Synthesis, structure and solvatochromism of the emission of cyano-substituted oligo(phenylenevinylene)s

Article abstract of DOI:10.1002/1099-0690(200108)2001:15<2927::AID-EJOC2927>3.0.CO;2-V

Strongly luminescent and highly soluble oligo(phenylenevinylene)s with five benzene rings and cyano groups in different positions of the terminal styrene units were prepared by means of Horner and Knoevenagel reactions. The substitution pattern - cyanide moieties on the vinyl or on the aromatic regions, together with the effect of auxochromic groups - has distinct influences on the electronic spectra, particularly on the fluorescence. Polar solvents induce red shifts and strongly reduce the fluorescence intensity of the vinyl-substituted oligomers. Cyano substitution increases the electron affinity of the oligomers; this effect is more pronounced for molecules with vinyl cyanides and can be altered by the presence of additional electron-donating or electron-withdrawing groups. The molecular structures of one oligomer bearing cyano groups on the vinylene segments and one with benzonitrile units have been resolved.

Full text of DOI:10.1002/1099-0690(200108)2001:15<2927::AID-EJOC2927>3.0.CO;2-V

FULL PAPER
Synthesis, Structure and Solvatochromism of the Emission of
Cyano-Substituted Oligo(phenylenevinylene)s
Heiner Detert,*[a] Dieter Schollmeyer,[a] and Erli Sugiono[a]
Keywords: Fluorescence / Materials science / Oligomers / Solvatochromism / Wittig reactions
Strongly luminescent and highly soluble oligo(phenylenevin- strongly reduce the fluorescence intensity of the vinyl-substi-
ylene)s with five benzene rings and cyano groups in different
tuted oligomers. Cyano substitution increases the electron af-
positions of the terminal styrene units were prepared by me- finity of the oligomers; this effect is more pronounced for mo-
ans of Horner and Knoevenagel reactions. The substitution lecules with vinyl cyanides and can be altered by the pres-
pattern − cyanide moieties on the vinyl or on the aromatic
regions, together with the effect of auxochromic groups − has
distinct influences on the electronic spectra, particularly on
the fluorescence. Polar solvents induce red shifts and
ence of additional electron-donating or electron-with-
drawing groups. The molecular structures of one oligomer
bearing cyano groups on the vinylene segments and one with
benzonitrile units have been resolved.
Introduction
Cyano substitution strongly alters the properties of oligo-
(phenylenevinylene)s; increased electron affinity is accom-
panied by strong bathochromic shifts of the absorption and
emission spectra.[18,19] Calculations on cyano-substituted
PPVs have shown an overall stabilisation and a distinct
sensitivity of the polymer properties towards the relative
positions of electron-withdrawing and electron-donating
groups.[20] The stabilization of the conduction band is more
pronounced if the nitrile is attached to the vinylene moiety
than if it is ring-substituted, but on the other hand vinylene
substitution greatly reduces the bandgap. Moreover, the
rates of reaction between OPVs and singlet oxygen Ϫ the
principal degradation pathway of these materials in LEDs
Ϫ are strongly reduced by substitution with cyano groups,
as has been shown with a series of distyrylbenzenes.[21] Cy-
ano-substituted OPVs have been studied intensively,[22Ϫ24]
the chromophores mostly being distyrylbenzenes with pro-
penenitrile segments; only a few compounds with extended
conjugated systems[25,26] or benzonitrile units have been re-
ported so far. These model compounds can also be valuable
materials for electrooptical devices, due to their luminescent
and semiconducting properties, and as luminescent seg-
ments in copolymers.[27,28]
Organic compounds with extended conjugated systems
display unusual semiconducting and luminescence proper-
ties. Since the discovery of electroluminescence from poly-
(phenylenevinylene) (PPV),[1] interest in this polymer and
its derivatives has increased steadily. These materials are
promising candidates as emissive layers in light-emitting di-
odes (LEDs),[2Ϫ6] as well as for non-linear optics or
photoconducting devices.[7,8]
The light emission of LEDs is generated by the recomb-
ination of electrons and holes injected from the electrodes
into the luminescent layer. Balanced charge injection and
charge carrier mobilities are decisive for high device effici-
encies.[9] The ease of charge injection is determined by the
barriers between the molecular frontier orbitals and the
work functions of the electrodes. Most PPV-type polymers
have smaller barriers to hole injection from ITO (indium
tin oxide) than to electron injection from aluminium. To
facilitate electron injection, metals with low work functions
(Mg or Ca) can be used as electrodes, but a more practical
approach is to increase the electron affinity of the lumin-
escent material. Cyano-substituted PPV has been used as
an electron-transporting material in a highly efficient two-
layer LED with PPV as hole-transporting layer.[10] Emitting
Here we present our work on cyano-substituted oligo-
materials of this type with increased electron affinity are of (phenylenevinylene)s 1؊13. The synthesis of a series of
great interest for improvement of the efficiencies of these OPVs with a variety of different cyano substitution patterns
devices.[11Ϫ13] In addition to conjugated polymers, copoly- is reported, and the electronic spectral influences of the po-
mers with luminescent segments or side chains are also at- sitions of the nitriles and their interaction with other aux-
tractive materials for LEDs.[14,15] Oligo(phenylenevinylene)s ochromic groups are discussed. To allow comparison, the
(OPVs) can serve as model compounds for the correspond- chromophore Ϫ an oligomer with five aromatic units Ϫ re-
ing polymers,[16] as emissive units in alternating copolymers mains unchanged; two alkoxy side chains on the central
and as electrooptical materials in their own right.[17]
ring guarantee good solubility in common solvents. The de-
pendence of the fluorescence characteristics on substitution
pattern and solvent polarity are investigated and the X-ray
structures of two oligomers with different cyano substitu-
tion patterns are reported.
[a]
Institut für Organische Chemie
Duesbergweg 10Ϫ14, 55099 Mainz, Germany
Fax: (internat.) ϩ 49-(0)6131/39-52396
Eur. J. Org. Chem. 2001, 2927Ϫ2938
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ193X/01/0815Ϫ2927 $ 17.50ϩ.50/0
2927

H. Detert, D. Schollmeyer, E. Sugiono
Table 1. Substitution pattern of OPVs 1؊12
FULL PAPER
Synthesis
WittigϪHorner olefinations are among the most import-
ant tools for the synthesis of stilbene compounds. The start-
ing materials are often easily available and these reactions
tolerate an enormous diversity of functional groups.
Thanks to the C2h symmetry of the OPVs 1؊13, a synthetic
strategy with two double olefination steps was advantage-
ous. The central building block for these compounds was
distyrylbenzene 18, with two carbaldehyde functions in the
terminal positions (Scheme 1, Table 1). Hydroquinone was
first alkylated with 1-bromooctane and then treated with
formaldehyde and hydrogen bromide in acetic acid, better
yields could be achieved by chloromethylation in dioxane.
The bis(halomethyl) compounds 15a and 15b were con-
verted into the bis(phosphonate) 16 in a MichaelisϪ
Arbuzov reaction. Double WittigϪHorner olefination with
the monoprotected terephthaldialdehyde 17 and subsequent
hydrolysis of the acetals directly afforded the highly fluores-
cent dialdehyde 18. A THF and KOtBu/18-crown-6 solvent/
base system proved superior to DMF/KOtBu in terms of
yield and workup procedure.
OPV
R1
R2
R3
H
R4
H
Yield (%)
1
OC6H13
CN
H
81
83
77
72
74
64
79
72
57
97
96
84
2
3
CN
CN
4
CN
5
OC6H13
6
CN
CN
CN
CN
CN
CN
CN
7
CF3
OCH3
8
9
OCH3
10
11
12
Cl
CF3
OCH3
22, were prepared from commercially available benzyl
bromides and chlorides (Scheme 2). 4-Hexyloxytoluene (33)
was brominated with bromine in acetic acid and halogen/
cyano exchange was performed with CuCN in DMF to give
34. Benzylic bromination of 33 and 34 with NBS and sub-
sequent MichaelisϪArbuzov treatment of the crude bromo-
methyl compounds gave the phosphonates 19 and 22.
Scheme 2. Synthesis of phosphonates 19 and 22 and OPV 13
OPV 13 was prepared in a similar way, using Knoevena-
gel condensation between the bis(cyanomethyl)benzene 32
and hexyloxystilbenecarbaldehyde 31, prepared from 17
and 19 as in Scheme 1. The cyano-substituted oligomers
form luminescent crystals with colours ranging from yellow
to dark red and are highly soluble in common solvents such
as dichloromethane or toluene. The yellow solutions of the
OPVs display very strong fluorescence as their outstand-
ing feature.
Scheme 1. Synthesis of cyano-substituted oligomers
Optical and Electronic Properties
The elaboration of the conjugated system of 18 to the
The electronic spectra were measured under ambient con-
OPVs 1؊12 was performed in two ways: PO-activated ol- ditions, solvents for spectroscopy being used as received,
efinations with substituted benzyl phosphonates 19؊23 and chloroform being filtered through basic alumina prior to
Knoevenagel condensations with different benzyl cyanides use. The concentrations were about 10Ϫ5 mol/L for absorp-
24؊30. The phosphonates, with the exceptions of 19 and tion and 10Ϫ8 mol/L for emission spectroscopy.
2928
Eur. J. Org. Chem. 2001, 2927Ϫ2938

Cyano-Substituted Oligo(phenylenevinylene)s
FULL PAPER
The two types of OPVs (ring substitution: 1؊5; vinylene (6؊12). The spectra of the first group (3, 5) were nearly
substitution: 6؊12) display very similar UV/Vis spectra, identical with that of the reference compound 1, whereas
with two small maxima at 305 and 360 nm and an intense the conjugated electron acceptors gave rise to bathochromic
maximum at either 422 to 433 nm, for the first group, or at shifts (8 nm) (2, 4). Vinylene substitution induced a stronger
441Ϫ452 nm for the latter. Relative to its isomers 8 and 12, red shift (up to 30 nm).
the absorption of 9 (433 nm) is exceptionally blue-shifted
All OPVs appear to be strongly fluorescent, with fluores-
(Figure 1). Similar hypsochromic absorption shifts have cence quantum yields being measured in cyclohexane solu-
been observed in oligomers with comparable local arrange- tion, using quinine sulfate as a standard. The photolumin-
ments of cyano and alkoxy groups and have been accounted escence efficiencies are in the range of 27 to 65%. In general,
for in terms of increased steric interaction and reduced the fluorescence of compounds with propenenitrile seg-
planarity of the π-system.[25] In the absorption spectra of ments (except for 8) is less efficient than that of ring-substi-
the cyano-substituted oligomers, only small changes were tuted OPVs, while additional electron-withdrawing or elec-
observed when the solvent polarity was varied over a broad tron-donating groups seem to favour radiationless decay of
range [cyclohexane (ε ϭ 2.06) Ϫ dichloromethane (ε ϭ the excited states Ϫ although here, again, 8 behaves differ-
9.00) Ϫ acetonitrile (ε ϭ 38.8)],[29] regardless of quadrupo- ently.
lar push-pull substitution in the OPVs 2؊12. With dichloro-
In cyclohexane, the fluorescence maxima are separated
methane taken as a reference solvent, small hypsochromic from the absorption maxima by Stokes shifts of 52Ϫ59 nm
shifts of up to 8 nm were observed when the spectra were (2476Ϫ2733 cmϪ1) and possess a distinct shoulder or se-
measured in the less polar cyclohexane or in the very polar cond maximum on the red side (∆λ ഠ 25Ϫ30 nm). The vi-
acetonitrile. The extinction coefficients remained constant brational structure is blurred in dioxane and chloroform
within the margins of error arising from several dilution and vanishes in ethanol or acetonitrile. A stepwise increase
steps. The different cyano-substituted OPVs in Table 2 can in the polarity or dielectric constant of the solvent differen-
be divided into three groups: ring substitution with the ni- tiates the fluorophores by the extent of the shift to lower
trile in the ‘‘nonconjugated’’ m-position (3, 5), ring substi- energy and by the reduction, even more pronounced, of the
tution with the nitrile in the ‘‘conjugated’’ o- and p-posi- fluorescence intensity. The fluorescence intensity of OPV
tions (2, 4) and the compounds with vinylene cyanides 1, without an electron-withdrawing cyano group, remains
nearly constant in all solvents used, and increasing polarity
causes only small bathochromic shifts of the emission, the
red shift increasing in going from cyclohexane to dioxane
and to chloroform and reaching its maximum value in
dichloromethane (485 cmϪ1). In the highly polar acetonitr-
ile, the red shift is equal to the value observed in dioxane
(219 cmϪ1), while only modest in the protic ethanol
(Table 3). A similar sequence was observed for the m-cyano-
substituted OPVs (3, 5). Bathochromic shifts and reduced
fluorescence intensities in polar solvents are more pro-
nounced in 3 than in 5, indicating that the auxochromic
hexyloxy group in 5 compensates for the influence of the
cyano group. Conjugated nitriles (2, 4) are subject to much
stronger influences on the shifts of fluorescence; the emis-
sion maxima in cyclohexane and acetonitrile are separated
by more than 1000 cmϪ1, while the fluorescence intensities
are reduced to 2/3 of their initial values. In contrast to the
sequence above, the positive solvatochromism and reduc-
tion in intensity follow the order of increasing solvent di-
electric constant.
In the series of OPVs with vinyl cyanide moieties (6؊12),
two aspects are striking: The fluorescence quantum yield is
much more sensitive to the polarity of the solvent, and the
positive solvatochromism in the slightly polar chloroform is
over 70% of the bathochromic shift found in acetonitrile.
The effects of additional substituents are clearly visible:
Electron-withdrawing trifluoromethyl substituents (7, 11)
diminish the red shift but greatly reduce the fluorescence
intensity. Auxochromic methoxy groups produce a partial
preservation of the fluorescence, particularly when the me-
thoxy group is connected to the conjugated o- or p-posi-
Figure 1. Fluorescence solvatochromism of 9 and 11
Eur. J. Org. Chem. 2001, 2927Ϫ2938
tions of the terminal rings (9, 12).
2929

H. Detert, D. Schollmeyer, E. Sugiono
FULL PAPER
Table 2. Absorption and emission maxima [nm] of OPVs 1؊12 in different solvents; CH ϭ cyclohexane, DCM ϭ dichloromethane,
AN ϭ acetonitrile, DIO ϭ 1,4-dioxane, CLO ϭ chloroform, ETH ϭ ethanol
OPV Abs. CH Abs. DCM log ε Abs. AN Fluo. CH Fluo. DIO Fluo. CLO Fluo. DCM Fluo. ETH Fluo. AN
1
422
433
424
429
421
440
450
441
433
446
452
442
426
434
425
434
425
445
451
447
437
450
453
447
4.96
4.93
4.83
4.82
4.96
4.92
4.85
4.88
4.94
4.97
4.87
5.05
424
432
423
426
422
438
445
440
433
442
446
440
475
485
479
486
477
499
508
500
489
505
512
498
480
493
482
492
481
515
522
514
503
517
527
512
485
503
492
501
487
525
533
528
516
529
538
522
486
510
490
504
486
531
538
534
520
536
543
527
477
517
486
504
481
535
540
532
525
538
543
530
480
521
491
513
483
536
538
534
528
541
544
531
2
3
4
5
6
7
8
9
10
11
12
Table 3. Fluorescence quantum yields, and Stokes shifts in cyclohexane, solvatochromism and fluorescence intensities relative to solutions
in cyclohexane (for solvent abbreviations see Table 1)
ΦF in CH Stokes shift in CH [cmϪ1
]
CH/DIO [cmϪ1
rel. If
]
CH/CLO [cmϪ1
rel. If
]
CH/DCM [cmϪ1
rel. If
]
CH/ETH [cmϪ1
rel. If
]
CH/AN [cmϪ1
]
rel. If
1
2
3
4
5
6
7
8
9
0.64
0.53
0.65
0.37
0.55
0.41
0.37
0.62
0.35
2644
2476
2708
2734
2789
2687
2537
2676
2645
2620
2593
2544
219
1.02
335
1.23
130
0.92
251
1.27
174
0.97
388
0.68
528
0.68
544
0.91
569
1.01
460
0.73
556
0.57
549
1.15
434
0.87
738
0.88
551
0.89
616
0.99
430
0.76
992
0.55
923
0.38
1061
0.75
1070
0.68
898
0.44
944
0.30
923
485
57
219
1.14
1011
0.83
487
0.78
735
0.90
1276
0.70
301
0.77
735
1.06
1425
0.64
510
0.67
1083
0.70
260
0.89
1343
0.14
1098
0.08
1273
0.24
1511
0.45
1318
0.14
1149
0.05
1248
0.43
0.89
388
0.84
174
0.94
1167
0.44
1098
0.24
1273
0.42
1219
0.53
1145
0.38
1115
0.19
1105
0.61
0.82
1308
0.26
1167
0.11
1203
0.30
1402
0.41
1215
0.20
1115
0.08
1212
0.46
10 0.32
11 0.37
12 0.27
0.77
The chromophore of OPV 13 differs from that of 12 in broad absorption peaks at 360 nm with a strong shoulder
the positions of the cyano groups; they are shifted from the on the red side, and the emission maximum is at 502 nm
terminal styrene units to the centre of the molecule. The with a fluorescence quantum yield of ΦF ϭ 0.04. The iso-
absorption spectrum has its maximum at 384 nm (CH2Cl2, mer 36 (λmax ϭ 453 nm, λem,max ϭ 536 nm) is strongly
log ε ϭ 4.51) and the fluorescence peaks at 494 nm. The fluorescent, with ΦF ϭ 0.7. Upon exposure to daylight or
sensitivities of the absorption (384Ϫ396 nm) and emission NUV, 13 isomerises rapidly, unlike the photochemically
(487Ϫ497 nm) towards solvent polarity are only small. fairly stable oligomers 1؊12.[26]
Comparison of the low fluorescence intensity of 13 with
The influence of different substituents and substitution
those of 1؊12 in solutions of similar optical density reveals patterns on the reduction potential of the oligomers 1؊12
a fluorescence quantum yield for 13 less than 10% of those in THF solution were studied by cyclic voltammetry (CV).
displayed by 1؊12. This is in good agreement with the re- The measured reduction potentials are shown in Table 4.
sults obtained by Gill et al.[25b] for the OPVs 35 and 36 As can be seen, the introduction of cyano groups onto the
(Figure 2). Compound 35 is structurally related to 13; the terminal rings of 1 results in an increase of 0.17 V in the
2930
Eur. J. Org. Chem. 2001, 2927Ϫ2938

Cyano-Substituted Oligo(phenylenevinylene)s
FULL PAPER
the polymer, and the observed emission results from inter-
molecular excitations.
We have used a series of different solvents to study the
emission behaviour of the highly soluble and strongly fluor-
escent, low molecular weight oligomers 1؊12. The indi-
vidual substitution pattern (ring substitution versus vinyl
cyanides, additional auxochromic groups) has distinct influ-
ences on the electronic spectra. Solvent effects on the ab-
sorption spectra are only small, a bathochromic shift of the
absorption maximum being observed in going from cyclo-
hexane to dichloromethane, with further increases in the
dielectric constant of the solvent inducing a hypsochromic
shift. This behaviour is more pronounced if the cyanide is
bound to the vinylene linkage. Inverted solvatochromism
had been observed for stilbazolium dyes and attributed to
a change in the ground state electronic structure.[32] The
ratio of the calculated dipole moments of the ground and
excited states of these molecules changes from µg Ͻ µe in
nonpolar solvents to µg Ͼ µe in polar solvents for the πϪπ*
transition. In contrast to the absorption, the fluorescence is
strongly dependent on the environment. Strong bathoch-
romic shifts of emission are observed for OPVs with nitriles
in the o- and p-positions and on the vinyl group (2, 4,
6؊12), while cyanides in the m-position (3, 5) induce only
small red shifts. Such a dependence on the solvent dielectric
constant can be attributed to the stabilisation of a charge
transfer state by reorientation of the solvent molecules.[33]
In the polar solvents, the emission of 2, 4, and 6؊12 eman-
ates from a state different from that in cyclohexane or diox-
ane. Though ring substitution (2, 4) and vinyl substitution
(6؊12) of the OPVs with cyano groups both give rise to
similar red shifts of the emission, their influences on the
emission intensities differ considerably. Much higher sensit-
ivity of the fluorescence intensity was found in vinyl-substi-
tuted OPVs than in ring-substituted OPVs. This response
of the chromophore 6 towards polarity can be tuned by
additional auxochromic or electron-withdrawing groups.
Electron-donating alkoxy groups maintain the quantum
yield remarkably (8, 9, 12), while electron-accepting trifluo-
romethyl groups further reduce the fluorescence by a factor
of 2Ϫ3 (7, 11). The latter groups promote charge transfer
from the centre of the molecules to the terminal moieties.
A strong reduction in fluorescence quantum yield arising
from increased nonradiative decay in polar solvents has re-
cently been reported for a distyrylbenzene with cyano
groups on the vinylene linkages.[34] The consequences of the
solvent polarity for the emission spectra are also of interest
in the context of the use of OPVs with both electron-donat-
ing and electron-accepting groups in electrooptical devices.
An influence of the strong electrical fields applied in light
Figure 2. OPVs with cyano groups in the centre of the oligomer
reduction potential (5), whereas an exchange of terminal
alkoxy and cyano moieties (2) produces a twofold increase
in the reduction potential, independent of the position of
the electron-withdrawing group on the ring (2Ϫ4). The elec-
tron affinities of compounds with vinyl cyanide segments,
such as 6, are substantially higher than those of the oligo-
mers with benzonitrile structure and can be reduced by
additional electron-donating groups (9, 12) or further in-
creased by electron-withdrawing groups (7, 10, 11). The ef-
fects of cyano substitution in the polymer PPV were studied
[30]
´
by Bredas,
using quantum chemical calculations. The
predicted increases in electron affinity are 0.18 V for the
polymer with cyano groups on the benzene ring and 0.37 V
for the polymer with vinyl cyanides.
Table 4. First reduction potentials of OPVs 1؊12
R1
(para)
R2
(meta)
R3
(ortho)
R4
(vinyl)
E01,red
[V]
1
OC6H13
CN
Ϫ2.21
Ϫ1.87
Ϫ1.87
Ϫ1.89
Ϫ2.04
Ϫ1.68
Ϫ1.54
Ϫ1.65
Ϫ1.83
Ϫ1.60
Ϫ1.47
Ϫ1.73
2
3
CN
CN
4
CN
5
OC6H13
6
CN
CN
CN
CN
CN
CN
CN
7
CF3
OCH3
8
9
OCH3
10
11
12
Cl
CF3
OCH3
Discussion
The photoluminescence of cyano-substituted PPV has re- emitting diodes (e.g. 106 V/cm) on the luminescence proper-
cently been measured in toluene/methanol and toluene/hex- ties is to be expected for push-pull substituted OPVs, as
ane mixed solvents, in order to distinguish between inter- solvatochromism and electrochromism have the same ori-
molecular and intramolecular photoexcitation.[31] Addition gin: the influencing of the electron bands by electric
of the poor solvents to the good solvent toluene caused a fields.[35] The colour of the emitted light and, particularly,
red shift of the emission of cyano-substituted PPV and the luminescence efficiency of these excited molecules are
some loss of photoluminescence intensity, depending on the strongly dependent on the local electrical fields of the re-
mixing ratio. Poor solvents tend to promote aggregation of arranged solvent molecules or on external electrical fields.
Eur. J. Org. Chem. 2001, 2927Ϫ2938
2931

H. Detert, D. Schollmeyer, E. Sugiono
FULL PAPER
Ring substitution with electron-accepting cyano groups is
superior to vinyl substitution in terms of high fluorescence
intensities in polar media.
Molecular Structures of OPVs 4 and 12
The solid-state structure of conjugated organic com-
pounds has a powerful impact on electrical and optical
properties. As the structure of polymers at the chain seg-
ment level is hard to characterise, conjugated oligomers are
finding increasing interest as model compounds. They are
often sufficiently crystalline to allow X-ray diffraction, of-
fering a means to correlate molecular structure and solid-
state properties. Hadziioannou et al.[25] have reported the
molecular structure of the nonluminescent (ΦF ϭ 0.04) oli-
gomer 35, possessing a wave-like shape with deviations of
planarity of both rings and vinylene moieties of up to 5°
and dihedral angles between the nitrile and the adjacent
benzene ring of 11.7°, comparable to the dihedral angles of
phenylenevinylene moieties in unsubstituted oligomers.[36]
Small single crystals of o-benzonitrile-terminated OPV 4
and of OPV 12, with cyanovinylene groups, were obtained
by crystallisation either from a cyclohexane/dichlorome-
thane mixture (4) or from chloroform (12) and studied by
X-ray diffraction. Though the formal structures of these
molecules are very similar (the differences are the additional
terminal methoxy groups and small shifts in the positions
of the cyanides), the solid-state structures are distinctly dif-
ferent. Both molecules have a crystallographically imposed
centre of inversion; the triclinic unit cell of 4 contains one
molecule, while two oligomers 12 fill the monoclinic unit
cell (Figure 3).
Figure 3. Molecular structure and packing of OPV 12
In the crystalline state of 12, the phenylenevinylene units
are packed in a ‘‘herringbone’’ arrangement; the molecules
are coplanar, but the molecular axes are inclined with re-
spect to the direct neighbours in the plane, while the neigh-
bouring molecules in the adjacent layers are shifted about
the length of a phenylenevinylene segment. The rigid and
the flexible parts of the X-shaped OPV 12 are nearly copla-
nar, with an angle of 62° between the all-trans-configured
heptyl segments of the side chains and the phenyleneviny-
lene axis. The latter consists of 5 planar benzene rings (devi-
ations from planarity: 1.2° or less) and four planar vinylene
segments (C1ϪC4ϪC5ϪC6: 177.4°, C9ϪC12ϪC13ϪC14:
179.9°). Viewed from the centre of the molecule to the me-
thoxy termini, the torsion angles between the planes of the
benzene rings and the vinylene units are Ϫ165.0°, ϩ172.3°,
ϩ166.5, and ϩ168.6°, the slightly bent cyano group
(NϪCϪC ϭ 178.1°) is twisted about 12° out of the plane
of the vinylene moiety. The terminal rings open dihedral
angles of approximately 25° with the plane of the penultim-
ate benzenes, whereas the rings of the central distyrylben-
zene segment are close to be coplanar (ca. 5°). All vinylene
bonds in the 1,4-divinylbenzene units are arranged in a
transoid configuration, giving a rod-like shape to the basic
chromophore.
tyloxy side chains are not coplanar with the chromophore;
a plane containing the all-trans-configured heptyl segments
and the molecular centre of inversion opens a dihedral
angle of about 50° with the ‘‘plane’’ of the conjugated unit.
The benzene rings and the vinylene units are essentially
planar and the dihedral angles between them are substan-
tially smaller than in 12, viewed from the dialkoxybenzene
to the benzonitrile units, torsion angles of 169.6, Ϫ174.1,
179.7, and Ϫ169.8° are found. The nitrile is linear
(NϪCϪC ϭ 179.3°) and coplanar with the benzene ring
(178.9°). Again, the rings of the central distyrylbenzene unit
are close to be coplanar (dihedral angle: 4.4°), whereas the
planes of the penultimate rings and the benzonitriles are
twisted about 9.9°. The vinylene bonds of the terminal styr-
ene units in 4 are connected to the penultimate benzenes in
an s-cis conformation relative to the vinylene moieties be-
tween the central and the penultimate rings, resulting in a
slight ‘‘S’’-type deviation of the conjugated system from lin-
earity.
Conclusion
In the crystalline state of OPV 4 (Figure 4), the axes of
Strongly fluorescent and highly soluble oligo(phenylene-
the conjugated units are parallel, with a face-to-face ar- vinylene)s with five benzene rings and cyano groups on the
rangement of the molecules in the adjacent layers. The oc- terminal styrene moieties have been prepared by two double
2932
Eur. J. Org. Chem. 2001, 2927Ϫ2938

Cyano-Substituted Oligo(phenylenevinylene)s
FULL PAPER
spectra were measured with a PerkinϪElmer Lambda 15 instru-
ment. Ϫ Fluorescence spectra were obtained with a PerkinϪElmer
LS50B, solvents for the electronic spectra were of spectroscopic
grade, chloroform was treated with basic alumina before use. The
fluorescence quantum yields were determined in aerated cyclohex-
ane solution with optical densities between 0.005 and 0.01, quinine
sulfate (Fluka, ‘‘for fluorescence’’) in 0.1  H2SO4 was used as a
reference (ΦF ϭ 0.577 at 350 nm).[38] Ϫ The elemental analyses
were performed in the microanalytical laboratory of the Chemical
Institute of the Johannes-Gutenberg-Universität, Mainz, Germany,
eluent mixtures are v/v. Ϫ Chemicals were used as received; solvents
were dried according to standard procedures and distilled. Ϫ Cyclic
voltammetry was performed using a PG Stat 12 (Eco Chemie),
glassy carbon as working electrode, Pt wire as counter-electrode
and Ag/AgCl/LiCl/EtOH as a reference electrode. THF was used
as solvent, tetrabutylammonium tetrafluoroborate as supporting
electrolyte (0.1 ) and 10Ϫ3  OPV, T ϭ 30 °C, v ϭ 100 mV/s.
ϩ
All measurements were calibrated vs. FeCp2/FeCp2 (ϩ0.35 V vs.
Ag/AgCl).[39]
X-ray Structure Determination of 4: Performed with an
EnrafϪNonius Turbo-Cad4 equipped with rotating anode, using a
transparent, yellow needle. Crystal data: C56H64N2O2, M ϭ
793.06 g·molϪ1, 0.128 ϫ 0.128 ϫ 1.02 mm, triclinic, space group
˚
¯
P1, Cu-Kα, graphite monochromation: λ ϭ 1.54180 A, T ϭ 296 K,
unit cell dimensions: a ϭ 423.92(6), b ϭ 1668.82(15), c ϭ
1697.46(23) pm, α ϭ 71.333(10), β ϭ 88.842(8), γ ϭ 86.137(8)°,
V ϭ 1.1351(3) nm3, Z ϭ 1, dcalcd. ϭ 1.116 g·cmϪ3, absorption µ ϭ
0.53 mmϪ1, Θ range for data collection 1.5Ϫ74°, index ranges Ϫ5
Յ h Յ 0, Ϫ20 Յ k Յ 20, Ϫ21 Յ l Յ 21. Number of reflections
collected: 5265; independent reflections: 4613 (Rint ϭ 0.0290). The
structure was solved by direct methods (program SIR 92, refine-
ment SHELXL-97).[40] Structure refinement by full-matrix least
squares on 293 parameters, weighted refinement: w ϭ 1/[σ2(F02) ϩ
(0.0790 ϫ P)2 ϩ 0.15 ϫ P] with P ϭ [max(F02,0) ϩ 2 ϫ Fc2]/3,
hydrogen atoms adapted geometrically from difference Fourier syn-
thesis with refinement, all non-hydrogen atoms improved with an-
isotropic temperature factors. Goodness-of-fit on S ϭ 1.033, max-
imum change of parameters 0.000 ϫ e.s.d, final R indices: R1
ϭ
Figure 4. Molecular structure and packing of OPV 4
0.0474, wR2 ϭ 0.1407, the final difference Fourier map showed
Ϫ3
˚
minimum and maximum values of Ϫ0.15 and 0.27 e·A
.
olefination steps. A small degree of solvatochromism in the
absorption and a strong responsiveness of the emission to
the solvent dielectric constant indicate intramolecular
charge transfer in the excited state. The fluorescence intens-
ity of oligomers with vinyl cyanides is much more sensitive
to the environment than that of ring-substituted chromo-
phores. In the solid state, the structurally related OPVs 4 and
12 have comparable torsion angles between the conjugated
segments, but the arrangement of the side chains and the
packing are distinctively dependent on the substitution pat-
tern.
X-ray Structure Determination of 12: Performed with an
EnrafϪNonius Turbo-Cad4 equipped with rotating anode, using a
transparent, orange single crystal. Crystal data: C58H64N2O4, M ϭ
853.11 g·molϪ1, 0.064 ϫ 0.192 ϫ 0.228 mm, monoclinic, space
˚
group P21/c, Cu-Kα, graphite monochromation: λ ϭ 1.54180 A,
T ϭ 296 K, unit cell dimensions: a ϭ 669.33(7), b ϭ 1335.69(4),
c ϭ 2723.0(4) pm, β ϭ 90.233(6)°, V ϭ 2.4791(4) nm3, Z ϭ 2,
dcalcd. ϭ 1.143 g·cmϪ3, absorption µ ϭ 0.55 mmϪ1, Θ range for
data collection 1.5Ϫ74°, index ranges 0 Յ h Յ 81, 0 Յ k Յ 16,
Ϫ34 Յ l Յ 34. Number of reflections collected: 5737; independent
reflections: 5041 (Rint ϭ 0.0443). The structure was solved by direct
methods (program SIR 92, refinement SHELXL-97).[40] Structure
refinement by full-matrix least squares on 310 parameters, weighted
refinement: w ϭ 1/[σ2(F02) ϩ (0.0615 ϫ P)2 ϩ 0.05 ϫ P] with P ϭ
[max(F02,0) ϩ 2 ϫ F2c]/3, hydrogen atoms adapted geometrically
from difference Fourier synthesis with refinement, all non-hydrogen
atoms improved with anisotropic temperature factors. Goodness-
of-fit on S ϭ 1.009, maximum change of parameters 0.000 ϫ e.s.d,
Experimental Section
General: Melting points were determined with a Büchi melting
point apparatus and are uncorrected. Ϫ IR spectra were obtained
1
with a Beckman Acculab 4 in KBr or in neat form. Ϫ H and 13C
NMR spectra were recorded in CDCl3 with Bruker AC 200 and final R indices: R1 ϭ 0.0574, wR2 ϭ 0.1565, the final difference
AM 400 instruments. Ϫ Mass spectra were obtained with Varian
MAT 711 (EI-MS) and MAT 95 (FD-MS) instruments. Ϫ UV/Vis
Fourier map showed minimum and maximum values of Ϫ0.16 and
Ϫ3
˚
0.13 e·A
.
Eur. J. Org. Chem. 2001, 2927Ϫ2938
2933

H. Detert, D. Schollmeyer, E. Sugiono
FULL PAPER
1,4-Dioctyloxybenzene (14): A stirred mixture of hydroquinone
(110.1 g, 1.0 mol), 1-bromooctane (424.9 g, 2.2 mol), potassium
ethanol (1:1) and water and dried. Purification was done by double
recrystallisation from dichloromethane/ethanol and chromato-
iodide (3 g), and Aliquat 336 (5 mL) in ethanol (600 mL) was graphy of the residual product in the mother liquors on silica gel
purged with nitrogen and heated to reflux. Under exclusion of air, with toluene/ethyl acetate. Yield 33.9 g (57%); bright orange to red
˜
a solution of sodium hydroxide (88.0 g, 2.2 mol) in water (100 mL) powder; m.p. 138 °C. Ϫ IR (KBr): ν ϭ 3035, 2920, 2848, 1685,
was added over a period of 3 d to the boiling mixture, and heating
and stirring were continued for a further 2 d. The mixture was
1588, 1557, 1487, 1461, 1416, 1301, 1205, 1163, 963, 812. Ϫ 1H
NMR (CDCl3): δ ϭ 0.83 (t, 6 H, CH3), 1.63Ϫ1.20 (m, 20 H, CH2),
cooled to room temperature and diluted with water (1.5 L), and 1.85 (quint, J ϭ 6.4 Hz, 4 H, β-CH2), 4.07 (t, J ϭ 7.5 Hz, 4 H,
the solid product was isolated by filtration and recrystallised from
OCH2), 7.11 (s, 2 H, 3-H, 6-H), 7.19 (d, J ϭ 17.6 Hz, 2 H, 1-H,
ethen), 7.58 (d, J ϭ 17.6 Hz, 2 H, 2-H, ethen), 7.66 (d, J ϭ 7.8 Hz,
4 H, 2Ј-H, 6Ј-H, ar), 7.86 (d, J ϭ 7.8 Hz, 4 H, 3Ј-H, 5Ј-H, ar), 9.97
(2 H, CHO). Ϫ 13C NMR (CDCl3): δ ϭ 14.0 (CH3), 22.6, 26.3,
29.3, 29.4, 29.4, 31.7 (CH2), 69.6 (OCH2), 111.0 (C-3, C-6), 126.9
(6 C), 127.0 (2 C), 128.0 (2 C), 130.2 (CH), 135.3 (2 C), 144.3 (2
C), 151.5 (C-2, C-5), 191.5 (CHO). Ϫ FD MS: m/z (%) ϭ 595.2
(17) [Mϩ], 567.1 (15) [Mϩ Ϫ CO], 539.1 (5) [Mϩ Ϫ 2 CO], 43.3
(100). Ϫ C40 H50 O4 (594.835): calcd. C 80.77, H 8.47; found C
80.87, H 8.54.
ethanol. Yield 273.9 g (82%); m.p. 56 °C (ref.[41]: 56 °C).
1,4-Bis(chloromethyl)-2,5-dioctyloxybenzene (15a): A solution of 14
(167.3 g, 0.5 mol) and hydrochloric acid (50 mL) in dioxane
(650 mL) was cooled in an ice bath. The solution was saturated
with gaseous hydrogen chloride and paraformaldehyde (30.0 g, 1.0
mol) was added. The stirred mixture was heated to reflux for 1 h,
cooled in an ice bath and saturated with hydrogen chloride. H2CO
(15.0 g, 0.5 mol) was added and the mixture was heated to reflux
for 1 h. The cooled mixture was diluted with 1 L water and filtered.
The solid residue was dried in a dessicator and recrystallized from
Diethyl [4-(Hexyloxy)benzyl]phosphonate (19): This compound was
1
prepared according to the literature.[42]
hexanes. Yield 146.2 g (68%); colourless needles; m.p. 72 °C. Ϫ H
NMR (CDCl3): δ ϭ 0.87 (t, 6 H, CH3), 1.20Ϫ1.48 (m, 10 H, CH2),
1.77 (quint, 4 H, β-CH2), 3.96 (t, J ϭ 6.4 Hz, 4 H, OCH2), 4.62 (s,
4 H, CH2Cl), 6.90 (s, 2 H, 3-H, 6-H). Ϫ EI MS (70 eV): m/z (%) ϭ
430.4 (43) Cl2 pattern [Mϩ], 206.3 (58) Cl2 pattern [Mϩ Ϫ 2 C8H16],
43.4 (100)
Diethyl (2-Cyanobenzyl)phosphonate (20),[43] Diethyl (3-Cyanoben-
zyl)phosphonate (21),[44] and Diethyl (4-Cyanobenzyl)phosphonate
(23)[45]: These compounds were prepared from the commercially
available chloromethyl benzonitriles and triethyl phosphite accord-
ing to the procedures given above.
Diethyl
4-[(Diethoxyphosphoryl)methyl]-2,5-bis(octyloxy)benzyl-
Diethyl [3-Cyano-4-(hexyloxy)benzyl]phosphonate (22): A mixture
of NBS (17.8 g, 0.10 mol), compound 34 (23.9 g, 0.11 mol), AIBN
(250 mg), and dry CCl4 (400 mL) was refluxed for 5 h. The cooled
mixture was filtered and the solvent evaporated. The crude bromide
was added to triethyl phosphite (20.0 g, 0.12 mol) and the stirred
mixture was heated to 170 °C. When the evolution of ethyl bromide
had ceased, the residual triethyl phosphite was distilled off and the
oily residue was purified by column chromatography on silica gel
(20 ϫ 12 cm), using toluene with increasing ethyl acetate content
phosphonate (16): A mixture of 15a (107.5 g, 0.25 mol) in triethyl
phosphite (124.5 g, 0.75 mol) was slowly heated until evolution of
chloroethane started (ca. 170 °C). The temperature was maintained
until the gas evolution had ceased, and the mixture was then heated
to 185 °C for 30 min. The excess of triethyl phosphite was removed
in vacuo, the oily residue was mixed with 50 mL of petroleum ether
and the product crystallised upon standing at ambient temperature
(2 weeks). Yield 154.8 g (98%); colourless solid; m.p. 47 °C. The
preparation of 16 from 15b[25b] followed the same procedure (T ϭ
160 °C), with the reaction flask connected to a vertical condenser
heated to 60 °C and the bromoethane being collected. Yield of 16
˜
as eluent. Yield 16.2 g (46%); yellowish oil. Ϫ IR (neat):ν ϭ 2975,
2920, 2850, 2224, 1600, 1493, 1477, 1385, 1290, 1260, 1160, 1050,
1
1028, 965, 850, 800, 735. Ϫ H NMR (CDCl3): δ ϭ 0.81 (m, 3 H,
˜
154.7 g (98%). Ϫ IR (KBr): ν ϭ 2980, 2900, 2840, 1500, 1460, 1410,
1
CH3), 1.10Ϫ1.50 (m, 12 H, CH2 hex, CH3 eth), 1.78 (quint, J ϭ
1385, 1265, 1205, 1030, 955, 638. Ϫ H NMR (CDCl3): δ ϭ 0.76
2
7 Hz, 2 H, β-CH2), 2.98 (d, J(H,
ϭ 21 Hz, 2 H, aryl-CH2),
(t, 6 H, CH3, oct), 1.4Ϫ1.05 (m, 32 H, CH2 oct, CH3 eth), 1.65
P)
2
3.90Ϫ4.05 (m, 6 H, OCH2), 6.84 (d, J ϭ 9.2 Hz, 1 H, 5-H),
(quint, J ϭ 7.2 Hz, 4 H, β-CH2 oct), 3.10 (d, J(H, P) ϭ 20.2 Hz, 4
7.33Ϫ7.43 (m, 2 H, 2-H, 6-H). Ϫ 13C NMR (CDCl3): δ ϭ 13.9
H, aryl-CH2), 3.80 (t, J ϭ 6.6 Hz, 4 H, OCH2 oct), 3.91 (m, 8 H,
4
4
OCH2 eth), 6.81 (d, J(H, P) ϭ 1.4 Hz, 1 H, 3-H, 6-H, ar). Ϫ 13C
(CH3 hex), 16.3 (d, J(H, P) ϭ 6.4 Hz, CH3 eth), 22.4, 25.4, 28.8,
1
31.3 (CH2 hex), 32.3 (d, J(C-P) ϭ 138 Hz, aryl-CH2), 62.2 (d,
NMR (CDCl3): δ ϭ 13.9 (CH3, oct), 16.2 (CH3, eth), 26.1 (d,
4
2J(C,P) ϭ 6.5 Hz, OCH2 eth), 69.1 (OCH2 hex), 102.0 (d, J(C, P)
ϭ
1J(C,
ϭ 139.5 Hz, aryl-CH2), 22.5, 26.0, 29.1, 29.2, 29.3, 31.7
P)
4
2.5 Hz, C-3), 112.4 (d, J(C, P) ϭ 3.2 Hz, C-4), 116.1 (CN), 124.2
(CH2 oct), 61.7 (OCH2 eth), 68.8 (OCH2 oct), 114.8 (C-3, C-6, ar),
2
3
2
(d, J(C, P) ϭ 8.8 Hz, C-1), 134.4 (d, J(C, P) ϭ 7.2 Hz), 135.6 (d,
119.3 (d, J(C, P) ϭ 2.3 Hz, C-1, C-4, ar), 150.2 (C-2, C-5, ar). Ϫ
3J(C, P) ϭ 6.4 Hz) (C-2, C-6), 159.7 (d, J(C, P) ϭ 2.3 Hz, C-4). Ϫ
5
EI MS (70 eV): m/z (%) ϭ 634.6 (100) [Mϩ], 522 (10) [Mϩ
Ϫ
FD MS: m/z (%) ϭ 353.3 [Mϩ]. Ϫ C18H28NO4P (353.393): calcd.
C8H16]. Ϫ C32H60O8P2 (631.77): calcd. C 60.55, H 9.53; found C
C 61.18, H 7.99, N 3.96; found C 60.98, H 7.91, N 3.98.
60.58, H 9.48.
4-[(E)-2-{4-[(E)-2-(4-Formylphenyl)ethenyl]-2,5-bis(octyloxy)- 4-{(E)-2-[4-(Hexyloxy)phenyl]ethenyl}benzaldehyde (31): This pre-
phenyl}ethenyl]benzaldehyde (18): Dry THF (150 mL) and KOtBu paration was performed using 17 (2.1 g, 0.01 mol), 19 (3.3 g, 0.01
(25.8 g, 0.23 mol) were placed in a three-necked, round-bottomed mol), and KOtBu (1.2 g, 0.01 mol) in THF (50 mL), according to
flask, together with 18-crown-6 (0.7 g). A connected dropping fun-
nel was charged with aldehyde 17 (43.7 g, 0.21 mol) and bis(phos-
phonate) 16 (63.5 g, 0.10 mol), dissolved in dry THF (15 mL).
the procedure described for 18. Yield 1.9 g (62%); colourless solid;
m.p. 168 °C. Ϫ IR (KBr): ν˜ ϭ 2950, 2922, 2860, 1680, 1590, 1545,
1505, 1465, 1300, 1250, 1218, 1171, 1160, 1030, 964, 830. Ϫ 1H
After the solutions had been purged with argon, the mixture was NMR (CDCl3): δ ϭ 0.9 (t, 3 H, CH3), 1.25Ϫ1.58 (m, 6 H, CH2),
added slowly (30 min) to a mechanically stirred solution of the base
at room temperature and stirring was continued for 2 h. The reac-
1.77 (quint, J ϭ 6.5 Hz, 2 H, β-CH2), 3.96 (t, J ϭ 7 Hz, 2 H,
OCH2), 6.91 (d, J ϭ 8 Hz, 2 H, 3Ј-H, 5Ј-H), 6.98 (d, J ϭ 16 Hz, 1
tion was quenched by addition of crushed ice/hydrochloric acid and H, olef. H), 7.19 (d, J ϭ 16 Hz, 1 H, olef. H), 7.46 (d, J ϭ 8 Hz, 2
stirred for 12 h (pH ഠ 2). The mixture was diluted with water and
the precipitate was collected by filtration, washed with water, water/
H, 2Ј-H, 6Ј-H), 7.61 (d, J ϭ 7.6 Hz, 2 H, 2-H, 6-H), 7.83 (d, J ϭ
7.6 Hz, 2 H, 3-H, 5-H), 9.99 (s, 1 H, CHO). Ϫ 13C NMR (CDCl3):
2934
Eur. J. Org. Chem. 2001, 2927Ϫ2938

Cyano-Substituted Oligo(phenylenevinylene)s
FULL PAPER
δ ϭ 14.0 (CH3), 22.6, 25.7, 29.2, 31.6 (CH2), 68.2 (OCH2), 114.9 tracted with dichloromethane. Purification of 4 and 5 was done by
(CH), 125.0 (CH), 126.6 (2 C, CH), 128.4 (2 C, CH), 129.1 (Cq), chromatography on silica gel with toluene, 1Ϫ3 were recrystallised
130.2 (2 C, CH), 131.9 (CH), 135.0, 143.9 (Cq), 159.7 (CϪO), 191.6 from chloroform/methanol. For purposes of comparison, the car-
(CHO). Ϫ EI MS (70 eV): m/z (%) ϭ 308.3 (80) [Mϩ], 223.9 (100) bon and hydrogen atoms are numbered according to Figure 5.
[Mϩ Ϫ C6H12]. Ϫ C21H24O2 (308.420): calcd. C 81.78, H 7.84;
found C 81.53 H 7.61
1,4-Bis[(E)-2-(4-{(E)-2-[4-(hexyloxy)phenyl]ethenyl}phenyl)ethenyl]-
2,5-bis(octyloxy)benzene (1): Yield 0.76 g (81%); light yellow pow-
˜
der; m.p. 164 °C. Ϫ IR (KBr): ν ϭ 3010, 2905, 2845, 1600, 1505,
2-(Hexyloxy)-5-methylbenzonitrile (34): Anhydrous sodium acetate
(9.3 g, 0.11 mol) was added to a solution of 4-(hexyloxy)toluene
(19.2 g, 0.10 mol) in glacial acetic acid (70 mL). The mixture was
stirred mechanically and a solution of bromine (5.1 mL, 0.10 mol)
in acetic acid (15 mL) was added dropwise, the temperature being
kept below 35 °C by external cooling. After the bromine had been
consumed, the mixture was diluted with water (200 mL), the or-
ganic layer was separated and the aqueous phase was extracted
with hexanes (3 ϫ 50 mL). The pooled organic solutions were
washed with water (3 ϫ 100 mL) and a saturated aqueous solution
of NaHCO3 (3 ϫ 100 mL) and brine (50 mL), and dried with
CaCl2. The solvent was evaporated. The residue was dissolved in
dry DMF (70 mL), CuCN (14.5 g, 0.15 mol) was added and the
mixture was heated to 150 °C and stirred for 36 h. The cooled mix-
ture was poured into aqueous ammonia (25%) (200 mL) and stirred
for 4 h. The blue solution was extracted with toluene (3 ϫ 50 mL)
and the pooled organic solutions were washed with water (2 ϫ
100 mL) and brine (100 mL) and dried with MgSO4. The solvent
was evaporated and the crude product was purified by chromato-
graphy on silica gel (20 ϫ 7 cm), with petroleum ether (40Ϫ70 °C)
and a gradually increasing content of ethyl acetate. Yield 13.9 g
(64%); yellowish oil. Ϫ IR (neat): ν˜ ϭ 2940, 2910, 2848, 2220, 1599,
1490, 1458, 1283, 1260, 1117, 1018, 810. Ϫ 1H NMR (CDCl3): δ ϭ
0.89 (t, J ϭ 5.5 Hz, 3 H, CH3), 1.25Ϫ1.58 (m, 6 H, CH2), 1.81
(quint, J ϭ 7 Hz, 2 H, β-CH2), 2.28 (s, 3 H, aryl-CH3), 4.02 (t, J ϭ
6 Hz, 2 H, OCH2), 6.82 (d, J ϭ 8.0 Hz, 1 H, 3-H), 7.28 (m, 2 H,
4-H, 6-H). Ϫ 13C NMR (CDCl3): δ ϭ 14.0 (CH3), 20.0, 22.6, 25.6,
28.9, 31.5, (CH2, CH3), 69.1 (OCH2), 101.6 (C-1), 112.3 (C-3),
116.6 (CN), 130.0 (C-5), 133.6, 134.9 (C-4, C-6), 158.8 (C-2). Ϫ EI
MS (70 eV): m/z (%) ϭ 217.1 (7) [Mϩ], 133.2 (100) [Mϩ Ϫ C6H12],
42.4 (42). Ϫ C14H19NO (217.307): calcd. C 77.38, H 8.81, N 6.45;
found C 77.12, H 8.92, N 6.15.
1460, 1415, 1248, 1200, 1170, 967, 848, 828. Ϫ 1H NMR: δ ϭ 0.89
(m, 12 H, CH3), 1.22Ϫ1.70 (m, 32 H, CH2), 1.70Ϫ1.95 (m, 8 H, β-
CH2), 3.95 (t, J ϭ 6.6 Hz, 4 H, OCH2 hex), 4.06 (t, J ϭ 6 Hz, 4
H, OCH2 oct), 6.89 (d, J ϭ 8 Hz, 4 H, 14-H, 16-H), 6.96 (d, J ϭ
16 Hz, 2 H, vin), 7.07 (d, J ϭ 16 Hz, 2 H, vin), 7.11 (s, 2 H, 2-H),
7.12 (d, J ϭ 16 Hz, 2 H vin), 7.40Ϫ7.54 (m, 14 H, 7-H, 8-H, 13-
H, 17-H, CH vin). Ϫ 13C NMR: δ ϭ 14.0, 14.1 (CH3 hex, oct),
22.6, 22.7, 25.7, 26.3, 29.3, 29.4, 29.5, 29.6, 31.6, 31.9 (CH2 hex,
oct), 68.1, 69.6 (OCH2 hex, oct), 110.6 (C-2), 114.8 (C-14, C-16),
123.2, 126.1, 127.0, 128.1, 128.4, 130.0, 136.9, 137.0 (CH, Cq ar,
vin), 151.2 (C-1), 158.9 (C-15). Ϫ FD MS: m/z (%) ϭ 943.4 (100)
[Mϩ], 471.7 (4) [M2ϩ]. Ϫ C66H86O4 (943.387): calcd. C 84.03, H
9.19; found C 84.14, H 9.06.
4-[(E)-2-{4-[(E)-2-{4-[(E)-2-{4-[(E)-2-(4-Cyanophenyl)ethenyl]-
phenyl}ethenyl]-2,5-bis(octyloxy)phenyl}ethenyl]phenyl}ethenyl]-
benzonitrile (2): Yield 0.66 g (83%); yellow needles; m.p. 208 °C
˜
(iPrOH/CHCl3). Ϫ IR (KBr): ν ϭ 3010, 2908, 2840, 2220, 1590,
1582, 1502, 1480, 1453, 1408, 1248, 1195, 1019, 957, 850, 830, 820.
Ϫ
1H NMR (CDCl3): δ ϭ 0.88 (t, J ϭ 6.4 Hz, 6 H, CH3),
1.25Ϫ1.45 (m, 20 H, CH2), 1.56 (quint, J ϭ 7.5 Hz, 4 H, CH2),
1.87 (quint, J ϭ 7.5 Hz, 4 H, β-CH2), 4.07 (t, J ϭ 6 Hz, 4 H,
OCH2), 7.06 (d, J ϭ 16.4 Hz, 2 H, vin), 7.11 (s, 2 H, 2-H), 7.13 (d,
J ϭ 16 Hz, 2 H, vin), 7.19 (d, J ϭ 16.4 Hz, 2 H, vin), 7.53 (d, J ϭ
16 Hz, 2 H, vin), 7.52 (AAЈBBЈ, 8 H, 7-H, 8-H), 7.59 (AAЈBBЈ, 8
H, 13-H, 14-H, 16-H, 17-H). Ϫ 13C NMR (CDCl3): δ ϭ 14.1
(CH3), 22.7, 26.3, 29.3, 29.4, 29.5, 31.8 (CH2), 69.6 (OCH2), 110.5
(C-15), 110.7 (C-2), 119.0 (CN), 124.1, 126.4 (CH vin), 126.8,
127.0, 127.3 (CH ar, C-7, C-8, C-13, C-17), 138.3, 132.0 (CH vin),
132.5 (CH ar, C-14, C-16), 135.4, 138.5, 141.9 (Cq, C-3, C-6, C-9),
151.3 (Cq, C-1). Ϫ FD MS: m/z (%) ϭ 792.7 (100) [Mϩ]. Ϫ
C56H60N2O2 (793.088): calcd. C 84.81, H 7.63, N 3.53; found C
84.60, H 7.79, N 3.51.
General Procedure for the Synthesis of OPVs 1؊5 by
Horner؊Wittig Olefination: A dried, three-necked, round-bot-
tomed flask was fitted with a magnetic stirring bar and a dropping
funnel. The flask was charged with KOtBu (336 mg, 3.0 mmol), 18-
crown-6 (100 mg) and abs. THF (15 mL), the funnel with a solution
of 18 (594 mg, 1.0 mmol) and a phosphonate (19؊23) (2.1 mmol)
in abs. THF (35 mL). The apparatus was evacuated and flushed
with argon (3 ϫ) and the starting materials were added to the base
while stirring at ambient temperature. The mixtures immediately
turned dark green and became fluorescent. The reaction was mon-
itored by TLC and quenched with water (15 mL) (reaction time 20
min to 4 h). The bulk of the solvent was stripped off, the residue
diluted with water. Solid products were filtered, 4 and 5 were ex-
2-[(E)-2-{4-[(E)-2-{4-[(E)-2-{4-[(E)-2-(3-Cyanophenyl)ethenyl]-
phenyl}ethenyl]-2,5-bis(octyloxy)phenyl}ethenyl]phenyl}ethenyl]-
benzonitrile (3): Yield 0.61 g (77%); dark orange crystals; m.p. 168
˜
°C. Ϫ IR (KBr): ν ϭ 3010, 2950, 2905, 2846, 2222, 1610, 1580,
1515, 1495, 1470, 1435, 1217, 1077, 1033, 1974, 820, 691. Ϫ 1H
NMR: δ ϭ 0.89 (t, 6 H, CH3), 1.20Ϫ1.65 (m, 20 H, CH2), 1.88
(quint, J ϭ 6.8 Hz, 4 H, β-CH2), 4.08 (t, J ϭ 6.6 Hz, 4 H, OCH2),
7.06 (d, J ϭ 16 Hz, 2 H, CH vin), 7.12 (s, 2 H, 2-H), 7.13Ϫ7.21
(m, 4 H, CH vin, ar), 7.40Ϫ7.58 (m, 14 H, 7-H, 8-H, CH ar, vin),
7.71 (d, J ϭ 7.8 Hz, 2 H, 15-H), 7.78 (s, 2 H, 13-H). Ϫ 13C NMR:
δ ϭ 14.1 (CH3), 22.7, 26.4, 29.4, 29.5, 29.5, 31.9 (CH2), 69.6
(OCH2), 110.7 (C-14), 113.0 (C-2), 118.8 (CN), 127.0, 127.2 (C-7,
C-8), 124.0, 125.8, 128.2, 129.0, 129.5, 129.8, 130.5, 130.6, 131.0,
135.5, 138.3, 138.7 (CH, Cq ar, vin), 151.2 (C-1). Ϫ FD MS: m/z
(%) ϭ 793.4 (100) [Mϩ]. Ϫ C56H60N2O2 (793.088): calcd. C 84.81,
H 7.63 N 3.53; found C 84.66, H 7.38, N 3.19.
2-[(E)-2-{4-[(E)-2-{4-[(E)-2-{4-[(E)-2-(2-Cyanophenyl)ethenyl]-
phenyl}ethenyl]-2,5-bis(octyloxy)phenyl}ethenyl]phenyl}ethenyl]-
benzonitrile (4): Yield 0.57 g (72%); yellow powder; m.p. 188 °C. Ϫ
˜
IR (KBr): ν ϭ 3017, 2910, 2840, 2222, 1620, 1582, 1503, 1485,
Figure 5. Notation of H, C for NMR data
1465, 1418, 1338, 1200, 1065, 960, 840, 808, 755. Ϫ 1H NMR
(CDCl3): δ ϭ 0.88 (t, J ϭ 6.3 Hz, 6 H, CH3), 1.22Ϫ1.65 (m, 20 H,
Eur. J. Org. Chem. 2001, 2927Ϫ2938
2935

H. Detert, D. Schollmeyer, E. Sugiono
FULL PAPER
CH2), 1.91 (quint, J ϭ 6.8 Hz, 4 H, β-CH2), 4.07 (t, J ϭ 6 Hz, 4 ethenyl}phenyl]-2-[3-(trifluoromethyl)phenyl]-2-propenenitrile
(7):
H, OCH2), 7.13 (s, 2 H, 2-H), 7.15 (d, J ϭ 16.2 Hz, 2 H, vin), 7.26
Yield 0.73 g (79%); dark orange crystals; m.p. 203 °C. Ϫ IR (KBr):
˜
(d, J ϭ 16 Hz, 2 H, vin), 7.31 (t, J ϭ 7.8 Hz, 2 H, 14-H), 7.44 (d, ν ϭ 2920, 2845, 2217, 1578, 1330, 1240, 1114, 1078, 960, 690. Ϫ
J ϭ 16.2 Hz, 2 H, vin), 7.47Ϫ7.62 (m, 12 H, 6-H, 7-H, 15-H, CH 1H NMR (CDCl3): δ ϭ 0.88 (t, 6 H, CH3), 1.20Ϫ1.65 (m, 20H,
vin), 7.64 (d, J ϭ 8 Hz, 2 H, 17-H), 7.79 (d, J ϭ 8 Hz, 2 H, 13-H). CH2), 1.90 (quint, J ϭ 6.5 Hz, 4 H, β-CH2), 4.08 (t, J ϭ 7 Hz, 4
Ϫ
13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3, 29.4, 29.5, 29.5,
H, OCH2), 7.14 (s, 2 H, 2-H), 7.19 (d, J ϭ 16 Hz, 2 H, vin),
31.8 (CH2), 69.6 (OCH2), 110.7, 111.2, 123.6, 124.2, 125.2, 127.0, 7.54Ϫ7.68 (m, 12 H, CH vin, ar), 7.84Ϫ7.93 (m, 8 H, CH vin, ar).
127.5 (CH), 118.0 (CN), 128.2, 132.7, 133.0, 133.2, 135.2, 138.6,
13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3, 29.3, 29.4, 29.5,
Ϫ
140.7 (CH, Cq), 151.3 (C-1). Ϫ FD MS: m/z (%) ϭ 793.0 (100) 31.8 (CH2), 69.6 (OCH2), 109.1 (C-11), 110.7 (C-2), 117.8 (CN),
[Mϩ], 396.5 (1) [M2ϩ]. Ϫ C56H60N2O2 (793.088): calcd. C 84.81, H
7.63, N 3.53; found C 84.76, H 7.56, N 3.48.
122.7 (m), 125.6 (m), 125.9, 127.9, 129.3, 129.7, 132.1, 135.6, 140.9,
143.2 (CH, Cq ar, vin), 127.0, 130.1 (C-7, C-8), 151.4 (C-1), 3 sig-
nals missing due to intensive C,F coupling. Ϫ FD MS: m/z (%) ϭ
928.8 (100) [Mϩ], 464.4 (4) [M2ϩ]. Ϫ C58H58F6N2O2 (929.084):
calcd. C 74.98, H 6.29, N 3.02; found C 75.02, H 6.27, N 3.17.
5-{(E)-2-[4-{(E)-2-[4-{(E)-2-[4-{(E)-2-[3-Cyano-4-(hexyloxy)phenyl]-
ethenyl}phenyl]ethenyl}-2,5-bis(octyloxy)phenyl]ethenyl}phenyl]-
ethenyl}-2-(hexyloxy)benzonitrile (5): Yield 0.73 g (74%); light or-
ange powder; m.p. 166 °C. Ϫ IR (KBr): ν˜ ϭ 3010, 2910, 2840,
2220, 1595, 1500, 1463, 1413, 1274, 1115, 1013, 954, 817, 730. Ϫ
1H NMR (CDCl3): δ ϭ 0.90 (m, 12 H, CH3), 1.20Ϫ1.62 (m, 32 H,
CH2), 1.85 (m, 8 H, β-CH2), 4.07 (m, 8 H, OCH2), 6.94 (d, J ϭ
8 Hz, 2 H, 16-H), 6.98 (m, 4 H, vin), 7.12 (s, 2 H, 2-H), 7.13 (d,
J ϭ 16 Hz, 2 H, vin), 7.48 (m, 10 H, 7-H, 8-H, CH vin), 7.63 (dd,
J ϭ 8.2 Hz, 1 H, JЈ ϭ 1.8 Hz, 17-H), 7.67 (d, J ϭ 1.8 Hz, 1 H, 13-
H). Ϫ 13C NMR (CDCl3): δ ϭ 13.9, 14.0 (CH3), 22.5, 22.6, 25.5,
26.3, 28.9, 29.3, 29.4, 29.5, 31.4, 31.8 (CH2), 69.4, 69.7 (OCH2),
102.7 (C-14), 110.8, 112.6 (C-2, C-16), 116.2 (CN), 126.8, 126.9 (C-
7, C-8), 123.7, 125.9, 127.0, 128.3, 128.5, 130.6, 131.4, 132.0, 136.0,
137.9 (CH, Cq ar, vin), 151.3 (C-1), 160.1 (C-15). Ϫ FD MS: m/z
(%) ϭ 993.2 (100) [Mϩ], 497.1 (6) [M2ϩ]. Ϫ C68H84N2O4 (993.406):
calcd. C 82.21, H 8.52, N 2.82; found C 81.87, H 8.46, N 2.78.
3-{4-[(E)-2-{4-[(E)-2-{4-[(Z)-2-Cyano-2-(3-methoxyphenyl)ethenyl]-
phenyl}ethenyl]-2,5-bis(octyloxy)phenyl}ethenyl]phenyl}-2-(3-
methoxyphenyl)-2-propenenitrile (8): Yield 0.61 g (72%); red solid;
˜
m.p. 148 °C. Ϫ IR (KBr): ν ϭ 2910, 2840, 2208, 1585, 1482, 1455,
1
1415, 1275, 1203, 1042, 960, 850. Ϫ H NMR (CDCl3): δ ϭ 0.89
(t, 6 H, CH3), 1.25Ϫ1.63 (m, 20 H, CH2), 1.90 (quint, J ϭ 6.5 Hz,
4 H, β-CH2), 3.86 (s, 6 H, OCH3), 4.08 (t, J ϭ 6.5 Hz, 4 H, OCH2),
6.93 (ddd, J ϭ 7.7 Hz, 1 H, 15-H), 7.13 (s, 2 H, 2-H), 7.17 (d, J ϭ
16 Hz, 2 H, vin), 7.20 (m, 1 H, 13-H), 7.29 (m, 2 H, 17-H), 7.36
(dd, J ϭ JЈϭ 7.5 Hz, 2 H, 16-H), 7.51 (s, 2 H, 10-H), 7.59 (d, 2 H,
vin), 7.62 (d, J ϭ 8 Hz, 4 H), 7.90 (d, J ϭ 8 Hz, 4 H, 8-H). Ϫ 13C
NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3, 29.3, 29.4, 29.5, 31.8
(CH2), 55.5 (OCH3), 69.6 (OCH2), 110.5, 110.7, 111.6, 114.7, 118.4
(CN), 125.5, 126.9 (2 ϫ), 128.0, 129.9 (2 ϫ), 130.1, 132.6, 136.1,
140.4, 141.9 (CH, Cq), 151.4, 160.1 (CϪO). Ϫ FD MS: m/z (%) ϭ
854.5 (100) [Mϩ], 427.0 (38) [M2ϩ]. Ϫ C58H64N2O4 (853.140):
calcd. C 81.65, H 7.56, N 3.28; found C 81.59, H 7.57, N 3.18.
General Procedure for the Synthesis of OPVs 6؊2 by Knoevenagel
Condensation: Under argon, solid KOtBu (224 mg, 2.0 mmol) was
added to a stirred solution of 18 (594 mg, 1.0 mmol) and benzyl
cyanide (24Ϫ30) (2.1 mmol) in abs. THF (20 mL) and tert-butyl
alcohol (15 mL). Upon addition of the base, the mixture turned
dark and spontaneous precipitation of the red to dark-red OPVs
(10, 11, 12) occurred. When the reaction was complete (15 min to
3 h), the mixture was poured into water (100 mL) and either the
precipitate was collected (7, 10Ϫ12) or the compounds (6, 8, and
9) were isolated by extraction with chloroform (3 ϫ 50 mL) and
the pooled organic solutions were washed with water and brine and
dried with Na2SO4. Purification was done by recrystallisation from
chloroform/isopropyl alcohol (6, 7, 10؊12) or chromatography on
silica gel, using toluene as eluent (8, 9).
(2Z)-3-{4-[(E)-2-{4-[(E)-2-{4-[(Z)-2-Cyano-2-(2-methoxyphenyl)-
ethenyl]phenyl}ethenyl]-2,5-bis(octyloxy)phenyl}ethenyl]phenyl}-2-
(2-methoxyphenyl)-2-propenenitrile (9): Yield 0.49 g (57%); dark
˜
yellow powder; m.p. 190 °C. Ϫ IR (KBr): ν ϭ 2910, 2840, 2210,
1590, 1480, 1450, 1255, 1195, 1020, 962. Ϫ 1H NMR (CDCl3): δ ϭ
0.88 (t, 6 H, CH3),1.22Ϫ1.60 (m, 24 H, CH2), 1.88 (quint, J ϭ
6.5 Hz, 4 H, β-CH2), 3.91 (s, 6 H, OCH3), 4.08 (t, J ϭ 6.5 Hz, 4
H, OCH2), 6.93Ϫ7.06 (m, 4 H, 14-H, 16-H), 7.13 (s, 2 H, 2-H),
7.16 (d, J ϭ 16 Hz, 2 H, vin), 7.31Ϫ7.45 (m, 6 H, 15-H, 17-H, CH
vin), 7.57 (d, J ϭ 16 Hz, 2 H, CH vin), 7.59 (d, J ϭ 8 Hz, 4 H, 7-
H), 7.88 (d, J ϭ 8 Hz, 4 H, 8-H). Ϫ 13C NMR (CDCl3): δ ϭ 14.1
(CH3), 22.6, 26.3, 29.3, 29.4, 29.5, 31.8 (CH2), 55.8 (OCH3), 69.7
(OCH2), 108.1, 110.9, 111.7, 118.3 (CN), 121.1, 125.0, 125.3, 126.8
(2 ϫ), 127.1, 128.1, 129.7 (2 ϫ), 129.9, 130.4, 133.1, 140.1, 145.4
(CH, Cq), 151.4, 157.1 (CϪO). Ϫ FD MS: m/z (%) ϭ 1707.0 (9)
[M2ϩ], 853.5 (100) [Mϩ], 426.8 (11) [M2ϩ]. Ϫ C58H64N2O4
(853.140): calcd. C 81.65, H 7.56, N 3.28; found C 81.59, H 7.57,
N 3.18.
(2Z)-3-{4-[(E)-2-{4-[(E)-2-{4-[(Z)-2-Cyano-2-phenylethenyl]-
phenyl}ethenyl]-2,5-bis(octyl oxy)phenyl}ethenyl]phenyl}-2-phenyl-2-
propenenitrile (6): Yield 0.51 g (64%); red powder, m.p. 156 °C. Ϫ
IR (KBr): ν˜ ϭ 2920, 2850, 2215, 1580, 1505, 1490, 1422, 1338,
1258, 1200, 966, 902, 860. Ϫ 1H NMR (CDCl3): δ ϭ 0.88 (m, 6 H,
CH3), 1.20Ϫ1.70 (m, 20 H, CH2), 1.90 (quint, J ϭ 7.5 Hz, 4 H, β-
CH2), 4.09 (t, J ϭ 6.0 Hz, 4 H, OCH2), 7.13 (s, 2 H, 1-H), 7.17 (d,
J ϭ 16 Hz, 2 H, vin), 7.38 (tt, J ϭ 8 Hz, 2 H, 15-H), 7.44 (m, 4 H,
14-H), 7.52 (s, 2 H, 10-H), 7.58 (d, 2 H, vin), 7.60 (d, J ϭ 8 Hz, 2
H, 7-H), 7.67 (dt, J ϭ 6.8 Hz, 2 H, 13.H), 7.89 (d, J ϭ 8 Hz, 4 H,
ar). Ϫ 13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3, 29.3, 29.4,
29.5, 31.9 (CH2), 69.6 (OCH2), 110.6 (C-2), 110.7 (C-12), 118.3
(CN), 126.0, 126.9, 129.1, 129.9 (C-7, C-8, C-12, C-13), 125.5,
127.9, 141.7 (CH), 129.1, 132.6, 134.7, 140.3 (Cq), 151.3 (C-1), 1
CH signal missing. Ϫ FD MS: m/z (%) ϭ 793.0 (100) [Mϩ], 396.6
(4) [M2ϩ]. Ϫ C56H60N2O2 (793.088): calcd. C 84.81, H 7.63, N 3.53
found C 84.31, H 7.73, N 3.16.
(2Z)-2-(4-Chlorophenyl)-3-{4-[(E)-2-{4-[(E)-2-{4-[(Z)-2-(4-chloro-
phenyl)-2-cyanoethenyl]phenyl}ethenyl]-2,5-bis(octyloxy)-
phenyl}ethenyl]phenyl}-2-propenenitrile (10): Yield 0.84 g (97%);
˜
dark red crystals; m.p. 192 °C. Ϫ IR (KBr): ν ϭ 3010, 2918, 2843,
2208, 1587, 1571, 1502, 1485, 1417, 1245, 1205, 1092, 964, 828. Ϫ
1H NMR (CDCl3): δ ϭ 0.88 (t, J ϭ 6 Hz, 6 H, CH3), 1.25Ϫ1.45
(m, 20 H, CH2), 1.52 (m, 4 H, CH2), 1.88 (quint, J ϭ 7 Hz, 4 H,
β-CH2), 4.08 (t, J ϭ 6 Hz, 4 H, OCH2), 7.12 (s, 2 H, 2-H), 7.16 (d,
J ϭ 16.4 Hz, 2 H, vin), 7.40 (d, J ϭ 8 Hz, 4 H, 13-H, 16-H), 7.46
(s, 2 H, 10-H), 7.55Ϫ7.62 (m, 10 H, CH ar, vin), 7.89 (d, J ϭ 8 Hz,
4 H, CH ar). Ϫ 13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3,
(2Z)-3-[4-{(E)-2-[4-{(E)-2-[4-{(Z)-2-Cyano-2-[3-(trifluoromethyl)- 29.3, 29.4, 29.5, 31.8 (CH2), 69.6 (OCH2), 109.4 (C-11), 110.7 (C-
phenyl]ethenyl}phenyl]ethenyl}-2,5-bis(octyloxy)phenyl]- 2), 118.1 (CN), 125.6, 127.9, 132.4, 133.2, 135.1, 140.6, 141.9 (CH,
2936
Eur. J. Org. Chem. 2001, 2927Ϫ2938

Cyano-Substituted Oligo(phenylenevinylene)s
FULL PAPER
Cq ar, vin), 127.2, 127.2, 129.3, 129.9 (C-7, C-8, C-13, C-14, C-16,
C-17), 151.4 (C-1). Ϫ FD MS: m/z (%) ϭ 860.7 (100) Cl2 pattern
[Mϩ], 431.5 (16) [M2ϩ]. Ϫ C56H58Cl2N2O2 (861.977): calcd. C
78.03, H 6.78, N 3.25; found C 78.41, H 6.95, N 3.23.
Acknowledgments
The authors gratefully thank Prof. Dr. H. Meier and the Deutsche
Forschungsgemeinschaft for financial support.
(2Z)-3-[4-{(E)-2-[4-{(E)-2-[4-{(Z)-2-Cyano-2-[4-(trifluoromethyl)-
phenyl]ethenyl}phenyl]ethenyl}-2,5-bis(octyloxy)phenyl]-
ethenyl}phenyl]-2-[4-(trifluoromethyl)phenyl]-2-propenenitrile (11):
Yield 0.89 g (96%); dark red powder; m.p. 187 °C. Ϫ IR (KBr):
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H, 2-H), 7.17 (d, J ϭ 16 Hz, 2 H, vin), 7.55 (s, 2 H, 10-H), 7.61
(d, 2 H, CH vin), 7.67 (d, J ϭ 8 Hz, 4 H, 7-H), 7.69Ϫ7.79 (AAЈBBЈ
system, 8 H, 13-H, 14-H, 16-H, 17-H), 7.93 (d, J ϭ 8 Hz, 4 H, 8-
H). Ϫ 13C NMR (CDCl3): δ ϭ 14.0 (CH3), 22.6, 26.2, 29.2, 29.3,
29.4, 31.7 (CH2), 69.5 (OCH2), 109.0 (C-11), 110.8 (C-2), 117.7
(CN), 123.7 (q, JC-F ϭ 271 Hz, CF3), 125.1, 125.9, 125.9, 126.0,
127.9, 132.0, 138.1, 140.1, 143.4 (CH, Cq ar, vin), 126.9, 127.9,
130.0 (2 ϫ, CH ar), 130.8 (q, JC-F ϭ 33 Hz, C-15), 151.4 (C-1). Ϫ
FD MS: m/z (%) ϭ 929.4 (100) [Mϩ], 464.8 (11) [M2ϩ]. Ϫ
C58H58F6N2O2 (929.084): calcd. C 74.98, H 6.29, N 3.02; found C
74.88, H 6.21, N 3.06.
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3-{4-[(E)-2-{4-[(E)-2-{4-[(Z)-2-Cyano-2-(4-methoxyphenyl)-
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U. Stalmach, H. Detert, H. Meier, V. Gebhardt, D. Haarer, A.
˜
solid; m.p. 177 °C. Ϫ IR (KBr): ν ϭ 3020, 2910, 2840, 2205, 1595,
1503, 1455, 1413, 1242, 1200, 1180, 1030, 965, 825. Ϫ 1H NMR
(CDCl3): δ ϭ 0.89 (t, 6 H, CH3), 1.25Ϫ1.63 (m, 20 H, CH2), 1.90
(quint, J ϭ 6.5 Hz, 4 H, β-CH2), 3.86 (s, 6 H, OCH3), 4.08 (t, J ϭ
6.5 Hz, 4 H, OCH2), 6.95 (d, J ϭ 8.5 Hz, 4 H, 14-H, 16-H), 7.11
(s, 2 H, 2-H), 7.15 (d, J ϭ 16 Hz, 2 H, vin), 7.38 (s, 2 H, vin),
7.50Ϫ7.64 (m, 10 H), 7.86 (d, J ϭ 8 Hz, 4 H, 8-H). Ϫ 13C NMR
(CDCl3): δ ϭ 14.1 (CH3), 22.7, 26.3, 29.3, 29.4, 29.5, 31.9 (CH2),
55.5 (OCH3), 69.6 (OCH2), 110.2, 110.7, 114.5 (2 x), 118.4 (CN),
125.2, 126.9 (2 ϫ), 127.3 (2 ϫ), 128.0, 129.6 (2 ϫ), 132.9, 139.6,
139.9(CH, Cq), 151.3, 160.4 (CϪO). Ϫ FD MS: m/z (%) ϭ 853.4
(100) [Mϩ], 427.3 (18) [M2ϩ]. Ϫ C58H64N2O4 (853.140): calcd. C
81.65, H 7.56, N 3.28; found C 81.62, H 7.53, N 3.23.
[15]
[16]
[17]
[18]
[19]
Bacher, H.-W. Schmidt, Opt. Mater. 1998, 9, 77Ϫ81.
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´
J.-L. Bredas, Adv. Mater. 1995, 7, 263Ϫ274.
[21]
N. Dam, R. D. Scurlock, B. Wang, L. Ma, M. Sundahl, P. R.
Ogilby, Chem. Mater. 1999, 11, 1302Ϫ1305.
(2Z)-2-[4-{(Z)-1-Cyano-2-[4-{(E)-2-[4-(hexyloxy)phenyl]-
ethenyl}phenyl]ethenyl}-2,5-bis(hexyloxy)phenyl]-3-[4-{(E)-2-[4-
(hexyloxy)phenyl]ethenyl}phenyl]-2-propenenitrile (13): The syn-
thesis was performed according to the procedure described for
6؊12, using 32[10] (356 mg, 1 mmol) and 31 (616 mg, 2 mmol).
Purification was done by repeated chromatography. Solutions of 13
were protected from light because of photoreactions. Yield: 0.35 g
[22]
[23]
U. Stalmach, H. Detert, J. Prakt. Chem. 2000, 10Ϫ16.
H. Tillmann, H.-H. Hörhold, presented at the 37th IUPAC
Congress, Berlin, 1999, Abstract EXP-2-084, p. 694.
A. Lux, S. C. Moratti, W.-C. Li, A. C. Grimsdale, J. E. Davies,
P. R. Raithby, J. Grüner, F. Cacialli, R.-H. Friend, A. B.
Holmes, Polym. Prepr. 1996, 37, 202.
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[25] [25a]
R. E. Gill, P. van Hutten, A. Meetsma, G. Hadziioannou,
Chem. Mater. 1996, 8, 1341Ϫ1346. Ϫ [25b] R. E. Gill, Proefsch-
rift, Rijksuniversiteit Groningen, 1996.
˜
(37%); yellow crystals; m.p. 156 °C. Ϫ IR (KBr): ν ϭ 3010, 2950,
2915, 2850, 2208, 1585, 1500, 1455, 1410, 1243, 1212, 1170, 1024,
962, 830. Ϫ 1H NMR (CDCl3): δ ϭ 0.88 (m, 12 H, CH3),
1.22Ϫ1.58 (m, 24 H, CH2), 1.81 (m, 8 H, β-CH2), 3.97 (t, J ϭ
6.5 Hz, 4 H, OCH2), 4.07 (t, J ϭ 6.3 Hz, 4 H, OCH2), 6.89 (d, J ϭ
8.7 Hz, 4 H), 6.97 (d, J ϭ 16.8 Hz, 2 H, vin), 7.08 (s, 2 H), 7.15
(d, J ϭ 16.8 Hz, 2 H, vin), 7.45 (d, J ϭ 8.7 Hz, 4 H), 7.55 (d, J ϭ
8.0 Hz, 4 H), 7.67 (s, 2 H, vin), 7.87 (d, J ϭ 8.0 Hz, 4 H). Ϫ 13C
NMR (CDCl3): δ ϭ 14.0 (2 ϫ CH3, hex), 22.6, 29.6, 31.6 (2 ϫ
CH2), 25.7, 25.9 (CH2), 68.1, 69.8 (OCH2), 107.0, 114.4, 114.8
(CH), 118.3 (CN), 125.4, 125.6, 126.6 (CH), 128.0 (CH), 129.5,
129.8 (CH), 130.3, 132.7, 140.1, 146.2, 150.6 (CϪO), 159.4 (CϪO).
Ϫ FD MS: m/z (%) ϭ 937.3 (100) [Mϩ], 468.7 (7) [M2ϩ]. Ϫ
C64H76N2O4 (937.299): calcd. C 82.01, H 8.17, N 2.99; found C
81.97, H 8.13, N 2.97.
[26]
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2937

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Atomic coordinates, bond lengths and angles, and thermal
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[45]
parameters of 4 (CCDC-149204) and 12 (CCDC-149205) can
be obtained on request from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK [Fax:
(int.) ϩ 44-1223/336-033, E-mail: deposit@ccdc.cam.ac.uk].
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Received November 23, 2000
1994, 6, 671.
[O00594]
2938
Eur. J. Org. Chem. 2001, 2927Ϫ2938