Charge transfer chromophore-stopped [2]rotaxane through [2 + 2] cycloaddition

Article abstract of DOI:10.1021/jo8014566

(Figure Presented) Three charge-transfer chromophore-terminated [2]rotaxanes were synthesized, using a high-yield [2 + 2]cycloaddition reaction in apolar solvent at room temperature. Two solvent-driving molecular shuttles were constructed, which exhibit d

Full text of DOI:10.1021/jo8014566

Charge Transfer Chromophore-Stopped [2]Rotaxane through
[2 + 2] Cycloaddition
Weidong Zhou, Jialiang Xu, Haiyan Zheng, Huibiao Liu, Yuliang Li,* and Daoben Zhu
Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Organic Solids
Institute of Chemistry, Chinese Academy of Sciences and Graduate school of Chinese
Academy of Sciences, Beijing 100190, P. R. China
ylli@iccas.ac.cn
ReceiVed July 6, 2008
Three charge-transfer chromophore-terminated [2]rotaxanes were synthesized, using a high-yield [2
+ 2]cycloaddition reaction in apolar solvent at room temperature. Two solvent-driving molecular
shuttles were constructed, which exhibit distinct conformations in different solvent as a result of the
shuttling movement of the macrocycle.
Introduction
construction of rotaxanes.6 As for the method of threading
followed by stopping methodology, many reactions have been
employed for pseudorotaxanes, in order to form rotaxanes, such
as click reaction7 and reductive amination.8 However, in
Biological molecular machines, such as the supramolecular
system in photosynthesis, which are able to transform chemical
energy into mechanical motion, have been well studied during
the past few years. In order to simulate these biological machines
with synthetic systems, many simple prototypes of artificial
molecular motors, consisting of a few components capable of
moving in a controllable way, have been proposed in recent
years.1 Mechanically interlocked molecules, such as catenanes
and rotaxanes, have become typical candidates in the design of
artificial molecular machines because some of their components
have the ability of reversibly moving among two or more
stations on application of external stimuli.1 Various stimuli have
been employed to induce such switches, ranging from illumina-
tion2 and variation of the electrochemical potential3 to solvent4
or pH change.5 Various methods for the preparation of such
bistable rotaxanes are being pursued actively in order to facilitate
the optimal realization of their applications. Threading followed
by stopping and “clipping” are two efficient strategies for the
(2) (a) Brouwer, A. M.; Frochot, C.; Gatti, F. G.; Leigh, D. A.; Mottier, L.;
Paolucci, F.; Roffia, S.; Wurpel, G.W. H. Science 2001, 291, 2124–2128. (b)
Balzani, V.; Clemente-Leon, M.; Credi, A.; Ferrer, B.; Venturi, M.; Flood, A. H.;
Stoddart, J. F. Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 1178–1183. (c) Wang,
Q. C; Qu, D. H.; Ren, J; Chen, K. C.; Tian, H. Angew. Chem., Int. Ed. 2004, 43,
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44, 5296–5299.
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Heath, J. R. Acc. Chem. Res. 2001, 34, 433–444. (b) Altieri, A.; Gatti, F. G.;
Kay, E. R.; Leigh, D. A.; Martel, D.; Paolucci, F.; Slawin, A. M. Z.; Wong,
J. K. Y. J. Am. Chem. Soc. 2003, 125, 8644–8654. (c) Mateo-Alonso, A.;
Fioravanti, G.; Marcaccio, M.; Paolucci, F.; Rahman, G. M. A.; Ehli, C.; Guldi,
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11092–11093. (b) Da Ros, T.; Guldi, D. M.; Morales, A. F.; Leigh, D. A.; Prato,
M.; Turco, R. Org. Lett. 2003, 5, 689–691. (c) Leigh, D. A.; Morales, M. A. F.;
Perez, E. M.; Wong, J. K. Y.; Saiz, C. G.; Slawin, A. M. Z.; Carmichael, A. J.;
Haddleton, D. M.; Brouwer, A. M.; Buma, W. J.; Wurpel, G.W. H.; Leon, S.;
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409–522. (c) Balzani, V.; Credi, A.; Venturi, M. Molecular DeVices and
Machines: A Journey into the Nano World; Wiley-VCH: Weinheim, Germany,
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J. Am. Chem. Soc. 1998, 120, 11932–11942. (b) Keaveney, C. M.; Leigh, D. A.
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10.1021/jo8014566 CCC: $40.75 2008 American Chemical Society
Published on Web 09/10/2008

Charge Transfer Chromophore-Stopped [2]Rotaxanes
SCHEME 1. Synthetic Route to T-1 and R-1
practice, the using of catalysts or molecular sieves sometimes
limits their application. So, the search for a mild and high-yield
reaction suitable for the construction of [2]rotaxane is still
Organic donor-acceptor molecules have been given much
attention as promising compounds for molecular electronics,
particularly in all optical computing and signal processing. Since
interlocked compounds are believed to be superior scaffolds for
molecular devices,1 interlocked compounds containing donor-
acceptor groups are of great interest. Herein, we describe three
[2]rotaxanes containing a charge transfer chromophore stopper
synthesized through a high efficiency [2 + 2] cycloaddition
reaction. This cycloaddition reaction developed by Diederich
occurs in apolar solvent at room temperature without the help
of catalyst.10 These conditions are ideal for strong hydrogen
9
important to scientists in this field.
(7) (a) Aucagne, V.; Hanni, K. D.; Leigh, D. A.; Lusby, P. J.; Walker, D. B.
J. Am. Chem. Soc. 2006, 128, 2186–2187. (b) Aucagne, V.; Berna, J.; Crowley,
J. D.; Goldup, S. M.; Hanni, K. D.; Leigh, D. A.; Lusby, P. J.; Ronaldson, V. E.;
Slawin, A. M. Z.; Viterisi, A.; Walker, D. B. J. Am. Chem. Soc. 2007, 129,
11950–11963. (c) Dichtel, W. R.; Miljanic´, O. S.; Spruell, J. M.; Heath, J. R.;
Stoddart, J. F. J. Am. Chem. Soc. 2006, 128, 10388–1039.
(8) (a) Glink, P. T.; Oliva, A. I.; Stoddart, J. F.; White, A. J. P.; Williams,
D. J. Angew. Chem., Int. Ed. 2001, 40, 1870–1875. (b) Williams, A. R.; Northrop,
B. H.; Chang, T.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem.,
Int. Ed. 2006, 45, 6665–6669. (c) Leung, K.C.-F.; Arico´, F.; Cantrill, S. J.;
Stoddart, J. F J. Am. Chem. Soc. 2005, 127, 5808–5810.
(9) (a) Chiu, C.-W.; Lai, C.-C.; Chiu, S.-H. J. Am. Chem. Soc. 2007, 129,
3500–3501. (b) Hsueh, S.-Y.; Cheng, K.-W.; Lai, C.-C.; Chiu, S.-H. Angew.
Chem., Int. Ed. 2008, 47, 4436–4439. (c) Hoffart, D. J.; Tiburcio, J.; Torre, A;
de, la; Knight, L. K.; Loeb, S. J Angew. Chem., Int. Ed. 2008, 47, 97–101. (d)
Mullen, K. M.; Gunter, M. J. J. Org. Chem. 2008, 73, 3336–3350.
(10) (a) Michinobu, T.; May, J. C.; Lim, J. H.; Boudon, C.; Gisselbrecht,
J.-P.; Seiler, P.; Gross, M.; Biaggio, I.; Diederich, F. Chem. Commun. 2005, D,
737–739. (b) Michinobu, T.; Boudon, C.; Gisselbrecht, J.-P.; Seiler, P.; Frank,
B.; Moonen, N. N. P.; Gross, M.; Diederich, F. Chem. Eur. J. 2006, 12, 1889–
1905. (c) Kivala, M.; Boudon, C.; Gisselbrecht, J.-P.; Seiler, P.; Gross, M.;
Diederich, F. Chem. Commun. 2007, 4731–4733.
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Zhou et al.
FIGURE 2. Partial 1H NMR spectra (400 MHz, 1 × 10-3 M, CDCl3)
of T-2 (a) and R-2 (b).
1
FIGURE 1. Partial H NMR spectra (600 MHz, 298 K, CDCl3, 1 ×
10-3 M) of T-1 (a), R-1(b), and macrocycle M-1 (c).
bonding induced recognition between macrocycle and thread
molecules containing amide.11
FIGURE 3. Partial 1H NMR spectra (400 MHz, 1 × 10-3 M, CDCl3)
of T-3 (a) and R-3 (b).
Results and Discussion
The shuttle was synthesized according to Scheme 1.
Amide-amide hydrogen bonding of short peptide units with
isophthalamide macrocycles has been well studied by the Leigh
group for template-induced synthesis of rotaxanes.11 In CH2Cl2,
macrocycle M-1 assembled with the monostoppered peptide
thread T-0, forming a pseudorotaxane (Scheme 1). Covalent
capture of the threaded intermediate compound by cycloaddition
reaction with tetracyanoquinodimethane (TCNQ) afforded the
free thread T-1 and [2]rotaxane R-1 in 62% and 30% yields,
respectively. This cycloaddition reaction developed by Diederich
occurs at room temperature and in apolar solvents without the
help of catalyst.10 All these conditions are ideal for strong
hydrogen binding of macrocycle M-1 with thread molecules
containing amide.11b,12 The synthesis of the intramolecular
charge transfer (ICT) chromophore and the stopping of the
pseudorotaxanes could be carried out in one step. This cycload-
dition reaction exhibits some advantages over typical methods
such as click reaction and reductive amination, where the
introduction of metal catalyst or molecular sieve sometimes put
limitations on their application.
Since the xylylene parts of the macrocycle shields encapsu-
lated regions of the thread, the position of the macrocycle could
be determined by comparing the chemical shift of the protons
in rotaxane with those of the corresponding thread.11,12 The 1H
NMR spectra (Figure 1) of thread T-1 and rotaxane R-1 confirm
the interlocked nature of R-1 and show that in R-1 the
macrocycle is localized on the peptide region of the thread
(Scheme 1). The upfield shifts of the methylene resonances of
the peptide station (He 1.00, Hc 0.48) in R-1 are characteristic11,12
of aromatic shielding by the encapsulating macrocycle. The
signals corresponding to phenylene protons Hb exhibited
substantial upfield shift of 0.23 ppm due to the shielding effect
from the macrocycle. The signals for Hq/q′ separated into two
different sets of signals as a consequence of losing their planes
of symmetry orthogonal to the principal axis in [2]rotaxane.5a,13
The amide resonance Hf shifted downfield by 0.84 ppm in the
rotaxane as a result of the hydrogen bonding to the macrocycle
polyether oxygens.11b The HRMS (N-SIMS NBA) of R-1
revealed a high intensity signal at m/z 1407.600 and 1430.580
corresponding to R-1 and R-1+Na (see Supporting Informa-
tion).
To put this synthesis strategy into the construction of
molecular shuttle, two [2]rotaxanes R-2 and R-3 containing a
C10-chain bridge between peptide and ICT chromophore were
synthesized with similar reaction mechanism and process
1
(Schemes 2 and 3). The H NMR spectra (Figures 2 and 3) of
[2]rotaxane R-2 and R-3 confirm their interlocked nature and
show that in R-2 and R-3 the macrocycle is localized on the
peptide region of the thread. The upfield shifts of the methylene
resonances of the peptide station (Hf 0.45, Hh 0.96, Figure 2b)
in R-2 are characteristic of aromatic shielding by the encapsu-
lating macrocycle. The amide proton resonance Hg in R-2
experienced an upfield shift of 1.06 ppm as a result of the shield
effect from the macrocycle. In addition, the alkyl-chain proton
resonances Hc and Hd in R-2 are still in the same station as
those in T-2, which indicate the independence of macrocycle
and alkyl-chain. All these features verify that the macrocycle
stay in the peptide station in R-2 in CDCl3. In R-3, the two
signals Hd and Hf adjacent to peptide group upfield shifted by
1.01 and 0.51 ppm, respectively, which indicates the shield effect
(11) (a) Leigh, D. A.; Murphy, A.; Smart, J. P.; Slawin, A. M. Z. Angew.
Chem., Int. Ed. 1997, 36, 728–732. (b) Leigh, D. A.; Thomson, A. R. Org. Lett.
2006, 8, 5377–5379.
(12) (a) Li, Y.; Li, H.; Li, Y.; Liu, H.; Wang, S.; He, X.; Wang, N.; Zhu, D.
Org. Lett. 2005, 7, 4835–4838. (b) Zhou, W.; Chen, D.; Li, J.; Xu, J.; Lv, J.;
Liu, H.; Li, Y. Org. Lett. 2007, 9, 3929–3932.
(13) (a) Badjic, J. D.; Ronconi, C. M.; Stoddart, J. F.; Balzani, V.; Silvi, S.;
Credi, A. J. Am. Chem. Soc. 2006, 128, 1489–1499. (b) Zhou, W.; Li, J.; He,
X.; Li, C.; Lv, J.; Li, Y.; Wang, S.; Liu, H.; Zhu, D. Chem. Eur. J. 2008, 14,
754–763.
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Charge Transfer Chromophore-Stopped [2]Rotaxanes
SCHEME 2. Synthetic Route to T-2 and R-2
from the macrocycle.(Figure 3b) The amide proton resonance
He in R-3 experienced an upfield of 1.12 ppm due to the shield
effect from the macrocycle. Furthermore, the alkyl-chain proton
resonance Hi did not exhibit obvious shift compared with that
in free thread T-3. These features verify that the macrocycle
stays in the peptide station in R-3 in CDCl3.
DMSO, while the upfield shifts of the methylene resonance
(Hc 0.32) in R-2 are characteristic of aromatic shielding by
the encapsulating macrocycle. The alkyl-chain proton signals
in R-2 experienced significant upfield shift compared with
the free thread T-2, which can be attributed to the shield
effect of the macrocycle. These features indicate the mac-
rocycle in R-2 moved toward the long alkyl chain and apart
from the ICT chromophore unit in DMSO (Scheme 4a). In
R-3, the amide signal of He and the methylene resonance Hd
exhibited the same shift as in free thread T-3 (Figure 5).
The signal assigned to methylene Hi experienced an upfield
shift of 0.44 ppm, which indicates the shield effect from the
macrocycle. The proton signals assigned to the long alkyl
chain exhibited obvious upfield shift compared to those in
free thread T-3, which indicate the aromatic shielding from
the encapsulating macrocycle. These features indicate the
The macrocycle can be dissociated from the peptide by
changing into a highly polar solvent, which solvates the
hydrogen-bonding sites of the macrocycle and the peptide
more strongly than they bind to each other.4 In DMSO, a
typical solvent that destroys hydrogen bonding, significant
1
changes occurred in H NMR spectra. The amide signal of
Hg and the methylene resonance Hh in R-2 exhibit shifts
similar to those in free thread T-2 (Figure 4), which can be
attributed to the disappearance of the hydrogen bonds and
the shield effect from the macrocycle when dissolved in
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Zhou et al.
SCHEME 3. Synthetic Route to T-3 and R-3
macrocycle in R-3 moved toward the long alkyl chain and
toward the ICT chromophore unit in DMSO (Scheme 4b).
So, two solvent-driving molecular shuttles were successfully
constructed through the [2 + 2] cycloaddition reaction, which
exhibit distinct conformations in different solvents as a result
of the shuttling movement of the macrocycle.
Experimental Section
2-Azido-acetyl-4-iodobenzenamine (1). 2-Chloroacetyl chloride
(0.67 g, 6mmol) was added to a solution of 4-iodobenzenamine
(1.31 g, 6mmol) and Et3N (1 mL) in CHCl3 at 0 °C. Then the
mixture was stirred at room temperature for 2 h and washed with
distilled water (3 × 50 mL). The collected organic layers were
dried over NaSO4, and the chloroform was removed in vacuo to
gain the product (1.55 g, 85%) which was used without further
purification. The 2-chloroacetyl-4-iodobenzenamine (1.32 g, 4.5
mmol) was dissolved in DMF, and NaN3 (1 g, 15 mmol) was added
in one portion. The temperature of the solution was raised to 80
°C, and stirring was continued at 80 °C for 10 h. The reaction was
cooled to room temperature, and solvent was then evaporated off.
The residue was dissolved in CHCl3, washed with water three times,
and dried over MgSO4. The crude product was purified by SiO2
In conclusion, three charge transfer chromophore-terminated
[2]rotaxanes were synthesized by virtue of a cycloaddition
reaction. The mild condition of this reaction provides extensive
opportunity for the construction of [2]rotaxane. The incorpora-
tion of the charge transfer chromophore to the molecular shuttle
as a bulk stopper will introduce more understanding of the
construction of future molecular shuttles.
7706 J. Org. Chem. Vol. 73, No. 19, 2008

Charge Transfer Chromophore-Stopped [2]Rotaxanes
SCHEME 4. Shuttling Movment of the Macrocycle in R-2 and R-3 in Different Solvents
chromatography with CH2Cl2/n-hexane (2/1, v/v) to obtain pure
2-azido-acetyl-4-iodobenzenamine (1.2 g, 90% yield) as a white
powder. 1H NMR (CDCl3) δ 8.00(s, 1H), 7.65(d, 2H, J ) 8.5 Hz),
7.34(d, 2H, J ) 8.5 Hz), 4.15(s, 2H). 13C NMR (CDCl3 + DMSO-
d6) δ 171.2, 143.1, 142.4, 126.7, 92.0, 56.9. MS (EI): 302 (M+).
Elemental Analysis for C8H7IN4O: C, 31.81; H, 2.34; N, 18.55.
Found: C, 31.87; H, 2.37; N, 18.41.
2-Amino-N-(4-iodophenyl)acetamide (2). To a solution of
2-azido-acetyl-4-iodobenzenamine (1.0 g, 3.3 mmol) in tetrahy-
drofuran (60 mL) were added triphenylphosphine (2.6 g, 10 mmol)
and water (3 mL). The reaction mixture was stirred at room
temperature for 16 h, and solvent was then evaporated off. The
mixture was purified by SiO2 chromatography with CH2Cl2/MeOH
(50/1, v/v) to obtain pure 2-amino-N-(4-iodophenyl)acetamide (0.68
g, 75% yield) as white powder. Mp 155 °C. 1H NMR (CDCl3, 600
MHz) δ 9.46(s, 1H), 7.63(d, 2H, J ) 8.55 Hz), 7.40(d, 2H, J )
8.55 Hz), 3.46(s, 2H). 13C NMR (DMSO-d6) δ 172. 8, 139.1, 137.8,
121.7, 86.9, 46.1. MS (EI): 275 (M+). Elemental Analysis for
C8H9IN2O: C, 34.80; H, 3.29; N, 10.15. Found: C, 34.77; H, 3.23;
N, 10.22.
FIGURE 4. Partial 1H NMR spectra (400 MHz, 1 × 10-3 M, DMSO-
d6) of T-2 (a) and R-2 (b).
J. Org. Chem. Vol. 73, No. 19, 2008 7707

Zhou et al.
873 (M), 896 (M + Na). Elemental Analysis for C57H43N7O3: C,
78.33; H, 4.96; N, 11.22. Found: C, 78.41; H, 4.99; N, 11.16.
1
R-1. H NMR (CDCl3, 600 MHz) δ 9.79(s, 1H), 8.31(s, 1H),
8.15(d, 2H, J ) 7.7 Hz), 7.53(m, 4H), 7.47(m, 2H), 7.28(m, 3H),
7.25-7.24(m, 5H), 7.20-7.17(m, 10H), 7.14(d, 2H, J ) 8.8 Hz),
7.10(d, 2H, J ) 9.3 Hz), 7.05(s, 2H), 6.87(s, 2H), 6.72(d, 4H, J )
7.9 Hz), 6.61(d, 2H, J ) 8.8 Hz), 6.40(d, 5H, J ) 8.3 Hz), 4.35(d,
2H, J ) 14.3 Hz), 4.20(d, 2H, J ) 14.3 Hz), 4.08(s, 2H), 3.93(m,
2H), 3.87(m, 2H), 3.83-3.76(m, 6H), 3.73(m, 2H), 3.72(s, 4H),
3.17(d, 2H, J ) 5.4 Hz), 3.06(s, 2H). 13C NMR (CDCl3, 150 MHz)
δ 171.4, 168.7, 168.3, 165.9, 157.6, 154.7, 154.2, 152.8, 152.1,
146.8, 142.9, 140.9, 134.5, 134.4, 134.3, 133.8, 132.5, 132.3, 131.9,
131.0, 129.9, 129.7, 129.3, 127.6, 126.0, 125.1, 123.4, 122.7, 119.5,
114.7, 113.9, 113.5, 112.7, 112.5, 112.4, 85.1, 77.3, 77.1, 76.9,
71.9, 70.6, 70.1, 69.9, 66.8, 66.7, 64.3, 53.5, 44.4, 40.3, 40.2. MS
(TOF): 1431.5 (M + Na). Mp 210 °C. HRMS: 1408.6000 (M),
1431.5874 (M + Na).
FIGURE 5. Partial 1H NMR spectra (400 MHz, 1 × 10-3 M, DMSO-
d6) of T-3 (a) and R-3 (b).
Compound 4. To a stirred solution of compound 2 (630 mg,
2.3 mmol), 11-bromoundecanoic acid (610 mg, 2.3 mmol), and
DMAP (305 mg, 2.5 mmol) in anhydrous CH2Cl2 (200 mL) cooled
on an ice bath was added EDCI ·HCl (480 mg, 2.5 mmol). After
16 h the solution was washed with a saturated solution of cit-
ric acid (3 × 80 mL) and H2O (3 × 50 mL), the organic layer
was dried over anhydrous Na2SO4 and filtered, and the filtrate was
reduced in volume to obtain a white solid. Purification was
accomplished by column chromatography on silica with CH2Cl2/
CH3OH (100/1, v/v) to give compound 4 (920 g, 75%). Mp 146
N-(4-Iodophenyl)-2-(2-(4-tritylphenoxy)acetamido)aceta-
mide (3). To a stirred solution of compound 2 (600 mg, 2.19 mmol),
1 (866 mg, 2.2 mmol), and DMAP (305 mg, 2.5 mmol) in
anhydrous CH2Cl2 (200 mL) cooled on an ice bath was added
EDCI·HCl (480 mg, 2.5 mmol). After 16 h the solution was washed
with a saturated solution of citric acid (3 × 80 mL) and H2O (3 ×
50 mL), the organic layer was dried over anhydrous Na2SO4 and
filtered, and the filtrate reduced in volume to obtain a white solid.
Purification was accomplished by column chromatography on silica
with CH2Cl2/CH3OH (100/1, v/v) to give 3 (1.11 g, 78%). Mp 253
1
°C. H NMR (CDCl3, 400 MHz) δ 10.04(s, 1H), 8.11(t, 1H, J )
5.7 Hz), 7.64(d, 2H, J ) 8.64 Hz), 7.43(d, 2H, J ) 8.64 Hz), 3.85(d,
2H, J ) 5.8 Hz), 3.51(t, 2H, J ) 6.7 Hz), 2.14(t, 2H, J ) 7.4 Hz),
1.78(m, 2H), 1.49(broad, 2H), 1.36(broad, 2H), 1.24(broad, 10H).
13C NMR (CDCl3, 150 MHz) δ 173.3, 168.7, 139.3, 137.9, 121.8,
87.1, 43.2, 35.7, 32.8, 29.6, 29.4, 29.3, 29.2, 29.0, 28.8, 28.6. EI-
MS 536. Elemental Analysis for C20H30BrIN2O2: C, 44.71; H, 5.63;
N, 5.21. Found: C, 44.77; H, 5.69; N, 5.31.
1
°C. H NMR (CDCl3) δ 8.30 (s, 1H), 7.60(d, 2H, J ) 8.7 Hz),
7.4(s, 1H), 7.29(d, 2H, J ) 8.7 Hz), 7.25-7.24(m, 5H), 7.20-7.16(m,
12H), 6.82(d, 2H, J ) 8.9 Hz), 4.57(s, 2H), 4.169(d, 2H, J ) 5.8
Hz). 13C NMR (DMSO-d6) δ 168.7, 168.1, 156.1, 147.1, 139.7,
139.2, 137.9, 132.1, 130.9, 128.2, 126.5, 121.9, 114.4, 87.3, 67.4,
64.4, 43.0. MS (TOF): 652 (M), 675 (M + Na). Elemental Analysis
for C35H29IN2O3: C, 64.42; H, 4.48; N, 4.29. Found: C, 64.37; H,
4.41; N, 4.32.
Compound 5. K2CO3 (1 g) was added to a DMF solution
containing compound 4 (860 mg, 1.6mmol) and 4-tritylphenol (570
mg, 1.7 mmol) under nitrogen. The mixture was stirred at 80 °C
for 10 h. The solvent was evaporated under vacuum and washed
with water three times. The organic layer was dried over anhydrous
Na2SO4, concentrated, and purified by column chromatography with
CH2Cl2/CH3OH (100/1, v/v). The white product was obtained with
a yield of 89%. Mp 165 °C.1H NMR (CDCl3, 400 MHz) δ 9.56(s,
1H), 7.57(d, 2H, J ) 8.4 Hz), 7.35(d, 2H, J ) 8.4 Hz), 7.19(broad,
15H), 7.08(d, 2H, J ) 8.6 Hz), 6.96(s, 1H), 6.75(d, 2H, J ) 8.7
Hz), 4.17(d, 2H, J ) 4.12 Hz), 3.9(t, 2H, J ) 6.4 Hz), 2.28(t, 2H,
J ) 7.3 Hz), 1.7(m, 2H), 1.63(m, 2H), 1.42(m, 2H), 1.27(broad,
10H). 13C NMR (CDCl3, 100 MHz) δ 174.5, 167.4, 157.1, 147.1,
138.8, 137.8, 132.2, 131.2, 127.4, 125.8, 121.7, 113.3, 87.6, 67.9,
64.4, 53.5, 44.5, 36.3, 29.6, 29.4, 29.3, 26.2, 25.7. MS(MALDI-
TOF) 801 (M + Na). Elemental Analysis for C44H47IN2O3: C,
67.86; H, 6.08; N, 3.60. Found C, 67.88; H, 6.09; N, 3.54.
Compound 6. To a stirred solution of 4-ethynyl-N,N-dimeth-
ylbenzenamine (220 mg, 1.5mol) and compound 5 (0.9 g, 1.15mmol)
in THF/Et3N (1/1, v/v) were added PdCl2(PPh3)2 (20 mg) and CuI
(20 mg) under a nitrogen flow at room temperature. The reaction
mixture was stirred for 12 h, and solvent was then evaporated off.
The mixture was purified by SiO2 chromatography with CH2Cl2/
MeOH (100/1, v/v) to obtain compound 6 (690 mg, 75% yield) as
a white powder. The crude product was used for the next reaction
directedly, because it was not stable enough for further purification.
Compound T-2 and R-2. Compounds T-2 and R-2 were
synthesized from compunds 6, TCNQ, and macrocycle with a
similar method to the preparation of compounds T-1 and R-1.
T-0. To a stirred solution of 4-ethynyl-N,N-dimethylbenzenamine
(224 mg, 1.55mol) and compound 3 (1.0 g, 1.53mmol) were added
PdCl2(PPh3)2 (10 mg) and CuI (10 mg) under nitrogen flow at room
temperature. The reaction mixture was stirred for 2 h, and solvent
was then evaporated off. The mixture was purified by SiO2
chromatography with CH2Cl2/MeOH (50/1, v/v) to obtain pure T-0
(760 mg, 75% yield) as white powder. 1H NMR (CDCl3, 400 MHz)
δ 8.27(s, 1H), 7.60(d, 1H, J ) 8.5 Hz), 7.46-7.38(m, 5H),
7.25-7.23(m, 5H), 7.20-7.15(m, 12H), 6.82(dd, J ) 8.9 and 2.58
Hz), 6.65(d, 2H, J ) 8.9 Hz), 4.57(s, 2H), 4.19(t, 2H, J ) 5.98
Hz), 2.99(s, 6H). 13C NMR (DMSO-d6) δ 168.6, 168.0, 156.1,
150.5, 147.1, 139.6, 139.1, 137.8, 132.7, 132.1, 130.9, 128.1, 126.4,
121.8, 119.5, 118.3, 114.3, 112.4, 109.2, 90.5, 87.6, 87.2, 67.3,
64.3, 42.9. MS (TOF): 669 (M), 692 (M + Na). Elemental Analysis
for C45H39N3O3: C, 80.69; H, 5.87; N, 6.27. Found: C, 80.72; H,
5.91; N, 6.20.
T-1. Macrocycle 1 (270 mg, 0.5mmol) was added to a solution
of T-0 (334 mg, 0.5mmol) in CH2Cl2 (100 mL) at room temper-
ature. The mixture was stirred under nitrogen flow for 30 min. Then,
TCNQ (102 mg, 0.5mmol) was added, and the mixture was stirred
for 12 h at 20 °C. The solvent was removed in vacuo, and the
product was purified by SiO2 chromatography with CH2Cl2/ MeOH
(100/1, v/v) to obtain pure T-1 (260 mg, 62% yield) and R-1 (210
1
mg, 30%) as copper-like metallic solids. Mp 190 °C. H NMR
(CDCl3, 600 MHz) δ 8.945(s, 1H), 7.645(s, 4H), 7.45(d, 2H, J )
9.5 Hz), 7.41(s, 1H), 7.27-7.20(m, 6H), 8.18-7.15(m, 14H),
6.94(d, 1H, J ) 9.5 Hz), 6.84(d, 2H, J ) 8.1 Hz), 6.81(d, 2H, J )
9.18 Hz), 4.56(s, 2H), 4.18(s, 2H), 3.14(s, 6H). 13C NMR (CDCl3,
150 MHz) δ 171.3, 170.0, 167.1, 154.8, 154.1, 152.3, 151. 8, 146.7,
142. 7, 141.1, 135.6, 134.5, 132.6, 131.9, 131.3, 131.1, 130.1, 127.6,
126.1, 125.4, 125.0, 124.6, 119.9, 114.8, 114.7, 113.6, 113.5, 113.4,
113.1, 112. 6, 85.4, 72.0, 67.0, 64.3, 53.5, 44.6. 40.6. MS (TOF):
1
Compounds T-2. H NMR (CDCl3, 400 MHz) δ 9.6(S, 1H),
7.66(q, 4H, J ) 5.4 Hz), 7.49(d, 1H, J ) 8.6 Hz), 7.27-7.17(m,
16H), 7.08(d, 2H, J)8.8 Hz), 6.95(d, 1H, J ) 8.4 Hz), 6.73(d, 2H,
J ) 8.8 Hz), 6.71(d, 2H, J ) 9.1 Hz), 6.53(s, 1H), 4.13(d, 2H, J
) 4.96), 3.90(t, 2H, 6.5 Hz), 3.11(s, 6H), 2.29(t, 2H, J ) 7.59
7708 J. Org. Chem. Vol. 73, No. 19, 2008

Charge Transfer Chromophore-Stopped [2]Rotaxanes
Hz), 1.74(m, 2H), 1.65(m, 2H), 1.40(m, 2H), 1.28(broad, 10H).
13C NMR (CDCl3, 100 MHz) δ 174.9, 171.5, 167.8, 157.2, 154.3,
152.9, 147.2, 143.1, 138.9, 134.6, 132.3, 131.8, 131.4, 131.2, 130.1,
127.5, 125.9, 125.4, 124.9, 124.0, 120.0, 114.9, 113.5, 113.3, 112.7,
85.4, 71.7, 67.9, 64.4, 45.1, 40.3, 36.5, 31.7, 29.6, 29.5, 29.3, 26.2,
25.7, 22.8. Mp 160 °C. MS (MALDI-TOF) 1022 (M + Na).Ele-
mental Analysis for C66H61N7O3: C, 79.25; H, 6.15; N, 9.80. Found:
C, 79.33; H, 6.19; N, 9.72.
under a nitrogen flow at room temperature. The reaction mixture
was stirred for 12 h, and solvent was then evaporated off. The
mixture was purified by SiO2 chromatography with CH2Cl2/MeOH
(100/1, v/v) to obtain pure compound 10 (600 mg, 75% yield) as
a white powder. 1H NMR (CDCl3, 400 MHz) δ 9.25(s, 1H), 7.47(d,
2H, J ) 8.58 Hz), 7.40(q, 4H, J ) 8.61 Hz), 7.25-7.18(m, 17H),
6.83(d, 2H, J ) 8.61 Hz), 6.65(d, 2H, J ) 8.73 Hz), 4.15(d, 2H,
J ) 4.81 Hz), 3.93(t, 2H, J ) 6.45 Hz), 2.97(s, 6H), 2.27(t, 2H, J
) 7.51 Hz), 1.75(m, 2H), 1.67(m, 4H), 1.42(m, 2H), 1.27(broad,
8H). 13C NMR (CDCl3) δ 174.6, 167.5, 158.9, 150.1, 146.9, 142.9,
136.0, 132.7, 131.9, 131.3, 130.2, 127.7, 126.1, 119.0, 116.3, 114.7,
112.1, 110.7, 89.2, 87.5, 68.2, 64.8, 44.7, 40.5, 36.5, 32.2, 29.9,
29.7, 29.7, 29.6, 29.5, 27.4, 26.2. MS (TOF): 795 (M), 818
(M+Na).
1
Compounds R-2. H NMR (CDCl3, 400 MHz) δ 9.78(s, 1H),
8.37(s, 1H), 8.25(d, 2H, J ) 7.73 Hz), 7.53(m, 5H), 7.29-7.17(m,
15H), 7.11(m, 5H), 6.75(m, 7H), 6.44(d, 4H, J ) 8.3 Hz), 5.21(s,
1H), 4.48(d, 2H, J ) 14.1 Hz), 4.16(d, 2H, J ) 14.1 Hz),
3.94-3.90(m, 6H), 3.79-3.74(m, 12H), 3.13(s, 2H), 1.83(t, 2H, J
) 7.6 Hz), 1.75(m, 2H), 1.42(m, 2H), 1.30-1.21(broad, 10H). 13
C
NMR (CDCl3, 150 MHz) δ 173.4, 171.4, 169.5, 157.7, 157.2, 154.2,
152.7, 151.9, 147.2, 143.1, 138.8, 135.8, 134. 5, 134.4, 133.9, 132.4,
132.2, 131.9, 131.2, 131.1, 129.8, 129.5, 127.5, 125.9, 125.7, 125.3,
123.6, 123.1, 119.5, 114.7, 114.2, 113.5, 113.3, 112.7, 85.1, 72. 1,
70.7, 70.2, 70.1, 67.9, 66.9, 64.4, 44.4, 40.4, 36.2, 31.7, 29.6, 29.5,
29. 3, 26.2, 25.4, 22.7. MS (MALDI-TOF) 1533.5. Mp 185 °C.
Elemental Analysis for C96H95N9O10: C, 75.12; H, 6.24; N, 8.21.
Found: C, 75.20; H, 6.31; N, 8.11.
Compound T-3 and R-3. Compounds T-3 and R-3 were
synthesized from compund 10, TCNQ, and macrocycle with a
similar method to the preparation of compounds T-1 and R-1.
1
Compounds T-3. H NMR (CDCl3, 400 MHz) δ 8.53(s, 1H),
7.68(d, 2H, J ) 8.76 Hz), 7.48(d, 1H, J ) 8.5 Hz), 7.41(d, 2H, J
) 8.48 Hz), 7.30-7.19(m, 15H), 6.92(m, 3H), 6.78(d, 2H, J ) 8.8
Hz), 6.42(s, 1H), 4.08(d, 2H, J ) 4.44 Hz), 3.98(t, 2H, J ) 7.5
Hz), 3.12(s, 6H), 2.27(t, 2H, J ) 7.4 Hz), 1.76(m, 2H), 1.63(m,
2H), 1.38(m, 2H), 1.26(broad, 10H). 13C NMR (CDCl3) δ 174.4,
171.5, 167.3, 163.9, 154.4, 153.0, 152.9, 146.8, 142.9, 135.7, 134.6,
132.4, 131.8, 131.4, 131.2, 127.6, 126.0, 125.2, 124.7, 123.9, 118.9,
115.7, 115.0, 114.9, 113.9, 113.0, 112.6, 83.4, 71.1, 68.8, 64.7,
44.5, 40.3, 36.4, 31.7, 29.5, 29.4, 29.3, 29.3, 29.3, 25.9, 25.7, 22.7.
Mp 130 °C. MS (TOF): 1022 (M + Na). Elemental Analysis for
C66H61N7O3: C, 79.25; H, 6.15; N, 9.80. Found: C, 79.29; H, 6.10;
N, 9.51.
Compound 8. To a stirred solution of compound 7 (900 mg,
2.3 mmol), 11-bromoundecanoic acid (610 mg, 2.3 mmol), and
DMAP (305 mg, 2.5 mmol) in anhydrous CH2Cl2 (200 mL) cooled
on an ice bath was added EDCI ·HCl (480 mg, 2.5 mmol). After
16 h the solution was washed with a saturated solution of cit-
ric acid (3 × 80 mL) and H2O (3 × 50 mL), the organic layer
was dried over anhydrous Na2SO4 and filtered, and the filtrate was
reduced in volume to obtain a white solid. Purification was
accomplished by column chromatography on silica with CH2Cl2/
CH3OH (100/1, v/v) to give compound 8 (1.14 g, 78%). Mp 107
1
Compounds R-3. H NMR (CDCl3, 400 MHz) δ 9.15(s, 1H),
8.47(s, 1H), 8.22(d, 2H, J ) 7.7 Hz), 7.68(d, 2H, J ) 8.92 Hz),
7.56(d, 1H, J ) 8.0 Hz), 7.48(d, 1H, J ) 8.6 Hz), 7.28-7.20(m,
15H), 7.13(m, 4H), 6.93(d, 2H, J ) 8.68 Hz), 6.87(d, 4H, J )
8.24 Hz), 6.81(d, 1H, J ) 8.0 Hz), 6.73(d, 2H, J ) 8.8 Hz), 6.53(d,
4H, J ) 8.28 Hz), 5.21(s, 1H), 4.57(d, 2H, J ) 14.6 Hz), 4.26(d,
2H, J ) 14.6 Hz), 3.99(t, 2H, J ) 7.2 Hz), 3.91(m, 4H), 3.78(m,
4H), 3.71(m, 4H), 3.67(m, 4H), 3.12(s, 6H), 3.08(d, 2HHHH, J )
4.9 Hz), 1.78(m, 4H), 1.62(m, 2H), 1.28(m, 2H), 1.26(broad, 10H).
13C NMR (CDCl3) δ 172.8, 171.4, 168.3, 166.1, 163.9, 157.7, 154.3,
152.8, 152.7, 146.9, 142.7, 136.1, 135.8, 134.5, 133.8, 132.4, 131.9,
131.5, 131.3, 131.1, 129.9, 129.4, 129.3, 127.9, 127.7, 126.7, 126.1,
125.3, 124.8, 124.1, 123.2, 118.3, 115.7, 114.9, 114.8, 114.3, 83.4,
71.5, 70.7, 70.2, 70.1, 68.8, 66.8, 64.8, 53.5, 44.5, 41.9, 40.3, 36.2,
31.7, 29.5, 29.4, 29.3, 29.0, 25.9, 25.4, 22.7. Mp 151 °C. MS (TOF):
1556 (M + Na), 1572 (M + K). Elemental Analysis for
C96H95N9O10: C, 75.12; H, 6.24; N, 8.21. Found C, 75.20; H, 6.19;
N, 8.11.
1
°C. H NMR (CDCl3): δ 9.38(s, 1H), 7.47(d, 2H, J ) 8.6 Hz),
7.23-7.13(broad, 17H), 6.99(s, 1H), 4.17(d, 2H, J ) 4.72 Hz),
3.36(t, 2H, J ) 6.85 Hz), 2.26(t, 2H, J ) 7.5 Hz), 1.82(m, 2H),
1.64(m, 2H), 1.37(m, 2H), 1.22(broad, 10H). 13C NMR (CDCl3) δ
174.6, 167.6, 146.9, 143.0, 136.0, 131. 9, 131.3, 127.7, 126.2, 119.0,
64.8, 52.1, 44.7, 36.5, 34.2, 33.0, 29.5, 29.5, 29.4, 28.9, 28.4, 25.9.
MS (TOF): 638 (M), 661 (M + Na). Elemental Analysis for
C38H43BrN2O2: C, 71.35; H, 6.78; N, 4.38. Found C, 71.41; H, 6.81;
N, 4.31.
Compound 9. K2CO3(450 mg, 3.2mmol) was added to a solution
of 4-iodophenol (356 mg, 1.6mmol) and compound 8 (1 g, 1.5
mmol) in 30 mL of DMF. Then the mixture was stirred at 60 °C
for 8 h, and the solvent was evaporated off. The residue was
dissolved in CHCl3, washed with water three times, and dried over
Na2SO4. The crude product was purified by SiO2 chromatography
with CH2Cl2/MeOH (100/1, v/v) to obtain pure compound 9 (1 g,
86%) as a white solid. Mp 90 °C. 1H NMR (CDCl3) δ 9.26(s, 1H),
7.51(d, 2H, J ) 8.51 Hz), 7.45(d, 2H, J ) 8.41 Hz), 7.23-7.13(m,
17H), 6.87(s, 1H), 6.64(d, 2H, J ) 8.57 Hz), 4.14(d, 2H, J ) 4.59
Hz), 3.86(t, 2H, J ) 6.6 Hz), 2.25(t, 2H, J ) 7.81 Hz), 1.62(m,
4H), 1.39(m, 2H), 1.25(broad, 10H). 13C NMR (CDCl3) δ 174.5,
167.4, 159.2, 146.8, 142.9, 138.3, 135.8, 131.8, 131.2, 128.1, 126.0,
118.9, 117.1, 82.5, 68.2, 64.7, 44. 6, 36.4, 34.5, 29.8, 29.5, 29.4,
28.8, 28.7, 25.7. MS (TOF): 778 (M), 801 (M + Na). Elemental
Analysis for C44H47IN2O3: C, 67.86; H, 6.08; N, 3.60. Found C,
67.88; H, 6.11; N, 3.55.
Acknowledgment. This work was supported by the National
Nature Science Foundation of China (20531060) and the
National Basic Research 973 Program of China (2006CB932102,
2006CB806200 and 2007CB936401).
Supporting Information Available: Full experimental details
pertaining to the preparation and characterization of all the
compounds including the NMR and MS spectra. This material
is available free of charge via the Internet at http://pubs.acs.org.
Compound 10. To a stirred solution of 4-ethynyl-N,N-dimeth-
ylbenzenamine (224 mg, 1.55mol) and compound 9 (0.8 g,
1.03mmol) were added PdCl2(PPh3)2 (20 mg) and CuI (20 mg)
JO8014566
J. Org. Chem. Vol. 73, No. 19, 2008 7709