Synthesis and properties of a tetrathiafulvalene-perylene tetracarboxylic diimide-tetrathiafulvalene dyad

Article abstract of DOI:10.1039/b719844b

A donor-acceptor-donor dyad 4 involving 2-sulfur-3-methylthio-6,7- bis(hexylthio)tetrathiafulvalene (TTF) as a donor attached directly to N,N′-dibutylperylene-3,4,9,10-tetracarboxylic diimide (PDI) as an acceptor was synthesized by condensation of N,N′-dibutyl-1,6-dibromo-3,4,9,10- perylenetetracarboxylic diimide and 2-(2-cyanoethylthio-3-methylthio-6,7- bis(hexylthio)tetrathiafulvalene. The cyclic voltammetric (CV) data implied significant intramolecular interaction and the absorption spectrum indicated that there was an intramolecular charge transfer (ICT) interaction between TTF and PDI moieties in dyad 4. Comparing with PDI 13, the fluorescence emission intensity of dyad 4 was quenched almost quantitatively, which might result from the photo-induced electron transfer (PET) interaction between the PDI and TTF moieties in dyad 4. The fluorescence intensity of dyad 4 could be reversibly modulated by sequential oxidation and reduction of the TTF unit using chemical methods. Thus dyad 4 can be regarded as a new reversible fluorescence-redox dependent molecular switch. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008.

Full text of DOI:10.1039/b719844b

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/njc | New Journal of Chemistry
Synthesis and properties of a tetrathiafulvalene–perylene tetracarboxylic
diimide–tetrathiafulvalene dyad
Yu Zhang,a Liang-Zhen Cai,b Cheng-Yun Wang,*a Guo-Qiao Laic and
Yong-Jia Shen*a
Received (in Durham, UK) 3rd January 2008, Accepted 18th April 2008
First published as an Advance Article on the web 4th June 2008
DOI: 10.1039/b719844b
A donor–acceptor–donor dyad 4 involving 2-sulfur-3-methylthio-6,7-bis(hexylthio)-
tetrathiafulvalene (TTF) as a donor attached directly to N,N0-dibutylperylene-3,4,9,10-
tetracarboxylic diimide (PDI) as an acceptor was synthesized by condensation of
N,N0-dibutyl-1,6-dibromo-3,4,9,10-perylenetetracarboxylic diimide and 2-(2-cyanoethylthio-
3-methylthio-6,7-bis(hexylthio)tetrathiafulvalene. The cyclic voltammetric (CV) data implied
significant intramolecular interaction and the absorption spectrum indicated that there was an
intramolecular charge transfer (ICT) interaction between TTF and PDI moieties in dyad 4.
Comparing with PDI 13, the fluorescence emission intensity of dyad 4 was quenched almost
quantitatively, which might result from the photo-induced electron transfer (PET) interaction
between the PDI and TTF moieties in dyad 4. The fluorescence intensity of dyad 4 could be
reversibly modulated by sequential oxidation and reduction of the TTF unit using chemical
methods. Thus dyad 4 can be regarded as a new reversible fluorescence-redox dependent
molecular switch.
electron orbitals of D and A. For the TTF–PDI dyads
reported, TTF and PDI units were all linked by the flexible
Introduction
Tetrathiafulvalene (TTF) 1 is well known as a good p-electron
donor in the field of organic metals and its numerous derivatives
spacers in the ‘‘imide’’ region to construct dyad 2 (donor–
3
(donor–s-acceptor–s-donor)8c
s-acceptor)8a,b or triad
have been widely used as a building block of organic conductors
and superconductors.1 The applications of TTF and its deriva-
tives in materials science have been widely searched, such as
molecular shuttles,2 and chemical sensors.3 In particular,
donor–acceptor (D–A) molecular systems based on TTF and
its derivatives are one focus of such intensive investigations,4
such as TTF–anthrancene,5 TTF–phthalocyanine,6 TTF–
porphyrin,7 TTF–perylene-3,4,9,10-tetracarboxylic diimide,8
TTF–ethynylbipyridine9 and TTF–dipyridophenazine.10
rather than connecting the TTF and PDI units in the ‘‘bay’’
region to gain a donor–acceptor–donor dyad 4 (Scheme 1).
Becher and co-workers12 have reported a straightforward
approach to synthesize the thioalkyl TTF derivatives.
Dithione 5 was treated as a key material, and an appropriate
electrophile (usually halide) as the realkylation reagent to form
the expected TTF derivatives. However, aromatic halides have
never been reported as realkylation reagents because of their
weak electrophile reactivity. We were very interested in using
the aromatic halides as new electrophiles to synthesize dyads
consisting of both TTF and perylene moieties. Herein we
report the synthesis (Scheme 2), spectroscopic and electro-
chemical properties of dyad 4.
Fine-tuning of the HOMO–LUMO gap for these molecular
systems was another concern during the designing process with
the aim to construct molecular electronic devices.8a,11 Most of
these molecular systems were designed according to the
D–s-A model in order to realize the charge, energy or electron
transfer processes between TTF and acceptor counterparts.
Within this typical model, the charge transfer processes from
donor to acceptor passed through spacer to form a stable
D–s-A system. The direct connection of donor and acceptor is
an important method to obtain a D–A system, in which the
charge transfer process was caused by the overlap of the
Results and discussion
Cyclic voltammetry (CV)
Cyclic voltammetry (Fig. 1, Table 1) of dyad 4 showed two
one-electron reversible reduction waves at Ered1 = ꢀ0.50 V
and Ered2 = ꢀ0.63 V, respectively, due to the successive
formation of the radical anion TTF–PDIꢁꢀ–TTF and dianion
TTF–PDI2ꢀ–TTF. They are both anodically shifted as
compared to the first and second reduction waves of the model
PDI 13, indicating that the LUMO orbital of dyad 4 was
located at lower energy than the LUMO orbital of 13.
a Labs for Advanced Materials and Institute of Fine Chemicals, East
China University of Science and Technology, Shanghai, 200237,
P. R. China. E-mail: yjshen@ecust.edu.cn; cywang@ecust.edu.cn;
Fax: +86 21 64252967; Tel: +86 21 64252967
b Department of Chemistry, East China University of Science and
Technology, Shanghai, 200237, P. R. China
Two clear and reversible two-electron TTF oxidation waves
were shown in the positive direction, at Eox1 = 0.70 V and
Eox2 = 1.01 V, respectively, corresponding to the radical
c Key Lab of Organosilicon Chemistry and Material Technology of
Ministry of Education, Hangzhou Normal University, Hangzhou,
310012, P. R. China
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008
1968 | New J. Chem., 2008, 32, 1968–1973

View Article Online
Scheme 1 The structures of TTF 1, dyads 2–4 and dithione 5.
+
+
cation TTFꢁ –PDI–TTFꢁ
and dication TTF2+–PDI–
Electronic absorption
TTF2+. The oxidation of the PDI moiety was not observed
in CH2Cl2 containing 0.1 M n-Bu4NPF6. Comparing with the
model TTF 10, there was about 100 mV anodic shift for dyad 4
(Table 1). This indicated that dyad 4 was more difficult to be
oxidized than TTF 10 and its HOMO orbital was also located
at a lower energy (HOMOdyad 4 = ꢀ5.68 eV) than the energy
of HOMO orbital of TTF 10 (HOMOTTF 10 = ꢀ5.58 eV). This
might be caused by the effect of electron withdrawing of the
20 p-electron perylene ring.7b
The UV-visible absorption spectrum of dyad 4 (bold line) in
CH2Cl2 showed a wide absorption in the whole range from 300
to 700 nm, with the maximum at l = 540 nm (Fig. 3). The
absorption spectra of TTF 10 (dash-dot line, lmax= 334 nm),
PDI 13 (solid line, lmax = 524 nm) and the mixture of these in
2 : 1 molar ratio (dashed line, lmax = 523 nm) are shown in
Fig. 3. The absorption spectrum of the mixture exhibited no
charge-transfer band or intermolecular interaction between
these two compounds in their ground states.
Comparing with dyad 2 and triad 3,8 the CV data of dyad 4
implied that there was a significant interaction between its
electro-active moieties in the ground state,8a as suggested by
the anodic shift of position of dyad 4. However, since the TTF
unit in dyad 4 showed the same electrochemical characteristics
as a normal TTF molecule, it could be concluded that the p
electrons in the sulfur atoms of the linking S–C bond were not
included in the delocalization pathway for the 20 p-electron
system. The electrochemical investigations indicated that the
perylene moiety and the TTF moiety in dyad 4 could show
their individual electrochemical characteristics and the inter-
action between the two components was not very strong.7b
The energetically minimized conformation of dyad 4 is shown
in Fig. 2. It is notable that two TTF groups were exposed to
different sides of the PDI plane, which is beneficial for
participation in redox processes.13
The absorption curve of dyad 4 indicated no sharp peak but
a wide absorption band (Fig. 3). By comparing with the other
three absorption curves, there was a 190 and 16 nm red
shifting relative to the maximum absorptions of TTF 10 and
PDI 13, respectively. In dyad 4, the PDI moiety displays a
strong electron withdrawing effect and the TTF exhibits a
strong electron-donating effect.14 Since these units are linked
directly by a C–S bond the two electro-active moieties can
readily interact with each other, which would predictably lead
to the existence of an intramolecular charge transfer (ICT)
interaction in the ground state. Using the relation Eg(eV) =
1240/l(nm), DE between the LUMO and HOMO orbital of
dyad 4 could be calculated as 1.96 eV, and the energy of
LUMO orbital of dyad 4 is ꢀ3.72 eV. This result also matched
the CV behavior of dyad 4 (LUMOPDI 13 = ꢀ3.67 eV). In
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008 New J. Chem., 2008, 32, 1968–1973 | 1969

View Article Online
Scheme 2 Synthetic processes for dyad 4 and compounds 8, 9, 10, 11, 12, 13.
addition, there was a weak broad absorption band in the
region from 600 and 900 nm (Fig. 3), which resulted from an
ICT interaction between the donor TTF and acceptor PDI,
according to the previous literature.8,15
coincident with the fluorescence spectrum of PDI 13, this
indicated there was an interaction taking place in the excited
state of dyad 4, which was probably the result of a PET
process.
The PET interaction between the TTF and PDI moieties in
dyad 4 might be caused by three reasons: (1) a PET process is
thermodynamically favorable as the calculated free energy
(DGPET) was estimated to be ꢀ1.33 eV (calculated using the
Rehm–Weller equation);16 (2) there was no spectral overlap of
the absorption curve of the TTF unit and the fluorescence
curve of the PDI unit, so not allowing the energy transfer
Fluorescence spectra
The fluorescence spectra of dyad 4, PDI 13 and a 2 : 1 mixture
of TTF 10–PDI 13 are shown in Fig. 4. The fluorescence
intensity of dyad 4 was nearly zero, that is, the fluorescence of
PDI moiety in dyad 4 was quenched almost quantitatively.
As the fluorescence spectrum of the mixture was almost
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008
1970 | New J. Chem., 2008, 32, 1968–1973

View Article Online
Fig. 1 Cyclic voltammogram of dyad 4 (c = 10ꢀ3 mol Lꢀ1) in
CH2Cl2 using 0.1 M n-Bu4NPF6 as supporting electrolyte, AgCl/Ag
as the reference electrode, platinum wires as counter and working
electrodes, scan rate: 50 mV sꢀ1, vs. AgCl/Ag.
Fig. 2 Energetically minimized structures of dyad 4, modeled using
SYBYL 7.3;19 white = carbon; cyan = hydrogen; red = oxygen; blue =
nitrogen; yellow = sulfur.
process from PDI to TTF, according to the Forster
mechanism;8c (3) the photoexcitation of the PDI unit
decreased its electron cloud density and electron transfer from
the TTF unit to the PDI unit became much easier, leading to
thorough quenching of the fluorescence of the PDI unit in
dyad 4.
recovered. Thus, the chemical oxidation and reduction pro-
cesses clearly indicated that dyad 4 possessed the potential to
act as a reversible fluorescence-redox switch.
Conclusions
Chemical oxidation
A
‘‘bay’’ type donor–acceptor–donor dyad containing
both TTF and PDI moieties was synthesized by condensation
Chemical oxidation experiments were carried out to measure
the potential of dyad 4 as a fluorescence switch by adding an
excess of diacetoxyiodobenzene in the presence of triflic acid
(PhI(OAc)2–CF3SO3H) in CH2Cl2 (Fig. 5).17 The fluores-
cence emission was recorded without any further addition of
oxidising reagent. Consequently, the fluorescence intensity was
recorded at the TTF2+–PDI–TTF2+ stage. The fluorescence
intensity reached a limiting value after 50 min and the value
corresponded to around 25% of the intensity of fluorescence
intensity of PDI 13 recorded under the same experimental
conditions. In the TTF–PDI–TTF triad system reported
previously,8c no increase of fluorescence emission was noted
for the TTFꢁ+–PDI–TTF species and no further oxidation to
TTF2+ was carried out by addition of Fe(ClO4)3 as oxidation
agent. Only in a TTF–PDI dyad system,8a was the further
oxidation to TTF2+ achieved and the fluorescence intensity
was recovered in a smaller degree.
of N,N0-dibutyl-1,6-dibromo-3,4,9,10-perylenetetracarboxylic
diimide
and
2-(2-cyanoethylthio-3-methylthio-6,7-bis-
(hexylthio)tetrathiafulvalene. Cyclic voltammetry, electronic
absorption and fluorescence spectra of the dyad indicated
both intramolecular charge transfer interaction and the photo-
induced charge transfer process occurred between the TTF
and PDI moieties in the dyad. The chemical oxidation experi-
ment indicated the fluorescence intensity was dependent on the
The reversible processes of dyad 4 were studied by adding
an excess of zinc power to the solution in order to reduce
TTF2+–PDI–TTF2+ to TTF0–PDI–TTF0. Upon reduction,
the fluorescence intensity of dyad 4 was quenched again and
the initial fluorescence spectra was almost completely
Table 1 Electrochemical data for dyad 4, TTF 10 and PDI 13 in
CH2Cl2
Compound
Ered2/V
ꢀ0.63
Ered1/V
ꢀ0.50
Eox1/V
Eox2/V
4
10
13
0.70
0.56
1.01
0.91
Fig. 3 Absorption spectra of dyad 4 (bold line) and references PDI 13
(solid line), TTF 10 (dotted line) and the mixture PDI 13–TTF
ꢀ1.03
ꢀ0.60
10 = 1 : 2 (dashed line) in CH2Cl2, c = 1 ꢃ 10ꢀ5 mol Lꢀ1
.
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008 New J. Chem., 2008, 32, 1968–1973 | 1971

View Article Online
electrodes, and AgCl/Ag as the reference electrode. The scan
rate was 50 mV sꢀ1
.
Synthesis
Compound 5–9 and 11 were synthesized according to the
reported procedures.12,18
2,3-Bis(methylthio)-6,7-bis(hexylthio)tetrathiafulvalene 10.
Compound 9 (284 mg, 0.5 mmol) was dissolved in dried
DMF (30 ml) and a solution of CsOHꢄH2O (84 mg,
0.53 mmol) in dried methanol (5 ml) was added dropwise over
a period of 15 min under N2. After stirring for 30 min, MeI
(0.5 ml, 8 mmol) was added and the solution turned from
dark-orange to yellow–orange. The reaction mixture was
stirred for a further 30 min under N2. The solvents and excess
MeI were removed under reduced pressure and the residue was
purified by column chromatography on silica gel (CH2Cl2–
petroleum ether, 1 : 1 v/v) to give the bismethylthio-substituted
tetrathiafulvalene 10 (180 mg, 68% yield) as a red–orange oil.
1H NMR (CDCl3, 500 MHz): d 2.79 (4H, t, J 6.90 = Hz,
SCH2CH2), 2.38 (6H, s, SCH3), 1.57–1.62 (4H, m, SCH2CH2),
1.32–1.38 (4H, m, CH2CH3), 1.18–1.28 (8H, m, –CH2–), 0.83
(6H, t, J = 6.96 Hz, –CH3); m/z (EI): 528.0 (M+, 100%),
513.0 (3.5), 410.0 (11), 237.9 (9).
Fig. 4 Fluorescence spectra of dyad 4 (bold line), PDI 13 (dotted line)
and a 2 : 1 mixture of TTF 10–PDI 13 (solid line) in CH2Cl2 (lexc
=
540 nm, = 10ꢀ5 mol Lꢀ1).
oxidation state of the TTF units in dyad 4, which could be
considered as a new fluorescence redox molecular switch.
Experimental
Chemicals and instruments
N,N0-Dibutyl-1,6-dibromo-3,4,9,10-perylenetetracarboxylic
diimide 12. n-Butylamine (2.97 ml, 30 mmol) was added to a
solution of 1,6-dibromo-3,4,9,10-perylenetetracarboxylic
dianhydride 11 (3.30 g, 6 mmol) in ethanol (100 ml). The
reaction mixture was heated to reflux under N2 for 20 h and
cooled to room temperature, poured into 10% HCl (v/v)
carefully and the dark brown precipitate was filtered off and
washed with water, and purified by column chromatography
on silica gel (CH2Cl2) to give 12 (2.30 g, 58% yield) as a brown
solid; mp 4300 1C. 1H NMR (CDCl3, 500 MHz): d 9.60 (2H,
d, J = 8.36 Hz, Ph), 8.56 (2H, d, J = 8.35 Hz, Ph), 8.34 (2H, s,
Ph), 4.16 (4H, t, J = 7.62 Hz, NCH2), 1.68–1.72 (4H, m,
NCH2CH2–), 1.41–1.46 (4H, m, –CH2CH3), 0.96 (6H, t,
J = 7.36 Hz, –CH3); m/z (EI): 660.02 (M+, 100%).
All chemicals were purchased commercially and the solvents
dried or distilled when necessary using standard procedures.
1H and 13C NMR spectra were obtained on a Bruker
AVANCE 500 spectrometer operating at 500 MHz: chemical
shifts were quoted downfield of TMS. Elemental analyses were
obtained from a German elementar vario ELIII C, H, N
analyzer. UV-Vis absorption spectra were recorded on a
CARY 100 Conc UV-visible spectrophotometer. The fluores-
cence spectra were recorded on a CARY Eclipse Fluorescence
spectrophotometer and were corrected for the spectral res-
ponse of the machines. All the electrochemical experiments
were performed in dichloromethane with n-Bu4NPF6 as the
supporting electrolyte, platinum as the working and counter
Fig. 5 (A) Fluorescence emission spectra of dyad 4 recorded before (dotted line) and after addition of an excess of diacetoxyiodobenzene in the
presence of triflic acid in CH2Cl2 (c = 10ꢀ5 mol Lꢀ1, lexc = 480 nm). (B) Fluorescence emission spectra of dyad 4 (solid line), of dyad 4 after
oxidation (dashed line), and of dyad 4 after oxidation and reduction processes (dotted line) (c = 10ꢀ5 mol Lꢀ1, lexc = 480 nm).
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008
1972 | New J. Chem., 2008, 32, 1968–1973

View Article Online
Dyad 4. Compound 9 (567 mg, 1 mmol) was dissolved in
dried DMF (60 ml) and a solution of CsOHꢄH2O (168 mg,
1.05 mmol) in dried methanol (10 ml) was added dropwise under
N2. After stirring for 30 min, N,N0-dibutyl-1,6-dibromo-
3,4,9,10-perylenetetracarboxylic diimide 11 (330 mg, 0.5 mmol)
dispersed in dried DMF (20 ml) was added. The reaction
mixture was stirred for 16 h, filtered to give a dark brown solid,
and purified by column chromatography on silica gel
(CH2Cl2–petroleum ether, 2 : 1 v/v) to afford dyad 4 (993 mg,
and M. R. Bryce, J. Org. Chem., 2007, 72, 1301–1308; (d) C. A.
Christensen, A. S. Batsanov and M. R. Bryce, J. Am. Chem. Soc.,
2006, 128, 10484–10490.
2 (a) C. P. Collier, J. O. Jeppesen, Y. Luo, J. Perkins, E. W.
Wong, J. R. Heath and J. F. Stoddart, J. Am. Chem. Soc.,
2001, 123, 12632–12641; (b) J. O. Jeppesen, J. Perkins, J.
Becher and J. F. Stoddart, Angew. Chem., Int. Ed., 2001, 40,
1216–1221.
3 (a) Z. Wang, D. Q. Zhang and D. B. Zhu, J. Org. Chem., 2005,
70, 5729–5732; (b) G. Trippe, E. Levillain, F. Le Derf, A.
Gorgues, M. Salle, J. O. Jeppesen, K. Nielsen and J. Becher,
Org. Lett., 2002, 4, 2461–2464; (c) K. A. Nielsen, J. O. Jeppesen,
E. Levillain and J. Becher, Angew. Chem., Int. Ed., 2003, 42,
187–191.
4 M. Bendikov, F. Wuld and D. F. Perepichka, Chem. Rev., 2004,
104, 4891–4945.
5 G. X. Zhang, D. Q. Zhang, X. F. Guo and D. B. Zhu, Org. Lett.,
2004, 6, 1209–1212.
6 C. Farren, C. A. Christensen, S. FitzGerald, M. R. Bryce and A.
Beeby, J. Org. Chem., 2002, 67, 9130–9139.
7 (a) J. Becher, T. Brimert, J. O. Jeppesen, J. Z. Pedersen, R.
Zubarev, T. Bjørnholm, N. Reitzel, T. R. Jensen, K. Kjaer and
E. Levillain, Angew. Chem., Int. Ed., 2001, 40, 2497–2500; (b) H. C.
Li, J. O. Jeppesen, E. Levillain and J. Becher, Chem. Commun.,
2003, 846–847.
8 (a) S. Leroy-Lhez, J. Baffreau, L. Perrin, E. Levillain, M. Allain,
M.-J. Blesa and P. Hudhomme, J. Org. Chem., 2005, 70,
6313–6320; (b) S. Leroy-Lhez, L. Perrin, J. Baffreau and P.
Hudhomme, C. R. Chim., 2006, 9, 240–246; (c) X. F. Guo, D. Q.
Zhang, H. J. Zhang, Q. H. Fan, W. Xu, X. C. Ai, L. Z. Fan and D.
B. Zhu, Tetrahedron, 2003, 59, 4843–4850.
9 C. Goze, S. X. Liu, C. Leiggener, L. Sanguinet, E. Levillain,
A. Hauser and S. Decurtins, Tetrahedron, 2008, 64,
1345–1350.
10 C. Y. Jia, S. X. Liu, C. Tanner, C. Leiggener, A. Neels, L.
Sanguinet, E. Levillain, S. Leutwyler, A. Hauser and S. Decurtins,
Chem.–Eur. J., 2007, 13, 3804–3812.
1
65% yield) as a dark maroon solid; mp 219–221 1C. H NMR
(CDCl3, 500 MHz): d 8.97–9.12 (1H, br, Ph), 8.70 (1H, s, Ph),
8.59–8.63 (1H, m, Ph), 8.47 (2H, d, J = 8.56 Hz, Ph), 8.13 (1H,
d, J = 7.62 Hz, Ph), 4.15 (4H, t, J = 7.62 Hz, NCH2), 2.55–2.75
(14H, m, SCH3, SCH2CH2), 1.65–1.78 (4H, m, –CH2–),
1.46–1.57 (12H, m, –CH2–), 1.30–1.36 (4H, m, –CH2–),
1.20–1.28 (20H, m, –CH2–), 0.79–0.95 (18H, m, –CH3), 13C
NMR (CDCl3, 100 MHz): d 163.48, 162.77, 133.50, 132.16,
131.87, 128.98, 128.77, 128.29, 126.60, 121.53, 40.64, 35.95,
35.76, 31.29, 31.26, 30.19, 29.69, 29.59, 28.24, 28.16, 22.51,
20.48, 19.18, 13.99, 13.85; Found: C, 55.12, H 5.40, N 1.67.
C70H82N2O4S16 requires C, 55.01, H 5.41, N 1.83%; m/z (ES+):
1551.1 (100%, M+ + Na), 1528.2 (26, M+).
N,N0-Dibutyl-3,4:9,10,-perylenetetracarboxylic diimide 13.
To a suspension of 3,4,9,10-perylenetetracarboxylic dianhy-
dride (1.96 g, 5 mmol) in NMP (80 ml) were added n-butyla-
mine (1.98 ml, 20 mmol). The reaction mixture was heated to
reflux under N2 for 20 h, cooled to room temperature, poured
into 10% HCl (v/v) carefully, filtered and washed with water to
obtain a dark maroon solid, and purified by column chromato-
graphy on silica gel (CH2Cl2–ethyl acetate, 10 : 1 v/v) to give 13
(1.91 mg, 76% yield) as a reddish brown solid; mp 4300 1C. 1H
NMR (CDCl3, 500 MHz): d 8.57 (8H, d, J = 8.12 Hz, Ph), 4.16
(4H, t, J = 8.85 Hz, –NCH2–), 1.58–1.62 (4H, m, –CH2–),
1.17–1.20 (4H, m, –CH2–), 0.94 (6H, t, J = 10.13 Hz, –CH3);
m/z (EI+): 502.2 (M+, 100), 390.1 (43), 485.2 (40).
11 D. F. Perepichka and M. R. Bryce, Angew. Chem., Int. Ed., 2005,
44, 5370–5373.
12 (a) K. B. Simonsen, N. Svenstrup, J. Lau, O. Simonsen, P. Mørk,
G. J. Kristensen and J. Becher, Synthesis, 1996, 3, 407–418; (b) C.
A. Christensen, M. R. Bryce and J. Becher, Synthesis, 2000, 12,
1695–1704.
13 M. R. Bryce, W. Devonport, L. M. Goldenberg and C. S. Wang,
Chem. Commun., 1998, 945–951.
14 J. Baffreau, L. Perrin, S. Leroy-Lhez and P. Hudhomme,
Tetrahedron Lett., 2005, 46, 4599–4603.
15 M. R. Bryce, Adv. Mater., 1999, 11, 11–23.
16 D. Rehm and A. Weller, Isr. J. Chem., 1970, 8, 259. For dyad 4:
DGPET = E(ox) ꢀ E(red) ꢀ E0ꢀ0(13) ꢀ De, with E(ox) = +0.56 eV,
E(red) = ꢀ0.53 eV, E0ꢀ0(13) = 2.32 eV, De E 0.1 eV.
17 M. Giffard, G. Mabon, E. Leclair, N. Mercier, M. Allain, A.
Gorgues, P. Molinie, O. Neilands, P. Krief and V. Khodorkovsky,
J. Am. Chem. Soc., 2001, 123, 3852–3853.
Acknowledgements
This work was supported by National Natural Science Foun-
dation of China (No. 20676036) and the Key Project of the
Ministry of Education of China (No. 03053).
18 (a) N. Svenstrup, K. M. Rasmussen, T. K. Hansen and J. Becher,
Synthesis, 1994, 8, 809–812; (b) M. J. Ahrens, L. E. Sinks, B.
Rybtchinski, W. H. Liu, B. A. Jones, J. M. Giaimo, A. V. Gusev,
A. J. Goshe, D. M. Tiede and M. R. Wasielewski, J. Am. Chem.
Soc., 2004, 126, 8284–8294.
References
1 (a) F. Wudl, G. M. Smith and E. J. Hufnagel, Chem. Commun.,
1970, 1453–1454; (b) J. L. Segura and N. Martın, Angew. Chem.,
Int. Ed., 2001, 40, 1372–1409; (c) C. A. Christensen, A. S. Batsanov
19 SYBYL 7.3, Tripos International, St. Louis, MO, USA.
ꢂc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2008 New J. Chem., 2008, 32, 1968–1973 | 1973