Synthesis and characteristics of a nonaggregating tris(tetrathiafulvaleno) dodecadehydro[18]annulene

Article abstract of DOI:10.1002/chem.200600986

A new tris(tetrathiafulvaleno)dodecadehydro[18]annulene with six peripheral n-hexyl substituents was prepared by oxidative Glaser-Hay cyclization of a corresponding diethynylated tetrathiafulvalene (TTF) precursor. The electronic properties of the neutral and oxidized species were studied by both UV/Vis absorption spectroscopy and electrochemistry. From these studies, it transpires that the strongly violet-colored macrocycle does not aggregate in solution to any significant degree, which was confirmed by ¹H NMR spectroscopy. This reluctance towards aggregation contrasts that observed for related TTF-annulenes containing other peripheral substitutents. Oxidation of the TTF-annulene occurs in two three-electron steps as inferred from both the peak amplitudes and the spectroelectrochemical study. We find that the tris(TTF)-fused dehydro[18]annulene is more difficult to oxidize (by + 0.20 V) than the silyl-protected diethynylated mono-TTF precursor. In contrast, the first vertical ionization energy calculated at the B3LYP/6-311 + G(2d,p) level for the parent tris(TTF)-fused dehydro[18]annulene devoid of peripheral hexyl substituents is in fact lower (by 0.44 eV). Moreover, the surface morphology of 1d drop-cast on a mica substrate was investigated by atomic force microscopy (AFM). Crystalline domains with slightly different orientations were observed. The thickness of individual layers seen in the crystalline domains and the thickness of a monolayer obtained from a very dilute solution were determined to 1.8-1.9 nm. This thickness corresponds to the diameter of the macrocycle and the layers seen in the film are apparently formed when the molecules stack in the horizontal direction relative to the substrate.

Full text of DOI:10.1002/chem.200600986

FULL PAPER
DOI: 10.1002/chem.200600986
Synthesis and Characteristics of a Nonaggregating
Tris(tetrathiafulvaleno)dodecadehydro[18]annulene
AHCTREUNG
[
a, b]
[b, c]
[c]
Asbjørn Sune Andersson,
Kristine Kilså,
Tue Hassenkam,
[d]
[
d]
[d]
Jean-Paul Gisselbrecht, Corinne Boudon, Maurice Gross,
Mogens Brøndsted Nielsen,* and FranÅois Diederich*
[
b]
[a]
Abstract:
A
new tris(tetrathiafulva-
Oxidation of the TTF–annulene occurs
in two three-electron steps as inferred
from both the peak amplitudes and the
spectroelectrochemical study. We find
stituents is in fact lower (by0.44 eV).
Moreover, the surface morphologyof
1d drop-cast on a mica substrate was
investigated byatomic force microsco-
py(AFM). Cr syt alline domains with
slightlydifferent orientations were ob-
served. The thickness of individual
layers seen in the crystalline domains
and the thickness of a monolayer ob-
tained from a verydilute solution were
determined to 1.8–1.9 nm. This thick-
ness corresponds to the diameter of the
macrocycle and the layers seen in the
film are apparentlyformed when the
molecules stack in the horizontal direc-
tion relative to the substrate.
ACHTREUNG
leno)dodecadehydro[18]annulene with
six peripheral n-hexyl substituents was
prepared byoxidative Glaser–Haycy-
A
C
H
T
R
E
U
N
G
clization of a corresponding diethynyl-
that
the
tris
A
H
R
U
G
dehy-
ated tetrathiafulvalene (TTF) precur-
sor. The electronic properties of the
neutral and oxidized species were stud-
ied byboth UV/Vis absorption spec-
troscopyand electrochemist r. y From
these studies, it transpires that the
stronglyviolet-colored macroc yc le does
not aggregate in solution to anysignifi-
cant degree, which was confirmed by
dro[18]annulene is more difficult to ox-
idize (by +0.20 V) than the silyl-pro-
tected diethynylated mono-TTF pre-
cursor. In contrast, the first vertical
ionization energycalculated at the
B3LYP/6–311+G
A
H
R
U
G
parent tris(TTF)-fused dehydro[18]an-
AHCTREUNG
nulene devoid of peripheral hexyl sub-
1
H NMR spectroscopy. This reluctance
Keywords: aggregation · alkynes ·
cyclization · dehydroannulenes · tet-
rathiafulvalenes
towards aggregation contrasts that ob-
served for related TTF–annulenes con-
taining other peripheral substitutents.
Introduction
For more than three decades, tetrathiafulvalene (TTF) and
its derivatives have been studied on account of their unique
p-electron-donor properties.
[
a] A. S. Andersson, Prof. Dr. F. Diederich
Laboratorium für Organische Chemie, ETH Zürich, HCI
[1]
8
093 Zürich (Switzerland)
Fax : (+41)44-632-1109
E-mail: diederich@org.chem.ethz.ch
Effective methods have been
developed for the preparation
[
b] A. S. Andersson, Prof. Dr. K. Kilså, Prof. Dr. M. Brøndsted Nielsen
Department of Chemistry, University of Copenhagen
Universitetsparken 5, 2100 Copenhagen Ø (Denmark)
Fax : (+45)3532-0212
of elaborate molecular architec-
tures containing TTF moieties,
such as macrocycles, cyclophanes, cages, catenanes, rotax-
anes, dendrimers, and polymers, which are of interest for
E-mail: mbn@kiku.dk
[
1]
[
c] Prof. Dr. K. Kilså, Prof. Dr. T. Hassenkam
Nano-Science Center, Universityof Copenhagen
Universitetsparken 5, 2100 Copenhagen Ø (Denmark)
both materials and supramolecular chemistry. Acetylenic
[2]
[3–5]
scaffolding with ethynylated derivatives of TTF
as well
[6]
as of its dithiafulvene “half-unit”
presents one such
[
d] Dr. J.-P. Gisselbrecht, Prof. Dr. C. Boudon, Prof. Dr. M. Gross
Laboratoire dꢀElectrochimie et de Chimie Physique du Corps Solide
UMR 7177, C.N.R.S, Universitꢁ Louis Pasteur
method for constructing highlyconjugated optoelectronic
materials.
[4]
Rubin and co-workers suggested in 1998 the tris(tetra-
thiafulvaleno)dodecadehydro[18]annulene macrocycle 1a as
an interesting target molecule with potential to form con-
4
, rue Blaise Pascal, 67000 Strasbourg (France)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2006, 12, 8451 – 8459
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
8451

Results and Discussion
Synthesis: The synthesis of macrocycle 1d was accomplished
byusing the route outlined in Scheme 1. After consulting
the literature about the preparation of nonsymmetrically
[11]
substituted TTFs, we decided to prepare the 4,5-diethynyl-
ated, 4’,5’-dihexyl-substituted 2d bya Horner–Wadsworth–
AHCTREUNG
Emmons condensation, which avoids formation of unwanted
symmetrically substituted TTF.
[12]
The readilyavailable ac yl oin
3
was treated with PPh3
and CCl4 to give the corresponding a-chloroketone 4 in
nearlyquantitative iye ld, which in turn was converted to
compound 5 byreaction with potassium piperidine-1-carbo-
[13]
dithioate in acetone. Concentrated sulfuric acid affected
ring closing and dehydration, and the crude hexafluorophos-
ductive charge-transfer salts.
Yet onlyrecentl y, after comple-
tion of the present study, Iyoda
[5]
and co-workers reported the
synthesis of the first derivatives
1
b and 1c, containing electron-
withdrawing ester groups as pe-
ripheral substituents. These
macrocycles were prepared
from the monomeric precursors
2
b and 2c, respectively, and
showed a remarkable propensi-
tyfor p–p stacking aggregation Scheme 1. Synthesis of tris(tetrathiafulvaleno)dodecahydro[18]annulene 1d. a) CCl4, PPh3, MeCN, 97%;
in apolar aromatic solvents.
A
H
R
U
G
2
SO
4
, 08C, then HPF
6
(aq) 08C, 85%;
CH I, 88%;
Cl , 08C,
A
T
E
N
2
2
In parallel to that work, we
had targeted macrocycle 1d
containing six peripheral n-
hexyl groups to ensure solubili-
tyin organic solvents. These
A
T
U
3
2
A
H
E
N
3
)
2
3
4
2
2
2
4
[14]
phate salt 6 was isolated in good yield. Next, the known
[15]
groups were expected to slightlyincrease the electron-do-
nating properties of the TTF moieties, resulting in more effi-
cient intramolecular charge-transfer interactions of these en-
tities with the electron-accepting all-carbon core. Here, we
describe the synthesis of tris(TTF)-fused dehydro[18]annu-
phosphonate ester 7
was deprotonated with nBuLi at
ꢀ788C, which was followed byaddition of electrophile 6.
Subsequent treatment with acetic acid at room temperature
gave 4,5-dihexyl-substituted TTF 8 in 73% yield. Deproto-
[7]
A
H
R
U
nation of 8 using an excess of lithium diisopropylamide
A
C
H
T
R
E
U
N
G
lene 1d and report its optical and electrochemical properties
which differ stronglyfrom those of 1b and 1c with peripher-
al electron-accepting ester substituents. In sharp contrast to
the last two macrocycles, hexyl-substituted 1d is reluctant to
aggregate in apolar aromatic solvents; this result demon-
strates the important contributions of the ester groups in 1b
and 1c to self-association. These groups greatlyextend the
p-conjugated perimeter, and interactions between the local
(LDA) in THF at ꢀ788C gave the dilithiated TTF, which
was trapped with 1,2-diiodoethane to afford 9 in high yield.
The subsequent conversion to 10 was achieved byusing a
Sonogashira cross-coupling reaction with triisopropylsilyl-
acetylene. This conversion was accompanied by the forma-
tion of mono-coupled hydrodeiodinated TTF as a byproduct,
which caused trouble for the column chromatographic pu-
rification on account of the small polaritydifferences be-
[16]
[8,9]
ester dipoles mayadditionallyassist aggregation.
Further-
tween mono-alkynylated byproduct and dialkynyl
A
C
H
T
R
E
U
N
G
ated 10.
more, it is well established bythe work of Hunter and Sand-
ers that electron-withdrawing substituents favor aromatic
The hydrodehalogenation side reaction in the Sonogashira
[
10]
[17]
cross-coupling has been reported byothers
and seems to
p–p stacking interactions bychanging the electrostatic prop-
erties of the chromophores.
be more pronounced for electrophiles containing more than
one halogen atom. Desilylation of 10 was accomplished with
[8]
Bu NF in wet THF, and the resulting unstable terminal
4
diyne 2d was not isolated, but immediatelysubjected to an
[18]
oxidative Hay-coupling protocol
to give the strongly
violet-colored annulene 1d in 47% yield.
8452
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Chem. Eur. J. 2006, 12, 8451 – 8459

Dehydroannulenes
FULL PAPER
In contrast to the findings for oxidative coupling of cis-
(2.7 eV) in CHCl , while this band is significantlyred-shifted
for annulene 1d (lmax =532 nm, 2.3 eV) (Figure 1). More-
over, 1d exhibits a new broad absorption band/tail that ex-
3
[7,19]
bisdeprotected tetraethynylethenes,
the formation of
cyclic dimers was not observed in the Hay coupling of 2d.
From X-raycr ys tallographic anal ys is, the inner C(sp) ꢀC=C
bond angles in the strained tetraalkynylatead octadehy-
[19]
dro[12]annulene were determined to 117.68 and 118.58.
Calculations on 1a and 2a (vide infra) revealed instead
C(sp)ꢀC=C bond angles of 124.88 and 123.98, respectively.
Thus, formation of the cyclic trimer 1d from 2d onlyre-
quires a minor decrease in this bond angle. It seems reason-
able to assume that the much larger bond angle deviation
required for formation of the cyclic dimer is thwarted by an-
nulation of the five-membered ring in the latter and there-
fore the pathwayleading to the octadeh dy ro[12]annulene
cannot compete with the formation of the trimer.
Differential scanning calorimetry(DSC) of 1d in the tem-
perature range from 25 to 2508C showed an exothermic
drop starting at ca. 1008C (see Supporting Information). As
this process was irreversible, it must correspond to a decom-
position reaction. Thus, no endothermic melting process was
observed upon further heating. The decomposed material
was completelyinsoluble in organic solvents.
Figure 1. Electronic absorption spectra of 1d and 10 in chloroform.
tends to approximately790 nm (1.6 eV). This broad band is
ascribed to an intramolecular charge transfer from the pe-
ripheral TTF donors to the electron-accepting all-carbon
[7]
core (vide infra). The characteristic absorption maximum
of 1d at lmax =532 nm is red-shifted relative to 1b and 1c
(lmax =496 nm for 1b/c in CH Cl ), but has a somewhat
1
H NMR spectroscopy: To investigate the degree of aggre-
2
2
1
gation of 1d, we performed H NMR spectroscopic studies
smaller molar absorptivity. Thus, the nature of the peripher-
al substitution has a substantial influence on the absorption
characteristics. The absorption properties of 1d were investi-
gated in a selection of solvents (see Supporting Informa-
tion), and a small degree of solvatochromism is observed in
in C D . The resonances for the TTF-CH protons only
6
6
2
change veryslightlyfrom
d=2.112 ppm to d=2.099 ppm
(
4
i.e., a shift of ꢀ0.013 ppm) upon diluting a sample from
[5]
.6mm to 0.31mm. In comparison, Iyoda and co-workers
observed a significant upfield shift of ꢀ0.135 ppm for the
CS , in which the absorption maxima are red-shifted.
Importantly, we find that in both toluene and 2-methylte-
2
TTF-CO CH protons on 1c when diluting a sample from
2
2
4
.10mm to 0.310mm. The noticeable downfield shift experi-
trahydrofuran, the absorption spectrum of 1d is concentra-
ꢀ
6
enced by 1c at higher concentrations was interpreted as re-
sulting from considerable aggregation in benzene. Thus sub-
stitution of the peripheral ester substituents (in 1c) for
hexyl groups (in 1d) profoundlychanges the propensityof
the TTF–annulene to aggregate as judged from H NMR
data.
tion independent (in the concentration range from 7”10 m
ꢀ4
to 1.5”10 m) and follows the Lambert–Beer law, indicating
that no aggregation of the macrocycle takes place. This ob-
1
servation is in agreement with the H NMR spectroscopic
1
study(vide supra). Not even upon cooling a sample (from
278C to ꢀ738C in toluene; from 278C to ꢀ1738C in 2-meth-
yltetrahydrofuran) were any indications of spectral shifts ob-
served. In contrast, absorption spectroscopysupported
Absorption spectroscopy: UV/Vis absorption data for the
two new compounds 1d and 10 are collected in Table 1 to-
gether with literature data for 1b and 1c. Compound 10
shows a longest wavelength absorption at lmax =461 nm
[5]
strong aggregation of macrocycles 1b and 1c in toluene.
[5]
Electrochemistry: Cyclic voltammetry data in CH Cl2
2
(
+0.1m nBu NPF ; all poten-
4 6
tials referenced against the fer-
ricinium/ferrocene couple (Fc /
Table 1. UV/Vis absorption maxima (lmax [nm]) and logarithmic molar extinction coefficients (loge) given in
parentheses.
+
[
a]
[
b]
Fc)) are collected in Table 2.
Solvent
l
max [nm]
Compound 10 experiences two
(
loge)
308 [4.0]
4.83)
308 [4.0]
4.85)
314 [3.9]
sh, 4.77)
ꢀ
[
c]
well-resolved reversible 1e ox-
1
1
1
b
CH
CH
2
Cl
Cl
2
2
344 [3.6]
(sh, 4.83)
344 [3.6]
(sh, 4.85)
328 [3.8]
(4.78)
359 [3.5]
(4.89)
359 [3.5]
(4.92)
355 [3.5]
(sh, 4.81)
397 [3.1]
(sh, 4.57)
397 [3.1]
(sh, 4.56)
373 [3.3]
(4.94)
496 [2.5]
(4.46)
496 [2.5]
(4.49)
407 [3.0]
(sh, 4.51)
685 [1.8]
(sh, 3.43)
685 [1.8]
(sh, 3.37)
532 [2.3]
(br, 4.29)
(
idations at +0.00 and +0.52 V.
For comparison, the parent tetra-
thiafulvalene (TTF) undergoes
[
c]
c
2
(
d
CHCl
CHCl
3
590–790
[1.6-2.1]
br t)
ꢀ
the two 1e oxidation steps at
(
ACHTREUNG
ꢀ
0.08 and +0.40 V under the
(
[20]
1
0
same conditions.
Thus, both
3
263 [4.7]
sh, 4.19)
299 [4.1]
(4.33)
338 [3.7]
(sh, 4.10)
461 [2.7]
(br, 3.26)
(
oxidations of 10 are rendered
[a] sh=shoulder; br=broad; t=tail. [b] The value in square brackets is the absorption maximum in eV. more difficult bythe introduc-
[c] Reference [5].
Chem. Eur. J. 2006, 12, 8451 – 8459
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8453

F. Diederich, M. B. Nielsen et al.
Table 2. Electrochemical data measured in CH
potentials versus Fc /Fc. Working electrode: glassycarbon electrode;
counter electrode: Pt; reference electrode: Ag/AgCl. Scan rate: 0.1 Vs
2
Cl
2
+0.1m nBu
4
NPF
6
. All
ethynyl groups as present in 10. The cyclic voltammogram
+
[5]
reported byI oy da and co-workers
for macrocycle 1b
ꢀ
1
.
showed oxidations to the tri- and hexacation at 0.43 V
o[a]
[b]
[c]
Compound
E
[V]
+0.20
0.64
DE
p
[mV]
E
p
[V]
+
(
broad) and 0.70 V, respectively, versus Fc /Fc in CH Cl .
2 2
1
d
0
90
110
Thus, these potentials are significantlyanodicallyshifted rel-
ative to those of 1d on account of the electron-withdrawing
ester groups.
Analysis of the CV parameters as a function of scan rate
revealed that adsorption occurs during the first oxidation of
+
+
ꢀ
ꢀ
1.20
1.40
1.70
1
+0.00
0.52
ꢀ0.08
60
65
60
+
1
d. Indeed the corresponding anodic peak current is propor-
TTF
[
d]
tional to the scan rate, characteristic of a weak adsorption
+
0.40
[21]
of the reactant. In contrast, the second oxidation behaves
as a reversible electron transfer. The peak potential is scan
rate independent; the peak current ratio is equal to unity,
and a linear correlation between the peak current and the
square root of the scan rate is observed. However, the peak
potential difference is equal to 90 mV for the first oxidation
and 110 mV for the second oxidation. These characteristics
indicate that small interactions between the TTF redox cen-
ters occur, which is expected due to the macrocyclic conju-
gation. These interactions are larger for the second oxida-
tion, since a peak potential difference of only60 mV would
o
[
a] E =(Epc +Epa)/2, in which Epc and Epa correspond to the cathodic and
anodic peak potentials, respectively. [b] DE =Eox-Ered, in which sub-
scripts ox and red refer to the conjugated oxidation and reduction steps,
respectively. [c] Peak potential E for irreversible electron transfer.
d] Deposition on electrode surface.
p
p
[
tion of the two electron-withdrawing alkynyl residues. Mac-
rocycle 1d undergoes two reversible oxidation steps at
0.20 and +0.64 V as well as two irreversible reductions
+
with peak potentials at ꢀ1.40 and ꢀ1.70 V. As shown in
[22]
Figure 2, a third irreversible oxidation (E =+1.20 V) is ob-
have been expected for three independent redox centres.
pa
Spectroelectrochemical investigation of 10 gave a nice
spectral evolution for both oxidation steps as shown in the
Supporting Information. The initial spectrum was recovered
quantitatively, which means that the generated species is
+
stable. The generated radical cation 10C is characterized by
absorptions at lmax =412, 468, and 713 nm (3.0, 2.6, and
2
+
1
.7 eV), while the dication 10 has a strong absorption at
lmax =537 nm (2.3 eV). Several studies have been performed
[23]
+
on TTF. Thus, TTFC experiences absorption maxima at
lmax =430 and 580 nm (2.9 and 2.1 eV) in MeCN and an ab-
sorption at lmax =714 nm (1.7 eV) in EtOH at 225 K that has
2
+
been assigned to the p dimer TTF2 . The abilityof TTF
radical cations to dimerize depends stronglyon the substitu-
+
tion pattern and the absorption of 10C at 713 nm maybe an
intrinsic absorption of the radical cation rather than imply-
[23d]
2+
Figure 2. Cyclic voltammetry of 1d in CH
2
Cl
2
(+0.1m nBu
4
NPF
6
) in the
ing p-dimer formation.
TTF absorbs at lmax =390 nm
presence of ferrocene on a GC working electrode at a scan rate of
(3.2 eV) in MeCN, that is, at significantlyhigher energythan
ꢀ
1
0
.1 Vs
.
2+
the absorption of 10
.
Spectroelectrochemical studies on 1d carried out during
oxidation showed for the first oxidation step nice isosbestic
+
served on the anodic electrolyte discharge. The peak ampli-
tude for the first two oxidations is about three times larger
than for the first reduction. It seems therefore reasonable to
assume that the first oxidation involves three electrons and
occurs on the three TTF moieties, generating the tris-radical
points (electrolysis at +0.30 V versus Fc /Fc; Figure 3). The
initial spectrum could be recovered quantitativelybyreduc-
tion of the electrogenerated oxidized species at 0 V versus
Fc /Fc. The evolving absorption bands at l =425, 467,
and 705 nm (2.9, 2.7, and 1.8 eV) are attributed to the tri-
+
max
3
+
+
3+
cation 1d
/
A
C
H
T
R
E
U
N
G
(TTFC ) , whereas the second oxidation yields
A
H
R
U
G
3
6
+
2+
the hexacation 1d
/
A
H
R
U
G
+0.80 V versus Fc /Fc; Figure 4), onlyone isosbestic point
could be observed. A broad absorption around 530 nm
(2.3 eV) evolves. Reduction of the generated species led
onlyto the recoveryof about 90% of the initial spectrum
on account of some degradation of the generated species.
As the absorption spectra of oxidized 1d and 10 resemble
each other, it seems reasonable to assume that the two oxi-
dation steps of 1d involve three electrons each. Still, howev-
3
is a one-electron step occurring on the conjugated all-
carbon macrocycle. In agreement with the strong electron-
accepting nature of the inner core, the TTF moieties in 1d
are poorer electron donors than the TTF moietyin dialky-
nylated 10 (first oxidation at +0.00 V). Each TTF unit in 1d
can also be considered to be functionalized with two buta-
diynyl groups that are stronger electron acceptors than two
8454
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Chem. Eur. J. 2006, 12, 8451 – 8459

Dehydroannulenes
FULL PAPER
Figure 5. Frontier orbitals of 2a (B3LYP/6–311+G(2d,p)).
A
H
R
U
Figure 3. Time-resolved UV/Vis spectroelectrochemical investigation of
1
d in CH
2
Cl
2
+0.1m nBu
4 6
NPF for the first oxidation step at +0.30 V
+
versus Fc /Fc.
Figure 4. Time-resolved UV/Vis spectroelectrochemical investigation of
d in CH Cl +0.1m nBu NPF for the second oxidation step. The initial
1
2
2
4
6
spectrum corresponds to the species obtained after the first oxidation
step. The final spectrum after oxidation at +0.80 V and subsequent re-
+
duction at +0.30 V versus Fc /Fc is shown in red.
Figure 6. Frontier orbitals of 1a (B3LYP/6–311+G(2d,p)). The
A
H
R
U
HOMOꢀ1 and HOMO are degenerate, as are the LUMO and
LUMO+1.
er, the three TTF units are not independent redox centers
as judged from the peak potential difference.
[25]
TTF is 6.49 eV. Thus, the donor strength decreases in the
gas phase along the sequence 1d>10>TTF, while it de-
creases along the opposite sequence TTF>10>1d in solu-
tion. That donor properties in solution and gas phase can be
difficult to correlate was previouslyobserved for alk yn e-ex-
Computational study: A computational studywas per-
formed on macrocycle 1a and its monomeric precursor 2a,
both devoid of peripheral substituents, byemplo iyn g the
Gaussian 03 program package. The molecules were geom-
etry-optimized at the semiempirical PM3 level, and then
single-point calculations were performed at the DFT level
[24]
[6f]
tended TTFs.
(
B3LYP/6–311+G
A
C
H
T
R
E
U
N
G
(2d,p)). The frontier orbitals resulting
Surface study: Figure 7 shows the surface morphologyof a
drop-cast solution of 1d in chloroform on a mica substrate.
from these calculations are presented in Figures 5 and 6. It
ꢀ
1
transpires that the HOMO and HOMOꢀ1 (degenerate) of
When the chloroform (approx 1 mgmL ) evaporates, it
forms a particular structure at the edge of the drop-cast
area, as seen in Figure 7A, which shows an optical differen-
tial interference contrast (DIC) image of the sample. The
morphologyof the edge of the drop-cast area is character-
ized bya thin band of cr ys talline domains as seen in the cen-
tral part of Figure 7A. This observation suggests an ordered
structure in which the molecules form crystalline domains
with slightlydifferent orientations. To verifythis, the region
displayed in Figure 7A was studied under an atomic force
1
a are mainlysituated at the TTF units, while the LUMO
and LUMO+1 (degenerate) are situated predominantlyat
the central core. Thus, the lowest energyabsorption of 1a
has significant charge-transfer character. Single-point ener-
gies of the neutral and radical cations of 1a and 2a provide
vertical ionization energies of 5.92 eV and 6.36 eV, respec-
tively. Thus, as would be expected, the donor properties are
enhanced in the gas phase for 1a as compared to 2a. For
comparison, the first vertical ionization energyof the parent
Chem. Eur. J. 2006, 12, 8451 – 8459
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8455

F. Diederich, M. B. Nielsen et al.
forms layered stacks as shown schematically in Figure 7D.
The molecules are probablyslightlytitled and the hexly
chains smear out along the top and bottom plane of the
layer. Interestingly, Iyoda and co-workers observed that 1b
formed threads on a silicon wafer that dried to a fibrous
[5]
structure.
Conclusion
Cyclization of the diethynylated TTF 10 after desilylation
under Glaser–Hayoxidative conditions provides an efficient
route to the well-soluble tris(tetrathiafulvaleno)dodecadehy-
dro[18]annulene 1d with six peripheral hexyl substituents.
1
According to both H NMR and UV/Vis absorption spec-
troscopystudies, the macroc yc le shows basicallyno aggrega-
tion in solution. This behavior stronglycontrasts that of
TTF–annulenes containing peripheral carboxylic ester sub-
[5]
stituents. The strong violet color of 1d is accordinglyas-
signed to an intramolecular charge-transfer transition rather
than to an intermolecular one. The three TTF moieties in
Figure 7. The structure of a drop-cast film from chloroform solution of
d. A) An optical differential interference coherence image of the edge
of a drop-cast film. A thin band of crystalline domains is visible in the
center of the image; the pink area to the right is the freshlycleaved mica
surface on which the films were drop-cast. B) A representative 10 mm”
1
d are oxidized in two three-electron steps. The number of
1
electrons involved in each step is supported byspectroelec-
trochemical characterization of the oxidized species formed
from 1d and 10. The first oxidation of 10 is cathodically
shifted by +0.20 V relative to that of 1d; that is, the TTF
moieties of the macrocyclic system are more difficult to oxi-
dize due to the strong electron-accepting properties of the
all-carbon core. In contrast, we find that the calculated first
1
0 mm AFM recording of the surface of a crystalline domain located in
the thin band seen in A). C) A representative 5 mm”5 mm AFM record-
ing of the surface of a verythin drop-cast film. The insets in both B and
C are topographycross sections extracted at the white lines in the AFM
recordings. The cross sections indicate that the thickness of the monolay-
er in both cases is just below 2 nm. D) A cartoon model of a possible ar-
rangement of the molecules, giving rise to the layered structure seen in
both B and C. The thickness of the molecules, standing edge on the sur-
face with the side chains smeared out on the stacked molecules, is close
to the observed value of 1.8–1.9 nm.
vertical ionization energyof the parent compound
1a
(
devoid of hexyl substituents) is 0.44 eV lower than that of
2
a. Drop-cast films of macrocycle 1d show crystalline do-
mains with slightlydifferent orientations. AFM studies sug-
gest that the molecules are deposited in successive monolay-
ers as the chloroform evaporates from the region. Drop-
casting of a verythin solution gave monola ye rs of thickness-
es 1.8–1.9 nm, which correspond to the diameter of the mac-
rocycle. Thus, the molecules seem to stack as schematically
depicted in Figure 7D.
microscope (AFM). An example of how the surface ap-
peared in the AFM in the thin band of domains is displayed
in Figure 7B, which is a 10”10 mm AFM tapping mode re-
cording. The molecules appear to form a layered structure
with abrupt edges. The direction of the image is such that
the right-hand side is toward the edge of the drop-cast area,
indicating that the molecules are deposited in successive
monolayers as the chloroform evaporates from the region,
thus creating the distinct step-like morphologyseen in the
image. We also created a monolayer of the molecule by
A veryimportant lesson concerning the p-stacking aggre-
gation tendencyof dodecadeh yd ro[18]annulenes is learned
through comparison of the results presented in this paper
for 1d and those reported byI yo da and co-workers for the
ester-substituted derivatives 1b and 1c. In previous work on
[7,19b,26]
dodecadehydro[18]annulenes,
perethynylated or fused
ꢀ
1
drop-casting a verydilute solution (less than 0.1 mgmL
)
with their olefinic moieties to other rings, we never had ob-
served substantial aggregation tendencies. In other words,
onto a mica substrate, but instead of waiting for the drop to
dry, we sucked away the excess chloroform by touching the
edge of the drop with a piece of filter paper. The chloroform
in the thin meniscus of solution left behind evaporated
shortlyafter, leaving behind an incomplete monola ey r as
seen in Figure 7C. The thicknesses of the monolayers seen
in Figure 7B and 7C are almost identical: 1.9 nm (SD 0.2)
for the layers seen in B and 1.8 nm (SD 0.1) for the layer
seen in C. From the geometryoptimization (vide supra) of
1
the Lambert–Beer law was obeyed and the H NMR chemi-
cal shifts were nearlyconcentration-independent. The same
behavior is observed for 1d, and we conclude that the p-
stacking aggregation tendencyis negligible and not an in-
trinsic property of these acetylenic macrocycles, including
the TTF derivatives. Therefore, we explain the veryinterest-
ing self-assemblyresults reported byI yo da and co-workers
with the presence of the six ester groups. These groups
render the entire p chromophore more electron-deficient,
1
a, a diameter of the macrocycle (excluding the side chains)
[10]
of 1.8–1.9 nm is estimated. We therefore assume that 1d
which favors p stacking. Theyalso extend the conjugated
8456
www.chemeurj.org
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2006, 12, 8451 – 8459

Dehydroannulenes
FULL PAPER
p perimeter, but most importantly, they can undergo inter-
tained bya Zeiss axiotech setup for differential interference contrast
with 20”10 magnification.
[8,9]
molecular dipolar interactions
that ultimatelylead to the
8
-Chlorotetradecan-7-one (4): PPh
solution of 3 (4.94 g, 21.6 mmol) in MeCN (100 mL). The mixture was
cooled to 108C, and CCl (10.5 mL, 108 mmol) was added bys yr inge.
3
(7.38 g, 28.1 mmol) was added to a
observed self-assembly. The fact that 1b and 1c onlyshow
aggregation in benzene or toluene, but not in the more
4
polar solvents CDCl , CH Cl , or THF, further corroborates
3
2
2
After the addition, the mixture was allowed to reach 208C and was stir-
red for 1 h. MeOH (30 mL) was added and the solution stirred for 0.5 h
and concentrated in vacuo. The residue was dissolved in a minimum of
the role of dipolar interactions in the self-association pro-
cess, since such interactions are highlydependent on the die-
lectric constant of the environment. We therefore feel that
the entire bodyof studies reported here and elsewhere by
CH
2 2
Cl and passed through a short silica column (hexane/EtOAc 9:1) to
1
afford 4 as a colorless oil (5.19 g, 97%). H NMR (300 MHz, CDCl
3
): d=
.19 (dd, J=5.6 Hz, J=8.4 Hz, 1H), 2.64 (t, J=6.9 Hz, 2H), 2.0–1.2
3
3
3
4
[5]
Iyoda and co-workers suggests that aromatic p-stacking
self-assemblycan be stronglyenhanced byadditional inter-
molecular dipolar interactions between appropriate func-
tional groups.
3
13
(
m, 18H), 0.88 ppm (t, J=6.9 Hz, 6H); C NMR (75 MHz, CDCl
3
): d=
205.5, 63.8, 38.6, 33.9, 31.6, 31.5, 28.8, 28.7, 26.1, 23.7, 22.6 (”2), 14.1 ppm
(
(
”2); IR (neat): n˜ =2956 (m), 2927 (s), 2858 (s), 1719 (s), 1462 (s), 1406
ꢀ
1
w), 1377 (m), 725 (m), 630 cm (s); EI-MS (70 eV): m/z (%): 246 (0.5)
+
+
[
M] , 113 (100) [C
7
H
13O] ; HR-EI-MS: m/z calcd for
C
14
H
27ClO:
2
46.1745; found: 246.1742; elemental analysis (%) calcd for C14
H27ClO
(
246.82): C 68.13, H 11.03; found: C 68.13, H 11.12.
Experimental Section
1-Hexyl-2-oxooctyl piperidine-1-carbodithioate (5): Potassium piperidine-
1
2
-carbodithioate (4.40 g, 22.0 mmol) was added to a solution of 4 (5.19 g,
1.0 mmol) in acetone (100 mL), and the mixture stirred at 208C for 3 h.
General methods: Chemicals were purchased from Acros, Fluka, or Al-
drich and used as received. THF was distilled from sodium/benzophe-
none. Acetonitrile was dried over 4 Š molecular sieves. Technical grade
solvents were distilled before use. Haycatal ys t refers to a freshlypre-
pared solution of CuCl (100 mg, 1.0 mmol) and N,N,N’,N’-tetramethyl-
The solvent was removed in vacuo, and Et
resulting mixture was extracted with H O (3”100 mL), the water phase
extracted with Et O (100 mL), and the combined organic phases dried
), filtered, and concentrated in vacuo. Column chromatography
, hexane/EtOAc 93:7) gave 5 (6.86 g, 88%) as a colorless oil.
2
O (200 mL) was added. The
2
2
(
(
MgSO
SiO
4
A
C
H
T
R
E
U
N
G
ethylenediamine (TMEDA; 0.15 mL, 1.0 mmol) in CH
actions were carried out under dryN or Ar. TLC: pre-coated silica gel
plates Alugram UV254 (Macherey-Nagel). Column chromatography:
Kieselgel 60 (Fluka, particle size 0.040–0.063 mm). Deactivation of SiO
was done byflushing the column with 10% Et N in hexane and then
2 2
Cl (25 mL). Re-
2
1
3
H NMR (300 MHz, CDCl
3
): d=4.95 (t, J=7.2 Hz, 1H), 4.25 (br s, 2H),
2
3
0
.91 (br s, 2H), 2.8–2.5 (m, 2H), 2.0–1.5 (m, 8H), 1.4–1.2 (m, 16H),
.86 ppm (t, J=6.9 Hz, 6H); C NMR (75 MHz, CDCl ): d=207.9,
3
3
13
2
193.8, 59.8, 53.5, 51.6, 41.6, 31.7, 31.6, 30.4, 29.1, 28.8, 27.3, 26.1, 25.5,
24.3, 23.8, 22.6 (”2), 14.1 ppm (”2); IR (neat): n˜ =2926 (s), 2856 (s),
2360 (w), 1711 (s), 1475 (m), 1427 (s), 1361 (w), 1280 (w), 1242 (s), 1227
3
washing with hexane. NMR: Varian Gemini 300 spectrometer; chemical
shifts (d) are given in ppm relative to TMS; coupling constants (J) are
given in Hz; solvent signals were used as internal references. Infrared
spectra (IR) were recorded on a Varian 800 FT-IR spectrometer. EI-MS
spectra were measured on a Hitachi–Perkin–Elmer VG-TRIBID spec-
trometer; ESI-MS spectra were measured on a Finnigan Mat TSQ 7000
spectrometer. High resolution (HR) FT-MALDI spectra were measured
on an Ionspec Ultima Fourier transform instrument with 3-hydroxypico-
ꢀ
1
(s), 1134 (w), 1113 (w), 1005 (w), 974 (w), 891 (w), 853 cm (w); EI-MS
+
+
(70 eV): m/z (%): 371 (0.8) [M] , 211 (48) [C14
H
27O] , 128 (100)
+
[C
6
H
10NS] ; HR-EI-MS calcd for
C
20
H
37NOS 371.2312; found:
2
:
371.2313; elemental analysis (%) calcd for C20
H
37NOS (371.64): C 64.64,
2
H 10.03, N 3.77, S 17.26; found: C 64.77, H 10.03, N 3.90, S 17.14.
N-(4,5-Dihexyl-1,3-dithiol-2-ylidene)piperidinium hexafluorophosphate
linic acid (3-HPA) in MeOH/H
CH Cl (two-layer technique). Differential scanning calorimetry (DSC)
was carried out on a Mettler Toledo DSC 822 under nitrogen flow, at a
2
O as matrix, and the compound in
(
6): Compound 5 (6.86 g, 18.5 mmol) was added dropwise to a stirred ice-
2
2
cold solution of concentrated sulfuric acid (15 mL). After the addition,
the mixture was allowed to reach 208C, stirred for 4 h, and then poured
ꢀ
1
heating rate of 28Cmin between 258C and 2508C. Melting points were
measured on a Büchi B-540 melting-point apparatus in open capillaries
and are uncorrected. Elemental analyses were performed by the Mikrola-
bor at the Laboratorium für Organische Chemie, ETH Zürich.
slowlyinto H
8.5 mmol) and cooled to 08C. CH
phases separated. The water phase was extracted with CH
2
O (65 mL) containing HPF
Cl (150 mL) was added and the
Cl (2”
0 mL), and the combined organic phases were washed sequentiallywith
6 2
(2.35 mL, 65 wt% in H O,
1
2
2
2
2
5
Electrochemistry: Electrochemical measurements were carried out in
3
water (50 mL), saturated aqueous NaHCO (50 mL), and water (50 mL),
CH
2
Cl
2
containing 0.1m nBu
4
NPF
6
in a classical three-electrode cell by
dried (MgSO ), filtered, and concentrated in vacuo to yield 6 (7.85 g,
4
cyclic voltammetry (CV) and rotating-disk voltammetry (RDV). The
working electrode was a glassycarbon (GC) disk (2 mm in diameter), the
auxiliaryelectrode a Pt wire, and the reference electrode an aqueous Ag/
AgCl electrode. The cell was connected to an Autolab PGSTAT20 poten-
tiostat (Eco Chemie, Holland) driven bya GPSE software running on a
85%) as a viscous orange oil of sufficient purityfor further reaction. An
analytically pure sample was obtained by column chromatography (SiO ,
2
1
3
hexane/acetone 3:2). H NMR (300 MHz, CDCl ): d=3.81 (t, J=6.5 Hz,
4H), 2.64 (t, J=7.8 Hz, 4H), 1.95–1.73 (m, 6H), 1.61 (m, 4H), 1.41–1.23
(m, 12H), 0.89 ppm (t, J=6.9 Hz, 6H); C NMR (75 MHz, CDCl ): d=
3
3
3
13
3
+
personal computer. All potentials are given versus Fc /Fc used as inter-
184.4, 133.7, 56.6, 31.3, 30.3, 28.7, 28.6, 25.0, 22.5, 21.5, 14.1 ppm; IR
nal reference and are uncorrected from ohmic drop. Spectroelectrochem-
ical studies were also carried out in the same medium, in a home-made
OTTLE cell placed in a diode arrayspectrophotometer HP 8453.
(neat): n˜ =2955 (w), 2930 (m), 2858 (w), 1609 (w), 1542 (m), 1448 (m),
ꢀ
1
1378 (w), 1258 (m), 1238 (w), 1115 (w), 1007 (w), 831 cm (s); ESI-MS:
[
27]
+
m/z (%): 354 (100) [C H NS ] ; elemental analysis (%) calcd for
2
0
36
2
UV/Vis spectroscopy: UV/Vis spectra were recorded on a Varian Cary
20 36 6 2
C H F NPS (499.60): C 48.08, H 7.26, N 2.80, S 12.84; found: C 47.99,
H 7.49, N 2.79, S 13.04.
5
00 or a Varian Cary50 spectrophotometer, using the pure solvent as
baseline. Low-temperature spectra were recorded using a temperature
controlled liquid nitrogen Oxford cryostat (OptistatDN).
4,5-Dihexyltetrathiafulvalene
8.1 mmol) was added dropwise to a suspension of 1,3-dithiolium iodide
(8):
Trimethylphosphite
(0.95 mL,
[
28]
Drop-cast and AFM: The drop-cast films were made from a solution of
(1.71 g, 7.43 mmol) in dryMeCN (40 mL) cooled to 0 8C. After the addi-
tion was complete, the reaction was stirred at 208C for 0.5 h and concen-
trated in vacuo to give the crude phosphonate ester 7, which was dis-
solved in dryTHF (40 mL) and cooled to ꢀ788C. BuLi (4.8 mL, 1.6m in
hexane, 7.7 mmol) was added dropwise and the milkywhite mixture stir-
red for 10 min, whereupon the crude hexafluorophosphate salt 6 (5.07 g,
10.2 mmol) in dryTHF (5 mL) was added in one portion. The mixture
was stirred for 15 min at low temperature and then heated to 208C and
ꢀ
1
1
mgmL of 1d in HPLC-grade chloroform. The monolayer was created
ꢀ1
[15]
using a verythin ( <0.1 mgmL ) solution of 1d in HPLC-grade chloro-
form. The films were drop-cast on a freshlycleaved mica surface and
were allowed to dryunder ambient conditions. The AFM images were re-
corded with a Nanoscope IIIa from Veeco Instruments, working in tap-
ping mode, byusing a silicon tapping mode tip from Ol ym pus (300 kHz),
under ambient conditions (238C). The optical image in Figure 7A was ob-
Chem. Eur. J. 2006, 12, 8451 – 8459
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8457

F. Diederich, M. B. Nielsen et al.
stirred for another 45 min. Acetic acid (4.0 mL, 70 mmol) was added, the
mixture stirred for 2 h, and the dark green solution concentrated in
128.7, 125.2, 85.1, 79.6, 31.5, 29.8, 28.8 (2C), 22.5, 14.1 ppm; IR (neat):
n˜ =2953 (m), 2920 (s), 2851 (s), 2172 (w), 2124 (w), 1611 (w), 1458 (s),
1377 (s), 1096 (s), 1046 (w), 1012 (w), 937 (m), 924 (m), 909 (m), 777 (s),
vacuo to a volume of about 10 mL. Et
mixture washed sequentiallywith H O (100 mL), saturated aqueous
NaHCO (100 mL), and H O (100 mL), and was then dried (MgSO ), fil-
tered, and concentrated in vacuo. Column chromatography(SiO
2
O (150 mL) was added and the
ꢀ
1
722 cm (m); UV/Vis (CHCl
3
): lmax (e)=314 (sh, 58300), 328 (60400),
2
355 (sh, 64300), 373 (87000), 407 (sh, 32000), 532 (19500), 590–790 nm
3
2
4
+
,
66 78
(br); HR-FT-MALDI-MS (3-HPA): m/z calcd for C H S12 [M] :
2
1
hexane/EtOAc 94:6) afforded 8 (2.02 g, 73%) as an orange oil. H NMR
1254.2747; found: 1254.2771; elemental analysis (%) calcd for C66
(1256.11): C 63.11, H 6.26, S 30.63; found: C 63.37, H 6.14, S 30.41.
78 12
H S
3
3
(
7
(
2
300 MHz, CDCl
.7 Hz, 4H), 1.36–1.24 (m, 12H), 0.89 ppm (t, J=6.8 Hz, 6H); C NMR
75 MHz, CDCl ): d=128.8, 119.1, 109.2, 108.3, 31.5, 29.6, 28.8 (x 2),
2.5, 14.1 ppm; IR (neat): n˜ =3069 (w), 2953 (m), 2924 (s) , 2855 (s), 1464
3
): d=6.28 (s, 2H), 2.33 (t, J=7.3 Hz, 4H), 1.50 (q, J=
3
13
3
ꢀ
1
(
m), 1377 cm (w); UV/Vis (CHCl ): lmax (e)=324 nm (11800); HR-EI-
3
Acknowledgements
+
MS (70 eV) calcd for C18
tal analysis (%) calcd for C18
found: C 57.95, H 7.68, S 34.43.
,5-Dihexyl-4’,5’-diiodotetrathiafulvalene (9): A freshlyprepared solution
H
28
S
4
[M] : 372.1069; found: 372.1068; elemen-
28 4
H S
(372.67): C 58.01, H 7.57, S 34.42;
Financial support from the ETH Research Foundation and the Danish
Research Agency(grant #2111-04-0018) is gratefullyacknowledged.
A.S.A. thanks the Universityof Copenhagen for a Ph.D. scholarship.
4
of LDA (9.16 mL, 0.59m in THF, 5.4 mmol) was added dropwise to a so-
lution of 8 (0.960 g, 2.58 mmol) in THF (50 mL) cooled to ꢀ788C and
the reaction mixture stirred at this temperature for 2 h. 1,2-Diiodoethane
[1] a) M. R. Bryce, Adv. Mater. 1999, 11, 11–23; b) M. B. Nielsen, C.
Lomholt, J. Becher, Chem. Soc. Rev. 2000, 29, 153–164; c) M. R.
Bryce, J. Mater. Chem. 2000, 10, 589–598; d) J. L. Segura, N. Martꢃn,
Angew. Chem. 2001, 113, 1416–1455; Angew. Chem. Int. Ed. 2001,
40, 1372–1409; e) Special issue on molecular conductors (Ed.: P.
Batail): Chem. Rev. 2004, 104, 4887–5781.
(
1.52 g, 5.40 mmol) was added in one portion. The mixture was stirred
for 1 h at ꢀ788C, then heated to 208C, and stirred for another 0.5 h. The
red solution was partitioned between saturated aqueous Na
150 mL) and Et O (150 mL), extracted with Et O (2”100 mL), and the
combined organic phases were washed with water (100 mL), dried
2 2 3
S O
(
2
2
(
MgSO
4
), filtered, and concentrated in vacuo. Column chromatography
, hexane/EtOAc 99:1) afforded 9 (1.42 g, 88%) as a red
[2] a) F. Diederich, Chem. Commun. 2001, 219–227; b) M. B. Nielsen,
F. Diederich, Synlett 2002, 544–552; c) M. B. Nielsen, F. Diederich,
Chem. Rec. 2002, 2, 189–198.
(
deactivated SiO
2
1
oil which solidified upon cooling. M.p. 46–478C; H NMR (300 MHz,
CDCl
(
1
n˜ =2949 (s), 2920 (s), 2848 (s), 1612 (w), 1541 (w), 1466 (s), 1451 (m),
1
8
HR-EI-MS (70 eV) calcd for C18
elemental analysis (%) calcd for C18
3
3
3
): d=2.32 (t, J=7.5 Hz, 4H), 1.48 (q, J=7.4 Hz, 4H), 1.35–1.23
[3] a) T. Yamamoto, T. Shimizu, J. Mater. Chem. 1997, 7, 1967–1968;
b) S. Shimada, A. Masaki, K. Hayamizu, H. Matsuda, S. Okada, H.
Nakanishi, Chem. Commun. 1997, 1421–1422; c) T. Shimizu, T. Ya-
mamoto, Chem. Commun. 1999, 515–516; d) M. Iyoda, M. Hasega-
wa, J. Takano, K. Hara, Y. Kuwatani, Chem. Lett. 2002, 590–591;
e) K. Hara, M. Hasegawa, Y. Kuwatani, H. Enozawa, M. Iyoda,
Chem. Commun. 2004, 2042–2043; f) M. Hasegawa, J. Takano, H.
Enozawa, Y. Kuwatani, M. Iyoda, Tetrahedron Lett. 2004, 45, 4109–
4112; g) M. Iyoda, H. Enozawa, Y. Miyake, Chem. Lett. 2004, 33,
3
13
m, 12H), 0.88 ppm (t, J=7.0 Hz, 6H); C NMR (75 MHz, CDCl
28.7, 124.3, 115.1, 110.8, 31.5, 29.7, 28.7 (”2), 22.5, 14.1 ppm; IR (neat):
3
): d=
375 (m), 1350 (w), 1316 (w), 1161 (w), 1113 (w), 914 (w), 895 (w),
ꢀ
1
31 cm (m); UV/Vis (CHCl ): lmax (e)=292 (13000), 328 nm (13400);
3
+
H
26
I
2
S
4
[M] : 623.9002; found: 623.9000;
26 2 4
H I S (624.5): C 34.62, H 4.20, S
2
0.54; found: C 34.87, H 4.11, S 20.63.
,5-Bis(triisopropylsilylethynyl)-4’,5’-dihexyltetrathiafulvalene (10): [Pd-
Cl ] (130 mg, 0.185 mmol) and CuI (70 mg, 0.37 mmol) were
added to a degassed solution of 9 (1.19 g, 1.91 mmol) and triisopropylsily-
lacetylene (1.03 mL, 4.58 mmol) in Et N (50 mL). The mixture was stir-
red at 208C under N for 24 h, filtered through a plug of silica gel
hexane), and concentrated in vacuo. Column chromatography(SiO
1
2
098–1099; h) M. Iyoda, M. Hasegawa, Y. Miyake, Chem. Rev.
004, 104, 5085–5113.
4
A
C
H
T
R
E
U
N
G
(PPh
3
)
2
2
[
[
4] D. Solooki, T. C. Parker, S. I. Khan, Y. Rubin, Tetrahedron Lett.
998, 39, 1327–1330.
5] H. Enozawa, M. Hasegawa, D. Takamatsu, K. Fukui, M. Iyoda, Org.
Lett. 2006, 8, 1917–1920.
1
3
2
(
2
,
1
[6] a) M. B. Nielsen, N. N. P. Moonen, C. Boudon, J.-P. Gisselbrecht, P.
Seiler, M. Gross, F. Diederich, Chem. Commun. 2001, 1848–1849;
b) M. B. Nielsen, N. F. Utesch, N. N. P. Moonen, C. Boudon, J.-P.
Gisselbrecht, S. Concilio, S. P. Piotto, P. Seiler, P. Günter, M. Gross,
F. Diederich, Chem. Eur. J. 2002, 8, 3601–3613; c) M. B. Nielsen,
Synlett 2003, 1423–1426; d) M. B. Nielsen, J.-P. Gisselbrecht, N.
Thorup, S. P. Piotto, C. Boudon, M. Gross, Tetrahedron Lett. 2003,
hexane) gave 10 (959 mg, 69%) as a dark red oil. H NMR (300 MHz,
CDCl ): d=2.33 (t, J=7.5 Hz, 4H), 1.49 (q, J=7.5 Hz, 4H), 1.36–1.24
3
(
(
2
2
3
3
3
13
m, 12H), 1.08 (s, 42H), 0.89 ppm (t, J=6.9 Hz, 6H); C NMR
75 MHz, CDCl ): d=128.6, 121.3, 114.7, 103.6, 102.5, 96.6, 31.5, 29.7,
8.8 (”2), 22.5, 18.6, 14.1, 11.1 ppm; IR (neat): n˜ =2941 (m), 2926 (s),
864 (s), 2359 (w), 2342 (w), 2141 (w), 1676 (w), 1462 (s), 1383 (w), 1368
3
ꢀ
1
(
(
(
7
(
w), 1244 (w), 1211 (w), 1069 (s), 1019 (w), 996 (m), 920 (w), 882 cm
s); UV/Vis (CHCl ): lmax (e)=299 (21200), 338 (sh, 12500), 461 nm
1800); HR-FT-MALDI-MS (3-HPA): m/z calcd for C40
32.3737; found: 732.3724; elemental analysis (%) calcd for C40
733.4): C 65.51, H 9.34, S 17.49; found: C 65.57, H 9.43, S 17.21.
Hexahexyl-1,2,7,8,13,14-tris(tetrathiafulvaleno)-
,4,5,6,9,10,11,12,15,16,17,18-dodecahydro[18]annulene (1d): nBu
4
4, 6721–6723; e) T. Kumagai, M. Tomura, J. Nishida, Y. Yamashita,
3
Tetrahedron Lett. 2003, 44, 6845–6848; f) K. Qvortrup, M. T. Jakob-
sen, J.-P. Gisselbrecht, C. Boudon, F. Jensen, S. B. Nielsen, M. B.
Nielsen, J. Mater. Chem. 2004, 14, 1768–1773; g) K. Qvortrup, A. S.
Andersson, J.-P. Mayer, A. S. Jepsen, M. B. Nielsen, Synlett 2004,
+
H
68
S
4
Si
H
2
[M] :
Si
68
S
4
2
2
2
818–2820; h) A. Gorgues, P. Hudhomme, M. Sallꢁ, Chem. Rev.
004, 104, 5151–5184; i) M. B. Nielsen, J. C. Petersen, N. Thorup,
3
4
NF
(
(
0.65 mL, 1m in wet THF, 0.65 mmol) was added to a solution of 10
223 mg, 0.304 mmol) in THF (15 mL) cooled to 08C, and the dark red
A. S. Jepsen, J.-P. Gisselbrecht, C. Boudon, M. Gross, J. Mater.
Chem. 2005, 15, 2599–2605; j) A. S. Andersson, K. Qvortrup, E. R.
Torbensen, J.-P. Mayer, J.-P. Gisselbrecht, C. Boudon, M. Gross, A.
Kadziola, K. Kilså, M. B. Nielsen, Eur. J. Org. Chem. 2005, 3660–
3671; k) M. B. Nielsen, Lett. Org. Chem. 2006, 3, 3–9; l) Y.-L. Zhao,
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3159.
solution stirred for 10 min. CH
filtered through a plug of silica gel (hexane/CH
vent was removed under reduced pressure to give 11 as a dark red oil,
which was dissolved in CH Cl (30 mL) and cooled to 08C. Haycatal ys t
6 mL) was added and the mixture stirred at this temperature open to air
2
Cl
2
(10 mL) was added, and the mixture
2
2
Cl 1:1). Most of the sol-
2
2
(
for 1 h. Et
of silica gel (hexane/CH
chromatography(SiO
3
N (2 mL) was added and the mixture filtered through a plug
Cl 1:1) and concentrated in vacuo. Column
, hexane/CH Cl 1:2) afforded 1d (60 mg, 47%) as
a dark purple, metallic solid. M.p. (DSC) ~1008C (decomp); H NMR
[7] F. Mitzel, C. Boudon, J, -P. Gisselbrecht, P. Seiler, M. Gross, F. Die-
derich, Helv. Chim. Acta 2004, 87, 1130–1157.
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2
2
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3
(
3
300 MHz, CDCl ): d=2.38 (t, J=7.5 Hz, 12H), 1.52 (m, 12H), 1.31 (m,
3
13
3
3
6H), 0.90 ppm (t, J=6.7 Hz, 18H); C NMR (75 MHz, CDCl ): d=
8458
www.chemeurj.org
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2006, 12, 8451 – 8459

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Chem. Eur. J. 2006, 12, 8451 – 8459
ꢂ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8459