Donor-acceptor-donor triads incorporating tetrathiafulvalene and perylene diimide units: Synthesis, electrochemical and spectroscopic studies

Article abstract of DOI:10.1016/S0040-4020(03)00700-2

Three donor-acceptor-donor triads 1-3 consisting of tetrathiafulvalene units attached to perylene diimides by flexible and rigid spacers were synthesized and characterized. UV/vis spectroscopic and cyclic voltammetric results indicate that they all show negligible intramolecular charge transfer interaction in their ground states. As compared to the reference compound 21, triads 1-3 display reduced fluorescence and their fluorescence lifetimes are shortened, which is probably owing to the photoinduced electron transfer interactions between the PI units and TTF units. The different photophysical behaviors between 1 and 2 (and 3) might be due to their difference in the spatial separation of TTF and PI units. It is preliminarily found that the steric hindrance of the groups attached to TTF units can affect their photostability.

Full text of DOI:10.1016/S0040-4020(03)00700-2

Tetrahedron 59 (2003) 4843–4850
Donor–acceptor–donor triads incorporating tetrathiafulvalene
and perylene diimide units: synthesis, electrochemical and
spectroscopic studies
a
a
a
a
Xuefeng Guo,a,b Deqing Zhang,a Huijuan Zhang, Qinghua Fan, Wei Xu, Xicheng Ai,
,
*
Louzheng Fanc and Daoben Zhua
,
*
aLaboratory of Organic Solids, Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080,
People’s Republic of China
bGraduate School, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China
cDepartment of Chemistry, Beijing Normal University, Beijing 100875, People’s Republic of China
Received 3 January 2003; revised 2 April 2003; accepted 28 April 2003
Abstract—Three donor–acceptor–donor triads 1–3 consisting of tetrathiafulvalene units attached to perylene diimides by flexible and rigid
spacers were synthesized and characterized. UV/vis spectroscopic and cyclic voltammetric results indicate that they all show negligible
intramolecular charge transfer interaction in their ground states. As compared to the reference compound 21, triads 1–3 display reduced
fluorescence and their fluorescence lifetimes are shortened, which is probably owing to the photoinduced electron transfer interactions
between the PI units and TTF units. The different photophysical behaviors between 1 and 2 (and 3) might be due to their difference in the
spatial separation of TTF and PI units. It is preliminarily found that the steric hindrance of the groups attached to TTF units can affect their
photostability. q 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction
porphyrin donors and one PI unit.16 Thus, it would be
interesting to study electron–donor–acceptor supra-
molecules containing both TTF and PI units. For this
purpose, electron donor–acceptor–donor triads 1–3
(Scheme 1) containing two TTF and one PI units were
synthesized. The two TTF units are linked to the PI unit by a
flexible spacer [–(CH2)12–] in 1, while a more rigid spacer
[–CH2CH(CH2CH2)2CHCH2–] is used to connect two TTF
units and PI unit in 2 and 3. Different end groups are
attached to two TTF units: n-hexyl group for 1, 2-ethylbutyl
group for 2 and G2 dendritic group for 3.17 Herein we
describe the synthesis, electrochemical and spectroscopic
studies of triads 1–3.
Tetrathiafulvalene (TTF) and its derivatives have been
extensively investigated as components of organic con-
ductors and superconductors.1 Meanwhile, on account of
their reversible redox properties, TTF derivatives have also
been used to construct supramolecules for studies of
molecular-based devices, especially in recent years.2–4
Many electron donor–acceptor supramolecules with TTF
units have been prepared for studies related to intra-
molecular photoinduced electron transfer processes, intra-
molecular charge-transfer interactions and construction of
molecular rectifiers.5 Various electron acceptor groups have
been covalently attached to TTF: fullerene,6–8 pyromellitic
diimide,9,10 quinones,6,11,12 tetracyanoanthraquino-
dimethane,6 thioindigo,13 polynitrofluorene,15 viologen
and related ones.6,9,14 Perylene diimide (PI) as a moderate
two-electron acceptor has been also employed in donor–
acceptor supramolecules, because of the characteristic
absorption bands of its radical ions. For instance,
Wasielewski et al. once reported a light intensity-dependent
molecular switch on a picosecond time scale based on an
electron donor–acceptor–donor triad consisting of two
2. Results and discussions
2.1. Synthesis
The usual approach to perylene diimide derivatives is by the
reaction of primary amines with perylene tetracarboxylic
acid bisanhydride. This strategy requires the preparation of
TTF derivatives with primary-amine groups (TTF-amines).
Becher et al once reported the preparation of TTF-amines
using the classic Gabriel transformation.10 Here we present
a new facile route to TTF-amines by using the unusual
reaction of TBA2[Zn(DMIT)2] reported recently by us.18
Keywords: donor–acceptor systems; tetrathiafulvalene; perylene diimide;
photoinduced electron transfer.
*
Corresponding authors. Tel.: þ86-10-62639355; fax: þ86-10-62559373;
e-mail: dqzhang@iccas.ac.cn
0040–4020/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0040-4020(03)00700-2

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X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
Scheme 1.
The key intermediate compound 4-(2-cyanoethyl)thio-1,3-
dithiole-2-thione (4) was easily synthesized starting from
TBA2[Zn(DMIT)2] and 3-bromopropionitrile in the
presence of pyridine hydrogen chloride.18 Compound 4
was converted to 5 using conventional methods in high yield
(Scheme 2). Cross-coupling of 5 with 6 and 7, which can be
easily accessible from TBA2[Zn(DMIT)2],19 in the presence
of tri(isopropyl)phosphite, led to compounds 8 and 9 in
yields of 67 and 62%, respectively. After removal of
2-cyanoethyl groups from 8 and 9, followed by the reaction
with dibromoelectrophiles, which were used in large excess,
compounds 10 and 11 were obtained in yields of 70 and
91%, respectively. Direct reaction of 10 and 11 with large
excess of NaN3 in dry DMF afforded 12 and 13 respectively
in high yield. Reduction of compounds 12 and 13 in THF
with PPh3 gave the TTF-amines 14 and 15, which were
purified by column chromatography, followed by
recrystallization from CH2Cl2/petroleum ether. Triads 1
and 2 were obtained by the reaction of perylene tetra-
carboxylic acid bisanhydride with compounds 14 and 15,
respectively, catalyzed by Zn(Ac)2·2H2O in quinoline under
an atmosphere of dry N2 at 1608C.
Triad 3 was prepared in a slightly different way as shown in
Scheme 3. Self-coupling of compound 5 in the presence of
tri(isopropyl)phosphite gave compound 16 with cis/trans
isomers. Deprotection of one cyanoethyl group from 16 by
controlling the reaction conditions and further reaction with
Scheme 2. Reagents: (i) BrCH2CH2CN, pyridinehydrochloride/CH3CN; (ii) C6H13Br or BrCH2CH(CH2CH3)2/CH3CN; (iii) Hg(OAc)2, CH2Cl2; (iv) tri(i-
propyl)phosphite, 1208C; (v) CsOH·H2O, THF, Br(CH2)12Br/BrCH2CH(CH2CH2)2CHCH2Br; (vi) DMF, NaN3; (vii) PPh3/H2O, THF; (viii) perylene
tetracarboxylic acid dianhydride, Zn(Ac)2·2H2O, quinoline, N2, 1608C.

X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
4845
Scheme 3. Reagents: (i) tri(i-propyl)phosphite, toluene, 1208C; (ii) CsOH·H2O, THF, G2-bromodendrimer; (iii) CsOH·H2O, THF, BrCH2CH(CH2CH2)2-
CH2Br; (iv) DMF, NaN3; (v) PPh3/H2O, THF; (vi) perylene tetracarboxylic acid dianhydride, DMF, N2, 1208C.
one G2-dendrimer featuring benzyl bromide group afforded
compound 17. Starting from compound 17, the TTF-amine
compound 20 was obtained following the same approaches
as for compounds 14 and 15. The condensation reaction
between 20 and perylene tetracarboxylic acid bisanhydride,
however, failed to give triad 3 by using the same condition
as for triads 1 and 2. Fortunately, direct reaction of 20 with
perylene tetracarboxylic acid bisanhydride in dry DMF
without any catalyst at 1208C overnight yielded the target
triad 320 in moderate yield after careful purification by
column chromatography.
intramolecular charge-transfer interactions for triads 1–3 in
their ground states are negligible. The mixture of reference
compounds 8 and 21 in solution (in a molar ratio of 1:1;
2.1£1023 M for both 8 and 21) shows a characteristic
charge-transfer absorption band with a maximum at
615 nm. As expected, such an intermolecular charge-
transfer absorption is strongly affected by the concentrations
of the reference compounds 8 and 21. Therefore, it might be
concluded that the spatial separation of electron donor and
acceptor units is the main reason for the negligible charge-
transfer interaction in triads 1–3.22
For comparative studies, reference compound N,N-dihexyl
perylene diimide 21 was prepared and characterized with
similar approaches.
Further insight into the electronic properties of these
compounds was gained by cyclic voltammetry. Table 1
lists the redox potentials of triads 1–3 together with those of
the reference compounds 8 and 21 for comparison. Triads
1–3 show almost the same reduction potentials at ca. 20.67
and 20.85 V, and oxidation potentials at ca. 0.47 and
0.85 V. Obviously, their reduction potentials are very close
to those of the reference compound 21 (–0.67 and
20.85 V), and their oxidation potentials are almost the
same as those of the reference compound 8 (0.47 and
0.85 V). Thus, the TTF and PI units in triads 1–3 can be
treated independently. This result is consistent with the UV/
vis spectral studies as mentioned above.
2.2. UV/vis absorption spectra and cyclic voltammetric
studies
Figure 1 shows the absorption spectra of triads 1–3 together
with those of the reference compounds 8 and 21 for
comparison.21 No new absorption bands or distinctive
spectroscopic shoulders were detected in the UV/vis spectra
of triads 1–3 as compared to the corresponding spectra of
the reference compounds 8 and 21. This fact indicates that
In addition, TTF units absorb strongly around 320 nm, while
PI unit shows strong absorption bands from 420 to 550 nm.
Hence, it is possible to selectively excite TTF and PI units.
Therefore, triads 1–3, in which no distinctive charge-
transfer interactions are found, are good examples for
studies of photoinduced electron transfer processes.
Table 1. Redox potentials of 1–3 (potentials vs. Ag/AgCl, scan rate
0.1 V s21, work electrode Pt, supporting eletrolyte NBu4PF4 in trichloro-
methane)
E 11/2/V (Re.)
E 21/2/V (Re.)
E 11/2/V (Ox.)
E 21/2/V (Ox.)
1
2
3
8
21
20.67
20.67
20.68
20.85
20.85
20.86
0.48
0.47
0.47
0.47
0.86
0.83
0.85
0.85
Figure 1. UV/vis absorption spectra of 1–3, 8 and 21 (5.0£1025 M) in
20.67
20.85
trichloromethane.

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X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
deduced: 1.01 ns for 1, 195 ps for 2 and 178 ps for 3. For
comparative studies, the fluorescence lifetime of compound
21 was also measured (3.66 ns). Similar to the fluorescence
intensity reduction from compound 21 to triads 1–3, their
fluorescence lifetimes show the same tendency.
We prefer to ascribe the photophysical properties of triads
1–3 (fluorescence intensity reduction and shorter fluor-
escence lifetimes) to photoinduced electron transfer reac-
tion between the PI units and TTF units in triads 1–3
because of the following facts: (1) DG values23 for the
photoinduced electron transfer reactions are negative, and
thus these reactions are thermodynamically favorable; (2)
there is no spectral overlap between the absorption spectrum
of TTF units and fluorescence spectrum of PI unit. Hence,
Figure 2. Fluorescence spectra of 1–3 and 21 (5.0£1025 M) in
¨
the energy transfer process due to the Forster mechanism
trichloromethane excited at 480 nm.
will be prohibited.24 Time-resolved absorption spectral
studies (detection of absorption of radical anions of the PI
unit and absorption of radical cations of the TTF unit) will
be needed to provide further evidence for the above
assumption. The different photophysical behavior between
1 and 2 (and 3) may be due to the difference in spatial
2.3. Fluorescence spectral studies
The fluorescent spectra of triads 1–3 are shown in Figure 2.
For comparison, the fluorescent spectrum of compound 21 is
also included in Figure 2. Clearly, except for the intensity
difference the fluorescent spectra of triads 1–3 are very
similar to that of compound 21 (for triads 2 and 3 the
fluorescent spectra are almost coincident). Their fluor-
escence spectra with two bands at lmax¼540 and 574 nm are
indeed the mirror images of UV/vis absorption spectrum of
compound 21 (see Figures 1 and 2). These results imply that
the fluorescence of triads 1–3 is due to the PI units. As
compared to that of compound 21, the fluorescent intensities
of triads are reduced. Moreover, on comparison with triad 1,
triads 2 and 3 show much lower fluorescence intensities, but
the fluorescence intensities of triads 2 and 3 are almost the
same.
˚
˚
separation between TTF and PI units: 25 A for 1; 12 A for 2;
22
˚
12 A for 3.
If the TTF units of 1–3 are oxidized chemically or
electrochemically, the photoinduced electron-transfer from
TTF to PI units would be hindered. As a result, the
fluorescence of 1–3 would be enhanced. Indeed, this
approach has been pursued in recent years for the
construction of new molecular switches.25 Unfortunately,
treatment of the solutions of 1–3, respectively with 2 equiv.
of Fe(ClO4)3 did not result in fluorescence enhancement. As
an example, Figure 4 shows the fluorescence spectra of 2
before and after oxidation by 2 equiv. of Fe(ClO4)3. This
result should be ascribed to the following facts: (1) the TTF
radical cation shows broad absorption in the wavelength
range of 580–800 nm as indicated in the inset of Figure 4,
which is in accordance with the previous report;26 (2)
The fluorescence lifetimes of triads 1–3 were measured by
time-resolved fluorescence spectroscopy. Their fluor-
escence decay curves (Fig. 3) can be well fitted by single-
exponential forms, and their fluorescence lifetimes were
Figure 3. Time-resolved fluorescence decay curves of triads 3 (a), 2 (b), 1 (c) and the reference compound 21 (d): the experimental and fitting curves are left;
the residual curves are right. The excitation wavelength is 480 nm.

X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
4847
Preliminary results imply that incorporation of groups with
steric hindrance into TTF units may improve the photo-
stability of such triads. Therefore, triads with structures
similar to 1–3 are worthwhile for further investigations,
which may lead to the design and construction of new fast
molecular switches.
3. Experimental
3.1. General
Melting points were measured with an XT4-100X apparatus
and uncorrected. 1H NMR spectra were recorded with
Bruker 300 MHz or Varian 200 MHz spectrometers. All
chemical shifts were quoted in ppm relative to TMS.
Infrared spectra were obtained on a Perkin–Elmer System
2000 FT-IR spectrometer. Mass spectra were determined
with AEI-MS50-MS or MALDI-TOF-MS. Elemental
analysis was performed on Carlo-Erba-1106 instrument.
Absorption spectra were measured with Hitachi (model
U-3010) UV–Vis spectrophotometer. Fluorescence
measurements were carried out with a Hitachi (model
F-4500) Spectrophotometer in a 1-cm quartz cell. Cyclic
voltammetric experiments were performed on an EGDG
PAR 370 system at a scan rate of 100 mV in CHCl3 using
Bu4NPF6 as electrolyte, platinum as counter and work
electrodes and Ag/AgCl as reference electrode. Time-
resolved fluorescence decay spectra were measured with a
picosecond time-correlated single-photo counting system. A
regeneratively amplified Ti: Sapphire laser (Tsunami,
Spectra Physics) pumped by a mode-locked argon ion
laser (Beamlock, Spectra Physics) was used as a light source
to produce a laser pulse at 800 nm (Fwhm¼120 fs, 1 kHz,
0.5 mJ). It was tuned to 480 nm through optical parametric
amplifier (OPA-800C, Spectra Physics) and was focused
onto the sample with pump energy 1.5 mJ. The resulting
Figure 4. Fluorescence spectra of triad 2 (5.0£1025 M) before (red) and
after addition of 2 equiv. of Fe(ClO4)3 (black) in trichloromethane excited
at 480 nm. Inset: UV/vis absorption spectra of triad 2 (5.0£1025 M) before
(red) and after addition of 2 equiv. of Fe(ClO4)3 (black) in
trichloromethane.
obviously, there is large spectral overlap between the
absorption spectrum of the TTF radical cation and the
fluorescence spectrum of the PI unit, and hence intra-
molecular energy transfer can take place effectively
between the PI unit and TTF cation. Consequently, the
fluorescence of the PI unit of 1–3, which would be
increased by oxidation of TTF units, was quenched due to
the energy transfer between the PI unit and TTF cation.
In addition, it was found that dark-colored precipitates27
occurred after the trichloromethane solution of 1
(5.2£1023 M) was irradiated by normal sunlight for 4 h. It
was also observed that the 1H NMR signal at 6.31 ppm (the
olefinic hydrogen of TTF units) disappeared and other
signals became broad after the d-trichloromethane solution
of 1 in a normal NMR tube was left under sunlight for 4 h. In
contrast, after leaving the solution of 1 in darkness for 10
1
days, the H NMR spectrum of 1 remained unchanged and
no colored precipitates were detected. In comparison, under
the same conditions, the solution of 2 was unchanged after
sunlight irradiation for about 5 h. Interestingly, no change
was observed for the solution of 3 even after exposure to
sunlight for 20 h. The formation of colored precipitates and
fluorescence was collected into
a multichromator
(Hamamatsu C5094) and detected with a streak camera
(Hamamatsu C2909). The instrumental response time was
about 30 ps. The software used to fit the fluorescence decay
curves was compiled based on Matlab 5.2 (Mathworks).
1
the change of its H NMR spectrum for 1 after sunlight
irradiation are probably owing to the generation of radical
ions (e.g. TTFzþ–PIz2–TTF) by photoinduced electron
transfer reaction. These radical ions tend to aggregate in
solution, probably due to p–p interactions which may lead
to formation of dark-colored precipitates. The incorporation
of steric groups such as the 2-ethylbutyl group in 2 and the
G2 dendritic group in 3 will reduce the tendency of such
aggregation, and hence improve their photostability.
Detailed investigations in this respect are underway.
THF was distilled from sodium/benzophenone immediately
prior to use. DMF was pre-dried by standing over molecular
˚
sieves (4 A) for at least 3 days before use. Pyridine
hydrogen chloride, 1,12-dibromodecane, and 1,4-cyclo-
hexanedimethanol were purchased from Acros Chemicals.
1,4-cyclohexanedibromomethane was prepared from
1,4-cyclohexanedimethanol according to Ref. 28, and
TBA2[Zn(DMIT)2] was prepared according to Ref. 29. All
other reagents and solvents (standard grade) were used as
received unless otherwise stated. All reactions involving
compounds containing TTF units were carried out under an
atmosphere of dry N2.
2.4. Summary
Three donor–acceptor–donor triads 1–3 each containing
two TTF units and one PI unit were synthesized and
characterized. They all show negligible intramolecular
charge transfer interactions in their ground states. Probably
due to photoinduced electron transfer interactions, their
fluorescences were partially quenched. The different photo-
physical behaviors between 1 and 2 (and 3) might be due to
their difference in the spatial separation of TTF and PI units.
3.1.1. Compound 5. To a solution of 4-(2-cyanoethythio)-
1,3-dithole-2-thione18 (0.27 g. 1.23 mmol) in dichloro-
methane (45 mL) was added mercuric acetate (1.18 g,
3.69 mmol), and the resulting white suspension was stirred
under N2 for 2 h at room temperature. The resulting
voluminous white precipitate was removed by filtration
using celite and washed thoroughly with dichloromethane.

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X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
The combined organic phases were concentrated in vacuum,
and then the remaining solid was subjected to crystallization
from dichloromethane and petroleum ether to give the
compound 5 (0.20 g, 80%) as colorless needles, mp 56–
578C. [Found: C, 35.29; H, 2.37; N, 6.77. C6H5NOS3
TOF): Mþ, found 655.9 (657.9). C26H41S7Br requires 656.0
(658.0).
3.1.6. Compound 12. A solution of 10 (1.30 g, 1.80 mmol)
in dry DMF (50 mL) was treated with NaN3 (2.13 g,
3.28 mmol) at 258C under N2. The resulting reaction
mixture was warmed at 808C for 12 h before 30 mL of
H2O was added. The aqueous solution was extracted with
dichloromethane (3£50 mL), and the combined extracts
were washed with H2O (2£50 mL) and saturated aqueous
NaCl (20 mL), dried (MgSO4) and concentrated in vacuo.
After column chromatography on silica gel with CH2Cl2/
petroleum (60–908C) (1:4, v/v) as eluant, 12 was obtained
as an orange oil (1.11 g) in 91% yield. [Found: C, 53.45; H,
7.86; N, 6.36. C30H51S7N3 requires C, 53.13; H, 7.58; N,
6.20%]; nmax (KBr, cm21) 2094 (–N3); dH (300 MHz,
CDCl3) 6.25 (1H, s, olefinic), 3.19 (2H, t, J¼6.3 Hz,
CH2N3); 2.74 (6H, m, 3SCH2), 1.55 (10H, br, 5CH2), 1.29
(26H, br, 13CH2), 0.83 (6H, t, J¼6.4 Hz, 2CH3); MS
(MALDI-TOF): Mþ, found 677.5. C30H51S7N3 requires
677.2.
requires C, 35.45; H, 2.48; N, 6.89%]; nmax (KBr, cm21
)
2247 (–CN); 1632 (–CvO). dH (200 MHz, CDCl3) 2.75
(2H, t, J¼6.8 Hz, CH2S), 3.06 (2H, t, J¼6.8 Hz, CH2CN),
7.12 (1H, s, olefinic); MS (EI): Mþ, found 203. C6H5NOS3
requires 203.
3.1.2. Compound 8. A solution of compound 5 (0.50 g,
2.46 mmol) and compound 6 (2.7 g, 7.39 mmol)19 in
triisopropyl phosphite (20 mL) was heated to 1208C under
N2 and stirred at this temperature for 3 h. Column
chromatography of the crude reaction mixture, after
removing the excess triisopropyl phosphite under reduced
pressure, on silica gel with CH2Cl2/petroleum (60–908C)
(1:3, v/v) as eluant afforded compound 8 as an orange oil
(0.86 g) in 67% yield. [Found: C, 48.41; H, 6.03; N, 2.73.
C21H31S7N requires C, 48.33; H, 5.99; N, 2.68%]; nmax
(KBr, cm21) 2249 (–CN); dH (200 MHz, CDCl3) 6.55 (1H,
s, olefinic), 2.96 (2H, t, J¼6.4 Hz, CH2CN), 2.82 (4H, t,
J¼5.2 Hz, 2SCH2), 2.70 (2H, t, J¼6.4 Hz, SCH2), 1.60–
1.20 (16H, br, 8CH2); 0.89 (6H, t, J¼4.6 Hz, 2CH3); MS
(EI): Mþ, found 521. C21H31S7N requires 521.
3.1.7. Compound 13. This was obtained similarly from 11
as an orange oil in 70% yield. [Found: C, 50.74; H, 6.88; N,
7.02. C26H41S7N3 requires C, 50.36; H, 6.66; N, 6.78%];
n
max (KBr, cm21) 2095 (–N3). dH (300 MHz, CDCl3) 6.33
(1H, s, olefinic), 3.18 (2H, d, J¼6.6 Hz, CH2N3), 2.84 (4H,
d, J¼5.0 Hz, 2SCH2), 2.67 (2H, d, J¼6.8 Hz, SCH2), 1.88
(4H, m, alkyl-H), 1.47 (12H, m, alkyl-H), 1.06 (4H, m,
alkyl-H), 0.94 (12H, m, 4CH3); MS (MALDI-TOF): Mþ,
found 619.1. C26H41S7N3 requires 619.1.
3.1.3. Compound 9. This was prepared in a similar manner
from 5 and 719 as an orange oil in 62% yield. [Found: C,
48.32; H, 6.03; N 2.59. C21H31S7N requires C, 48.33; H,
5.99; N, 2.68%]; nmax (KBr, cm21) 2252 (–CN); dH
(300 MHz, CDCl3) 6.58 (1H, s, olefinic), 2.96 (2H, t,
J¼6.8 Hz, CH2CN), 2.83 (4H, d, J¼4.8 Hz, 2SCH2), 2.70
(2H, t, J¼6.8 Hz, SCH2), 1.46 (10H, m, 4CH2þ2CH), 0.89
(12H, t, J¼7.2 Hz, 4CH3); MS (EI): Mþ, found 521.
C21H31S7N requires 521.
3.1.8. Compound 14. A solution of 12 (1.20 g, 1.77 mmol)
in THF (60 mL) was treated with PPh3 (0.93 g, 3.54 mmol)
and H2O (318 mL, 17.7 mmol) at 258C under N2. The
resulting reaction mixture was warmed at 458C for 10 h. The
solvents were removed in vacuo and the residue was purified
by column chromatography on silica gel with CH2Cl2 as
eluant to afford compound 14 as an orange oil (0.90 g) in
78% yield. [Found: C, 55.35; H, 8.17; N, 2.02. C30H53S7N
3.1.4. Compound 10. To a solution of 8 (1.00 g, 1.92 mmol)
in anhydrous degassed THF (80 mL) was added a solution
of CsOH·H2O (0.48 g, 2.85 mmol) in anhydrous
degassed MeOH (30 mL) over a period of 30 min. The
mixture was stirred for an additional 30 min whereupon a
solution of 1,12-dibromododecane (1.25 g, 3.81 mmol) in
anhydrous degassed THF (30 mL) was added. The
solution was stirred overnight. After separation by
column chromatography compound 10 was obtained
(1.23 g) in 90% yield. [Found: C, 50.70; H, 7.30.
C30H51S7Br requires C, 50.32; H, 7.18%]; nmax (KBr,
cm21): 2954, 2926, 2854 (alkyl C–H); dH (300 MHz,
CDCl3) 6.32 (1H, s, olefinic), 3.40 (2H, t, J¼6.2 Hz,
CH2Br), 2.80 (6H, m, 3SCH2), 1.82 (2H, m, CH2); 1.59 (8H,
m, 4CH2), 1.39 (26H, br, 13CH2), 0.89 (6H, t, J¼6.4 Hz,
2CH3). MS (MALDI-TOF): Mþ, found 714.3 (716.3).
C30H51S7Br requires 714.1 (716.1).
requires C, 55.25; H, 8.19; N, 2.15%]; nmax (KBr, cm21
)
3320, 3307 (2NH2); dH (300 MHz, CDCl3) 6.32 (1H, s,
olefinic), 2.81 (6H, m, 3SCH2), 2.68 (2H, t, J¼6.8 Hz,
NCH2), 1.63 (10H, m, 5CH2), 1.27 (28H, br, 13CH2þNH2),
0.89 (6H, t, J¼6.3 Hz, 2CH3). MS (MALDI-TOF): Mþ,
found 651.4. C30H53S7N requires 651.2.
3.1.9. Compound 15. This was synthesized in a similar
manner from 13 as an orange oil in 81% yield. [Found: C,
52.01; H, 7.14; N, 2.20. C26H43S7N requires C, 52.57; H,
7.30; N, 2.36%]; nmax (KBr, cm21) 3445, 3315 (–NH2); dH
(300 MHz, CDCl3) 6.28 (1H, s, olefinic), 2.79 (4H, d,
J¼5.3 Hz, 2SCH2), 2.63 (2H, d, J¼6.8 Hz, SCH2), 2.51
(2H, d, J¼6.4 Hz, CH2N), 1.89 (4H, br, alkyl-H), 1.40 (14H,
br, alkyl-HþNH2), 0.89 (16H, br, alkyl-H); MS (MALDI-
TOF): Mþ, found 593.2. C26H43S7N requires 593.1.
3.1.5. Compound 11. This was obtained similarly from 9
and 1,4-cyclohexanedibromomethane as an orange oil in
70% yield. [Found: C, 47.20; H, 6.14. C26H41S7Br requires
C, 47.46; H, 6.28%]; nmax (KBr, cm21): 2960, 2921 (alkyl
C–H). dH (300 MHz, CDCl3) 6.31 (1H, s, olefinic), 3.30
(2H, d, J¼6.5 Hz, CH2Br), 2.80 (4H, d, J¼5.8 Hz, 2SCH2),
2.65 (2H, d, J¼6.8 Hz, SCH2), 1.94 (4H, br, alkyl-H), 1.43
(12H, br, alkyl-H), 0.90 (16H, br, alkyl-H); MS (MALDI-
3.1.10. Triad 1. Perylene-1,4,5,8-tetracarboxylic acid
dianhydride (0.08 g, 0.20 mmol) was mixed with 14
(0.31 g, 0.47 mmol) and zinc acetate (0.043 g, 0.20 mmol)
in quinoline (10 mL), and the mixture was stirred at 1608C
for 3–4 h under N2. The reaction mixture was cooled down
to room temperature and poured into HCl (1 M, 100 mL).

X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
4849
The resulting precipitate was collected on a glass filter
funnel, washed with water (50 mL) and methanol (20 mL),
then purified by column chromatography on silica gel with
CHCl3/CH3OH (100:1, v/v) as eluant. After removing the
solvents in vacuo, the remaining solid was crystallized from
CH2Cl2/petroleum ether to afford the product as a red
powder (0.23 g) in 69% yield: mp 169–1708C. [Found: C,
60.76; H, 6.73; N, 1.86. C84H110S14O4N2 requires C, 60.75;
H, 6.68; N, 1.69%]; nmax (KBr, cm21) 1695, 1657, 1594,
1346 (–CON–); dH (300 MHz, CDCl3) 8.66 (4H, d,
J¼7.9 Hz, Ar-H), 8.56 (4H, d, J¼8.0 Hz, Ar-H), 6.30 (2H,
s, olefinic), 4.20 (4H, t, J¼7.6 Hz, 2CH2N), 2.77 (12H, m,
6SCH2), 1.81 (4H, m, 2CH2), 1.64 (16H, m, 8CH2), 1.37
(52H, m, 26CH2), 0.89 (12H, t, J¼6.4 Hz, 4CH3); MS
(MALDI-TOF): Mþ, found 1658.5. C84H110S14O4N2
requires 1658.5.
7.46 (20H, m, Ar-H), 6.73–6.55 (9H, m, Ar-H), 6.22–6.13
(2H, m, olefinic), 5.09 (8H, s, 4CH2O), 4.99 (4H, s, 2
OCH2), 3.90 (2H, s, SCH2O), 3.31 (2H, d, J¼6.3 Hz,
BrCH2), 2.65 (2H, d, J¼5.6 Hz, SCH2), 1.96 (4H, m, alkyl-
H), 1.32 (2H, m, alkyl-H), 0.91 (4H, m, alkyl-H); MS
(MALDI-TOF): Mþ, found 1182.0. C63H59S6O6Br requires
1182.2.
3.1.15. Compound 19. This was obtained in a similar
manner as for compound 12 from compound 18 as an orange
oil in 73% yield. [Found: C, 66.40; H, 5.31; N, 3.78.
C63H59S6O6N3 requires C, 66.00; H, 5.19; N, 3.66%]; nmax
(KBr, cm21) 2096 (–CN), 1596, 1450 (Ar); dH (300 MHz,
CDCl3) 7.40 (20H, m, Ar-H), 6.67–6.49 (9H, m, Ar-H),
6.20–6.00 (2H, m, olefinic), 5.04 (8H, s, 4 OCH2), 4.95 (4H,
s, 2 OCH2), 3.85 (2H, s, SCH2), 3.10 (2H, d, J¼5.4 Hz,
CH2N3), 2.63 (2H, d, J¼5.7 Hz, SCH2), 1.82 (4H, m, alkyl-
H), 1.26 (2H, m, alkyl-H), 0.95 (4H, m, alkyl-H); MS
(MALDI-TOF): Mþ, found 1144.8. C63H59S6O6N3 requires
1145.3.
3.1.11. Triad 2. This was obtained in a similar manner from
15 and Perylene-1,4,5,8-tetracarboxylic acid dianhydride as
a red powder in 62% yield: mp .2808C. [Found: C, 58.90;
H, 5.92; N, 1.96. C76H90S14O4N2 requires C, 59.11; H, 5.87;
N, 1.81%]; nmax (KBr, cm21) 1695, 1657, 1594, 1343
(–CON–); dH (300 MHz, CDCl3) 8.70 (4H, d, J¼8.0 Hz,
Ar-H), 8.63 (4H, d, J¼8.1 Hz, Ar-H), 6.31 (2H, s, olefinic),
4.14 (4H, d, J¼7.0 Hz, 2CH2N), 2.83 (8H, d, J¼4.3 Hz,
4SCH2), 2.63 (4H, d, J¼6.7 Hz, 2SCH2), 1.94 (8H, m,
alkyl-H), 1.45–1.21 (24H, m, alkyl-H), 0.89 (32H, m, alkyl-
H); MS (MALDI-TOF): Mþ, found 1542.6. C76H90S14O4N2
requires 1542.3.
3.1.16. Compound 20. This was prepared in a similar
manner as for compound 14 from compound 19 as an orange
oil in 82% yield. [Found: C, 67.14; H, 5.09; N, 1.04.
C63H59S6O6N3 requires C, 67.53; H, 5.49; N, 1.25%]; nmax
(KBr, cm21) 3447, 3323 (–NH2), 1595, 1450 (Ar); dH
(300 MHz, CDCl3) 7.48 (20H, m, Ar-H), 6.92–6.57 (9H, m,
Ar-H), 6.22–6.07 (2H, m, olefinic), 5.04 (8H, s, 4 OCH2),
4.95 (4H, s, 2 OCH2), 3.85 (2H, s, SCH2O), 2.68 (2H, d,
J¼6.5 Hz, CH2N), 2.62 (2H, d, J¼6.2 Hz, SCH2), 1.89 (4H,
m, alkyl-H), 1.28 (2H, m, alkyl-H), 0.97 (4H, m, alkyl-H),
MS (MALDI-TOF): Mþ, found 1119.1. C63H61S6O6N
requires 1119.3.
3.1.12. Compound 16. To a solution of compound 5
(0.20 g, 0.98 mmol) in toluene (10 mL) was added tri-
isopropyl phosphite (2 mL). The resulting suspension was
heated to 1208C under N2 and stirred at this temperature for
3 h. Column chromatography of the crude reaction mixture,
after removing the excess triisopropyl phosphite under
reduced pressure, on silica gel with CH2Cl2/petroleum (60–
908C) (1:2, v/v) as eluant afforded compound 16 as a yellow
powder (0.12 g) in 63% yield: mp 114–1158C. [Found: C,
38.08; H, 2.66; N, 7.46. C12H10S6N2 requires C, 38.48; H,
2.69; N, 7.48%]; nmax (KBr, cm21) 2248 (–CN); dH
(300 MHz, CDCl3) 6.29 (2H, s, olefinic), 3.04 (4H, t,
J¼8.4 Hz, 2CH2CN), 2.72 (4H, t, J¼8.4 Hz, 2SCH2); MS
(EI): Mþ, found 374. C12H10S6N2 requires 374.
3.1.17. Triad 3. A solution of compound 20 (0.20 g,
0.18 mmol) and perylene-1,4,5,8-tetracarboxylic acid dian-
hydride (0.03 g, 0.08 mmol) in dry DMF (15 mL) was
heated to 1208C under N2 and stirred at this temperature for
3 h. Column chromatography of the crude reaction mixture,
after removing the solvent under reduced pressure, on silica
gel with CHCl3/CH3OH (100:3, v/v) as eluant afforded cis/
trans mixture 3 as a red powder (0.13 g) in 61% yield:
mp168–1698C. [Found: C, 68.99; H, 4.74; N, 1.26.
C150H126S12O16N2 requires C, 69.39; H, 4.89; N, 1.08%];
nmax (KBr, cm21) 1694, 1657 (–CON–), 1595, 1448 (Ar);
dH (300 MHz, CDCl3) 8.71 (4H, d, J¼7.6 Hz, Ar-H), 8.66
(4H, d, J¼7.9 Hz, Ar-H), 7.45–7.32 (40H, m, Ar-H), 6.68–
6.51 (18H, m, Ar-H), 6.21–6.07 (4H, m, olefinic), 5.05
(16H, s, 8CH2O), 4.97 (8H, s, 4 OCH2), 4.12 (4H, d,
J¼6.9 Hz, 2 NCH2), 3.87 (4H, s, 2SCH2O), 2.59 (4H, t,
J¼6.2 Hz, 2SCH2), 1.85 (8H, m, alkyl-H), 1.17 (4H, m,
alkyl-H), 0.94 (8H, m, alkyl-H); MS (MALDI-TOF): Mþ,
found 2594.3. C150H126S12O16N2 requires 2594.6.
3.1.13. Compound 17. This was prepared in a similar
manner as compound 10 using compound 16 and the G2
dendrimer with benzyl bromide units as an orange oil in
72% yield. [Found: C, 66.14; H, 4.64; N, 1.11.
C58H49S6O6N requires C, 66.45; H, 4.71; N, 1.34%]; nmax
(KBr, cm21) 2250 (–CN). dH (300 MHz, CDCl3) 7.57
(20H, m, Ar-H), 6.66–6.49 (9H, m, Ar-H), 6.40 (1H, d,
J¼7.7 Hz, olefinic), 6.08 (1H, s, olefinic), 5.03 (8H, s,
4CH2), 4.90 (s, 4H, 2CH2), 3.83 (2H, s, CH2), 2.83 (2H, t,
J¼7.3 Hz, CH2CN), 2.56 (2H, t, J¼6.9 Hz, SCH2); MS
(MALDI-TOF): MHþ, found 1048.6. C58H49S6O6N
requires 1048.2.
Acknowledgements
We thank Professor J.- P. Zhang of our institute for his kind
help. The present research was financially supported by
NSFC (90101025), Chinese Academy of Sciences and State
Key Basic Research Program (G2000077500). D.- Q. Zhang
thanks National Science Fund for Distinguished Young
Scholars. We also thank the anonymous reviewers for their
3.1.14. Compound 18. This was synthesized similarly as for
compound 10 using compounds 17 and 1,4-cyclohexane-
dibromomethane as an orange oil in 60% yield. [Found: C,
64.20; H, 5.30. C63H59S6O6Br requires C, 63.89; H, 5.02%];
nmax (KBr, cm21) 1595, 1449 (Ar); dH (300 MHz, CDCl3)

4850
X. Guo et al. / Tetrahedron 59 (2003) 4843–4850
due to p–p interactions. This is due to fact that both neutral
TTF and PI units as well as their radical ions after oxidation or
after reduction tend to aggregate in solution.
critical comments and suggestion, which help us to improve
the manuscript.
18. Jia, C-Y.; Zhang, D-Q.; Xu, W.; Zhu, D-B. Org. Lett. 2001, 3,
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these groups will affect their tendency to aggregate, possibly