.4, 27.8, 25.7, 25.5; Anal. calcd for C46H53NO5: C
functional molecular shuttles, rendering the possibility for 78.94, H 7.63, N 2.00; found: C 78.62, H 7.61, N 1.95.
the construction of chiral molecular switches and even
molecular logic gates.
Compound 11: 4-Methylbenzene-1-sulfonyl chloride (0.63 g,
3.3 mmol) and triethylamine (1 mL) in CH2Cl2 (10 mL) was added
at 0 °C to a solution of 10 (2.2 g, 3 mmol) in
dry CH2Cl2 (20 mL). The reaction mixture was
stirred at room temperature for 24 h. The sol-
vent was removed in vacuo and the residue
was dissolved with CH2Cl2 (60 mL) and water
(40 mL). The aqueous layer was extracted with
CH2Cl2 (3 × 50 mL). The combined organic
extracts were washed with water (25 mL),
dried (MgSO4), filtered and evaporated in
vacuo. The residue was dissolved in N,N-
dimethylformamide (DMF; 50 mL), then NaN3
(0.23 g, 3.5 mmol) was added cautiously. The
mixture was stirred at 80 °C overnight. After
concentrated in vacuo, the crude product
was purified by chromatography (SiO2:
Figure 3. Comparation for the 1H NMR of the protons (Hg and Hh) adjacent to the binaphthalene
in 3 and 4.
CH2Cl2/MeOH, 60:1) to afford compound 11
as slightly yellow oil in 72% yield. 1H NMR
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A Controllable Chiral Molecular Machine: Movement on Molecular Level
(CDCl3, 400 MHz, δ): 7.34–6.98 (m, 21H), 6.82 (d, J = 8.4 Hz, 2H), was extracted with CH2Cl2 (3 × 30 mL). The organic layers were
6.73 (d, J = 8.6 Hz, 2H), 4.37 (m, 2H), 3.92 (t, J = 6.3 Hz, 4H), 3.29 combined, dried over Na2SO4, and concentrated to obtain the
(m, 4H), 1.92 (m, 2H), 1.85–1.70 (m, 2H), 1.69–1.57 (m, 3H), [3]rotaxane 4 (45 mg, 85%) as an orange solid. 1H NMR (CD3CN,
1.45 (m, 13H); 13C NMR (CDCl3, 100 MHz, δ): 158.3, 156.8, 147.1, 400 MHz, δ): 8.17 (d, J = 9.2 Hz, 2H), 8.00 (d, J = 8.4 Hz, 2H), 7.91
146.8, 139.0, 132.2, 131.2, 129.3, 127.5, 125.9, 114.5, 113.2, (s, 2H), 7.69 (d, J = 9.1 Hz, 2H), 7.43 (t, J = 7.3 Hz, 2H), 7.32–7.07
85.2, 79.7, 67.7, 64.3, 51.4, 29.2, 28.9, 28.5, 27.5, 26.6, 25.7; (m, 40H), 6.86–6.76 (m, 16H), 6.59 (m, 8H), 5.35 (d, J = 14.0 Hz,
MS (MALDI-TOF): m/z 747.5 [M+Na]; Anal. calcd for C46H52N4O4: C 2H), 5.24 (d, J = 14.0 Hz, 2H), 4.53–4.48 (m, 4H), 4.48–4.46
76.21, H 7.23, N 7.73; found: C 75.91, H 7.21, N 7.69.
(m, 2H), 4.32 (d, J = 3.1 Hz, 4H), 4.05 (m, 14H), 3.86–3.70
Compound 1: Trifluroacetic acid (1 mL) was added to the (m, 22H), 3.62 (m, 20H), 3.39 (m, 6H), 1.98 (m, 4H), 1.86–1.76
solution of compound 11 (1.5 g, 2 mmol) in CH2Cl2 (10 mL). The (m, 4H), 1.68–1.60 (m, 4H), 1.41 (m, 4H), 1.26 (d, J = 13.0 Hz,
mixture was stirred at room temperature overnight. The solvent 4H); 13C NMR (CD3CN, 100 MHz, δ): 160.3, 157.2, 153.6, 148.3,
was evaporated off and the residue was dissolved in a mixture 148.2, 140.2, 140.0, 134.2, 132.8, 131.9, 131.6, 131.1, 130.0,
of acetone and water. Then the aqueous of NH4PF6 (500 mg, 129.7, 128.6, 128.1, 126.9, 125.9, 125.5, 125.0, 122.2, 121.6,
3 mmol) was added. The mixture was stirred for 1 h and then the 115.1, 114.4, 113.4, 71.6, 71.1, 68.8, 68.3, 65.2, 60.6, 54.7,
acetone was evaporated off. The aqueous solution was extracted 52.7, 46.8, 38.3, 29.6, 27.3, 26.2, 25.9; MS (MALDI-TOF): m/z:
with CH2Cl2 several times. The collected organic layers were dried 2683.3 [M–3PF6]3+; Anal. calcd for C158H178F24N8O22P4: C, 60.80;
over Na2SO4, filtered, and concentrated in vacuo. The crude H, 5.75; N, 3.59. Found: C, 60.32; H, 5.71; N, 3.55.
product was purified by chromatography (SiO2: CH2Cl2/MeOH,
Compound 5: A mixture of compound 1 (385 mg, 0.50 mmol),
60:1) to afford compound 1 as a yellow solid (1.16g, 75%). 1H compound 2 (90 mg, 0.25 mmol), and [Cu(MeCN)4]PF6 (185 mg,
NMR (400 MHz, CDCl3, δ): 7.36 (d, J = 8.7 Hz, 2H), 7.31–7.24 0.5 mmol) was stirred in dry CH2Cl2 at room temperature under
(m, 12H), 7.21 (m, 6H), 6.95 (d, J = 8.7 Hz, 2H), 6.83 (d, J = nitrogen for 48 h. After removal of the solvent, the crude product
9.0 Hz, 2H), 4.11–4.05 (m, 4H), 4.00 (t, J = 6.5 Hz, 2H), 3.31 (t, J = was purified by column chromatography (SiO2: CH2Cl2/MeOH 30:1)
6.9 Hz, 2H), 3.17 (t, J = 6.7 Hz, 2H), 2.15–2.06 (m, 2H), 1.96 (m, to afford thread 5 (390 mg, 82%). 1H NMR (CD3CN, 400 MHz, δ):
3H), 1.82–1.73 (m, 2H), 1.68–1.56 (m, 2H), 1.53–1.38 (m, 4H); 8.01 (d, J = 9.1 Hz, 2H), 7.92 (d, J = 8.2 Hz, 2H), 7.59 (d, J = 9.1 Hz,
13C NMR (CDCl3, 100 MHz, δ): 161.4, 157.7, 148.6, 141.0, 133.3, 2H), 7.39–7.11 (m, 48H), 7.03 (d, J = 7.5 Hz, 4H), 6.87 (d, J = 8.4
132.9, 132.1, 129.1, 127.3, 124.4, 116.2, 114.8, 69.2, 67.0, Hz, 4H), 6.76 (d, J = 8.7 Hz, 4H), 5.06 (d, J = 5.5 Hz, 4H), 4.15
65.7, 52.6, 52.4, 47.2, 30.1, 29.8, 27.5, 27.0, 26.6; MS (MALDI- (d, J = 5.0 Hz, 4H), 4.00 (m, 8H), 3.89 (t, J = 6.4 Hz, 4H), 3.07 (t, J =
TOF): m/z 625.3 [M]; Anal. calcd for C41H45F6N4O2P: C 63.89, 6.8 Hz, 5H), 2.10–2.00 (m, 3H), 1.76–1.61 (m, 8H), 1.44–1.33
H 5.88, N 7.27; found: C 63.64, H 5.84, N 7.25.
(m, 4H), 1.16 (d, J = 7.4 Hz, 4H); 13C NMR (CD3CN, 100 MHz, δ):
Compound 3: A dilute mixture of 1 (77 mg, 0.1 mmol), 159.5, 156.4, 153.9, 147.2, 143.6, 139.5, 133.8, 131.8, 131.0,
DB24C8 (45 mg, 0.1 mmol), and [Cu(MeCN)4]PF6 (37 mg, 130.6, 129.4, 128.1, 127.6, 127.2, 126.5, 125.9, 124.9, 123.9,
0.1 mmol) was stirred in dry CH2Cl2 (100 mL) at room temperature 123.1, 120.2, 116.0, 114.7, 113.4, 67.6, 65.6, 64.3, 63.2, 51.4,
under nitrogen for 0.5 h, then a dilute solution of compound 2 49.7, 45.7, 29.5, 28.5, 26.3, 25.6, 24.9; MS (MALDI-TOF): m/z:
(18 mg, 0.05 mmol) in CH2Cl2 (30 mL) was added to the solution 1611.9 [M–H]+, 1633.9 [M–H+Na]+, 1673.9 [M–H+Na+K]+; Anal.
slowly over 2 h and stirred for another 48 h under nitrogen. After calcd for C108H108N8F12O6P2: C 68.13, H 5.72, N 5.89; found:
removal of the solvent, the crude product was purified by column C 67.62, H 5.69, N 5.86.
chromatography (CH2Cl2/MeOH 30:1) to afford [3]rotaxane 3
Compound 6: Compound 6 was synthesized by using the same
(78 mg, 56%). 1H NMR (CD3CN, 400 MHz, δ): 8.01 (d, J = 9.1 procedure as described for the preparation of compound 4. 1H
Hz, 2H), 7.91 (d, J = 8.1 Hz, 2H), 7.63 (d, J = 9.1 Hz, 2H), 7.34 NMR (CD3CN, 400 MHz, δ): 8.17 (d, J = 8.9 Hz, 2H), 8.00 (d, J = 8.1
(m, 2H), 7.31–7.26 (m, 13H), 7.24 (m, 3H), 7.22–7.15 (m, 12H), Hz, 2H), 7.88 (s, 2H), 7.69 (d, J = 9.0 Hz, 2H), 7.47–7.13 (m, 46H),
7.08 (m, 8H), 7.00 (d, J = 8.5 Hz, 2H), 6.80 (s, 15H), 6.62–6.54 6.93 (d, J = 8.5 Hz, 3H), 6.79 (t, J = 8.9 Hz, 5H), 5.28 (dd, J = 48.4,
(m, 8H), 5.11 (d, J = 3.6 Hz, 4H), 4.52–4.44 (m, 4H), 4.16 (t, J = 14.1 Hz, 4H), 4.32 (m, 4H), 4.07 (m, 7H), 3.94 (t, J = 6.4 Hz, 4H),
7.0 Hz, 4H), 4.03 (m, 15H), 3.85–3.69 (m, 23H), 3.66–3.47 3.38 (s, 6H), 3.20 (t, J = 6.6 Hz, 4H), 1.81 (m, 4H), 1.69 (m, 4H),
(m, 20H), 1.99 (m, 3H), 1.77–1.66 (m, 4H), 1.65–1.55 (m, 4H), 1.43 (m, 4H), 1.27 (m, 8H); 13C NMR (CD3CN, 100 MHz, δ): 159.2,
1.42–1.32 (m, 4H), 1.18 (m, 4H); 13C NMR (CD3CN, 100 MHz, δ): 155.3, 151.7, 146.3, 138.8, 138.1, 132.3, 131.1, 130.7, 129.7,
161.1, 157.8, 155.4, 148.9, 148.8, 145.2, 140.9, 135.3, 133.4, 129.2, 128.1, 127.4, 126.7, 126.2, 125.0, 124.0, 123.5, 121.3,
132.5, 132.2, 131.0, 130.6, 129.6, 129.2, 128.0, 127.5, 126.4, 119.8, 113.9, 112.5, 66.8, 64.6, 64.3, 63.4, 58.7, 52.8, 50.1,
125.6, 125.5, 124.6, 122.8, 121.7, 117.5, 115.8, 115.0, 114.1, 44.9, 36.4, 27.7, 24.3, 24.0; ESI-MS: m/z: 411.1; Anal. calcd for
72.2, 71.7, 69.4, 69.0, 65.8, 64.8, 53.4, 51.2, 47.4, 31.2, 30.1,
C110H114N8F24O6P4: C 59.41, H 5.17, N 5.04; found: C 59.23, H
27.9, 27.2, 26.6; MS (MALDI-TOF): m/z: 2508.3 [M–H–2PF6]+; 5.15, N 5.02.
Anal. calcd for C156H172N8F12O22P2: C 66.89, H 6.19, N 4.00;
found: C 66.69, H 6.15, N 3.97.
Compound 4: [3]Rotaxane 3 (50 mg, 0.017 mmol) was dis-
solved in iodomethane (5 mL), and the mixture was stirred for
48 h at 40 °C. Then iodomethane was evaporated, and the solid
was washed with Et2O to give a red solid. Then, to a suspension
of the previous solid in H2O (10 mL) were added NH4PF6 (16.5 mg,
0.1 mmol) and CH2Cl2 (15 mL). The resulting bilayer solution was
vigorously stirred for 3 h. After separation, the aqueous layer
Supporting Information
Supporting Information is available from the Wiley Online Library
or from the author.
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DOI: 10.1002/smll.201200670
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Received: March 28, 2012
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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DOI: 10.1002/smll.201200670
6