Self-assembly of a novel series of hetero-duplexes driven by donor-acceptor interaction

Article abstract of DOI:10.1016/j.tet.2005.05.039

The self-assembly of a novel series of donor-acceptor interaction-driven artificial hetero-duplexes in organic media has been described. Four linear compounds 1a-1d, bearing two to five electron rich 1,5-dioxynaphthalene units connected by the tetra(ethylene glycol) linker, respectively, have been prepared and used as donors, while eight compounds 2a-2d, 13-16, bearing one to four electron deficient pyromellitic diimide, 1,4,5,8-naphthalene- tetracarboxydiimide, or perylene-3,4,9,10-tetracarboxydiimide units, respectively, have been used as acceptors. The structure of the hetero-duplexes has been characterized by the ¹H NMR, UV-vis spectroscopy and vapor pressure osmometry. It is revealed that the binding stability of the duplexes vary greatly, depending on the length and structure of the monomers and also the solvent, and hetero-duplex 1d·2d displays a maximum association constant of ca. 1.0×10⁴ M^-1 in chloroform.

Full text of DOI:10.1016/j.tet.2005.05.039

Tetrahedron 61 (2005) 7117–7124
Self-assembly of a novel series of hetero-duplexes driven by
donor–acceptor interaction
Qi-Zhong Zhou,a Mu-Xin Jia,b Xue-Bin Shao,a Li-Zhu Wu,c Xi-Kui Jiang,a Zhan-Ting Lia,
*
and Guang-Ju Chenb,
*
aState Key Laboratory of Bio-Organic & Natural Products Chemistry, Shanghai Institute of Organic Chemistry,
Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
bDepartment of Chemistry, Beijing Normal University, Beijing 100875, China
cTechnical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101, China
Received 28 March 2005; revised 13 May 2005; accepted 16 May 2005
Available online 13 June 2005
Abstract—The self-assembly of a novel series of donor–acceptor interaction-driven artificial hetero-duplexes in organic media has been
described. Four linear compounds 1a–1d, bearing two to five electron rich 1,5-dioxynaphthalene units connected by the tetra(ethylene
glycol) linker, respectively, have been prepared and used as donors, while eight compounds 2a–2d, 13–16, bearing one to four electron
deficient pyromellitic diimide, 1,4,5,8-naphthalene-tetracarboxydiimide, or perylene-3,4,9,10-tetracarboxydiimide units, respectively, have
been used as acceptors. The structure of the hetero-duplexes has been characterized by the 1H NMR, UV–vis spectroscopy and vapor pressure
osmometry. It is revealed that the binding stability of the duplexes vary greatly, depending on the length and structure of the monomers and
also the solvent, and hetero-duplex 1d$2d displays a maximum association constant of ca. 1.0!104 MK1 in chloroform.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
class of aromatic stacking-based hetero-duplexes from
1,5-dialkoxynaphthalene (DAN) and 1,4,5,8-naphthalene-
tetracarboxydiimide (NDI)-incorporated peptide in aqueous
solutions.12 Although, donor–acceptor interaction between
the electron-rich DAN unit and the electron-deficient NDI
unit played a significant role in controlling the aromatic
stacking pattern, hydrophobic interaction was revealed to be
the main driving force for the formation of the peptide-
derived duplexes. We previously reported that new zipper-
styled hetero-duplexes could be constructed in less polar
chloroform from DAN and pyromellitic diimide (PDI)-
incorporated monomers by utilizing the cooperative donor–
acceptor interaction between DAN and electron-deficient
PDI units as the driving force.13 We herein, describe the
self-assembly of a novel series of hetero-duplexes which are
driven by the multi-site donor–acceptor interaction between
linear DAN and PDI-incorporated oligomers.14
Self-assembly of linear molecules into functional com-
plexes is a common phenomenon in biological systems.1,2 In
recent years, there has been intensive interest in construct-
ing duplexes or dimers of defined structures through the
self-assembly of synthetic molecules. Most artificial
duplexes have been constructed by making use of hydrogen
bonding3,4 and metal ion–ligand coordination5,6 as the
dominant driving forces. Examples of duplexes based on
electrostatic interaction between ionic acid and base
monomers have also been reported.7 Although, it has been
well-established that cyclophanes incorporating electron
rich or deficient aromatic units could, through donor–
acceptor interaction, complex linear electron-deficient or
rich molecules to give rise to another kind of threading
dimeric supramolecular structures8–10 and supramolecular
materials,11 much less attention has been paid to this non-
covalent interaction for constructing duplex architectures
probably due to its low directionality.
2. Results and discussion
In 2002, Iverson et al. described the self-assembly of a new
Two series of compounds 1a–1d and 2a–2d were designed
as monomeric donors and acceptors. Because compounds 1
and 2 possess two different skeletons, it was envisioned that
complexation between them would lead to the formation of
new series of hetero-duplex architectures. The syntheses of
Keywords: Self-assembly; Donor–acceptor interaction; Aromatic stacking;
Dimer; Oligo(glycol).
*
Corresponding authors. Tel.: C86 21 5492 5122; fax: C86 21 6416
6128; e-mail: ztli@mailc.sioc.ac.cn
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.05.039

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Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
compounds 1a–1d are outlined in Scheme 1.15 Thus,
compound 3 was first, reacted with ditosylate 4 in
acetonitrile in the presence of potassium carbonate to give
1a and 5 in 13 and 55% yield, respectively. Compound 5
was then treated with diol 6 in acetonitrile with potassium
carbonate as a base to give 1b in 52% yield. In a similar
way, compound 1c was prepared in 80% yield from the
reaction of 5 and 7.16 For the preparation of 1d, compound 8
was first, treated with 5 to afford 9 in 90% yield, the latter
was then hydrogenated in methanol with Pd–C as catalyst to
yield compound 10 in 80% yield. Finally, the reaction of 10
with an excessive amount of ditosylate 11 in acetonitrile
in the presence of potassium carbonate afforded 1d in
80% yield. Compounds 2a17 and 2b–2d13 were prepared
according to the reported procedures.
Scheme 1.
monomers. It can also be found (notes b–d) that increasing
the polarity of the solvent significantly reduces the binding
stability of the complexes. Similar results have been
observed for the complexes with two comb-shaped mono-
mers.13 These results suggest that, instead of the hydro-
phobic interaction, the donor–acceptor interaction is the
dominant driving force for the present complexes.21
1H NMR dilution experiments in CDCl3 from 50 to 1.0 mM
revealed no significant chemical shifts (%0.04 ppm) for
compounds 1a–1d (with one of the sharp Ar-H’s as probe).
This small change of chemical shifts indicates that no
important intermolecular aggregation took place in chloro-
form.18 Quantitative binding studies were then performed in
CDCl3 solutions by titrating compounds 2a–2d with 1a–1d,
respectively, with the Ar-H signal of one PDI unit as
probe.13 As examples, the chemical shift summaries for the
titration experiments of 1c with 2c and 15 (vide infra) are
displayed in Figure 1. Association constants Kassoc’s for
complexes 1$2 were obtained by fitting the changing data of
the chemical shifts of the probe to a 1:1 binding isotherm
and presented in Table 1.19 Job’s plots of the probe signals
provide evidence that the complexes follow a 1:1 binding
mode,20 which displayed maximum chemical shift change
at the equimolar ratio of 1 and 2 when the total
concentration of both compounds was kept unchanged.
The data in Table 1 show that the association improves
remarkably with the increase in the donor or acceptor units
of both 1 and 2 as a result of the strengthened intermolecular
donor–acceptor interaction of the DAN and PDI units of the
Figure 1. 1H NMR titration results of the H-1 of 2c (0.5 mM) and 15
(0.5 mM, vide infra) with 1c in CDCl3 at 25(G1) 8C.

Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
7119
Table 1. Association constants Kassoc’s of novel series of hetero duplexes
1$2 in CDCl3 at 25 8Ca
Table 2. Association constants Kassoc’s of donor–acceptor interaction-
driven complexes or duplexes in CDCl3 at 25 8Ca
Complex
Kassoc (MK1
)
Complex
Kassoc (MK1
)
Complex
Kassoc (MK1
)
Complex
Kassoc (MK1
)
1a$2a
1a$2c
1b$2c
1c$2c
1d$2c
1b$2bb
1b$2bd
12
1a$2b
1b$2b
1b$2d
1c$2d
1d$2d
1b$2bc
1c$2de
35
180
1150
4700
10200
115
1a$12
1a$14
1a$15
1c$15
1a$12b
42
48
410
2500
32
1a$13
1b$14
1b$15
1d$15
!5
220
950
2650
124
430
1200
1250
140
125
a Performed at 25 8C with an error %20%.
4500
b With 10% CD3SOCD3 (v/v).
a With an error %20%.
b With 10% CD3OD (v/v).
c With 20% CD3OD (v/v).
d With 10% CD3SOCD3 (v/v).
Previously, Iverson et al. had reported that two linear ionic
monomers incorporating DAN and NDI units could form
stable duplexes in aqueous solution.12 The successful self-
assembly of the new class of duplexes 1$2 prompted us to
explore the formation of duplexes from two neutral linear
monomers. Therefore, compounds 14 and 15 were designed
and synthesized. The synthetic route for 14 is outlined in
Scheme 2. In brief, acid 19 was prepared in 32% yield from
the reaction of 16, 17 and 18 in refluxing DMF and then
converted into acyl chloride 20 with thionyl chloride.
Subsequent reaction of 20 with diol 21 in chloroform
afforded 14 and 22 in 20 and 60% yields, respectively.
e Obtained by UV dilution method with the absorption at 451 nm as probe
peak.
As expected, the complexes formed from longer monomers
displayed stronger electron-transfer absorption band.
Quantitative UV dilution studies were also carried out
with 1:1 mixture of 1c and 2d in chloroform with the
maximum charge transfer absorbance as probe, which gave
a Kassoc of approximately 4.5!103 MK1 for 1c$2d.13 The
value is comparable to that obtained by the 1H NMR
titration method. A vapor pressure osmometric (VPO)
experiment was performed for the most stable duplex 1d$2d
in chloroform–toluene (4:1, v:v) at 30 8C, which afforded
an average molecular mass of 2900(G400) u. The value is
agreeable to that calculated mass (3306 u) for the 1:1
binding stoichiometry of the complex.
In order to investigate the diversity of this new series of
binding mode and also to explore the possibility of
developing more stable duplex structures, molecules with
the skeletons of 2b and 2c but with two or three electron
deficient NDI22 or perylene-3,4,9,10-tetracarboxydiimide
unit (PTI)23 were also designed. However, no pure samples
could be synthesized following the procedures to prepare 2b
and 2c possibly as a result of the poor solubility of the
required compounds. Compounds 12 and 13, which are
soluble in chloroform, were then prepared from the reaction
of n-dodecyl amine with naphthalene-1,4,5,8-tetra-
carboxylic acid dianhydride or perylene-3,4,9,10-tetra-
carboxylic acid dianhydride in DMF. Binding study for 12
Scheme 2.
For preparing 15 (Scheme 3),24 compound 24 was first,
produced in 20% yield from the reaction of 16, 18 and 23 in
hot DMF and then treated with thionyl chloride to afford 25.
The later was reacted with 22 in chloroform to give 26 in
60% yield. Chloride 28 was then produced from 26 after
Pd–C-catalyzed hydrogenation, followed by the treatment
of the intermediate acid 27 with thionyl chloride. Com-
pound 28 was then reacted with 22 to afford 15 in 20% yield.
Both 14 and 15 are soluble in organic solvents such as
chloroform and dichloromethane.
1
and 13 towards 1a was then carried out in CDCl3 by H
NMR titration of 12 and 13 with 1a and the derived
association constants Kassoc are shown in Table 2. It can be
found that Kassoc of complex 1a$12 is larger than that of
1a$2a, which is consistent with the greater electron
deficiency of NDI relative to PDI,22a and addition of
DMSO to the solvent reduced the stability of the complex
(note b, Table 2). The Kassoc of complex 1a$13 is very low,
indicating that PTI unit is only a weak acceptor in non-polar
solvent like chloroform.
Quantitative binding study of 14 and 15 towards 1a–1d in

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Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
Figure 2. The proposed twine-featured binding motif and the minimized
structure for hetero-duplex 1d$2d.
CDCl3 was performed by the 1H NMR titration method with
the PDI proton signal (H-1 for 15) as the probe. The
corresponding association constants Kassoc derived by non-
linear regression for a 1:1 binding mode are provided in
Table 2. It can be found that both 14 and 15 exhibit notably
increased binding ability towards the corresponding donor
molecules than 2b and 2c, respectively.
All the complexes displayed pale to dark orange color in
chloroform, depending on their stability and concentration.
Consistently, UV–vis investigations revealed broad electron
transfer absorbance between 400–600 nm for the new
complexes. The corresponding molar extinction coefficient
3’s obtained in chloroform at room temperature at a fixed
concentration are shown in Table 3. Also, it can be found
that the 3’s were increased substantially with the increase of
the donor or acceptor units. This observation supports that
important multiple donor–acceptor interaction exists within
the complexes.
Based on the above binding studies, we propose a twine-
styled binding mode for the new series of hetero duplexes,
as shown in Figure 2 with complex 1d$2d as an example.
Although, such a binding mode requires a twining
conformation, which would lead to negative entropic effect
for the binding, for the longer monomers 1, it could
facilitate multi-site donor–acceptor interactions and
Scheme 3.
Table 3. Molar extinction coefficients 3’s of the 1:1 complexes in chloroform at 25 8C ([monomer]Z0.02 M at 25 8C)
Complex
3 (MK1 cmK1
)
lmax (nm)
Complex
3 (MK1 cmK1
)
lmax (nm)
1a$2aa
1a$2c
1a$13
1a$15
1b$2c
1c$2c
1c$15
1d$2db
10
87
15
165
165
220
190
130
445
450
455
448
450
451
450
450
1a$2b
1a$12
1a$14
1b$2b
1b$2d
1c$2d
1d$2d
24
25
110
94
210
280
320
447
448
449
448
450
451
450
a Obtained at [monomer]Z0.05 M. No detectable absorbance was exhibited in the visible range at [1a] (Z[2a])Z0.02 M.
b Obtained at [monomer]Z8.0!10K3 M.

Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
7121
consequently increase the stability of hetero duplexes
generated from the longer monomers. Comparison of the
binding constants of 1a$2a, 1b$2b, 1c$2c and 1d$2d
revealed no favorable cooperativity of binding, indicating
that other multiple ‘two-points’ interactions may also exist.
were used without further purification. All solvents were
dried before use following standard procedures. The
methods for the determination of binding constants have
been reported in a previous paper.13
4.1.1. Compounds 1a and 5. To a solution of compound 326
(5.22 g, 30.0 mmol) in acetonitrile (300 mL) was added
potassium carbonate (17.0 g, 0.12 mol). The suspension was
stirred at room temperature for 1 h and a solution of
ditosylate 427 (45.2 g, 90.0 mmol) in acetonitrile (100 mL)
was added. The suspension was heated under reflux for 12 h
and then filtered. The filtrate was concentrated in vacuo, and
the resulting residue triturated in chloroform (400 mL). The
organic phase was washed with aqueous HCl solution (1 N,
100 mL), water (100 mL), brine (100 mL), and dried over
sodium sulfate. After removal of the solvent under reduced
pressure, the crude products were subjected to column
chromatography (chloroform/AcOEt 20:1) to give com-
pounds 1a (1.97 g, 13%, colorless solid) and 5 (8.32 g, 55%,
To obtain more insight for the structural characteristics of
this kind of complexes, molecular mechanic calculations
were also carried out for 1d–2d. The dodecyl groups have
been substituted with methyl groups for the sake of
simplicity. The conformation was optimized and obtained
by using the conjugate gradient method with the AMBER
force field,25 and is provided in Figure 2. It can be found that
1d and 2d bind each other by means of multiple p–p
interactions. The distances between the adjacent donor and
˚
acceptor units are about 3.4–3.6 A. The binding mode of
hetero-duplex 1c$15 should be similar to the twined dimeric
structure assembled from ionic linear monomers by Iverson
et al.12 and is shown in Figure 3.
1
oily solid). Compound 1a. Mp 46 8C. H NMR (CDCl3): d
7.84 (t, JZ8.4 Hz, 4H), 7.31–7.37 (m, 4H), 6.81 (d, JZ
7.5 Hz, 4H), 4.26 (t, JZ4.8 Hz, 4H), 3.97 (t, JZ4.5 Hz,
10H), 3.78–3.81 (m, 4H), 3.70–3.73 (m, 4H). MS (EI): m/z:
506 [M]C. Anal. Calcd for C30H34O7: C, 71.13; H, 6.76.
Found: C, 70.76; H, 6.78. Compound 5: 1H NMR (CDCl3): d
7.76–7.86 (m, 4H), 7.26–7.39 (m, 4H), 6.84 (d, JZ7.5 Hz,
2H), 4.29 (t, JZ4.8 Hz, 2H), 4.12 (t, JZ4.5 Hz, 2H), 3.97–
4.00 (m, 5H), 3.77–3.80 (m, 2H), 3.63–3.67 (m, 4H), 3.56–
3.60 (m, 4H), 2.41 (s, 3H). MS (EI): m/z: 504 [M]C. Anal.
Calcd for C26H32SO8: C, 61.89; H, 6.39. Found: C, 61.83;
H, 6.58.
Figure 3. A possible binding mode of hetero-duplex 1c$15.
3. Conclusion
4.1.2. Compound 1b. A suspension of 5 (2.52 g,
5.00 mmol), 6 (0.40 g, 2.50 mmol), and potassium carbo-
nate (1.38 g, 10.0 mmol) in acetonitrile (50 mL) was heated
under reflux for 24 h. After work-up as described for
preparing 1a and 5, the crude product was purified by
column chromatography (chloroform/AcOEt 10:1) to afford
compound 1b as a white solid (1.07 g, 52%). Mp 56–58 8C.
1H NMR (CDCl3): d 7.81–7.86 (m, 6H), 7.28–7.37 (m, 6H),
6.76–6.82 (m, 6H), 4.22–4.27 (m, 8H), 3.94–3.98 (m, 8H),
3.77–3.80 (m, 8H), 3.70–3.73(m, 8H). MS (EI): m/z: 825
[MCH]C. Anal. Calcd for C48H56O12$0.5H2O: C, 69.13; H,
6.89. Found: C, 69.00; H, 6.89.
In conclusion, the multiple donor–acceptor interaction has
been successfully utilized for the self-assembly of a new
series of twine-styled hetero-duplexes from readily avail-
able linear and/or comb-shaped molecules. By modifying
the molecular skeletons of the monomers or introducing
new and more electron deficient units into the acceptor
molecules, it is expected that more stable binding motifs
may be generated. Further, applications of the new binding
motif in the self-assembly of new generation of supra-
molecular species are also under investigation.
4.1.3. Compound 1c. A suspension of compound 5 (0.80 g,
1.59 mmol), 722a (0.38 g, 0.79 mmol), and potassium
carbonate (2.00 g, 14.5 mmol) in acetonitrile (50 mL) was
heated under reflux for 24 h. Upon cooling to room
temperature, the solid was filtered and the filtrate was
concentrated in vacuo. Chloroform (100 mL) was added to
the resulting residue and the solution was washed with
dilute hydrochloric acid, water, brine, and dried over
sodium sulfate. After removal of the solvent under reduced
pressure, the crude product was purified by column
chromatography (chloroform/acetone 25:1) to produce 1c
4. Experimental
4.1. General methods
Melting points are uncorrected. All reactions were
performed under an atmosphere of dry nitrogen. The H
1
NMR spectra were recorded on 500, 400, or 300 MHz
spectrometers in the indicated solvents. Chemical shifts are
expressed in parts per million (d) using residual solvent
protons as internal standards. Chloroform (d 7.26 ppm) was
used as an internal standard for chloroform-d. Vapour
pressure osmometric experiment was performed on a
Knauer K-7000 instrument with sucrose octaacetate for
calibration. Elemental analysis was carried out at the SIOC
analytical center. Unless otherwise indicated, all starting
materials were obtained from commercial suppliers and
1
as a white solid (0.73 g, 80%). Mp 78–80 8C. H NMR
(CDCl3): d 7.81–7.86 (m, 8H), 7.24–7.36 (m, 8H), 6.75–
6.81 (m, 8H), 4.21–4.25 (m, 12H), 3.90–3.95 (m, 18H),
3.76–3.79 (m, 12H), 3.69–3.72 (m, 12H). MS (ESI): m/z:
1160 [MC NH3]C. Anal. Calcd for C66H78O17: C, 69.33; H,
6.88. Found: C, 69.50; H, 7.02.

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Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
4.1.4. Compound 9. The title compound was prepared from
the reaction of 5 and 828 by using the procedure analogous to
5. The crude product was purified by column chroma-
tography (n-hexane/AcOEt 20:1) to afford 9 as a colorless
(1.26 g, 2.84 mmol), oxalyl chloride (5 mL), and DMF
(0.05 mL) in benzene (50 mL) was heated under reflux for
6 h and then concentrated in vacuo to give 20 as a white
solid. This crude product was used for the next step without
further purification. 1H NMR (CDCl3): d 8.35 (s, 2H), 4.88
(s, 2H), 3.75 (t, JZ7.2 Hz, 2H), 1.68–1.70 (m, 2H), 1.25–
1.33 (m, 18H), 0.88 (t, JZ6.6 Hz, 3H). MS (EI): m/z: 460
[M]C.
1
gel (90%). H NMR (CDCl3): d 7.81–7.93 (m, 4H), 7.31–
7.54 (m, 9H), 6.80–6.90 (m, 4H), 5.22 (s, 2H), 4.24–4.28
(m, 4H), 3.97 (t, JZ5.4 Hz, 7H), 3.78–3.81 (m, 4H), 3.71–
3.74 (m, 4H). Ms (EI): m/z: 582 [M]C. HRMS (EI): Calcd
for C36H38O7: 582.2618. Found: 582.2612.
4.1.11. Compounds 14 and 22. To a solution of compound
21 (1.28 g, 11. 3 mmol), triethylamine (1.50 mL), and
DMAP (0.1 g) in chloroform (60 mL) was added with
stirring a solution of the above 20 in chloroform (10 mL) at
room temperature. Stirring was continued for 12 h and
chloroform (40 mL) was added. The solution was washed
with dilute hydrochloric acid (1 N, 50 mL!2), water
(50 mL!2), brine (50 mL), and dried over sodium sulfate.
After removal of the solvent under reduced pressure, the
resulting residue was chromatographed (chloroform/
acetone 20:1) to give 14 (0.54 g, 20%) and 22 (0.90 g,
60%) both as white solid. Compound 14. Mp 190–191 8C.
1H NMR (CDCl3): d 8.32 (s, 4H), 4.57 (s, 4H), 4.34–4.37
(m, 4H), 3.71–3.76 (m, 8H), 1.68–1.72 (m, 4H), 1.20–1.33
(m, 36H), 0.88 (t, JZ6.9 Hz, 6H). MS (ESI): m/z: 955 [MC
H]C. Anal. Calcd for C52H66O13N4: C, 65.39; H, 6.96; N,
5.87. Found: C, 65.42; H, 6.95; N, 5.82. 22. Mp 112–114 8C.
1H NMR (CDCl3): d 8.32 (s, 2H), 4.54 (s, 2H), 4.36–4.39
(m, 2H), 3.71–3.77 (m, 6H), 3.58–3.61 (m, 2H), 2.13 (t, JZ
3.6 Hz, 1H), 1.65–1.72 (m, 2H), 1.20–1.33 (m, 18H), 0.88
(t, JZ6.6 Hz, 3H). MS (MALDI): m/z: 531 [MCH]C. Anal.
Calcd for C28H38O8N2: C, 63.38; H, 7.22; N, 5.28. Found:
C, 63.33; H, 7.19; N, 5.16.
4.1.5. Compound 10. The title compound was prepared by
hydrogenation of 9 with hydrogen gas (1 atm) in the
presence of Pd–C (10%) in methanol. The crude product
was purified by column chromatography (chloroform/
1
methanol 20:1) to give 10 as a white gel (80%). H NMR
(CDCl3): d 7.71–7.86 (m, 4H), 7.20–7.37 (m, 4H), 6.76–
6.82 (m, 4H), 4.22–4.26 (m, 4H), 3.95–3.97 (m, 7H), 3.78–
3.81 (m, 4H), 3.71–3.74 (m, 4H). MS (EI): m/z: 492 [M]C.
HRMS (EI): m/z: Calcd for C29H32O7: 492.2148. Found:
492.2143.
4.1.6. Compound 1d. The title compound was prepared
from the reaction of 10 and 1110 with a method analogous to
1b. The crude product was purified by column chroma-
tography (chloroform/methanol 20:1) to give the desired
1
compound as a white solid (80%). Mp 50–52 8C. H NMR
(CDCl3): d 7.81–7.86 (m, 10H), 7.26–7.37 (m, 10H), 6.79 (t,
JZ7.8 Hz, 10H), 4.22–4.26 (m, 24H), 3.94–3.96 (m, 32H),
3.77–3.80 (m, 22H), 3.69–3.72 (m, 22H). MS (MALDI):
m/z: 1483 [MCNa]C. Anal. Calcd for C84H100O22: C,
69.02; H, 6.90. Found: C, 69.12; H, 6.61.
4.1.7. Compound 12. The title compound was prepared
1
according to the reported method.29 Mp 160–162 8C. H
4.1.12. Compound 24. The title compound was prepared
from the reaction of 16, 18, and 23 by a method analogous to
19. The crude product was purified by column chroma-
tography (chloroform/methanol 10:1) to give the desired
NMR (CDCl3): d 8.76 (s, 4H), 4.19 (t, JZ7.2 Hz, 4H), 1.72–
1.77 (m, 4H), 1.25–1.43 (m, 36H), 0.86 (t, JZ6.6 Hz, 6H).
MS (MALDI): m/z: 603 [MCH]C. Anal. Calcd for
C38H54N2O4: C, 75.71; H, 9.03; N, 4.65. Found: C, 75.87;
H, 9.05; N, 4.34.
1
product as a white solid (20%). MpO240 8C. H NMR
(CDCl3–DMSO-d6 1:1): d 8.33 (s, 2H), 7.36 (s, 5H), 5.21 (s,
2H), 4.58 (s, 2H), 4.41 (s, 2H). MS (MALDI): m/z: 422
[M]C. Anal. Calcd for C21H14N2O8: C, 59.72; H, 3.34; N,
6.63. Found: C, 59.41; H, 3.21; N, 6.50.
4.1.8. Compound 13. The title compound was prepared
according to the reported method.30 Mp O240 8C. 1H NMR
(CDCl3): d 8.696 (s, 2H), 8.67 (s, 2H), 8.62 (s, 2H), 8.59 (s,
2H), 4.21 (t, JZ7.5 Hz, 4H), 1.74–1.79 (m, 4H), 1.26–1.47
(m, 36H), 0.87 (t, JZ6.6 Hz, 6H). MS (MALDI): m/z: 727
[MCH]C. Anal. Calcd for C48H58N2O4: C, 79.30; H, 8.04;
N, 3.85. Found: C, 79.05; H, 7.98; N, 3.43.
4.1.13. Compound 26. Compound 24 (1.27 g, 3.00 mmol)
was first, converted into 25 by treating with oxalyl chloride
according to the method described for preparing 20. The
solution of this acyl chloride in chloroform (10 mL) was
added to the solution of 22 (1.59 g, 3.00 mmol), triethyl-
amine (1.0 mL), DMAP (0.05 g) in chloroform (50 mL) at
room temperature. After stirring for 24 h, the solution was
washed with diluted hydrochloric acid, water, brine, and
dried over sodium sulfate. Upon removal of the solvent, the
crude product was purified by column chromatography
(chloroform/methanol 30:1) to give 26 as a white solid
(1.68 g, 60%). Mp 178–180 8C. 1H NMR (CDCl3): d 8.37 (s,
2H), 8.31 (s, 2H), 7.36 (s, 5H), 5.21 (s, 2H), 4.58 (s, 2H),
4.57 (s, 2H), 4.55 (s, 2H), 4.34–4.37 (m, 4H), 3.71–3.76 (m,
6H), 1.68–1.72 (m, 2H), 1.25–1.33 (m, 18H), 0.86 (t, JZ
6.0 Hz, 3H). MS (MALDI): m/z: 952 [MCNH4]C. HRMS
(MALDI): Calcd for C49H50N4O15: 957.3149 [MC Na]C.
Found: 957.3165.
4.1.9. Compound 19. A solution of compounds 16 (21.8 g,
0.10 mol), n-C12H25NH2 17 (18.5 g, 0.10 mol), and glycine
18 (7.50 g, 0.10 mol) in DMF (200 mL) was heated under
reflux for 6 h and then poured onto ice (1000 mL). The
solids were filtered and washed thoroughly with water, dried
in vacuo, and subjected to column chromatography (chloro-
form/methanol 50:1 to 10:1). Compound 19 was obtained as
a white solid (12.4 g, 28%). Mp 246–247 8C. 1H NMR
(CDCl3): d 8.32 (s, 2H), 4.55 (s, 2H), 3.74 (t, JZ7.5 Hz,
2H), 1.63–1.79 (m, 2H), 1.25–1.33 (m, 18H), 0.88 (t, JZ
3.0 Hz, 3H). MS (EI): m/z: 442 [M]C. Anal. Calcd for
C24H30N2O6: C, 65.14; H, 6.83; N, 6.33. Found: C, 64.99;
H, 6.80; N, 6.27.
4.1.10. Compound 20. A suspension of compound 19
4.1.14. Compound 27. A solution of 26 (1.40 g, 1.50 mol)

Q.-Z. Zhou et al. / Tetrahedron 61 (2005) 7117–7124
7123
2. Venkatraman, J.; Shankaramma, S. C.; Balaram, P. Chem. Rev.
2001, 101, 3131–3152.
and Pd–C (10%, 0.30 g) in methanol (30 mL) and chloro-
form (30 mL) was stirred at 1 atm of hydrogen gas for 5 h.
After work-up, the crude product was subjected to flash
chromatography (chloroform/methanol 15:1) to give 27 as a
white solid (1.20 g, 95%). Mp 184–186 8C. 1H NMR
(CDCl3): d 8.36 (s, 2H), 8.32 (s, 2H), 7.36 (s, 5H), 4.36–
4.57 (m, 12H), 3.74–3.76 (s, 6H), 1.70–1.71 (m, 2H), 1.25–
1.32 (m, 18H), 0.87 (t, 3H). MS (MALDI): 867 [MCNa]C.
HRMS (MALDI): Calcd for C42H44N4O15: 844.2803.
Found: 844.2798.
3. (a) Zimmerman, S. C.; Corbin, P. S. Struct. Bonding 2000, 96,
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4.1.15. Compound 15. A suspension of compound 27
(0.84 g, 1.00 mmol) in thionyl chloride (10 mL) and
benzene (50 mL) was heated under reflux for 6 h and then
concentrated in vacuo to give acyl chloride 28. Without
further purification, this crude product was dissolved in
chloroform (10 mL) and the solution was added dropwise to
a stirred solution of 22 (0.53 g, 1.00 mmol), triethylamine
(0.5 mL), DMAP (0.05 g) in chloroform (50 mL). Stirring
was continued for 48 h at room temperature and chloroform
(50 mL) was added. The solution was washed with dilute
hydrochloric acid (1 N, 50 mL!2), water (50 mL), brine
(50 mL), and dried over sodium sulfate. Upon removal of
the solvent under reduced pressure, the resulting residue was
subjected to column chromatography (chloroform/AcOEt
3:1) to afford compound 15 as a white solid (0.27 g, 20%).
Mp 204 8C. 1H NMR (CDCl3): d 8.38 (s, 2H), 8.32 (s, 4H),
4.58 (d, JZ2.7 Hz, 8H), 4.36 (t, JZ4.5 Hz, 8H), 3.71–3.76
(m, 12H), 1.68–1.69 (m, 4H), 1.25–1.33 (m, 36H), 0.88 (t,
JZ6.3 Hz, 6H). MS (MALDI): m/z: 1379 [MCNa]C.
HRMS (MALDI): Calcd for C70H80N6O22: 1356.5326.
Found: 1356.5320. Anal. Calcd for C70H80N6O22: C,
61.94; H, 5.94; N, 6.19. Found: C, 61.57; H, 5.81; N, 6.02.
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4.2. Computational method
The binding patterns were constructed with the Builder
program within the package HyperChem.31 Then they were
optimized by the conjugate gradient with the AMBER force
field and the RMS derivative criteria of 0.00001 kcal/mol.
To explore the lower energy structure, molecular dynamics
calculations were performed without constraints. After
100 ps of molecular dynamics simulation, an additional
round of energy minimization was again completed.
Molecular mechanics and molecular dynamics are used to
obtain the geometry of the dimers.32
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Acknowledgements
We thank the Ministry of Science and Technology
(G2000078101), the National Natural Science Foundation
and the Chinese Academy of Sciences of China for financial
support.
13. Zhou, Q.-Z.; Jiang, X.-K.; Shao, X.-B.; Chen, G.-J.; Jia, M.-X.;
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