Harnessing "click"-type chemistry for the preparation of novel electronic materials

Article abstract of DOI:10.1002/adfm.201001893

Sequence-independent or "click"-type chemistry is applied for the preparation of novel π-conjugated oligomers. A variety of bi-functional monomers for Wittig-Horner olefination are developed and applied in a sequential protection-deprotection process for the preparation of structurally similar π-conjugated oligomers. Selected oligomers are incorporated as the organic semiconductors in light-emitting diodes and a field-effect transistor, demonstrating the potential of the approach. Sequence-independent or "click"-type chemistry is applied for the preparation of novel π-conjugated oligomers. A variety of bi-functional monomers for Wittig-Horner olefination are developed and applied in a sequential protection-deprotection process for the preparation of structurally similar π-conjugated oligomers. Selected oligomers are incorporated as the organic semiconductors in light-emitting diodes and a field-effect transistor, demonstrating the potential of the approach.

Full text of DOI:10.1002/adfm.201001893

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Harnessing “Click”-Type Chemistry for the Preparation
of Novel Electronic Materials
Michal Firstenberg, Kammasandra Nanjunda Shivananda, Irit Cohen,
Olga Solomeshch, Vladislav Medvedev, Nir Tessler, and Yoav Eichen*
chains defines their functionality. Due to
the importance of these two reactions to
molecular biology, two families of most
powerful in vitro syntheses were developed
Sequence-independent or “click”-type chemistry is applied for the prepara-
tion of novel π-conjugated oligomers. A variety of bi-functional monomers
for Wittig–Horner olefination are developed and applied in a sequential
protection–deprotection process for the preparation of structurally similar
π-conjugated oligomers. Selected oligomers are incorporated as the organic
semiconductors in light-emitting diodes and a field-effect transistor, demon-
strating the potential of the approach.
for the preparation of peptide and nucleic
acid sequences, both in solutions and on
solid supports.[3]
The analogous organic synthesis
approach is often referred to as “click”
chemistry. Recently, it has been applied to
the preparation of π-conjugated materials.
Yu presented a stepwise reaction of oligo(p-
1. Introduction
phenylene-vinylene) species with two different monomers,
using alternating Heck and Horner–Wadsworth–Emmons
(HWE) reactions.[4] Following a similar approach, Tour pre-
pared a large library of phenylene vinylene derivatives.[5]
A stepwise HWE protection-deprotection process was utilized
by Nierengarten,[6] to synthesize new dumbbell-shaped bis
(pyrazolino- [60] fullerene) – oligo phenylene vinylene deriva-
tives, and by Krebs,[7] to prepare oligo phenylene vinylenes for
solar cells. Suginome[8] used a protection-deprotection version
of the Suzuki-Miyora coupling reaction to make oligoarenes.
Bauerle et al.[9] used combinatorial parallel synthesis and con-
structed a library of 16 and then 256 tetramers, as candidates
for a liquid crystals device. A combinatorial synthesis on solid
support was used by Baurele[10] and Anderson[11] to make oligo-
thiophene library and phenylene-ethynylene pentamers library,
respectively, both showing optoelectronic characteristics.
Young and Moore[12] have utilized the same method to prepare
oligo(1,3-phenylene ethynylene). Recently we have reported on
the solution synthesis of oligo homo- and hetero- π-conjugated
peptides and their optical and electrical properties.[13]
Here, we apply a Lego-like sequence independent bio-
inspired procedure of double-bond formation to produce struc-
turally controlled functional oligomers. We report on the prep-
aration of novel electrically active oligomers using a two step
Wittig and Wittig–Horner procedure for making oligo arylene
vinylene systems. By fabricating an organic light-emitting diode
and a field-effect transistor of these oligomers, we demonstrate
the potential embedded in this approach.
A major obstacle for the full realization of the potential
embedded in organic optoelectronics and molecular nano-
electronics is the difficulty in assembling by design (i.e., engi-
neering) complicated structures with molecular, electronic
grade, precision.[1] In the biology, one finds two sequence-inde-
pendent synthesis approaches that by far exceed the human
capabilities in forming complex materials.
Most of the biological chemical entities are prepared by a
target-specific machinery that is tailored to produce one mate-
rial or a very narrow set of structurally similar compounds. This
approach is being utilized in most cases where high fidelity
in synthesis is required, as is the case in the biosynthesis of
most small molecules. On the other hand, when versatility is
the goal, nature adopts a Lego-like sequence-independent syn-
thesis approach.[2] In these cases, nature’s machinery produces
large numbers of materials that differ in structure and prop-
erties out of a very limited number of small building blocks.
This approach is being used for the synthesis of oligo- and
polynucleic acids, where the sequence of the monomers in
the polymer represents the genetic code, and for making pep-
tides, where the sequence of the monomers in the polypeptide
Dr. M. Firstenberg, Dr. K. N. Shivananda, I. Cohen, Prof. Y. Eichen
Schulich Faculty of Chemistry
Technion – Israel Institute of Technology
Technion City, 32000 Haifa, Israel
The general protection-deprotection Horner–Wadsworth–
Emmons (HWE) process using bi-functional monomers is out-
lined in Scheme 1. A monofunctional end group, is used for the
first coupling step with a bi-functional monomer, having one of
its functionalities (an aldehyde in the present case) protected.
The next step is the deprotection of the protected aldehyde of
the dimer. This sequence may be repeated several times, using
E-mail: chryoav@tx.technion.ac.il
Dr. O. Solomeshch, Dr. V. Medvedev, Prof. N. Tessler
Nanoelectronics Center
Department of Electrical Engineering
Technion – Israel Institute of Technology
Technion City, 32000 Haifa, Israel
DOI: 10.1002/adfm.201001893
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Scheme 3. Synthetic route to 7, i) DIBAL-H, tetrahydrofuran (THF),
0 °C, 88% yield; ii) 2,3-dimethyl-butane-2,3-diol + H+, benzene, reflux,
60% yield; iii) Ph3P, THF, reflux, 93% yield.
Aldehyde 5 was then protected by reacting it with 2,3-dimethyl-
butane-2,3-diol under acidic conditions, yielding the acetal 6
(60% yield). 6 was then converted to the phosphonium 7 using
a Michaelis–Arbuzov reaction in 93% yield.
5-(4,4,5,5-Tetramethyl-[1,3]dioxolan-2-yl)thiophen-2-ylmethyl-
triphenyl-phosphonium-chloride, 12, was produced by pro-
tecting 2-thiophen-aldehyde with 2,3-dimethyl-butane-2,3-diol
under acidic conditions, yielding the acetal 8. Lithiation of 8
with n-butyllithium followed by a quenching with dry dimethyl-
formamide (DMF) gave aldehyde 9. Reduction of 9 with NaBH4
afforded the alcohol, 10. Substitution reaction with thionyl chlo-
ride yielded 11 and reaction with triphenylphosphine afforded
12 in 47% yield.
Scheme 1. Schematic illustration of the uni- and bi-directional “click”
concept.
different bi-functional monomers to construct the oligomer
with the desired sequence.
2. Results and Discussions
2.1. Monomers
Benzaldehyde, 1, thiophene-2-carbaldehyde, 2, 4-diphenylamino-
benzaldehyde,[14] 3, and 9-hexyl-9H-carbazole-3-carbaldehyde, 4,
presented in Scheme 2, were used as the start units for the uni-
directional process. Schemes 3–6 present the synthetic routes
to bi-functional monomers 7, 12, 16, and 19, respectively.
4-(4,4,5,5-Tetramethyl-[1,3]dioxolan-2-yl)-benzyl-tripenyl
phosphonium bromide, 7, was produced by converting
4-bromomethyl-benzonitrile[15] to the aldehyde in 88% yield.
Scheme 4. Synthetic route to 12, i) 2,3-dimethyl-butane-2,3-diol + H+,
benzene, reflux, 90% yield; ii) a: n-butyllithium, b: dimethylformamide
(DMF), THF, 0 °C to room temperature (rt), 66% yield; iii) NaBH4, THF,
rt, 64% yield; iv) SOCl2, reflux, 53% yield; v) Ph3P, THF, reflux, 47%
yield.
Scheme 5. Synthetic route to 16, i) POCl3/DMF, −10 °C to rt, quantitative
yield; ii) 2,2-dimethyl-propane-1,3-diol + H+, toluene, reflux, 70% yield;
iii) N-bromosuccinimide (NBS), acetonitrile, −78 °C to rt, quantita-
tive yield; iv) (4-boronic acid-benzyl)-phosphonic acid diethyl ester,[16]
Na2CO3, (Ph3P)2PdCl2, toluene/water, 100 °C, 45% yield.
Scheme 2. Start units 1 , 2, 3, and 4 of the unidirectional process.
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Oct
Oct
Oct
Oct
All four reactions were performed using the same conditions: eth-
anol as the solvent, 2 equivalents of sodium ethoxide (with respect
to the phosphor derivative) as the base, 1 h at room temperature,
Scheme 7. NMR spectra taken for the crude clearly show that all
the reactions proceeded in a quantitative yields (>98% yield, Z/E
(cis/trans) ratio: 2/3, 2/3, 1/3 and 2/3 for 20–23, respectively).
The second library of dimers consists of Wittig coupling
products from aldehydes 3 and 4 with bi-functional monomers
16 and 19. Here too, all four reactions were performed using
the same conditions: tetrahydrofuran (THF) as the solvent,
3 equivalents of t-BuOK as the base, 1 h at room temperature,
Scheme 8. NMR spectroscopy revealed quantitative yields for all
four dimers E-24 – E-27 (E isomers).
O
Br
Br
Br
i
H
17
Oct
Oct
O
Br
ii
iii
O
18
O
O
O
Oct
Oct
P
O
2.3. Trimers and Higher Oligomers
O
19
E-dimers E-20, E-21, and E-22 were deprotected in an acid
catalyzed process, yielding E-dimers E-28, E-29, and E-30 in
quantitative yields. The deprotected dimers were coupled with
a second bi-functional monomer, yielding trimers E,E-31, E,E-
32, and E,E-33, Scheme 9. All three reactions were performed
using the same conditions: deprotection step: 10% HCl in 1:2
water:THF, 3 h, rt. Coupling step: 2 equivalents of sodium
ethoxide in ethanol, 1 h, rt. NMR spectra taken for the crude
clearly show that all the reactions proceeded in a quantitative
yields (>98% yield, predominantly the E,E isomers).
In a similar manner, dimer E-25 was deprotected using TFA
and the resulting aldehyde, E-34, was reacted with bi-functional
monomer 19 (THF, t-BuOK, 1 h, rt.), yielding trimer E,E-35,
which was, in turn, deprotected under 5% HCl to yield alde-
hyde E,E-36, Scheme 10. In an alternative route, two equiva-
lents of dimer 25 were coupled with the symmetrical bi-func-
tional reagent 37[17] (THF, t-BuOK, 2 h, 0 °C), forming oligomer
38, Scheme 11.
Scheme 6. Synthetic route to 19, i) a: n-butyllithium, b: DMF, THF,
−78 °C to rt, 33% yield; ii) 2,2-dimethyl-propane-1,3-diol + H+, toluene,
reflux, quantitative yield; iii) (4-boronic acid-benzyl)-phosphonic acid die-
thyl ester,[16] Na2CO3, (Ph3P)2PdCl2, toluene/water, 100 °C, 80% yield.
Monomers 16 and 19 consist of two π-conjugated rings, one
being a phenyl ring and the other a 2,3-dihydro-thieno[3,4-b]
[1,4]dioxine and a 9,9-dioctyl-fluorene, in 16 and 19 respec-
tively. 16 was obtained by reacting 2,3-dihydro-thieno [3,4-b]
[1,4]dioxine, 3,4-ethylenedioxythiophene (EDOT), with POCl3
and DMF to yield aldehyde 13, which is then protected with
2,2-dimethyl-1,3-propandiol under acidic conditions to afford
the acetal 14. Bromination of 14 with N-bromosuccinimide
(NBS) in acetonitrile yielded 15. (Ph3P)2PdCl2 catalyzed Suzuki
heterocoupling between 15 and (4-boronic acid – benzyl)-phos-
phonic acid diethyl ester[16] in the presence of sodium carbonate
afforded 16 as a yellow solid in 45% yield.
19 was made by mono lithiation of 2,7-dibromo-9,9-dime-
thyl-9H-fluorene with n-butyllithium, followed by quenching
with dry DMF. The resulting aldehyde, 17, was protected with
2,2-dimethyl-1,3-propandiol under acidic conditions, affording
acetal 18. (Ph3P)2PdCl2 catalyzed Suzuki heterocoupling
between 18 and (4-boronic acid – benzyl)-phosphonic acid die-
thyl ester[16] in the presence of sodium carbonate afforded 19 as
colorless oil in 80% yield.
2.4. Characterization of the New Oligomers
The absorption and emission spectra of E-20 – E-27, E,E-35,
and E,E,E,E-38 are depicted in Figure 1 and 2. Interestingly,
despite the structural similarities, E-20, E-21, E-22, and E-23
Each of the bi-functional monomers
consists of a π-conjugated backbone and
bears two functional groups: a phosphine/
phosphonate and a protected aldehyde.
These monomers are thus suitable for
recurrent Wittig/Wittig–Horner reactions,
both as the aldehyde and as the phos-
phine/phosphonate moieties.
2.2. Dimers
The synthesis of
a small library of
first-generation dimers was achieved by cou-
pling monomers 1 and 2 with the aldehyde
protected bi-functional monomers 7 and 12. sodium ethoxide, rt, 1 h, quantitative yields.
Scheme 7. The synthesis of four first generation arylene-vinylenes dimers (20, 21, 22, and 23),
made from Wittig coupling of 1 and 2 with bi-functional monomers 7 and 12. i = ii = iii = iv: ethanol,
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Scheme 8. The synthesis of four first generation arylene-vinylenes dimers (E-24, E-25, E-26, and E-27), made from Wittig–Horner coupling of 3 and 4
with bi-functional monomers 16 and 19. i = ii = iii = iv: THF, t-BuOK, rt, 1 h, quantitative yield).
display different absorption and emission spectra, even in the
case of E-21 vs. E-22, where the molecules differ only by the
position of the protective group substituent. The electronic
levels of the different oligomers were deduced from the
absorption edge in their absorption spectra and from their
cyclic voltammograms.[18] Table 1 depicts the resulting highest
occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) values and the optical properties
of the different oligomers. Figure 3 presents the calculated
band gap as a function of 1/NDB, where NDB denotes the
number of conjugated double bonds in the systems, a simple
measure of the conjugation length, L. Clearly, the band gap
of the systems does not obey a simple L−1 dependency, as
was frequently observed for oligo conjugated systems.[19]
Furtheremore, in some subsets of the oligomer family in
question, a negative slope is observed. One may attribute
this discrepancy to the differences in the contribution of
thiophene and phenyl rings to the degree of conjugation,
i
O
O
O
H
7, ii
O
O
E -20
E -21
E-28
E-29
E,E-31
E,E-32
O
O
O
i
7, i i
O
S
S
S
O
H
O
O
O
i
12, ii
O
S
S
S
S
O
H
E -22
E-30
E,E-33
Scheme 9. The synthesis of a partial library of second-generation arylene-vinylenes trimers E,E-31, E,E-32, and E,E-33. i) 10% HCl : THF, 60 °C, 3 h.
ii) ethanol, sodium ethoxide, rt, 1 h, quantitative yields.
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2.5. Organic Light-Emitting Diode (OLED)
E,E-35 and E,E,E,E-38 form good quality
and luminescent films when spin-coated
from THF solutions. The absorption and
emission spectra of films of E,E-35 and
E,E,E,E-38 were given in Figure 1 and 2.
The quantum efficiencies of luminescence
of E,E-35 and E,E,E,E-38 were 45% (excita-
tion wavelength, λex = 370 nm, emission
wavelength, λem = 550 nm) and 17% (λex
=
500 nm, λem = 630 nm) respectively.[20]
Both E,E-35 and E,E,E,E-38 were
incorporated as the emissive layer in
a
simple light-emitting diode struc-
ture consisting of indium tin oxide
(ITO), poly(3,4-ethylenedioxythiophene)
(PEDOT), the emissive oligomer, Ca, and
Al.[21] An ITO-covered glass substrate
is spin coated with a 60–70 nm layer of
PEDOT and annealed at 110 °C under
vacuum. 60–70 nm of the relevant oli-
Scheme 10. Preparation of trimer E,E-35 and E,E- 36. i: TFA. ii: 19, THF, t-BuOK, 1 h, rt. iii: 5%
HCl.
gomer are subsequently spin coated atop
the PEDOT and covered with Ca (30 nm)
and Al (120 nm) cathodes.
irrespective of their position in the oligomeric structure.
This may be related to the improved stability of the quinoid
structure of thiophene ring relative to the phenyl ring.[19]
Thus, the correlation between the calculated band-gap and
conjugation length could be better linearized by applying a
different contribution to thiophene and phenyl rings. As evi-
dent from Figure 3b, the best-fit to a linear form (yielding
the minimal linear-regression residue) is Leff = NDB + (2 ×
NTR), where NTR denotes the number of thiophene rings.
Applying this correction, the spread in all the libraries is
much smaller in the corrected graph. The linear fit (dashed
line) yields a band gap of 1.7 eV at (1/conjugation)→0, sug-
gesting the minimal band-gap obtainable for this family of
mixed thiophene vinylene phenylene systems. The HOMO
and LUMO versus the corrected measure of conjugation is
given in Figure 4.
Figure 5 presents the current and brightness of the OLEDs
made of E,E-35 and E,E,E,E-38 as a function of the applied bias.
The emission of E,E-35 and E,E,E,E-38 onsets at about 6.5 V
and 3.5 V, respectively. The lower threshold and higher bright-
ness of the E,E,E,E-38 based LED is directly related to its lower
bandgap and the lower barrier to electron injection as its LUMO
is closer to the workfunction of Ca. The Commission Interna-
tionale de l’Eclairage (CIE) chroma coordinates of the OLEDs
were CIE = (x,y) = (0.3598, 0.5982) and CIE = (x,y) = (0.6354,
0.3625) for E,E-35 and E,E,E,E-38, respectively.
2.6. Organic Field-Effect Transistors (OFET)
Organic field effect transistors[22,23] were fabricated in a bottom-
contacts configuration[24] by spin coating a 40 nm thick film of
oligomer E,E,E,E-38 atop an OFET struc-
ture using a previously described proce-
dure.[25] E,E,E,E-38 functions as the hole
conducting channel in the p-type FET,
which is switched on at negative gate-
source voltages.
Figure 6 depicts the OFET’s transfer
characteristics, i.e. the drain-source cur-
rents (IDS) as a function of gate-source
voltage (VG) for several drain-source
voltages (VDS = −2, −7, and −12 V). The
logarithmic graph (left) reveals the very
low VG threshold (VT ≈ 0). The off cur-
rent measured at VG = 0 is IDS ≈ 0.1 nA
and is at least an order of magnitude
lower at slightly postive gate bias, very
low compared to previously published
phenyl-thiophene co-oligomers.[26] The
Scheme 11. Preparation of oligomer E,E,E,E-38. i: THF, t-BuOK, 2 h, 0 °C.
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4
3.6
3.2
2.8
2.4
2
(a)
E-20 E-23
16, 19, E-24 –E-27
E,E-35
–
E,E,E,E-38
1.6
0
0.1
1/(conjugation) = 1/NDB
0.2
(b)
4
3.6
3.2
2.8
2.4
2
E-20 E-23
–
16, 19, E-24 – E-27
E,E-35
E,E,E,E-38
Figure 1. Absorption spectra of conjugated oligomers E-20 – E-27, E,E-
35, and E,E,E,E-38.
1.6
0
0.05
0.1
0.15
1/(conjugation) = 1/(NDB+2NTR)
Figure 3. Energy band-gap versus the inverse conjugation for the (E-20 –
E-23) library, the (16, 19, E-24 – E-27) library, and the complex oligomers (E,E-
35 and E,E,E,E-38): a) without correction and b) with a corrected conjugation
measure, incorporating the additional contribution of the thiophene rings.
Figure 2. Emission spectra of conjugated oligomers E-20 – E-27, E,E-35,
and E,E,E,E-38 (legend as in Figure 1).
linear region at large enough |VG| is clearly distinguishable.
Figure 7 depicts the current as a function of VDS for different
VG values. The initial linear incline, followed by the quadratic
region, is saturated at VDS = VG, as expected [23] when VT ≈ 0 .
Figure 4. HOMO and LUMO energies as a function of the corrected
measure of inverse conjugation.
T a b le 1 . Electronic and optical properties of the different oligomers.
Material
HOMO [eV] LUMO [eV] Absorption Absorption Emission
(edge) [eV] (max) [eV] (max) [eV]
E-20
5.6
5.4
5.3
5.3
1.9
1.9
1.9
2.0
3.7
3.4
3.4
3.3
3.0
2.9
3.0
2.9
2.4
2.1
3.8
3.5
3.5
3.4
3.3
3.2
3.4
3.3
3.1
2.5
3.5
3.2
3.2
3.1
2.8
2.7
2.8
2.7
2.3
2.0
E-21
E-22
E-23
E-24
E-25
5.2
2.3
E-26
E-27
5.0
5.0
5.0
2.1
2.6
2.9
Figure 5. Device performance: brightness (solid lines) and current
(dashed) of the three-layer OLED devices, with oligomers E,E-35 (green)
and E,E,E,E-38 (red).
E,E-35
E,E,E,E-38
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chemistry, based on Wittig and Wittig-Horner protection-depro-
tection procedures. Tuneability of the optical and HOMO–
LUMO band positions was demonstrated, showing the potential
in using such an approach. A direct relation between the band
gap of the oligomers and their degree of conjugation was dem-
onstrated. The latter is given by the number of double bonds
along the molecule backbone, with an additional contribution
of two effective bonds for each thiophene ring. Low band gap
energies (2.4 eV and 2.15 eV) were deducted for the longest oli-
gomers, only 20–30% higher than the minimal possible band
gap determined for this family (1.7 eV). Finally, OLEDs and
OFETs were made of selected materials, demonstrating the
potential embedded in the “click” chemistry approach.
4. Experimental Section
Figure 6. Field effect characteristics of a transistor made of E,E,E,E-38.
Source-drain current as a function of VG, for various values of VDS. Inset is
in logarithmic scale; the source electrode is set as ground. The blue ellipse
marks the “linear region”, from which the mobility was calculated.
General: All the starting materials and solvents described in the
manuscript were purchased from Sigma-Aldrich and Fluka. Solvents
and starting materials were used as received unless noted. Anhydrous
solvents were obtained using standard methods.
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication no. CCDC
792056 – 792064. Copies of the data can be obtained free of charge from
www.ccdc.cam.ac.uk/conts/retrieving.html.
Apparatus: NMR spectra were recorded on Bruker-AM-300 and
Bruker-AM-500 spectrometers. Mass spectra were recorded using matrix-
assisted laser desorption ionization (MALDI) micro MX (MICROMASS)
and TSQ-70B (FINNIGAN MAT). Melting points were recorded on a
PL-DSC (Polymer Laboratories) machine. Absorption and emission
spectra were recorded on a Shimadzu UV-1601 spectrometer and a
Perkin Elmer LS 50 luminescence spectrometer respectively. All optical
measurements were performed in analytical grade solvents.
Solution processing and all films and devices were made in a nitrogen
glove-box (LABMASTER 130, M. Braun, GmbH, Germany) integrated
with a thermal evaporator. PL quantum efficiency measurements were
carried out using a IS-040-SL integrating sphere (Labsphere) that was
fiber coupled to the FS920 fluorimeter (Edinburgh Instruments) and
the procedure was as previously described.[31] The substrates of the
FET devices were prepared as described in reference 25.. All current–
voltage characteristics of OLEDs and FETs were recorded using a 4155B
Semiconductor Parameter Analyzer (Agilent).
Figure 7. Field effect characteristics of a transistor made of E,E,E,E-38. Source-
drain current as a function of the drain-source voltage, for various values of
the gate-source voltage. The dashed line passes through VDS = VG points.
Materials: 4-bromomethyl-benzaldehyde (5):[15] 34 mL of a 1.5 M solution
of diisobutylaluminium hydride, DIBAL-H, in toluene were added to a
stirred solution of 5 g (25 mmol) 4-bromomethyl-benzonitrile in 50 mL
of dry THF, over a period of 10 min at 0 °C. After stirring for 24 h at 0 °C
the solution was diluted with 50 mL of diethyl ether, treated with 100 mL
of an aqueous HCl solution (10%) and extracted with diethyl ether. The
combined organic extracts were dried over Na2SO4 and evaporated. The
product was separated over alumina (7:3, hexane:methylene chloride) to
give 4.5 g (88% yield) of 5 in the form of a yellow oil. 1H NMR (300 MHz,
CDCl3, δppm): 9.99 (s, 1H), 7.85 (d, 2H), 7.52 (d, 2H), 4.48 (s, 2H). 13C
NMR (75 MHz, CDCl3, δppm): 191.6, 136.8, 129.7, 32.1. melting point
(mp) = 89 °C. Mass spectrum (MS) (CI+): m/z: 199.0 (M+).
As a material characterization, one may extract the charge
(holes) mobility of E,E,E,E-38 from the transfer curves. In the
linear region (VDS << VG; blue ellipse in Figure 6), and assuming
VT ≈ 0, the drain-source current is approximately given by[23]
VDS
∼
,
IDS
WCOX VG × : ×
L
=
(1)
where μ is the mobility, W = 11 mm and L = 4 μm are
respectively the effective length and separation of the elec-
trodes, and Cox = 40 nF cm−2 is gate capacitance per unit of
area. For IDS = 70 nA, VDS = 2 V, and VG = 20 V, we find μ =
5·10−5 cm2 V−1 s−1 .
2-(4-bromomethyl-phenyl)-4,4,5,5-tetramethyl-[1,3]dioxolane
(6):[27]
A solution of 5 (4.5 g, 22 mmol), 2,3-dimethyl-butane-2,3-diol (5.3 g,
45 mmol) and a catalytic amount of p-toluenesulfonic acid in benzene
(100 mL) was refluxed for 72 h. The reaction mixture was then washed
with brine, dried over Na2SO4 and evaporated. The product was purified
over alumina (7:3, hexane:methylene chloride) to give 4.0 g. (60% yield)
of 6 in the form of a white solid. 1H NMR (300 MHz, CDCl3, δppm):
7.46 (d, 2H), 7.34 (d, 2H), 5.94 (s, 1H), 4.47 (s, 2H), 1.26 (s, 6H), 1.19
(s, 6H). 13C NMR (75 MHz, CDCl3, δppm): 128.9, 126.5, 99.4, 82.7, 24.2,
22.1. mp = 40 °C. MS (CI+): m/z: 299.0 (M+).
3. Conclusions
A series of novel π-conjugated oligomers were prepared in very
high yields using a sequence-independent and Lego-like “click”
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2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Funct. Mater. 2011, 21, 634–643

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Triphenyl-[4-(4,4,5,5-tetramethyl-[1,3]dioxolan-2-yl)-benzyl] phosphonium
bromide (7): Triphenyl phosphine (6 g, 26 mmol) was added to a stirred
solution of 6 (4 g, 13 mmol) in 15 mL of dry THF and the reaction was
refluxed for 72 h under nitrogen. The white precipitate was filtered,
washed with several portions of hexane and dried, affording 6.5 g (93%
yield) of 7 in the form of a white solid. 1H NMR (300 MHz, CDCl3, δppm):
7.74 (m, 9H), 7.61 (m, 6H), 7.25 (d, 2H), 7.06 (d, 2H), 5.85 (s, 1H),
5.42 (s, 1H), 5.37 (s, 1H), 1.26 (s, 6H), 1.19 (s, 6H). 13C NMR (75 MHz,
CDCl3, δppm): 140.2, 140.1, 134.9, 134.4, 134.3, 131.4, 131.3, 130.1,130.0,
126.8, 118.1, 117.4, 99.2, 82.7, 24.2, 22.1. mp > 200 °C. MS (time of
flight (TOF) by laser deposition (LD+)): m/z: 481.2 (M+).
2,3-Dihdro-thieno[3,4-b][1,4]dioxine-5-carbaldehyde (13):[28] 3,4-Ethyle-
nedioxythiophene (2 mL, 18 mmol) was dissolved in dry DMF
(10 mL, 126 mmol), the solution was cooled to −10 °C and POCl3
(1.76 mL, 18 mmol) was added dropwise over 15 min. The mixture was
then allowed to reach room temperature then stirred for an additional
hour. The reaction was poured into an ice bath and neutralized using
a basic aqueous solution. The product, in the form of white needles,
was filtered and dried, yielding a quantitative yield (3.06 g). 1H NMR
(300 MHz, CDCl3, δppm): 9.84 (s, 1H), 6.73 (s, 1H), 4.31 (d, 2H), 4.21
(d, 2H). 13C NMR (75 MHz, CDCl3, δppm): 180.0, 141.7, 110.8, 110.7,
65.2, 64.3. mp = 140 °C. MS (TOF LD+) m/z: 170 (M+H+).
4,4,5,5-Tetramethyl-2-thiophen-2-yl-[1,3]dioxalane (8):
containing thiophen-2-carbaldehyde (2.8 mL, 30 mmol), 2,3-dimethyl-
butane-2,3-diol (7 g, 60 mmol), and catalytic amount of
A
solution
5-(5,5-Dimethyl-[1,3]dioxin-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]dioxine
(14): 2,2-dimethyl-1,3-propandiol (1.2 g, 11 mmol) and a catalytic
amount of p-toluenesulfonic acid were added to a solution of 13 in
50 mL of toluene. The mixture was refluxed for 1 h then cooled and
washed with brine. The organic phase was dried over Na2SO4 and
evaporated. The crude was purified over alumina (7:3, hexane:methylene
a
p-toluenesulfonic acid in 100 mL of benzene was refluxed for 72 h. The
reaction mixture was then washed with brine, dried and evaporated and
the product was isolated using chromatography over alumina (9.5:0.5,
hexane:ethyl acetate) yielding 5.7 g (90% yield) of 8 as a pail yellow oil.
1H NMR (300 MHz, CDCl3, δppm): 7.29 (d, 1H), 7.13 (d, 1H), 6.95 (t,
1H), 6.19 (s, 1H), 1.30 (s, 6H), 1.28 (s, 6H). 13C NMR (75 MHz, CDCl3,
1
chloride), yielding a white solid (2.5 g, 90% yield). H NMR (300 MHz,
dimethyl sulfoxide (DMSO)-d6, δppm): 6.55 (s, 1H), 5.60 (s, 1H), 4.17
(m, 4H), 3.57 (s, 4H), 1.12 (s, 3H), 0.70 (s, 3H). 13C NMR (75 MHz,
CDCl3, δppm): 101.4, 97.3, 79.5, 66.6, 66.4, 24.7, 23.6. mp = 134 °C. MS:
(TOF LD+) m/z: 256.46 (M+H+).
δ
ppm): 143.7, 126.4, 126.0, 96.6, 82.8, 24.2, 22.0. MS (TOF by electron
spray (ES+)): m/z: 213.19 (M+H+).
5-(4,4,5,5-Tetramethyl-[1,3]dioxalan-2-yl)-thiophen-2-carbaldehyde (9):
8 mL (11 mmol) of a n-butyllithium solution (1.6 M in hexane) were
added slowly to a solution of 8 (2 g, 9 mmol) in 20 mL of dry THF at
0 °C. The solution was then left to reach room temperature and stirred
for additional 5 h. A solution of 3 g ammonium chloride in 50 mL water
was added and the mixture stirered for 10 min. The layers were separated
and the aqueous layer was extracted with diethyl ether. The combined
organic layers were dried over Na2SO4, filtered and evaporated under
reduced pressure. The product was purified over alumina (8 :2 hexane:
ethyl acetate) to give 1.5 g of 9 as a yellow oil (66% yield). 1H NMR
(300 MHz, CDCl3, δppm): 9.87 (s, 1H), 7.64 (d, 1H), 7.20 (d, 1H), 6.14
(s, 1H), 1.27 (s, 6H), 1.26 (s, 6H). 13C NMR (75 MHz, CDCl3, δppm):
183.6, 152.3, 133.5, 133.6, 126.6, 99.4, 65.2, 22.5, 13.9. MS (TOF ES+):
m/z: 241.32 (M+H+).
5-Bromo-7-(5,5-dimethyl-[1,3]dioxin-2-yl)-2,3-dihydro-thieno[3,4-b]
[1,4]dioxine (15):[28] 14 (1.5 g, 5.8 mmol) was suspended in 40 mL of
dry acetonitrile, at −78 °C, in the dark and under nitrogen, then NBS
(1.17 g, 6.6 mmol) was added and the mixture was allowed to reach
room temperature. After 20 min at room temperature, water was added
and the product, a white solid, precipitated and filtered, yielding 15 in
a quantitative yield (1.94 g). 1H NMR (300 MHz, CDCl3, δppm): 5.58
(s, 1H), 4.17 (m, 4H), 3.67 (d, 2H), 3.52 (d, 2H), 1.18 (s, 3H), 0.70
(s, 3H). 13C NMR (75 MHz, CDCl3, δppm): 96.9, 89.8, 79.4, 66.8, 66.5,
31.9, 24.6, 23.6. mp = 114 °C. MS (TOF LD+): m/z: 335.45 (M+).
{4-[7-(5,5-Dimethyl-[1,3]dioxan-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]dioxin-
5-yl]-benzyl}-phosphonic acid diethyl ester (16): 15 (0.6 g, 1.8 mmol),
(4-boronic acid – benzyl)-phosphonic acid diethyl ester[16] (0.49 g,
1.8 mmol), 15 mL of 2M aqueous sodium bicarbonate and [P(Ph)3]2PdCl2
(57 mg, 0.08 mmol) were added to 30 mL of toluene. The reaction
mixture was stirred at 100 °C overnight, then the organic phase was
separated, dried over Na2SO4 and evaporated. The crude was purified
over alumina (methylene chloride) affording 0.35 g of a yellow solid
(45% yield). 1H NMR (300 MHz, DMSO-d6, δppm): 7.58 (d, 2H), 7.26
(d, 2H), 5.56 (s, 1H), 4.27 (m, 4H), 3.91 (m, 4H), 3.58 (s, 4H), 3.24
(s, 1H), 3.17 (s, 1H), 1.29 (s, 3H), 1.09 (t, 6H), 0.71 (s, 3H). 13C NMR
(75 MHz, DMSO-d6, δppm): 139.7, 137.8, 125.8, 115.4, 112.3, 94.7, 76.8,
65.2, 64.7, 61.8, 32.9, 31.8, 30.1, 23.0, 21.6, 16.6. mp = 113 °C. MS (TOF
LD+): m/z: 482.31 (M+).
[5-(4,4,5,5-Tetramethyl-[1,3]dioxalan-2-yl)-thiophen-2-yl]-methanol
(10): Sodium borohydride (0.54 g, 14 mmol) was added to a stirred
solution of 9 (1.4 g, 6 mmol) in 10 mL THF. The reaction was stirred
under nitrogen at room temperature for 30 min then excess sodium
borohydride was destroyed by slow addition of acetone (5 mL). The
solution was evaporated and the crude was dissolved in ethylacetate. The
organic layer was washed with brine, dried over Na2SO4 and evaporated
under reduced pressure. The product was purified over alumina (6.5:3.5,
1
hexane:ethyl acetate) to give 0.9 g of 10 as a yellow oil (64% yield). H
NMR (300 MHz, CDCl3, δppm): 6.99 (d, 1H), 6.84 (d, 1H), 6.12 (s, 1H),
4.76 (s, 2H), 1.27 (s, 6H), 1.26 (s, 6H). 13C NMR (75 MHz, CDCl3,
7-Bromo-9,9-dioctyl-9H-fluorene-2-carbaldehyde (17):[29] 2.3 mL of
a n-butyllithium solution (1.6 M in hexane) were added dropwise to a
solution of 2,7-dibromo-9,9 dioctyl-9H-fluorene (2 g, 3.6 mmol) in 30 mL
of dry THF at −78 °C under nitrogen. After stirring for 1 h at −78 °C,
0.36 mL (4.7 mmol) of dry DMF were added to the solution and it was
allowed to reach room temperature overnight. The solvent was evaporated
and the residue washed with several portions of methylene chloride. The
combined organic layers were dried over Na2SO4 and evaporated. The
product was purified over alumina (7:3, hexane:methylene chloride)
affording 0.7 g (33% yield) of 17 in the form of a yellow oil. 1H NMR
(300MHz,CDCl3,δppm):9.99(s,1H),7.78(m,3H),7.55(d,1H),7.45(m,2H),
δ
ppm): 126.1, 124.8, 96.6, 60.3, 22.0, 14.0. MS (TOF MS AP+): m/z: 241.1
(M-H+).
2-(5-Chloromethyl-thiophen-2-yl)-4,4,5,5-tetramethyl-[1,3]dioxolane(11):
Thionyl chloride (7 mL, 36 mmol) was added to 0.5 g of 10 (2 mmol) and
the mixture was refluxed under nitrogen for 3 h. Exsess thionyl chloride
was removed under reduced pressure and the crude was re-dissolved in
methylene chloride and washed with a slightly basic aqueous solution.
The organic layer was dried over Na2SO4 and evaporated under reduced
pressure. The product, a yellow oil, was obtained in 53% yield (0.2 g). 1H
NMR (300 MHz, CDCl3, δppm): 6.97 (d, 1H), 6.91 (d, 1H), 6.10 (s, 1H),
4.75 (s, 2H), 1.28 (s, 6H), 1.26 (s, 6H).
1.93 (m, 4H), 1.93 (t, 4H), 1.21 (m, 20H), 0.80 (t, 6H), 0.72 (m, 4H). 13
C
Triphenyl-[5-(4,4,5,5-tetramethyl-[1,3]dioxolan-2-yl)-thiophen-2-ylmethyl]-
phosphane (12): Triphenyl phosphine (0.4 g, 1.6 mmol) was added to a
stirred solution of 11 (0.2 g, 0.8 mmol) in 15 mL of dry THF and the
reaction was refluxed for 72 h under nitrogen. The yellow precipitate was
isolated by filtration, washed with hexane and dried, affording 0.19 g of
12 (47% yield). 1H NMR (300 MHz, CDCl3, δppm): 7.78 (m, 9H), 7.63
(m, 6H), 7.09 (d, 2H), 6.86 (d, 2H), 5.97 (s, 1H), 5.83 (s, 1H), 5.78
(s, 1H), 1.20 (s, 6H), 1.13 (s, 6H). 13C NMR (75 MHz, CDCl3, δppm):
134.9, 130.2, 118.2, 117.5, 96.2, 83.0, 67.9, 25.5, 24.0, 21.9. mp > 200 °C.
MS (TOF LD+): m/z: 487.3 (M+).
NMR (75 MHz, CDCl3, δppm): 192.2, 154.5, 151.1, 146.3, 138.5, 135.5,
130.5, 130.4, 126.4, 123.0, 122.2, 120.0, 55.5, 40.0, 31.7, 31.5, 29.8, 29.1,
23.6, 22.6, 22.5, 14.0. MS (TOF LD+): m/z: 497.36 (M+).
2-(7-Bromo-9,9-dioctyl-9H-fluorene-2-yl)-5,5-dimethyl-[1,3]dioxane (18):
2,2-dimethyl-1,3-propandiol (0.34 g, 3.2 mmol) and a catalytic amount of
p-toluenesulfonic acid were added to a solution of 17 (0.8 g, 1.6 mmol)
in 80 mL of toluene. The mixture was refluxed for 48 h then cooled,
washed with brine, dried over Na2SO4 and evaporated. The product was
purified over alumina (hexane). 18 (0.9 g) was isolated as a white solid
in a quantitative yield. 1H NMR (300 MHz, CDCl3, δppm): 7.58 (d, 1H),
©
wileyonlinelibrary.com
Adv. Funct. Mater. 2011, 21, 634–643
2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
641

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7.46 (m, 2H), 7.34 (m, 3H), 5.38 (s, 1H), 3.72 (d, 2H), 3.60 (d, 2H),
was neutralized using a basic aqueous solution, then evaporated. The
residue was re-dissolved in methylene chloride, dried over Na2SO4 and
evaporated. The products are normally received in a quantitative yield.
3-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxin-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]
dioxin-5-trans-4-styryl-benzaldehyde (E-28): 1H NMR (300 MHz, CDCl3,
1.87 (t, 4H), 1.27 (s, 3H), 1.02 (m, 26H), 0.81 (m, 4H), 0.73 (s, 3H). 13
C
NMR (75 MHz, CDCl3, δppm): 153.3, 150.2, 140.6, 139.7, 137.8, 129.8,
126.1, 125.1, 121.2, 121.1, 120.7, 102.1, 77.7, 55.4, 40.1, 31.7, 30.2, 29.8,
29.1, 29.0, 23.5, 23.0, 22.5, 14.0. mp = 62 °C. High-resolution (HR) MS
(TOF ES+): m/z: 583.3144 (M+).
δ
ppm): 9.93 (s, 1H), 7.82 (d, 2H), 7.61 (d, 2H), 7.50 (d, 2H), 7.35
{4-[7-(5,5-Dimethyl-[1,3]dioxan-2-yl)-9,9-dioctyl-9H-fluoren-2-yl]-
benzyl}-phosphonic acid diethyl ester (19): 18 (1 g, 1.7 mmol), (4-boronic
acid – benzyl)-phosphonic acid diethyl ester[16] (0.5 g, 1.7 mmol),
15 mL of 2 M aqueous sodium bicarbonate and [P(Ph)3]2PdCl2 (0.4 mg,
0.00057 mmol) were added to 15 mL of toluene and the reaction mixture
was kept overnight at 100 °C. The organic phase was separated, dried
over Na2SO4 and evaporated. The product was purified over alumina
(methylene chloride) yielding 1 g (80% yield) of 19 in the form of a
yellow oil. 1H NMR (300 MHz, CDCl3, δppm): 7.72 (m, 2H), 7.62 (d, 2H),
7.53 (m, 3H), 7.45 (s, 1H), 7.40 (d, 2H), 5.47 (s, 1H), 4.06 (m, 4H), 3.83
(d, 2H), 3.68 (d, 2H), 3.24 (s, 1H), 3.19 (s, 1H), 1.99 (t, 4H), 1.35 (s,
3H), 1.26 (m, 20H), 0.89 (m, 10H), 0.83 (d, 4H), 0.81 (s, 3H), 0.79 (s,
2H). 13C NMR (75 MHz, CDCl3, δppm): 153.6, 152.8, 143.1, 142.1, 142.0,
141.9, 141.4, 139.2, 1323, 132.2, 132.0, 131.9, 129.1, 127.6, 126.8, 123.2,
122.6, 121.9, 121.4, 104.1, 79.6, 64.0, 57.0, 55.2, 42.1, 35.8, 34.7, 33.6,
33.4, 32.0, 31.8, 31.0, 30.9, 25.5, 24.9, 24.4, 24.3, 23.7, 18.2, 18.1, 15.9,
15.8. HRMS (TOF ES+): m/z: 731.4817 (M+H+).
General Wittig Reaction Procedure 1: 1.8 mmol of the phosphonium
salt were added to a solution of sodium ethoxide (82 mg, 3.6 mmol)
in ethanol then 2 mmol of the aldehyde were added. The reaction was
stirred for 1 h under nitrogen at room temperature. The solution was
then evaporated and the residue extracted with methylene chloride. The
organic layer was dried over Na2SO4 and evaporated. The product was
purified using chromatography.
(t, 2H), 7.30 (d, 2H), 7.05 (d, 1H). 13C NMR (75 MHz, CDCl3, δppm):
191.6, 143.4, 136.5, 135.6, 132.1, 130.2, 129.4, 128.7, 126.8. MS
(chemical ionization (CI)): m/z: 208.0 (M+).
Trans-4-(2-thiophen-2-yl-vinyl)-benzaldehyde
(E-29):
1H
NMR
(300 MHz, CDCl3, δppm): 9.98 (s, 1H), 7.80 (d, 2H), 7.52 (d, 2H), 7.35
(d,1H), 7.22 (s, 1H), 7.09 (d, 1H), 6.98 (m, 1H), 6.86 (d, 1H). 13C NMR
(75 MHz, CDCl3, δppm): 143.1, 142.1, 135.2, 130.3, 127.8, 127.6, 126.7,
126.6, 125.7, 125.1, 2.8. MS (TOF by affinity purification (AP+)): m/z:
215.1 (M+H+).
General Wittig Reaction Procedure 2: 2 mmol of the phosphonium
salt were added to a solution of t-BuOK (0.7 g, 6 mmol) in dry THF
(10 mL) and cooled to 0 °C. Then 2 mmol of the aldehyde were added.
The reaction was stirred for 1 h under nitrogen at room temperature. The
solution was then evaporated and the residue extracted with methylene
chloride. The organic layer was dried over Na2SO4 and evaporated. The
product was purified using chromatography.
3-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxin-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]
dioxin-5-yl]-phenyl}-vinyl)-9-hexyl-9H-carbazole (E-24): 1H NMR (500 MHz,
DMSO-d6, δppm): 8.39 (s, 1H), 8.18 (d, 1H), 7.65 (m, 7H), 7.40 (d, 2H),
7.23 (s, 1H), 7.21 (m, 1H), 5.67 (s, 1H), 4.39 (m, 4H), 4.29 (t, 2H), 3.61
(s, 4H), 1.76 (m, 2H), 1.22 (m, 6H), 1.16 (s, 3H), 0.82 (t, 3H), 0.73 (s,
3H). 13C NMR (125 MHz, CDCl3, δppm): 140.8, 140.2, 139.3, 137.3, 136.3,
131.6, 129.4, 128.5, 126.3, 125.7, 125.5, 124.4, 123.1, 122.8, 120.4, 118.9,
118.6, 117.4, 119.3, 108.8, 95.4, 77.7, 71.8, 64.7, 43.1, 31.5, 30.1, 29.6,
28.9, 26.9, 22.6, 14.1. mp = 103 °C. MS (TOF LD+): m/z: 607.29 (M+).
[4-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxin-2-yl)-2,3-dihydro-thieno[3,4-b]
[1,4]dioxin-5-yl]-phenyl}-vinyl)-phenyl]-diphenyl-amine (E-25): 1H NMR
(500 MHz, CDCl3, δppm): 7.64 (d, 2H), 7.57 (d, 2H), 7.51 (d, 2H), 7.31
(t, 4H), 7.17 (s, 1H), 7.10 (s, 1H), 7.06 (m, 6H), 6.95 (d, 2H), 4.33 (d,
2H). 4.32 (d, 2H), 3.60 (s, 4H), 1.15 (s, 3H), 0.72 (s, 3H). 13C NMR (125
MHz, CDCl3, δppm): 149.3, 149.1, 141.2, 139.2, 137.8, 133.7, 133.4, 131.1,
129.7, 129.1, 128.4, 128.3, 128.2, 126.3, 125.4, 124.8, 119.2, 113.8, 97.2,
79.5, 66.5, 32.0, 24.7, 23.6. mp = 200 °C. MS (TOF MS ES+): m/z: 602.23
(M+H+).
Trans-4,4,5,5-tetramethyl-2-(4-styryl-phenyl)-[1,3]dioxolane
(E-20):
1H NMR (300 MHz, CDCl3, δppm): 7.51 (m, 6H), 7.36 (t, 2H), 7.26
(d, 1H), 7.12 (s, 2H), 5.99 (s, 1H), 1.34 (s, 6H), 1.29 (s, 6H). 13C NMR
(75 MHz, CDCl3, δppm): 139.1, 137.7, 137.3, 128.9, 128.7, 128.4, 127.6,
126.6, 126.5, 126.4, 82.7, 99.7, 24.3, 22.2. mp = 87 °C. MS (TOF LD+):
m/z: 308.2 (M+).
Trans-4,4,5,5-tetramethyl-2-[4-(2-thiophen-2-yl-vinyl)-phenyl]-[1,3]
dioxolanle (E-21): 1H NMR (300 MHz, CDCl3, δppm): 7.44 (s, 4H), 7.18
(d, 1H), 7.05 (d, 1H), 6.98 (t, 1H), 6.92 (s,1H), 6.87 (s, 1H), 5.95
(s, 1H), 1.31 (s, 6H), 1.26 (s, 6H). 13C NMR (75 MHz, CDCl3, δppm):
139.0, 128.0, 127.6, 126.6, 126.2, 124.4, 122.0, 99.7, 82.7, 24.3, 22.2.
mp = 94 °C. MS (TOF LD+): m/z: 314.3 (M+).
Trans-4,4,5,5-tetramethyl-2-(5-styryl-thiophen-2-yl)-[1,3]dioxolane (E-22):
1H NMR (300 MHz, CDCl3, δppm): 7.46 (d, 2H), 7.36 (t, 3H), 7.26 (s, 1H),
7.16 (d, 1H), 7.03 (d,1H), 6.90 (d, 1H), 6.15 (s, 1H), 1.46 (s 6H), 1.35 (s,
6H). 13C NMR (75 MHz, CDCl3, δppm): 143.6, 142.3, 136.9, 128.7, 128.5,
127.6, 126.7, 126.3, 125.7, 121.9, 96.7, 83.1, 24.3, 22.2. mp = 93 °C. MS
(TOF LD+): m/z: 314.1 (M+).
4,4,5,5-tetramethyl-2-{4-[2-(4-styryl-phenyl)-vinyl]-phenyl}-[1,3]dioxolane
(E,E-31): 1H NMR (500 MHz, CDCl3, δppm): 7.49 (m, 10H), 7.34 (t, 3H),
7.10 (s, 4H), 5.97 (s, 1H), 1.31 (s, 6H), 1.26 (s, 6H). 13C NMR
(125 MHz, CDCl3, δppm): 139.0, 137.2, 129.4, 129.0, 128.8, 128.3, 99.8,
82.5, 21.9. mp = 98 °C. MS (TOF LD+): m/z: 410.2 (M+).
4,4,5,5-tetramethyl-2-(4-{2-[4-(2-thiophen-2-yl-vinyl)-phenyl]-vinyl}-
phenyl)-[1,3]dioxolane (E,E-32): 1H NMR (500 MHz, CDCl3, δppm): 7.47
(m, 8H), 7.20 (d, 1H), 7.17 (d, 1H), 7.06 (s, 2H), 7.03 (d, 1H), 6.98
(m, 1H), 6.87 (d, 1H),5.97 (s, 1H), 1.31 (s, 6H), 1.26 (s, 6H). 13C NMR
(125 MHz, CDCl3, δppm): 142.9, 129.2, 128.7, 126.6, 126.0, 124.3, 121.6,
99.8, 82.6, 24.8, 22.1. MS (TOF LD+): m/z: 416.20 (M+).
3-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxan-2-yl)-9,9-dioctyl-9H-fluorene-2-yl]-
phenyl}-vinyl)-9-hexyl-9H-carbazole (E-26): 1H NMR (500 MHz, CDCl3,
δppm): 8.27 (s, 1H), 8.02 (d, 1H), 7.72 (m, 7H), 7.62 (d,1H), 7.59
(s, 1H), 7.54 (d, 1H), 7.48 (d, 1H), 7.45 (s, 1H), 7.41 (m, 2H), 7.34
(s, 1H), 7.20 (s, 2H), 5.48 (s, 1H), 4.31 (t, 2H), 3.84 (d, 2H), 3.71 (d,
2H), 2.02 (t, 4H), 1.89(m, 2H), 1.36 (s, 3H), 1.18 (m, 33H), 0.88(m,
6H), 0.80(s, 3H). 13C NMR (125 MHz, CDCl3, δppm): 153.6, 152.8, 143.2,
142.7, 142.1, 142.0, 141.9, 141.5, 139.1, 138.7, 131.4, 130.1, 129.2, 128.4,
127.6, 127.5, 127.3, 126.8, 126.2, 125.0, 124.7, 123.1, 122.6, 122.2, 121.9,
121.5, 120.8, 120.5, 110.7, 104.2, 79.6, 57.0, 55.2, 45.0, 42.1, 33.6, 33.4,
32.1, 31.85, 31.05, 31.0, 30.8, 28.7, 25.5, 24.9, 24.4, 24.3, 23.7, 15.9, 15.8.
HRMS (TOF MS ES+): m/z: 856.6003 (M+H+).
[4-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxan-2-yl)-9,9-dioctyl-9H-fluoren-2-yl]-
phenyl}-vinyl)-phenyl]-diphenylamine (E-27): 1H NMR (500 MHz, CDCl3,
δ
ppm): 7.77 (dd, 2H), 7.70 (d, 2H), 7.63 (d, 4H), 7.57 (d,1H), 7.50 (s,
1H), 7.46 (d, 2H), 7.30 (t, 4H), 7.16 (d, 4H), 7.14 (s, 1H), 7.12(d, 2H),
7.07 (t, 3H), 5.15 (s, 1H), 3.85 (d, 2H), 3.74 (d, 2H), 2.04 (t, 4H), 1.39
(s, 3H), 1.12 (m, 24H), 0.86 (m, 6H), 0.83 (s, 3H). 13C NMR (125 MHz,
CDCl3, δppm): 153.7, 152.8, 149.4, 149.2, 143.2, 142.3, 142.0, 141.4, 139.2,
138.4, 133.4, 131.1, 129.9, 129.2, 128.7, 128.6, 128.4, 127.5, 126.9, 126.4,
126.3, 125.4, 124.9, 123.1, 122.7, 122.0, 121.5, 104.2, 79.6, 57.1, 42.1,
33.6, 32.1, 31.8, 31.1, 31.0, 30.1, 25.6, 25.0, 24.4, 23.8, 15.9, 2.9. mp =
180 °C. MS (TOF ES+): m/z: 850.55 (M+H+).
4,4,5,5-tetramethyl-2-{5-[2-(5-styryl-thiophen-2-yl)-vinyl]-thiophen-
2-yl}-[1,3]dioxolane (E,E-33): 1H NMR (500 MHz, CDCl3, δppm): 7.37
(d, 2H), 7.27 (t, 2H), 7.18 (s, 1H), 7.16 (s, 1H), 7.05 (d, 1H), 7.00
(s, 1H), 6.94 (m, 5H), 6.17 (s, 1H), 1.37 (s, 6H), 1.33 (s, 6H). 13C NMR
(125 MHz, CDCl3, δppm): 143.1, 141.8, 136.8, 128.5, 127.1, 127.0, 126.9,
125.7, 121.7, 121.6, 96.4, 83.0, 24.2, 22.0. MS (TOF LD+): m/z: 422.
General Deprotection Procedure: Protected materials, such as 20–23,
were deprotected by heating their solution in a 1:2 mixture of 10%
HCl:THF to 60 °C under an inert atmosphere for 3 h. The solution
7-{4-[2-(4-Diphenylamino-phenyl)-vinyl]phenyl}-2,3-dihydro-
thieno[3,4-b][1,4]dioxin-5-carbaldehyde, (E-34): E-25 (0.3 g, 0.5 mmol)
was dissolved in 1:1 water/methylene chloride bi phasic mixture
(10 mL) and cooled to 0 °C. TFA (2 mL, 25 mmol) was added and
the resulting mixture was stirred at rt under nitrogen for 2 h. The
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methylene chloride layer was then dried over Na2SO4 and evaporated.
The product was purified over alumina (3:7, methylene chloride:hexane)
affording 0.23 g (92% yield) of E-34 in the form of an orange solid. H
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NMR (500 MHz, DMSO-d6,δppm): 9.87 (s, 1H), 7.80 (d, 2H), 7.66 (d,
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[4-(2-{4-[7-(2-{4-[7-(5,5-Dimethyl-[1,3]dioxan-2-yl)-9,9-dioctyl-9H-
fluorene-2-yl]-phenyl}-vinyl)-2,3-dihydro-thieno[3,4-b][1,4]dioxin-5-yl]-
phenyl}-vinyl)-phenyl]-dipheyl-amine (E,E-35): 19 (0.32 g, 0.4 mmol)
was dissolved in dry THF (10 mL), the solution was cooled to 0 °C then
t-BuOK (0.15 g, 1.2 mmol) was added. After 3 min 34 (0.23 g, 0.4 mmol)
in 8 mL of dry THF was added to the solution. The resulting mixture
was stirred at 0 °C under nitrogen for 1 h. The solvent was removed
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(3 : 7 methylene chloride : hexane) affording 0.34 g (70% yield) E,E-35
in the form of a yellow solid. 1H NMR (500 MHz, CDCl3, δppm): 7.74 (m,
4H), 7.63 (d, 2H), 7.55 (m, 8H), 7.48 (d, 2H), 7.39 (d, 2H), 7.28 (s, 2H),
7.05 (m, 10H), 6.90 (d, 2H), 5.47 (s, 1H), 4.37 (s, 4H), 3.83 (d, 2H),
3.71 (d, 2H), 2.01 (t, 4H), 1.62 (m, 24H), 1.35 (s, 3H), 0.83 (s, 3H),
0.81 (m, 6H). 13C NMR (125 MHz, CDCl3, δppm): 149.3, 149.1, 133.3,
131.1, 129.6, 129.1, 128.3, 127.9, 126.3, 125.4, 124.8, 99.4, 79.6, 66.6,
66.3, 33.6, 31.8, 31.0, 30.9, 24.4, 23.7, 15.9, 15.8. mp = 89 °C. MS (TOF
ES+): m/z: 1093.41 (M+H+).
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7-{4-[2-(7-{4-[2-(4-Diphenylamino-phenyl)-vinyl]-phenyl}2,3-dihydro-
thieno[3,4-b][1,4]dioxin-5-yl)-vinyl]-phenyl}-9,9-dioctyl-9H-fluorene-2-
carbaldehyde (E,E-36): E,E-35 (0.05 g, 0.04 mmol) was dissolved in 2:1
THF: 5% HCl and heated to 70 °C for 4 h. The reaction was neutralized
using an aqueous solution of NaHCO3 and extracted with ether. The
organic phase was dried over Na2SO4 and evaporated. The product was
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1
(87% yield) of E,E-36 in the form of a yellow solid. H NMR (500 MHz,
CDCl3, δppm): 10.00 (s, 1H), 7.82 (m, 4H), 7.67 (d, 2H), 7.58 (m, 8H),
7.44 (d, 2H), 7.32 (d, 2H), 7.23 (s, 2H), 6.97 (m, 10H), 6.83 (d, 2H),
4.31(s, 4H), 2.01 (t, 4H), 1.20 (m, 24H), 0.73 (m, 6H). 13C NMR (125
MHz, CDCl3, δppm): 192.2, 152.9, 151.7, 147.5, 147.3, 147.2, 141.3, 139.7,
138.7, 136.8, 135.9, 135.2, 131.8, 131.5, 129.2, 127.3, 126.5, 126.1, 124.4,
123.5, 123.0, 121.2, 115.8, 115.2, 64.8, 55.3, 40.1, 31.8, 31.6, 30.2, 30.0,
29.8, 29.7, 29.6, 29.4, 29.3, 23.7, 23.6, 14.0, 13.9. mp = 85 °C. MS (TOF
ES+): m/z: 1006.52 (M+H+).
Oligomer (E,E,E,E-38): Bi-functional reagent 37[30] (0.12 g, 0.19 mmol)
was dissolved in dry THF (8 mL) then the solution was cooled to 0 °C
and t-BuOK (0.17 g, 1.55 mmol) was added. After 3 min E-34 (0.2 g,
0.39 mmol) was added and the resulting mixture was stirred at rt
under nitrogen for 2 h. The solvent was then removed under reduced
pressure and the product was purified over alumina (3:7, methylene
chloride:hexane) affording 0.13 g (53% yield) of E,E,E,E-38 in the form of
a red solid. 1H NMR (500 MHz, CDCl3,δppm): 7.66 (d, 4H), 7.43 (d, 4H),
7.34 (d, 4H), 7.23 (m,12H), 7.06 (d, 8H), 6.94 (m, 14H), 4.29 (s, 8H),
3.88 (d, 4H), 1.78 (t, 2H), 1.34 (m, 4H), 1.19 (m, 12H), 0.9 (m, 12H). 13
C
NMR (125 MHz, CDCl3, δppm): 151.0, 147.5, 147.2, 131.5, 129.2, 127.2,
126.4, 126.0, 124.4, 123.3, 122.9, 116.6, 71.7, 66.4, 39.8, 30.8, 29.2, 24.2,
23.1, 14.1, 11.4. mp = 262 °C. MS (TOF LD-): m/z: 1356.52 (M+).
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Acknowledgements
The authors thank the European Community Marie Curie Actions,
Marie Curie Research Training Network (BIMORE, Project No.: 35859)
and the Russel Berry Nanotechnology Institute at the Technion (RBNI)
for the financial support. O.S. acknowledges support of the Center of
Absorption in Science, Ministry of Immigrant Absorption, Israel.
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New Jersey 2002.
Received: September 10, 2010
Published online: December 14, 2010
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Adv. Funct. Mater. 2011, 21, 634–643
2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
643