New multi(tetrathiafulvalene) dendrimers

Article abstract of DOI:10.1055/s-2000-8203

The convergent synthesis of multi(TTF) dendrimers with glycol chains as the branches is reported. Key methodology in the iterative steps involves nucleophilic displacement of reactive halides by transient TTF-thiolate anions. Core units in the dendrimers

Full text of DOI:10.1055/s-2000-8203

PAPER
1695
New Multi(tetrathiafulvalene) Dendrimers
Christian A. Christensen,a,b Martin R. Bryce,*a Jan Becherb
a Department of Chemistry, University of Durham, Durham, DH1 3LE, UK
Fax +44(191)3844737; E-mail: m.r.bryce@durham.ac.uk
b Department of Chemistry, Odense University, DK-5230 Odense M, Denmark
Received 29 March 2000
Dedicated to Professor Fred Wudl on the occasion of his 60th birthday
troactive centres giving rise to a single n-electron wave)
or they may interact intra- or inter-molecularly, in which
case overlapping or closely-spaced redox waves are ob-
served at different potentials.
Abstract: The convergent synthesis of multi(TTF) dendrimers with
glycol chains as the branches is reported. Key methodology in the
iterative steps involves nucleophilic displacement of reactive ha-
lides by transient TTF-thiolate anions. Core units in the dendrimers
are 1,3,5-trisubstituted benzene, TTF and hexa-substituted benzene,
providing three-, four- and six-directional cores, respectively. Cy-
clic voltammetry (CV) and thin layer CV studies establish that the
TTF redox chemistry is retained in the dendrimer structures, with
clean sequential formation of multi(cation radical) and multi(dica-
tion) species upon electrochemical oxidation.
We have exploited recent advances in the synthesis of
functionalised tetrathiafulvalene (TTF) derivatives to as-
semble dendrimers bearing TTF units.14 The incorpora-
tion of TTF into dendrimers presents a fascinating
prospect for the following reasons:15 (i) oxidation of TTF
to the cation radical and dication species occurs sequen-
tially and reversibly at low potentials in a range of organic
solvents; (ii) the oxidation potentials can be finely tuned
by substituents on the TTF ring system; (iii) TTF cation
radicals are thermodynamically very stable; and (iv) oxi-
dised TTF units have a high propensity to form dimers or
ordered stacks, along which there can be high electron
mobility. Most multi-TTF derivatives16 are dimers,17 al-
though some trimers,18 higher oligomers,19 and main-
chain and side-chain polymeric TTFs20 are known. A fea-
ture of these multi-TTF systems is that in general they
readily yield multiply-charged species upon electrochem-
ical oxidation in solution.
Key words: dendrimer, tetrathiafulvalene, cesium hydroxide, nu-
cleophilic displacements, coupling, cyclic voltammetry
The synthesis and characterisation of new dendrimers
continues to attract considerable attention.1 These macro-
molecules possess well-defined, three-dimensional struc-
tural order, and they provide unique frameworks for
placing functional groups in predetermined spatial ar-
rangements in a polymeric structure. The aim of early re-
search into dendrimers1a was to obtain higher generation
systems with large molecular weights and dense surface
packing.2 As this topic has developed, the emphasis has
changed towards systems which incorporate more elabo- In a previous communication14d we described TTF den-
rate functional groups at the periphery of, or embedded drimers incorporating glycol chains as the branches to im-
within, the dendrimer framework, to impart special prop- part good solubility in a wide range of solvents, and air-
erties to the molecules. In this context, a variety of redox- stability, thereby facilitating their characterisation. We
active organic and organometallic groups have been in- now describe this work in full, and extend these studies to
corporated into the structures with several long-term aims new TTF-glycol dendrimers.
in mind.3 These include: (i) new electron-transfer cata-
We chose a convergent approach to multi-TTF dendrim-
lysts; (ii) studies on the dynamics of electron transport at
ers, with the cesium salts of TTF thiolate anions21 as key
surfaces and within restricted reaction spaces; (iii) new
intermediate species in the iterative steps, and identified
compound 8 as a versatile branch monomer unit. Glycol
chains were constructed from compound 1, which was
cleanly converted via tosyl derivative 2 into the corre-
materials for energy conversion; (iii) organic semicon-
ductors; (iv) organic magnets; and (v) mimics of biologi-
cal redox processes.
Some dendrimers contain a single redox-active unit at the sponding bromo derivative 3. Compound 422 was depro-
core [e.g. metalloporphyrin,4 ruthenium(II)bis(terpyridyl) tected by reaction with cesium hydroxide, and the
complex,5 ferrocene,6 C607 or an iron-sulfur cluster8] and resulting dithiolate species was trapped with either tosy-
for some systems the solution redox behaviour of this cen- late 2 or bromide 3 to afford product 5. The latter reaction
tral ’encapsulated’group is modulated by the shielding ef- proceeded more rapidly and was higher yielding (82 vs
fect of the dendrimer hierarchy, which hinders access of 64%). Cross-coupling of thione 5 with ketone 623 in the
the redox site to the electrode surface.9 Alternatively, the presence of triethyl phosphite, under standard conditions,
redox units, e.g. ferrocene and related metal sandwiches,10 gave TTF derivative 7 in 67% yield. Halogen exchange
metal(bipyridyl),11 fullerenes,12 naphthalene diimides,13 or using sodium iodide in acetone yielded the more reactive
tetrathiafulvalenes14 are emplaced at peripheral sites and/ diiodo analogue 8 (84%) (Scheme 1).
or within the branches. The redox groups may behave in-
dependently in multi-electron processes (n identical elec-
yields by cross-coupling of 6 and compounds 9a,24 9b25
TTF derivatives 10a–c were synthesised in 66 73%
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C. A. Christensen et al.
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Scheme 1
and 9c,26 respectively (Scheme 2). As the next step, as- minor products were isolated and identified (by 1H NMR)
sembly of the tris-TTF dendron wedges 11a c proceeded as 14c minus one and two of the silyl protecting groups,
smoothly by reaction of two equivalents of the thiolate an- i.e. defect dendrimers. Apparently, cesium hydroxide was
ions of 10a c with the difunctional reagent 8. Following cleaving some of the protecting groups as well as generat-
analogous procedures to those described above, com- ing the thiolate. (This effect was also seen in the synthesis
pound 11a (2 equiv) reacted with 8 to yield compound 12 of the series of wedges 11, where 11c was formed in the
(79%) containing TTF units at the focal point, at branch lowest yield.) Removal of the TBDPS protecting group of
sites and at the periphery (Scheme 3). Three-fold reac- 14c with fluoride ion in THF afforded compound 15 in
tions of the thiolates of compounds 11a–c and 12 with the 47% yield.
trifunctional core reagent 1327 gave the multi-TTF den-
We have used two other core units for reactions involving
drimers 14a c (Scheme 4) and 16 (Scheme 5), respective-
the transient thiolate anion obtained from 11a. The ben-
ly. The formation of 14a, b and 16 proceeded in
zylic chlorides of the four-directional TTF core reagent
remarkably high yield (75 95%) whereas the formation
1714b were readily displaced to yield the TTF13 dendrimer
of 14c was less efficient (28%) with several, more polar,
18, (Scheme 6) containing TTF units at the core, at branch
minor products also formed (TLC evidence). Two of these
points and at the periphery. Analogous six-fold reaction of
Scheme 2
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New Multi(tetrathiafulvalene) Dendrimers
1697
Scheme 3
the hexa-functional core 1928 gave the beautiful TTF18 We demonstrated14b that TLCV is a reliable method for
structure 20, comprising 12 peripheral and 6 inner TTF determining the extent of oxidation of multi(TTF) deriva-
units constructed around a benzene core (Scheme 7).
tives. Using the same procedures with 14a, 16, 18 and 20
as those described previously14b (i.e. integrating the volta-
mmetric waves against the one-electron reduction peak of
the internal standard 2,3-dichloronaphthoquinone) pro-
vided clear evidence that complete oxidation occurs for all
the TTF units. Thus for 16 the redox waves represent the
sequential formation of 1621+. and 1642+, while for 20 they
represent the formation of 2018+. and 2036+ species. As not-
ed previously for various multi-TTF systems,14b,c,d,19b,30
the second TTF oxidation wave tends to be slightly nar-
rower than the first wave, which is probably due to ad-
sorption phenomena of the highly oxidised species on the
electrode surface. There is no evidence from the CV data
for any shielding of the inner TTF units in these dendrim-
ers.
Dendrimers 14, 15, 16, 18 and 20 are all air-stable com-
pounds, which possess good solubility in a wide range of
organic solvents. In this respect they are considerably eas-
ier to isolate and characterise than the arylester dendrim-
ers with TTF functionality which we studied
previously.14a,c Their structures were unambiguously es-
tablished by a combination of elemental analysis, mass
spectrometry (plasma desorption, MALDI and electro-
1
spray) and H NMR spectroscopy. Their oxidised states
were generated in conventional cyclic voltammetry (CV)
and thin layer CV experiments in organic solvents. The
dendrimers and their precursor wedges all display the
two-stage redox behaviour typical of tetra(alkylsulfa-
nyl)TTF derivatives.29 (It is known that alkylsulfanyl sub-
stitution raise the oxidation potential of the TTF system).
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Scheme 4
By analogy with crown-annulated TTF systems,31 we con-
sidered the possibility that these dendrimers could display
a voltammetric response in the presence of metal cat-
ions,32 due to metal coordination to the glycol units. How-
ever, no significant change (i.e. < ±20 mV) was observed
in the potentials of the redox waves in the CV response of
dendrimer 16 in the presence of Li, Na, K and Ag cations.
CHCl3, which were used as supplied. CV data were measured with
iR compensation using either a BAS CV50 electrochemical analy-
ser or an EGG 263 potentiostat. TLCV data were obtained using
methods described previously.14b
2-[2-(2-Chloroethoxy)ethoxy]ethyl Tosylate (2)
A solution of 1 (18.49 g, 110 mmol) in anhyd pyridine (80 mL) was
stirred at 0 °C under argon and freshly recrystallised tosyl chloride
(23.00 g, 121 mmol) was added in small portions during 2 h. The
reddish solution was stirred for another 6 h at 0 °C, whereupon the
reaction was allowed to attain r.t. over 12 h. The mixture was care-
fully poured onto a mixture of concd HCl (80 mL) and crushed ice
(300 mL) whilst stirring vigorously. The aqueous phase was ex-
tracted with CH2Cl2 (3 × 150 mL) and the combined organic phases
washed with H2O (200 mL). The solution was dried (MgSO4), con-
centrated in vacuo and the residue was purified by column chroma-
tography (silica gel, CH2Cl2/EtOAc, 95:5 v/v) affording 233 as a
colourless oil; (27.62 g, 78%).
1H NMR (CDCl3/TMS): = 7.80 (d, 2 H, J = 8.4 Hz), 7.35 (d, 2 H,
J = 7.9 Hz), 4.17 (t, 2 H, J = 4.7 Hz), 3.70 (m, 4 H), 3.61 (m, 6 H),
2.45 (s, 3 H).
13C NMR (CDCl3/TMS): = 144.91, 133.00, 129.87, 127.98,
71.28, 70.63, 70.49, 69.16, 68.66, 42.62, 21.47.
In summary, we have exploited the versatility of TTF-thi-
olate chemistry to develop expedient syntheses of a range
of new dendritic TTF macromolecules which enjoy good
air-stability and solubility in organic solvents, thereby of-
fering significant advantages over previous polymeric
TTFs.
1H and 13C spectra were obtained on Varian Unity 300, Oxford 200
and Varian VXR 400s spectrometers; chemical shifts are quoted in
ppm, relative to TMS as an internal reference (0 ppm). Mass spectra
(EI and CI) were recorded on a Micromass Autospec spectrometer
operating at 70 eV with the ionisation mode as indicated. Plasma
desorption mass spectra (PDMS), MALDI mass spectra and electro-
spray mass spectra were obtained on Bio-Ion 10K, Kratos IV and
Finnigan MAT SSQ 710 instruments, respectively. Melting points
were recorded on a Reichert-Kofler hot-stage microscope and are
uncorrected. Elemental analyses were obtained on a Carlo-Erba
Strumentazione instrument. Column chromatography was carried
out using Prolabo silica (70 230 mesh). Solvents were distilled pri-
or to use for chromatography, with the exception of CH2Cl2 and
MS(EI): m/z (%) = 322 (M+, 0.25), 229 (18), 199 (92), 155 (100),
91 (88).
1-(2-Bromoethoxy)-2-(2-chloroethoxy)ethane (3)
To a solution of 2 (29.0 g, 89.8 mmol) in anhyd acetone (200 mL)
was added LiBr (8.58 g, 98.8 mmol) and the solution was refluxed
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New Multi(tetrathiafulvalene) Dendrimers
1699
Scheme 5
for 16 h in which time a colourless salt precipitated. The salt was fil-
tered off and the solution concentrated in vacuo. The residue was re-
dissolved in CH2Cl2 (300 mL), washed with H2O (3 × 150 mL) and
dried (MgSO4). The solvent was removed under reduced pressure
and the residue purified by column chromatography (silica gel,
CH2Cl2/hexane, 1:1 v/v) affording 334 as a colourless oil; (19.7 g,
95%).
ed via a syringe, and the mixture was refluxed for 16 h to give back
an orange solution. The solvent was removed in vacuo and the res-
idue redissolved in CH2Cl2 (300 mL). The solution was washed
with H2O (3 × 150 mL), dried (MgSO4) and concentrated in vacuo.
The product was purified by column chromatography (silica gel,
CH2Cl2/EtOAc, 97:3 v/v) which afforded 5 as a yellow oil; (3.66 g,
64%).
1H NMR (CDCl3/TMS): = 3.81 (t, 2 H, J = 6.4 Hz), 3.75 (t, 2 H,
J = 5.8 Hz), 3.67 (s, 4 H), 3.62 (t, 2 H, J = 5.8 Hz), 3.46 (t, 2 H,
J = 6.4 Hz).
13C NMR (CDCl3/TMS): = 71.27, 71.10, 70.50, 70.38, 42.64,
30.24.
Method B: The method was similar to Method A. Compound 4
(4.78 g, 15.7 mmol) was deprotected using CsOH•H2O (5.54 g,
33.0 mmol), and then reacted with 3 (8.00 g, 34.6 mmol). It was
necessary for the reaction to reflux for only 2 h. Workup similar to
Method A afforded 5 as a yellow oil; (6.46 g, 82%).
1H NMR (CDCl3/TMS): = 3.72 (m, 8 H), 3.63 (m, 12 H), 3.06 (t,
4 H, J = 6.4 Hz).
+
MS(CI): m/z (%) = 250 (MNH4 , 100).
13C NMR (CDCl3/TMS): = 210.88, 136.47, 71.29, 70.49, 70.45,
69.79, 42.74, 36.04.
MS(PDMS): m/z = 498.0 (M+, calcd: 499.6).
4,5-Bis{2-[2-(2-chloroethoxy)ethoxy]ethylthio}-1,3-dithiole-2-
thione (5)
Method A: To a solution of 422 (3.54 g, 11.6 mmol) in anhyd de-
gassed MeCN (140 mL) was added a solution of CsOH•H2O
(4.29 g, 25.9 mmol) in anhyd degassed MeOH (25 mL), whereupon
the colour changed from orange to dark red. The solution was stirred
under argon at r.t. for 30 min before 2 (7.50 g, 23.2 mmol) was add-
Anal. C15H24Cl2O4S5 (499.6): calcd C 36.07, H 4.84; found C 35.93,
H 4.86.
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C. A. Christensen et al.
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Scheme 6
2,3-Bis{2-[2-(2-chloroethoxy)ethoxy]ethylthio}-6-(2-cyanoeth-
ylthio)-7-methylthiotetrathiafulvalene (7)
2,3-Bis{2-[2-(2-iodoethoxy)ethoxy]ethylthio}-6-(2-cyanoethyl-
thio)-7-methylthiotetrathiafulvalene (8)
A mixture of 5 (5.00 g, 10.0 mmol) and 623 (5.00 g, 20.0 mmol) was
suspended in degassed (OEt)3P (45 mL) and stirred at 120 °C for 5
h. The solution was cooled to r.t. and concentrated in vacuo, afford-
ing a very dark red residue which was chromatographed (silica gel,
CH2Cl2 until the first band was off the column, then CH2Cl2/EtOAc,
95:5 v/v). The fractions containing the middle band were combined
and concentrated in vacuo to give 7 as an orange solid; (4.68 g,
67%), mp 44–45 °C.
To a solution of 7 (4.60 g, 6.56 mmol) in anhyd degassed acetone
(150 mL) was added NaI (20.0 g, 133 mmol) and the mixture was
refluxed under argon for 3 d. The solvent was removed in vacuo and
the dark red residue redissolved in CH2Cl2 (200 mL). The solution
was washed with H2O (3 × 150 mL), dried (MgSO4) and concen-
trated in vacuo. Purification by column chromatography (silica gel,
CH2Cl2/EtOAc, 94:6 v/v) afforded 8 as an orange-red solid; (4.87 g,
84%), 62–63 °C.
1H NMR (CDCl3/TMS): = 3.77 (t, 4 H, J = 5.6 Hz), 3.68 (m, 16
H), 3.03 (m, 6 H), 2.72 (t, 2 H, J = 7.2 Hz), 2.48 (s, 3 H).
13C NMR (CDCl3/TMS): = 135.14, 128.07, 127.72, 119.93,
117.54, 111.96, 109.51, 71.37, 70.57, 70.47, 70.02, 42.76, 35.45,
31.16, 19.10, 18.71.
1H NMR (CDCl3/TMS): = 3.75 (t, 4 H, J = 6.8 Hz), 3.69 (t, 4 H,
J = 6.8 Hz), 3.65 (s, 8 H), 3.26 (t, 4 H, J = 6.8 Hz), 3.02 (t, 6 H,
J = 6.4 Hz), 2.71 (t, 2 H, J = 7.2 Hz), 2.47 (s, 3 H).
13C NMR (CDCl3/TMS): = 135.10, 128.02, 127.67, 119.84,
117.48, 111.94, 109.44, 71.86, 70.40, 70.08, 69.99, 35.41, 31.10,
19.07, 18.68, 3.01.
MS(CI): m/z (%) = 700 (MH+, 3.41).
MS(PDMS): m/z = 883.7 (M+, calcd: 883.8).
Anal. C22H31Cl2NO4S8 (700.9): calcd C 37.70, H 4.46, N 2.00;
found C 37.64, H 4.33, N 1.97.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.60 V, E21/2 = 0.92 V.
Anal. C22H31I2NO4S8 (883.8): calcd C 29.90, H 3.54, N 1.58; found
C 29.88, H 3.54, N 1.64.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.60 V, E21/2 = 0.92 V.
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New Multi(tetrathiafulvalene) Dendrimers
1701
Scheme 7
2-(2-Cyanoethylthio)-3,6,7-trimethylthiotetrathiafulvalene
(10a); General Procedure for 10a c
2-(2-Cyanoethylthio)-3-methylthio-6,7-bis[2-(tert-
butyldiphenylsilyloxy)ethylthio]tetrathiafulvalene (10c)
Compounds 9a24 (3.17 g, 14.0 mmol) and 6 (1.75 g, 7.00 mmol)
were dissolved in degassed (OEt)3P (25 mL) and stirred at 120 °C
for 4 h. The very dark red solution was cooled to 0 °C and MeOH
(150 mL) was added, which caused formation of an orange precip-
itate. The precipitate was filtered, washed with MeOH (4 × 25 mL)
and dried in vacuo. The crude product was chromatographed (silica
gel, CH2Cl2/hexane, 3:1 v/v) and the fractions containing the middle
band were combined and concentrated to give 10a as an orange
powder; (1.97 g, 66%); mp 102 103 °C (Lit.35 102 104 °C).
Prepared like 10a from 9c26 (7.00 g, 9.17 mmol) and 6 (2.00 g,
8.00 mmol) except that the mixture was concentrated in vacuo. The
very dark red residue was chromatographed (silica gel, CH2Cl2/hex-
ane, 1:1) and the fractions containing the middle band were com-
bined and concentrated in vacuo to give 10c as an orange syrup;
(5.63 g, 73%).
1H NMR (CDCl3/TMS): = 7.67 (dd,
8
H, J1 = 7.6 Hz,
J2 = 1.2 Hz), 7.40 (m, 12 H), 3.81 (t, 4 H, J = 6.4 Hz), 3.01 (t, 2 H,
J = 7.2 Hz), 2.93 (t, 4 H, J = 7.2 Hz), 2.67 (t, 2 H, J = 7.4 Hz),
2.48 (s, 3 H), 1.06 (s, 18 H).
13C NMR (CDCl3/TMS): = 135.52, 135.14, 133.24, 129.74,
127.77, 127.72, 127.49, 120.00, 117.49, 112.91, 108.46, 63.05,
63.02, 38.40, 38.34, 31.19, 26.77, 19.17, 19.16, 19.12, 18.68.
2-(2-Cyanoethylthio)-3-methylthio-6,7-bis(hexylthio)tetrathia-
fulvalene (10b)
Prepared like 10a from compound 9b25 (2.93 g, 8.00 mmol) and 6
(2.00 g, 8.00 mmol) except that the reaction mixture was concen-
trated in vacuo. The very dark red residue was chromatographed
(silica gel, CH2Cl2/hexane, 2:1 v/v) and the fractions containing the
middle band were combined and concentrated in vacuo to give 10b
as an orange powder; (3.07 g, 68%); mp 88 89 °C.
MS(PDMS): m/z = 963.3 (M+, calcd: 964.6).
Anal. C46H53NO2S8Si2 (964.6): calcd C 57.28, H 5.54, N 1.45;
found C 57.21, H 5.67, N 1.38.
1H NMR (CDCl3/TMS): = 3.01 (t, 2 H, J = 7.2 Hz), 2.81 (t, 4 H,
J = 7.2 Hz), 2.70 (t, 2 H, J = 7.3 Hz), 2.46 (s, 3 H), 1.62 (m, 4 H),
1.41 (m, 4 H), 1.28 (m, 8 H), 0.88 (t, 6 H, J = 6.6 Hz).
13C NMR (CDCl3/TMS): = 135.09, 127.88, 127.61, 119.91,
117.53, 112.81, 108.13, 36.30, 31.26, 31.14, 29.64, 28.14, 22.50,
19.05, 18.70, 14.00.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.60 V, E21/2 = 0.95 V.
Wedge 11a; Typical Procedure for 11a c, 12
To a solution of 10a (1.03 g, 2.41 mmol) in anhyd degassed DMF
(50 mL) was added a solution of CsOH•H2O (0.424 g, 2.53 mmol)
in anhyd degassed MeOH (10 mL). The mixture was stirred for 1 h
in which it changed colour from orange to dark red. Addition of a
solution of 8 (1.06 g, 1.20 mmol) in anhyd degassed DMF (15 mL),
followed by stirring for 16 h, afforded an orange mixture which was
concentrated in vacuo. The residue was redissolved in CH2Cl2
(200 mL), washed with H2O (2 × 150 mL), dried (MgSO4) and con-
centrated in vacuo. The product was purified by column chromato-
graphy (silica gel, CH2Cl2/EtOAc, 98:2 v/v) which afforded 11a as
a sticky dark red oil (1.28 g, 77%).
MS(PDMS): m/z = 567.1 (M+, calcd: 568.0).
Anal. C22H33NS8 (568.0): calcd C 46.52, H 5.86, N 2.47; found C
46.54, H 5.89, N 2.40.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.58 V, E21/2 = 0.92 V.
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1H NMR (CDCl3/TMS): = 3.69 (t, 8 H, J = 6.8 Hz), 3.65 (s, 8 H),
(silica gel, CH2Cl2/EtOAc, 95:5 v/v) afforded 14a as an orange tof-
3.01 (m, 10 H), 2.72 (t, 2 H, J = 7.2 Hz), 2.48 (s, 3 H), 2.43 (s, 18
fee (0.650 g, 89%).
H).
1H NMR (CDCl3/TMS): = 4.14 (s, 6 H), 3.68 (m, 24 H), 3.64 (s,
24 H), 3.00 (m, 24 H), 2.55 (s, 9 H), 2.42 (m, 63 H).
MS(PDMS): m/z = 1375.3 (M+, calcd: 1377.3).
Anal. C40H49NO4S24 (1377.3): calcd C 34.88, H 3.59, N 1.02; found
C 34.65, H 3.49, N 1.01.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.57 V, E21/2 = 0.89 V.
MS(PDMS): m/z = 4128.6 (M+, calcd: 4128.9).
Anal. C123H150O12S72 (4128.9): calcd C 35.78, H 3.66; found C
35.69, H 3.63.
1/2
Wedge 11b
CV (CH2Cl2/MeCN 5:1 v/v, vs. Ag/AgCl): E1 = 0.55 V,
Prepared like 11a from 10b (0.954 g, 1.68 mmol), CsOH•H2O
(0.296 g, 1.76 mmol) and 8 (0.707 g, 0.800 mmol). Chromato-
graphic purification (silica gel, CH2Cl2) afforded 11b as a red-or-
ange oil (1.09 g, 82%).
1H NMR (CDCl3/TMS): = 3.68 (t, 8 H, J = 6.6 Hz), 3.64 (s, 8 H),
3.02 (m, 10 H), 2.81 (t, 8 H, J = 7.2 Hz), 2.71 (t, 2 H, J = 7.2 Hz),
2.47 (s, 3 H), 2.43 (s, 6 H), 1.62 (m, 8 H), 1.40 (m, 8 H), 1.29 (m,
16 H), 0.88 (t, 12 H, J = 6.8 Hz).
E21/2 = 0.85 V.
Dendrimer 14b
Prepared like 14a from wedge 11b (0.663 g, 0.400 mmol),
CsOH•H2O (0.0705 g, 0.420 mmol) and 13 (0.0519 g,
0.130 mmol). Chromatographic purification (silica gel, CH2Cl2/
EtOAc, 99:1 v/v) afforded 14b as a red oil (0.614 g, 95%).
1H NMR (CDCl3/TMS): = 4.14 (s, 6 H), 3.69 (m, 24 H), 3.64 (s,
24 H), 3.01 (m, 24 H), 2.80 (t, 24 H, J = 7.2 Hz), 2.56 (s, 9 H),
2.43 (s, 18 H), 2.42 (s, 9 H), 1.62 (quintet, 24 H, J = 7.6 Hz),
1.40 (quintet, 24 H, J = 7.6 Hz), 1.29 (m, 48 H), 0.88 (t, 36 H,
J = 6.8 Hz).
MS(PDMS): m/z = 1658.1 (M+, calcd: 1657.9).
Anal. C60H89NO4S24 (1657.9): calcd C 43.47, H 5.41, N 0.84; found
C 43.52, H 5.50, N 0.81.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.57 V, E21/2 = 0.89 V.
MS(MALDI): m/z = 4969.9 (M+, calcd: 4970.8).
Anal. C183H270O12S72 (4970.8): calcd C 44.22, H 5.48; found C
44.28, H 5.67.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.56 V, E21/2 = 0.88 V.
Wedge 11c
Prepared like 11a from 10c (2.41 g, 2.50 mmol), CsOH•H2O
(0.441 g, 2.63 mmol) and 8 (1.05 g, 1.19 mmol). Chromatographic
purification (silica gel, CH2Cl2) afforded 11c as an orange syrup
(2.01 g, 69%).
1H NMR (CDCl3/TMS): = 7.66 (dd, 16 H, J1 = 7.6 Hz,
J2 = 1.2 Hz), 7.39 (m, 24 H), 3.79 (t, 8 H, J = 6.4 Hz), 3.68 (t, 8 H,
J = 6.8 Hz), 3.63 (s, 8 H), 3.01 (m, 10 H), 2.92 (t, 8 H, J = 7.2 Hz),
2.67 (t, 2 H, J = 7.2 Hz), 2.46 (s, 3 H), 2.44 (s, 6 H), 1.05 (s, 36 H).
Dendrimer 14c
Prepared like 14a from wedge 11c (1.13 g, 0.461 mmol),
CsOH•H2O (0.0813 g, 0.484 mmol) and 13 (0.0598 g,
0.150 mmol). Chromatographic purification (silica gel, CH2Cl2/
EtOAc, 98:2 v/v) afforded 14c as an orange glass (0.307 g, 28%).
1H NMR (CDCl3/TMS): = 7.65 (d, 48 H, J = 7.6 Hz), 7.38 (m, 72
H), 4.14 (s, 6 H), 3.79 (t, 24 H, J = 6.4 Hz), 3.67 (m, 24 H), 3.62 (s,
24 H), 3.01 (m, 24 H), 2.91 (t, 24 H, J = 7.2 Hz), 2.55 (s, 9 H),
2.42 (s, 18 H), 2.40 (s, 9 H), 1.04 (s, 108 H).
MS(PDMS): m/z = 2451.2 (M+, calcd: 2451.1).
Anal. C108H129NO8S24Si4 (2451.1): calcd C 52.92, H 5.30, N 0.57;
found C 53.13, H 5.62, N 0.58.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.57 V, E21/2 = 0.90 V.
MS(MALDI): m/z = 7395 (M + K)+, (calcd: 7389).
Anal. C327H390O24S72Si12 (7350.4): calcd C 53.43, H 5.35; found C
53.40, H 5.58.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.58 V, E21/2 = 0.90 V.
Wedge 12
Prepared like 11a from wedge 11a (0.382 g, 0.277 mmol),
CsOH•H2O (0.0489 g, 0.291 mmol) and 8 (0.123 g, 0.139 mmol).
Chromatographic purification (silica gel, CH2Cl2/EtOAc, 97:3) af-
forded 12 as an orange-red oil (0.358 g, 79%).
1H NMR (CDCl3/TMS): = 3.68 (t, 24 H, J = 6.4 Hz), 3.63 (s, 24
H), 3.01 (m, 26 H), 2.71 (t, 2 H, J = 7.2 Hz), 2.47 (s, 3 H), 2.43 (s,
42 H).
Dendrimer 15
To a solution of dendrimer 14c (0.354 g, 0.048 mmol) in THF
(50 mL) was added a solution of Bu4NF (0.90 mL, 0.90 mmol of a
1.0 M solution in THF) and the mixture was stirred for 16 h in
which a dark red oil precipitated. Addition of H2O (5 mL) made the
oil go into solution before the mixture was concentrated in vacuo.
The residue was purified twice by column chromatography. First
(silica gel, CH2Cl2/MeOH, 9:1 v/v) then a second column (silica
gel, CH2Cl2/MeOH, 95:5 v/v) which afforded 15 as a viscous dark
red oil (0.102 g, 47%).
MS(PDMS): m/z = 3273.1 (M+, calcd: 3276.4).
Anal. C96H121NO12S56 (3276.4): calcd C 35.19, H 3.72, N 0.43;
found C 35.67, H 2.93, N 0.31.
1/2
CV (CH2Cl2/MeCN 9:1, vs. Ag/AgCl): E1
E21/2 = 0.87 V.
= 0.57 V,
1H NMR (CDCl3/TMS): = 4.16 (s,
6 H), 3.76 (t, 24 H,
J = 5.3 Hz), 3.70 (t, 24 H, J = 6.7 Hz), 3.65 (s, 24 H), 3.11 (br s, 12
H), 3.01 (m, 48 H), 2.56 (s, 9 H), 2.44 (s, 18 H), 2.43 (s, 9 H).
Dendrimer 14a; General Procedure for 14a c, 16, 18 and 20
To a solution of wedge 11a (0.732 g, 0.531 mmol) in anhyd de-
gassed DMF (50 mL) was added a solution of CsOH•H2O
(0.0982 g, 0.585 mmol) in anhyd degassed MeOH (1.0 mL). The
solution was stirred for 1 h, in which the colour changed from or-
ange to red-brown. A solution of 1327 (0.0707 g, 0.177 mmol) in an-
hyd degassed DMF (3 mL) was added dropwise to the mixture over
5 min. The colour changed back to orange and the reaction was
stirred for 16 h in which a red oil precipitated. The solvent was re-
moved in vacuo and the residue redissolved in CH2Cl2 (150 mL).
The solution was washed with H2O (2 x 150 mL), dried (MgSO4)
and concentrated in vacuo. Purification by column chromatography
MS(ES): m/z = 1495.7, 1122.1, 897.6 (calcd: 1496.5 [M3+],
1122.4 [M4+], 897.9 [M5+]).
Anal. C135H174O24S72 (4489.5): calcd C 36.12, H 3.91; found C
36.20, H 3.76.
CV (CH2Cl2/MeCN 3:1, vs. Ag/AgCl): E11/2 = 0.55 V, E21/2 = 0.85
V.
Dendrimer 16
Prepared like 14a from wedge 12 (0.345 g, 0.105 mmol),
CsOH•H2O (0.0186 g, 0.111 mmol) and 13 (0.0140 g,
0.0350 mmol). Purification by column chromatography (silica gel,
Synthesis 2000, No. 12, 1695–1704 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
New Multi(tetrathiafulvalene) Dendrimers
1703
CH2Cl2/EtOAc, 94:6 v/v) afforded 16 as an orange toffee (0.257 g,
75%).
(2) Xu, Z.; Moore, J. S. Angew. Chem. Int. Ed. Engl. 1993, 32,
875.
(3) For a review of redox-active dendrimers see: Bryce, M. R.;
Devonport, W. In Advances in Dendritic Macromolecules,
Newkome, G. R., Ed.; JAI Press: London, 1996, Volume 3,
115.
1H NMR (CDCl3/TMS): = 4.10 (s, 6 H), 3.68 (m, 72 H), 3.63 (s,
72 H), 3.01 (m, 72 H), 2.55 (s, 9 H), 2.42 (m, 135 H).
MS(MALDI): m/z = 9874 (M + K)+, (calcd: 9865).
(4) Weyermann, P.; Gisselbrecht, J.-P.; Boudon, C.; Diederich,
F.; Gross, M. Angew. Chem. Int. Ed. 1999, 38, 3215.
(5) Kimura, M.; Shiba, T.; Muto, T.; Hanabusa, K.; Shirai, H.
Chem. Commun., Chem. Commun. 2000, 11.
(6) Cardona, C. M.; Kaifer, A. E. J. Am. Chem. Soc. 1998, 120,
4023.
(7) Camps, X.; Dietel, E.; Hirsch, A.; Pyo, S.; Echegoyen, L.;
Hackbarth, S.; Röder, B. Chem. Eur. J. 1999, 5, 2362.
(8) Gorman, C. B.; Smith, J. C.; Hager, M. W.; Parkhurst, B. L.;
Sierzputowska-Gracz, H; Haney, C. A. J. Am. Chem. Soc.
1999, 121, 9958.
(9) For a review of encapsulated redox centres in dendrimers and
other structures, see: Cardona, C. M.; Mendoza, S.; Kaifer, A.
E. Chem. Soc. Rev. 2000, 29, 37.
(10) (a) Valério, C.; Alonso, E.; Ruiz, J.; Blais, J.-C.; Astruc, D.
Angew. Chem. Int. Ed. 1999, 38, 1747.
Anal. C291H366O36S168 (9826.2): calcd C 35.57, H 3.75; found C
35.50, H 3.70.
1/2
CV (CH2Cl2/MeCN 3:1 v/v, vs. Ag/AgCl): E1 = 0.56 V,
E21/2 = 0.86 V.
Dendrimer 18
Prepared like 14a from wedge 11a (0.606 g, 0.440 mmol) and
CsOH•H2O (0.0776 g, 0.462 mmol), but this time alkylation was
carried out using 1714b (0.0887 g, 0.100 mmol) dissolved in anhyd
degassed DMF (15 mL). Purification by column chromatography
(silica gel, CH2Cl2/EtOAc, 97:3 v/v) afforded 18 as a red toffee
(0.346 g, 57%).
1H NMR (CDCl3/TMS): = 7.27 (d, 8 H, J = 8.2 Hz), 7.22 (d, 8 H,
J = 8.2 Hz), 3.99 (s, 8 H), 3.88 (s, 8 H), 3.68 (m, 32 H), 3.64 (s, 32
H), 3.01 (m, 32 H), 2.42 (s, 72 H), 2.25 (s, 12 H).
MS(MALDI): m/z = 6070 (M + K)+, (calcd: 6077).
(b) Review: Hearshaw, M. A.; Moss, J. R. Chem. Commun.
1999, 1.
(c) Nlate, S.; Ruiz, J.; Blais, J.-C.; Astruc, D. Chem. Commun.
2000, 417.
Anal. C186H212O16S104 (6038.0): calcd C 37.00, H 3.54; found C
37.26, H 3.57.
CV (CH2Cl2, vs. Ag/AgCl): E11/2 = 0.56 V, E21/2 = 0.87 V.
(11) (a) Serroni, S.; Juris, A.; Venturi, M.; Campagna, S.; Resino,
I. R.; Denti, G.; Credi, A.; Balzani, V. J. Mater. Chem. 1997,
7, 1227.
Dendrimer 20
Prepared like 14a from wedge 11a (0.551 g, 0.400 mmol) and
CsOH•H2O (0.0739 g, 0.440 mmol), except that this time alkylation
was carried out using 1928 (0.0381 g, 0.0600 mmol) and the den-
drimer core was added as a solid, against a positive pressure of ar-
gon, and the mixture stirred for 16 h at 60 °C. Purification by
column chromatography (silica gel, CH2Cl2/EtOAc, 95:5 v/v) af-
forded 20 as a dark red glass; (0.181 g, 37%).
(b) Balzani, V.; Campagna, S.; Denti, G.; Juris, A.; Serroni, S.;
Venturi, M. Accts. Chem. Res. 1998, 31, 26.
(c) Newkome, G. R.; Patri, A. K.; Godínez, L. A. Chem. Eur.
J. 1999, 5, 1445.
(12) Armaroli, N.; Boudon, C.; Felder, D.; Gisselbrecht, J.-P.;
Gross, M.; Marconi, G.; Nicoud, J.-F.; Nierengarten, J.-F.;
Vicinelli, V. Angew. Chem. Int. Ed. 1999, 38, 3731.
(13) Tabakovic, I.; Miller, L. L.; Duan, R. G.; Tully, D. C.;
Tomalia, D. A. Chem. Mater. 1997, 9, 736.
1H NMR (CDCl3/TMS): = 4.46 (br s, 12 H), 3.69 (m, 48 H),
3.65 (s, 48 H), 3.01 (m, 48 H), 2.48 (s, 18 H), 2.43 (m, 108 H).
MS(ES): m/z = 2698.0, 2024.4, 1619.4 (calcd: 2698.7 [M3+],
(14) (a) Bryce, M. R.; Devonport, W.; Moore, A. J. Angew. Chem.
Int. Ed. Engl. 1994, 33, 1761.
2024.0 [M4+], 1619.2 [M5+]).
(b) Wang, C.; Bryce, M. R.; Batsanov, A. S.; Goldenberg, L.
M.; Howard, J. A. K. J. Mater. Chem. 1997, 7, 1189.
(c) Devonport, W.; Bryce, M. R.; Marshallsay, G. J.; Moore,
A. J.; Goldenberg, L. M. J. Mater. Chem. 1998, 8, 1361.
(d) Christensen, C. A.; Goldenberg, L. M.; Bryce, M. R.; J.
Becher, J. Chem. Commun. 1998, 509.
Anal. C234H282O24S144 (8096.06): calcd C 34.72, H 3.51; found C
35.24, H 3.44.
1/2
CV (CH2Cl2/MeCN 4:1 v/v, vs. Ag/AgCl): E1 = 0.57 V,
E21/2 = 0.86 V.
(e) Bryce, M. R.; de Miguel, P.; Devonport, W. Chem.
Commun. 1998, 2565.
(15) Reviews: (a) Bryce, M. R.; Devonport, W.; Goldenberg, L.
M.; Wang, C. Chem. Commun. 1998, 945.
Acknowledgement
We thank the EPSRC for funding, and ESF/SMARTON for a travel
grant (C.A.C.) and Dr. L. M. Goldenberg for TLCV experiments.
(b) Bryce, M. R. J. Mater. Chem. 2000, 10, 589.
(16) Reviews: (a) Adam, M.; Müllen, K. Adv. Mater. 1994, 6, 439.
(b) Otsubo, T.; Aso, Y.; Takimiya, K. Adv. Mater. 1996, 8,
203.
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Synthesis 2000, No. 12, 1695–1704 ISSN 0039-7881 © Thieme Stuttgart · New York

1704
C. A. Christensen et al.
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(33) For an alternative synthesis of 2 see: Tomohiro, T.; Avval, P.
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Article Identifier:
1437-210X,E;2000,0,12,1695,1704,ftx,en;P02900SS.pdf
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Synthesis 2000, No. 12, 1695–1704 ISSN 0039-7881 © Thieme Stuttgart · New York