Electron-rich ligands with multiple tetrathiafulvalene arms

Article abstract of DOI:10.1007/s00706-011-0520-8

We have synthesized a series of oligodentate ligands, the structure of which consists of a central aromatic core and three or four tetrathiafulvalene- based arms. Their syntheses exploited a simple general protocol based on the reaction of a bromomethylated core with a thiolate generated in situ from an appropriate tetrathiafulvalene precursor. According to molecular modeling, proper positioning of the fulvalene arms over the central platform gives rise to an electron-rich cavity suitable for inclusion of spatial electron-deficient guests such as fullerenes. Springer-Verlag 2011.

Full text of DOI:10.1007/s00706-011-0520-8

Monatsh Chem (2011) 142:821–826
DOI 10.1007/s00706-011-0520-8
ORIGINAL PAPER
Electron-rich ligands with multiple tetrathiafulvalene arms
•
Jan Holec Jirı Rybacek Milos Budesınsky
•
•
ˇ´
´ ˇ
Lubomır Pospısil Petr Holy
ˇ
ˇˇ´
´
•
´
´ˇ
´
Received: 21 December 2010 / Accepted: 2 May 2011 / Published online: 8 June 2011
Ó Springer-Verlag 2011
Abstract We have synthesized a series of oligodentate
ligands, the structure of which consists of a central aro-
matic core and three or four tetrathiafulvalene-based arms.
Their syntheses exploited a simple general protocol based
on the reaction of a bromomethylated core with a thiolate
generated in situ from an appropriate tetrathiafulvalene
precursor. According to molecular modeling, proper posi-
tioning of the fulvalene arms over the central platform
gives rise to an electron-rich cavity suitable for inclusion of
spatial electron-deficient guests such as fullerenes.
molecules are also interesting as host molecules for inor-
ganic cations or organic electron-deficient guests [17–21].
A photo-induced electron-transfer in TTF containing
donor–acceptor dyads was also studied [22].
In recent decades, fullerenes have received much
attention because of their unique properties. Many ligands,
both cyclic and non-cyclic, were synthesized and the for-
mation of their inclusion complexes with fullerenes was
studied [23], but until recently, only a few of them featured
dithiolthione or TTF units [24–30]. Lately, TTF-based
molecular tweezers [31–33] or calixarene–porphyrin con-
jugates with C60/C70 selectivity appeared [34–36]. Very
recently, TTF–calixpyrroles and tripodal extended TTF–
cyclotriveratrylenes were presented as efficient fullerene
receptors [37, 38]. Herein we report on the synthesis of tri-
and tetrapodal ligands containing TTF arms as prospective
fullerene hosts.
Keywords Donor–acceptor effects ꢀ Supramolecular
chemistry ꢀ Ligands ꢀ Tetrathiafulvalenes
Introduction
Tetrathiafulvalene (TTF) derivatives, well-known electron-
rich redox-active components, have been widely used in
numerous scientific areas, especially macrocyclic, supra-
molecular, and materials chemistry [1–4]. In order to study
the interactions between individual TTF units and the
properties of mixed-valence radical cation salts, several
macrocyclic [5–7] and branched [8–16] TTF oligomers
have been prepared during the past 10 years. Some of these
Results and discussion
Syntheses of all new tri- and tetrapodal TTF ligands
exploited a simple general protocol. Easily available hexa-
substituted benzene derivatives bearing three bromomethyl
groups were selected as the central units for the tripodal
ligands. 1,3,5-Tris(bromomethyl)-2,4,6-trimethylbenzene
(1) was prepared from mesitylene according to the procedure
developed earlier by our group [39]. 1,3,5-Tris(bromo-
methyl)-2,4,6-triethylbenzene (2) was a commercial product
and 1,3,5-tris(bromomethyl)-2,4,6-trimethoxybenzene (3)
was obtained from 1,3,5-trimethoxybenzene by a slightly
modified literature procedure [40]. The synthesis of the core
of the tetrapodal ligand started from 4,40-dihydroxybiphenyl,
which was converted first into 4,40-dibutoxybiphenyl (4)
[41]. Then, bromomethylation of 4 under harsh conditions
´ˇ
ˇˇ´
´
´ˇ
J. Holec ꢀ J. Rybacek ꢀ M. Budesınsky ꢀ L. Pospısil ꢀ
´
P. Holy (&)
Institute of Organic Chemistry and Biochemistry, v.v.i.,
Academy of Sciences of the Czech Republic,
´
Flemingovo nam. 2, 166 10 Prague 6, Czech Republic
e-mail: petrholy@uochb.cas.cz
123

822
J. Holec et al.
[39] smoothly yielded the target 3,30,5,50-tetrakis(bromo-
methyl)-4,40-dibutoxybiphenyl (5).
in the vicinity of TTF units (at 4.08 and 2.76 ppm for the
free ligand 8).
3,30-[[2-[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]-1,3-
dithiole-4,5-diyl]bis(thio)]bis(propanenitrile) (6) [42]
was chosen as the key intermediate for the attachment of
TTF units. It was prepared in several steps from a stable
salt, namely bis(tetraethylammonium) bis(thioxo-1,3-
dithiole-4,5-dithiol) zincate [43], according to the original
synthetic procedure [44]. One of the two cyanoethyl pro-
tecting groups in 6 was selectively removed [45] by a
stoichiometric amount of CsOHꢀH2O and the resulting
mono-thiolate was alkylated with MeI affording 3-[[2-[4,5-
bis(butylthio)-1,3-dithiol-2-ylidene]-5-(methylthio)-1,3-
dithiol-4-yl]thio]propanenitrile (7) in 98% yield. Syn-
theses of the new structural blocks are shown in Scheme 1.
The remaining cyanoethyl moiety of TTF derivative 7 was
then cleaved by the action of additional CsOHꢀH2O and the
in situ generated thiolate readily reacted with the bromo-
methyl groups located on the central core. Using the
bromomethyl derivatives 1, 2, 3, and 5, we obtained the
target ligands 8, 9, 10, and 11, respectively, in good yields
(Scheme 2). Their structures were unambiguously confirmed
by NMR and mass spectrometry. Notably, the reaction of
1,4,5,8-tetrakis(bromomethyl)naphthalene [46, 47] with TTF
derivative 7 performed analogously failed totally.
All new ligands were characterized by cyclic voltam-
metry. For a more precise evaluation of reversible formal
redox potentials all voltammograms were baseline cor-
rected, numerically transformed by semi-integration to neo-
polarograms, and analyzed by a standard method of log-plot
analysis [48]. This procedure allowed the identification of
two overlapped electron-transfer steps corresponding to the
first oxidation of TTF units. The formal redox potentials
E1,1 and E1,2 of the two overlapped waves of the first oxi-
dation step and the potentials of the second oxidation step
E2 are summarized in Table 1. A representative cyclic
voltammogram is shown in Fig. 2.
Experimental
Melting points were determined on a Mikro-Heiztisch
Polytherm A apparatus (Hund Wetzlar, Germany). NMR
spectra were measured on Bruker Avance 400 (1H at
400 MHz and 13C at 101 MHz) and Bruker Avance 600
(1H at 600 MHz and 13C at 151 MHz) spectrometers.
Chemical shifts (in ppm) were referenced to tetramethyl-
silane or residual solvent peaks as internal standards.
Coupling constants (J) are given in hertz. Mass spectra
were recorded on spectrometers LCQ Classic (Thermo
Finnigan) and Q-Tof micro (Waters) with EI (70 eV) or ES
ionization. UV–Vis spectra were measured on a double-
beam spectrometer VARIAN Cary 5000 (1-cm quartz cell)
at 25 °C. The reaction progress was monitored by
thin-layer chromatography (TLC) on aluminum sheets
The study of interactions of the prepared ligands with
electron-deficient guests is now in progress. Preliminary
experiments proved remarkable changes in 1H NMR
spectra of the ligands after addition of fullerene C60 in
excess. The spectral changes observed for the ligand 8
are shown in Fig. 1. Particularly noteworthy are the
transformations of signals corresponding to S–CH2 groups
Scheme 1
a
HO
OH
O
O
4
b
Br
Br
Br
Br
O
O
5
S
S
S
S
S
S
S
S
S
S
S
S
S
CN
CN
c
CN
S
S
S
6
7
Reagents and yields: (a) n-BuBr, K2CO3, MeCN, 85%; (b) (CH2O)n, KBr,
AcOH/H2SO4, 53%; (c) CsOH·H2O, MeOH/DMF, CH3I, 98%
123

Electron-rich ligands with multiple tetrathiafulvalene arms
823
Scheme 2
S
S
S
S
S
S
S
S
R
R
R
Br
a
R
R
Br
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
R
Br
1: R = CH3
2: R = CH2CH3
3
8: R = CH3; 9: R = CH2CH3; 10: R = OCH3
: R = OCH3
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
O
S
b
O
5
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
11
Reagents and yields: (a) 7 (3 equiv), CsOH·H2O (3.3 equiv), MeOH/DMF,
65% of 8, 65% of 9, 71% of 10; (b) 7 (4 equiv), CsOH·H2O (4.4 equiv),
MeOH/DMF, 63% of 11
1
Fig. 1 600 MHz H NMR
spectra of the free ligand 8
(bottom) and its mixture with
4 equiv. of C60 (top), both
recorded in a CS2/CD2Cl2
2:1 mixture at 25 °C
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
ppm
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
ppm
pre-coated with silica gel 60 F254 (Merck), and column
chromatography was carried out using silica gel 60
(Merck). Commercially available reagent grade chemicals
and dry solvents were used as received. The term ‘‘hex-
anes’’ indicates a mixture of aliphatic hydrocarbons with
b.p. 60–80 °C.
123

824
J. Holec et al.
Sigma-Aldrich. The indifferent electrolyte TBAPF6 was
recrystallized and dried under vacuum. 1,2-Dichloroethane
was dried over activated molecular sieves. Oxygen was
removed from the solution by passing through a stream of
argon saturated with solvent vapors.
Table 1 Reversible redox potentials of compounds 8–11 versus the
ferrocene/ferricenium couple in 1,2-dichloroethane
Compound
E1,1 (V)
E1,2 (V)
E2 (V)
8
0.034
0.023
0.024
0.019
0.064
0.073
0.069
0.099
0.399
0.394
0.399
0.414
9
10
11
1,3,5-Tris(bromomethyl)-2,4,6-trimethoxybenzene (3)
Into a stirred mixture of 2.50 g 1,3,5-trimethoxybenzene
(14.9 mmol) and 2.00 g paraformaldehyde (66.6 mmol) in
5 cm3 acetic acid heated to 70 °C 11 cm3 of a solution of
hydrogen bromide in acetic acid (33% HBr) was dropped.
The reaction mixture was kept at this temperature for 20 h,
then 300 cm3 water was added and the mixture was
extracted with dichloromethane (3 9 120 cm3). The com-
bined extracts were washed with water (2 9 100 cm3) and
dried over MgSO4. After evaporation of the solvent the
crude product was purified by column chromatography on
silica gel (eluent hexanes/acetone/diethyl ether 80:10:10).
Recrystallization of relevant fractions from n-hexane
afforded 1.55 g (23%) of 3. M.p.: 130–132 °C (Ref. [40]
126 °C); 1H and 13C NMR spectra were found to be
identical with those described in Ref. [40].
4,40-Dibutoxy-1,10-biphenyl (4)
A
mixture of 9.31 g 4,40-dihydroxy-1,10-biphenyl
(50.0 mmol), 16.4 g 1-bromobutane (120 mmol), and
13.8 g anhydrous potassium carbonate (100 mmol) in
300 cm3 acetonitrile was refluxed for 40 h. After evapo-
ration to dryness, 200 cm3 water was added and the organic
portions were extracted with toluene (3 9 150 cm3).
Combined extracts were dried (MgSO4) and concentrated
to 200 cm3. Upon diluting the solution with 200 cm3 n-
hexane the product crystallized. Crystals were filtered,
washed with n-hexane, and dried. Yield of 4 was 12.6 g
(85%). M.p.: 151 °C (Ref. [41] 145–146 °C); 1H NMR
spectrum was found to be identical with that described in
Ref. [41].
Fig. 2 Cyclic voltammogram of 0.56 mM ligand 8 and 0.1 M
TBAPF6 in 1,2-dichloroethane (glassy carbon electrode, scan rate
0.1 V s-1, EFc/Fc?ꢀ = 0.491 V)
Elemental analyses (C, H, N, S) of the new starting
compounds were conducted using a PE 2400 Series II
CHNS/O Analyzer (Perkin Elmer, USA), and their results
were found to be in good agreement ( 0.2%) with the
calculated values. On the contrary, the character of the
target ligands in this study hampered the determination of
elemental composition with satisfactory precision. We
found that the substances in general bind solvent molecules
very tightly in non-stoichiometric ratio and their thermal
stability prevents long-term vacuum drying at an elevated
temperature. Nevertheless, HRMS data provided adequate
confirmation of their composition.
3,30,5,50-Tetrakis(bromomethyl)-4,40-dibutoxy-1,10-
biphenyl (5, C24H30Br4O2)
To a suspension of 2.69 g 4 (9.00 mmol), 1.90 g parafor-
maldehyde (63.3 mmol), and 9.00 g potassium bromide
(7.56 mmol) in 15 cm3 acetic acid a mixture of 7 cm3
sulfuric acid and 7 cm3 acetic acid was added dropwise.
The resulting mixture was heated to 95 °C for 6 h, diluted
with 100 cm3 water, and extracted with dichloromethane
(3 9 120 cm3). The combined extracts were washed with
water (2 9 100 cm3) and dried with MgSO4, then the
solvent was evaporated. The oily residue was dissolved in
300 cm3 n-hexane, the brown solution was decolorized
with silica gel (ca. 1 g), silica gel was filtered off, and the
solution was concentrated to 100 cm3. After standing in the
fridge overnight the crystals were filtered, washed with
n-hexane, and dried. Yield of 5 was 3.20 g (53%). M.p.:
Electrochemical measurements were performed using a
potentiostat/galvanostat Autolab PGSTAT30 equipped with
a frequency response module (Eco Chemie, The Nether-
lands). A three-electrode electrochemical cell was used.
The reference electrode, Ag|AgCl|3 M KCl, was separated
from the test solution by a non-aqueous salt bridge. The
working electrode was a glass-sealed glassy carbon disc of
0.5-mm diameter. The auxiliary electrode was a platinum
wire. The scan rate of the applied DC potential was in the
range 0.05–10 V/s. Tetrabutylammonium hexafluorophos-
phate (TBAPF6) and 1,2-dichloroethane were supplied by
123

Electron-rich ligands with multiple tetrathiafulvalene arms
825
167 °C; 1H NMR (400 MHz, CDCl3): d = 1.05 (t, 3H,
J = 7.6 Hz), 1.62 (m, 4H), 1.92 (m, 4H), 4.15 (t, 4H,
J = 6.6 Hz), 4.60 (s, 8H), 7.54 (s, 4H) ppm; 13C NMR
(101 MHz, CDCl3): d = 13.97, 19.22, 27.54, 32.43, 74.94,
130.58, 132.51, 136.33, 155.35 ppm; MS (70 eV):
m/z = 670 (M?), 614, 558, 477, 453, 387, 317, 165, 149,
80; HRMS (EI?): for C24H30Br4O2 [M?] calcd.
m/z = 665.8979, found 665.8999.
crystallization from acetone afforded the ligand 8 (102 mg,
65%). M.p.: 66–69 °C; 1H NMR (600 MHz, CD2Cl2):
d = 0.847 (t, 9H, J = 7.4 Hz), 0.850 (t, 9H, J = 7.4 Hz),
1.36 (m, 12H), 1.54 (m, 12H), 2.34 (s, 9H), 2.47 (s, 9H),
2.76 (m, 12H), 4.08 (s, 6H) ppm; 13C NMR (151 MHz,
CD2Cl2): d = 15.26, 15.28, 17.92, 20.96, 23.51,
33.66, 33.68, 37.85, 38.62, 125.66, 129.61, 129.72,
132.88, 134.85, 139.14 ppm; UV–Vis (dichloromethane,
c = 9.79 9 10-5 mol dm-3): kmax (e) = 333 (61,600),
311 (65,600) nm (mol-1 dm3 cm-1); HRMS (ES?): for
C57H78S24Na [(M?Na)?] calcd. m/z = 1,552.9293, found
1,552.9270.
3,30-[[2-[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]-1,3-
dithiole-4,5-diyl]bis(thio)]bis(propanenitrile) (6) [42]
The coupling reaction [44] of 4.89 g 4,5-bis(cyanoethyl-
thio)-1,3-dithiol-2-one [42] (17.0 mmol) and 5.27 g 4,5-
bis-(butylthio)-1,3-dithiol-2-thione [42] (17.0 mmol) in
15 cm3 triethyl phosphite gave 5.00 g (53%) of the TTF
derivative 6. M.p.: 95–96 °C (Ref. [42] 94–95 °C); 1H and
13C NMR spectra were found to be identical with those
described in Ref. [42].
4,40,400-[(2,4,6-Triethylbenzene-1,3,5-triyl)tris(methylene-
thio)]tris[2-[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]-5-
(methylthio)-1,3-dithiole] (9, C60H84S24)
The reaction procedure described for the ligand 8 was
applied to 169 mg TTF derivative 7 (0.330 mmol) and
44.8 mg tris(bromomethyl) derivative 2 (0.100 mmol).
Column chromatography of the crude product on silica
gel (eluent hexanes/CH2Cl2 2:1) afforded the pure ligand 9
(103 mg, 65%). M.p.: 92–94 °C; 1H NMR (600 MHz,
CD2Cl2): d = 0.847 (t, 9H, J = 7.4 Hz), 0.851 (t, 9H,
J = 7.4 Hz), 1.20 (t, 9H, J = 7.5 Hz), 1.36 (m, 6H), 1.37
(m, 6H), 1.54 (m, 12H), 2.37 (s, 9H), 2.76 (m, 12H), 2.93
(m, 6H), 4.04 (s, 6H) ppm; 13C NMR (151 MHz, CD2Cl2):
d = 15.26, 15.27, 17.88, 21.00, 23.51, 24.98, 33.66, 33.70,
37.38, 37.85, 111.61, 112.76, 125.86, 129.62, 129.74,
131.84, 134.62, 146.27 ppm; UV–Vis (dichloromethane,
c = 9.84 9 10-5 mol dm-3): kmax (e) = 333 (63,000),
312 (67,400) nm (mol-1 dm3 cm-1); HRMS (ES?): for
C60H84S24Na [(M?Na)?] calcd. m/z = 1,594.9762, found
1,594.9758.
3-[[2-[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]-5-
(methylthio)-1,3-dithiol-4-yl]thio]propanenitrile
(7, C18H25NS8)
To a solution of 2.20 g 6 (4.00 mmol) in 90 cm3 N,N-
dimethylformamide (DMF) a degassed solution of 0.739 g
CsOHꢀH2O (4.40 mmol) in 10 cm3 MeOH was added
under Ar, followed after 15 min by 0.682 g iodomethane
(4.80 mmol). The reaction mixture was stirred for 5 h at r.t.
Then, the mixture was diluted with 400 cm3 water, the
precipitate was filtered, washed with water, and dried.
Crystallization from 300 cm3 n-heptane afforded 2.01 g
(98%) of 7. M.p.: 89–91 °C; 1H NMR (400 MHz, CDCl3):
d = 0.93 (t, 6H, J = 7.2 Hz), 1.45 (m, 4H), 1.62 (m, 4H,
J = 7.6 Hz), 2.48 (s, 3H), 2.71 (t, 2H, J = 7.2 Hz), 2.83 (t,
4H, J = 7.6 Hz), 3.03 (t, 2H, J = 7.2 Hz) ppm; 13C NMR
(126 MHz, CDCl3): d = 13.58, 18.75, 19.07, 21.65, 31.20,
31.77, 36.04, 112.89, 117.52, 120.10, 127.71, 127.99,
130.29, 135.11 ppm; MS (70 eV): m/z = 511 (M?), 457,
322, 223, 88, 44; HRMS (EI?): for C18H25NS8 [M?] calcd.
m/z = 510.9753, found 510.9743.
4,40,400-[(2,4,6-Trimethoxybenzene-1,3,5-triyl)tris(methylene-
thio)]tris[2-[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]-5-
(methylthio)-1,3-dithiole] (10, C57H78O3S24)
The reaction conditions and purification procedure
described for the ligand 8 was applied to 169 mg TTF
derivative 7 (0.330 mmol) and 45.0 mg tris(bromomethyl)
derivative 3 (0.100 mmol). Column chromatography of the
crude product on silica gel (eluent hexanes/CH2Cl2 3:2)
yielded the pure ligand 10 (112 mg, 71%). M.p.: 65–67 °C;
1H NMR (600 MHz, CD2Cl2): d = 0.847 (t, 9H,
J = 7.4 Hz), 0.849 (t, 9H, J = 7.4 Hz), 1.36 (m, 12H),
1.54 (m, 12H), 2.32 (s, 9H), 2.75 (m, 12H), 3.91 (s, 9H),
4.04 (s, 6H) ppm; 13C NMR (151 MHz, CD2Cl2):
d = 15.26, 15.28, 20.99, 23.51, 32.38, 33.67, 33.68,
37.84, 65.25, 111.89, 112.66, 122.64, 126.49, 129.62,
134.30, 161.22 ppm; UV–Vis (dichloromethane, c =
9.84 9 10-5 mol dm-3): kmax (e) = 333 (56,200), 311
(59,600) nm (mol-1 dm3 cm-1); HRMS (ES?): for
C57H78O3S24Na [(M?Na)?] calcd. m/z = 1,600.9140,
found 1,600.9144.
4,40,400-[(2,4,6-Trimethylbenzene-1,3,5-triyl)tris(methylene-
thio)]tris[2-[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]-5-
(methylthio)-1,3-dithiole] (8, C57H78S24)
CsOHꢀH2O (67.1 mg, 0.400 mmol) was dissolved in 3 cm3
methanol and added dropwise under Ar to a solution of
169 mg TTF derivative 7 (0.330 mmol) in 9 cm3 dry and
degassed DMF over 10 min and the resulting solution was
stirred for 15 min. Tris(bromomethyl) derivative
1
(40.2 mg, 0.100 mmol) in 7 cm3 dry and degassed DMF
was added dropwise during 2 h and the reaction mixture
was stirred for 5 h at r.t. Then, the mixture was diluted with
150 cm3 water, the precipitate was filtered, washed with
water, and dried. Column chromatography of the crude
product on silica gel (eluent hexanes/CH2Cl2 2:1) and
123

826
J. Holec et al.
4,40,400,4000-[(4,40-Dibutoxy-[1,10-biphenyl]-3,30,5,50-tetrayl)-
tetrakis(methylenethio)]tetrakis[2-[4,5-bis(butylthio)-
1,3-dithiol-2-ylidene]-5-(methylthio)-1,3-dithiole]
´ˇ ´ˇ ´ ˇ
´ ´ ˚
16. Rybacek J, Rybackova M, Høj M, Belohradsky M, Holy P, Kilsa
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(11, C84H114O2S32)
´
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´
20. Canevet D, Salle M, Zhang G, Zhang D, Zhu D (2009) Chem
The reaction conditions and chromatographic purification
described for the ligand 8 was applied to 225 mg
TTF derivative 7 (0.440 mmol) and 67.2 mg tetrakis
(bromomethyl) derivative 5 (0.100 mmol). Column chro-
matography of the crude product on silica gel (eluent
hexanes/CH2Cl2 3:2) afforded the pure ligand 11 (137 mg,
63%, orange semicrystalline compound). 1H NMR
(600 MHz, CD2Cl2): d = 0.84 (t, 12H, J = 7.4 Hz), 0.85
(t, 12H, J = 7.4 Hz), 0.96 (t, 6H, J = 7.4 Hz), 1.36 (m,
16H), 1.52 (m, 4H), 1.53 (m, 16H), 1.81 (m, 4H), 2.75 (m,
16H), 4.00 (t, 4H, J = 6.5 Hz), 4.01 (s, 8H), 7.40 (s, 4H)
ppm; 13C NMR (151 MHz, CD2Cl2): d = 15.30, 15.89,
17.88, 20.86, 21.35, 23.54, 33.68, 33.70, 34.54, 37.01,
37.85, 37.88, 111.30, 112.26, 125.36, 129.55, 129.80,
130.84, 132.99, 135.95, 137.30, 157.12 ppm; UV–Vis
(dichloromethane, c = 9.95 9 10-5 mol dm-3): kmax (e)
= 333 (71,700), 310 (80,100) nm (mol-1 dm3 cm-1);
HRMS (ES?): for C84H114O2S32 [M2?] calcd. m/z =
1,088.9935; found 1,088.9928.
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Acknowledgments This work was carried out under the research
project Z4 055 0506. The financial support provided by the Grant
Agency of the Academy of Sciences of the Czech Republic (grant No.
IAA400550704) is gratefully acknowledged.
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