Red- and blue-shifts in oligo(1,4-phenyleneethynylene)s having terminal donor-acceptor substitutions

Article abstract of DOI:10.1002/ejoc.200300676

Four series of oligo(1,4-phenyleneethynylene)s (OPEs), 1-4 (a-d), each having a terminal dialkylamino group as their electron donor, were prepared by applying Sonogashira-Hagihara reactions and a protecting group strategy. To study the influence that the

Full text of DOI:10.1002/ejoc.200300676

FULL PAPER
Red- and Blue-Shifts in Oligo(1,4-phenyleneethynylene)s Having Terminal
Donor؊Acceptor Substitutions
Herbert Meier,*[a] Bastian Mühling,[a] and Heinz Kolshorn[a]
Keywords: Absorption / Conjugation / Intramolecular charge transfer / Oligomers / PushϪpull effect
Four series of oligo(1,4-phenyleneethynylene)s (OPEs), 1−4
(a−d), each having a terminal dialkylamino group as their
the donor and acceptor groups. In the case of the relatively
weak acceptor CN, both effects annihilate one another,
whereas the reduction of the ICT predominates in the CHO
electron
donor,
were
prepared
by
applying
Sonogashira−Hagihara reactions and a protecting group and NO2 series. Therefore, E(n) is virtually independent of n
strategy. To study the influence that the push−pull effect has
on the long-wavelength absorption, three of the four series
of OPEs contain terminal acceptor groups (CN, CHO, NO2).
Extending the conjugation (increasing the number of repeat
units, n) lowers the energy E(n) of the electron transition in
the purely donor-substituted series 1a−4a (bathochromic
shift). This effect is superimposed in the push−pull series 1−4
(b−d) by the effect of the intramolecular charge transfer
(ICT), which decreases with increasing the distance between
in the CN series 1b−4b and shows a hypsochromic effect in
the CHO and NO2 series (1c−4c and 1d−4d, respectively). We
rationalize these results based on AM1−INDO/S calculations.
The results of the commonly used intuitive VB model having
electroneutral and zwitterionic resonance structures are com-
pared with those of a more appropriate MO model having
dipole segments at both chain ends.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
of comparing the pushϪpull series 1Ϫ4 (bϪd) with ‘‘nor-
mal’’ OPEs.
Conjugated oligomers and polymers, such as the 1,4-
phenyleneethenylenes (OPVs and PPVs) and the corre-
sponding 1,4-phenyleneethynylenes (OPEs and PPEs), at-
tract a lot of attention in organic chemistry and materials
science.[1] Recently we reported the preparation and non-
linear optical properties of a series of eight oligo(2,5-di-
propoxy-1,4-phenyleneethynylene)s.[2,3] Because of the pres-
ence of a center of symmetry in these molecules, we studied
the third harmonic generation (THG)/second hyperpolariz-
ability, γ. In this paper, we deal with the preparation of
donorϪacceptor-substituted OPEs. These molecules do not
have a center of symmetry; moreover, they should exhibit a
large intramolecular charge transfer (ICT) upon S0 Ǟ S1
excitation. Thus, these compounds should have high values
of the second harmonic generation (SHG)/hyperpolariz-
ability (β). We chose the solubilizing didodecylamino
groups as the electron donors, D, and CN (series 1bϪ4b),
CHO (series 1cϪ4c), and NO2 groups (series 1dϪ4d) as the
electron acceptors (A, Scheme 1). The series 1aϪ4a lacking
the terminal acceptor (A ϭ H) was prepared for the sake
Scheme 1. Donor-substituted oligo(1,4-phenyleneethynylene)s
1aϪ4a and donorϪacceptor-substituted oligo(1,4-phenyleneethyn-
ylene)s 1bϪ4b, 1cϪ4c, and 1dϪ4d
Conjugated oligomers usually exhibit a convergent ba-
thochromic shift of both the absorption and fluorescence
when the number of repeat units, n, is increased.[4] Recently,
however, we found some DϪOPV(n)ϪA series (OPV ϭ
oligo-p-phenylenevinylene) that display the opposite be-
havior: a hypsochromic shift is induced upon extending the
length of the chromophores.[5Ϫ8] These results stimulated us
to investigate also the OPEs 1Ϫ4 (aϪd).
[a]
Institute of Organic Chemistry, University of Mainz,
Duesbergweg 10Ϫ14, 55099 Mainz, Germany
Fax: (internat.) ϩ49-(0)6131-3925396
E-mail: hmeier@mail.uni-mainz.de
Eur. J. Org. Chem. 2004, 1033Ϫ1042
DOI: 10.1002/ejoc.200300676
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H. Meier, B. Mühling, H. Kolshorn
FULL PAPER
Results and Discussion
Synthesis
reactions are high (98Ϫ73%) for the shorter systems (n ϭ
1,2) and somewhat lower (84Ϫ39%) for the longer ones
(n ϭ 3,4).
For a coupled synthesis of the 16 compounds 1Ϫ4 (aϪd),
we started with N,N-didodecyl-4-iodoaniline (5) and first
prepared the OPE series 7, 10, 12, and 14 having terminal
trimethylsilylethynyl groups and the corresponding depro-
tected OPE series, 8, 11, 13, and 15 (Scheme 2). The
SonogashiraϪHagihara reaction[9] of 5 and trimethyl-
silylacetylene (6) gave N,N-didodecyl-4-(trimethylsilylethyn-
yl)aniline (7) in quantitative yield. After deprotection with
K2CO3, the alkyne 8 was transformed to the next higher,
protected OPE 10, again by applying a quantitative Pd-cat-
alyzed C(sp2)ϪC(sp) coupling reaction (8 ϩ 9 Ǟ 10). The
process was repeated twice, i.e., 10 was deprotected to give
11, which was coupled with 9 to give 12, which was depro-
tected to give 13, which was coupled again with 9 to give
14, which was deprotected to give 15. The yields of these
steps are high (91Ϫ59%), although they are somewhat
lower than those for the shorter-chain compounds
(Scheme 2). The two series of OPEs have good solubilities
because the didodecylamino group is present in every one
of these compounds.
Scheme 3. Synthesis of the donor-substituted series 1aϪ4a and the
donorϪacceptor-substituted series 1bϪ4b, 1cϪ4c, and 1dϪ4d: (a)
Pd0, CuI, piperidine, Ar
Our synthetic principle was based on a construction set
of compounds (coupled synthesis) and relying, from the
very beginning, on the presence of the solubilizing didode-
cylamino groups.
Push؊Pull Effect and Intramolecular Charge Transfer
Conjugated oligomers bearing donor and acceptor
groups in their terminal positions are often described by a
valence bond model, which consists of resonance between
an electroneutral and a zwitterionic structure. Such a model
in the OPE series requires quinoid segments connected by
cumulene units (Scheme 4): the longer the chain, the higher
the energy for the charge separation in the quinoid form.
Alternatively, an MO model can be conceived. It contains
two dipolar segments, one at each end of the chain. The
partial dipole moments µi (i ϭ 1,2) consist of intrinsic and
induced parts and sum to the total dipole moment µ(n) ϭ
Scheme 2. Preparation of the donor-substituted oligo(1,4-pheny-
leneethynylene) series 7, 10, 12, and 14 and 8, 11, 13, and 15: (a)
Pd0, PPh3, CuI, piperidine, (b) K2CO3, CH2Cl2/CH3OH
The final step toward obtaining the target compounds
1Ϫ4 (aϪd) was SonogashiraϪHagihara coupling of the de-
protected members of the OPE series [8, 11, 13, and 15
(n ϭ 1Ϫ4)] with the corresponding iodo compounds 16Ϫ19
Scheme 4. VB and MO models of the donorϪacceptor-substituted
(Scheme 3). Again, the yields of these 16 CϪC coupling OPEs 1Ϫ4 (bϪd)
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Eur. J. Org. Chem. 2004, 1033Ϫ1042

Oligo(1,4-phenyleneethynylene)s Having Terminal DonorϪAcceptor Substitutions
FULL PAPER
µ1(n) ϩ µ2(n). The intrinsic fraction is due to the polar
All compounds exhibit values of δ (13C-sp) that are be-
group at the chain end; the induced fraction is caused by tween δ ϭ 86.9 and 94.8 ppm, which are close to the chemi-
the dipole moment on the opposite chain end and should cal shift of tolane (δ ϭ 89.4 ppm). Thus, any discernible
decrease upon increasing the number of repeat units, n.
contribution of a cumulene structure can be excluded.
The 13C NMR spectroscopy of 1Ϫ4 (bϪd) not only per- Moreover, the data in Table 1 reveal the polarization of the
mits a statement to be made about the charge distribution CϭC bonds, which is expressed by the ∆δ values. The pola-
in these compounds, but it should also indicate the degree rization of the longer chains (n ϭ 2) is particularly high
of participation of the cumulene substructures because the at the chain ends. This result corresponds exactly to the
chemical shifts for the acetylene and cumulene carbon polarization obtained by an AM1 calculation.[10] Figure 2
atoms differ by more than 100 ppm. Table 1 summarizes shows the calculated charge differences on the sp-hybridized
selected δ (13C) values of tolane and the series 1Ϫ3 (aϪd). C atoms of 1dϪ4d and the corresponding ∆δ values from
The solubility of 4aϪ4d was too low to for us to obtain Table 1.
exact δ (13C) data for these compounds. The correlation of
the signals with certain carbon atoms is based on 2D meas-
urements (HMQC and HMBC). Figure 1 shows an example
for compound 3b and the assignment of the six acetylenic
3
carbon atoms by making use of the J (13C,1H) couplings.
Table 1. Selected 13C NMR spectroscopic data (sp-C) of tolane and
OPEs 1Ϫ3 (aϪd): δ values in CDCl3, TMS as internal standard
Figure 2. Charge differences (upper values) of the acetylenic carbon
atoms calculated for the pushϪpull oligomers 1dϪ4d;[10] the posi-
tive and negative signs relate to the partial charge in tolane. Below
them are the ∆δ values measured from the 13C NMR spectrum
recorded in CDCl3
Table 2 summarizes the long-wavelength absorption max-
ima of 1Ϫ4 (aϪd) in CHCl3. Apart from the inaccuracy of
the spectrometer (∆λ ϭ Ϯ 1 nm, which corresponds to a
value of ∆ν of 60Ϫ70 cmϪ1), the longer chromophores give
˜
overlapping bands, which cause the λmax. values to have
somewhat higher intervals ∆ ν˜. A separation of two overlap-
ping absorption bands is feasible by an algorithm based on
Gauss functions.[11] However, even the bands that are not
overlapping for S0 Ǟ S1 and S0 Ǟ S2 are slightly unsym-
metrical. Therefore, we suggest the following modified ex-
ponential function for the analysis of these spectra. Figure 3
illustrates the separation of the bands for 2d.
(1)
Figure 1. HMBC measurements of 3b in CDCl3: correlation of the
six sp-hybridized C atoms with aromatic protons by making use of
3J (1H,13C) couplings. 1H NMR: (a) low-field portion of the
AAЈXXЈ pattern of the donor-substituted benzene ring; (b,c) nar-
row AAЈBBЈ pattern; (d) pseudo-singlet (collapsed AAЈBBЈ); (e,f)
AAЈBBЈ pattern of the acceptor-substituted benzene ring.
The parameters ∆ν˜ for compounds having m repeat units
were evaluated from the corresponding bands of the shorter
compounds in which n ϭ m Ϫ 1.
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H. Meier, B. Mühling, H. Kolshorn
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∆ν˜ ϭ 0.5(ν˜2 Ϫ ν˜1)
whereby
in the series 1bϪ4b, which has the CN group as its relatively
weak acceptor, does not have an appreciable influence on
the long-wavelength band; the slight increase of ν˜max. from
n ϭ 1 to n ϭ 4 is within the limits of error.
(2)
(3)
ε(ν˜1) ϭ ε (ν˜2) ϭ εmax.·eϪ1
Apart from the extension of conjugation, the intramol-
ecular charge transfer (ICT) also must be considered. The
transition energy, EDA(n), of the donorϪacceptor-substi-
tuted oligomers can be split into two terms.[5,8] The first
term, ED(n), refers to the extension of conjugation and
(4) takes the substituent effect of the donor group into account.
This term, which is derived from the series 1aϪ4a, causes
a pronounced bathochromic effect. The second term,
∆EDA(n), refers to the effect of the ICT in the three
pushϪpull series 1Ϫ4 (bϪd); ∆EDA decreases with decreas-
This algorithm has its advantages for slightly unsym-
metrical bands with
ν˜2 Ϫ ν˜max. ϶ ν˜max. Ϫ ν˜1
Table 2. UV/Vis absorption of the oligomer series 1Ϫ4 (aϪd) in
CHCl3
Compound
n
ν˜max. [103·cmϪ1
]
λmax. [nm] ε [cm2·mmolϪ1
]
ing ICT (increasing n). The convergence limit of all four
series is located at 25840 Ϯ 100 cmϪ1
.
1a
2a
3a
4a
1b
2b
3b
4b
1c
2c
3c
4c
1d
2d
3d
4d
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
29.33 Ϯ 0.07
26.74 Ϯ 0.07
26.28 Ϯ 0.18
26.16 Ϯ 0.30
25.84 Ϯ 0.07
25.84 Ϯ 0.07
25.97 Ϯ 0.18
26.09 Ϯ 0.30
25.00 Ϯ 0.06
25.64 Ϯ 0.06
26.00 Ϯ 0.20
26.02 Ϯ 0.25
23.15 Ϯ 0.06
24.81 Ϯ 0.06
26.15 Ϯ 0.30
26.15 Ϯ 0.30
341
25000
44900
57800
77100
38900
45300
56800
86000
26300
37700
56300
78600
23700
30100
57500
81700
374
379[a]
378[a]
387
EDA(n) ϭ ED(n) Ϫ ∆EDA(n)
(5)
(6)
EDA(n) ϭ Eϱ ϩ [ED(1) Ϫ Eϱ]eϪa(n Ϫ 1) Ϫ
387
[ED(1) Ϫ EDA(1)]e∆a(n Ϫ 1)
384[a]
379[a]
400
Thus, Equations (5) and (6) show that the conjugation
effect and the effect of the ICT are opposite to one another.
The decrease of the ICT effect with increasing n prevails in
series 1cϪ4c and 1dϪ4d; the result is an overall hypsoch-
romic shift. In the oligomer series 1bϪ4b, however, both
effects annihilate one another. Obviously, it depends on the
acceptor strength in 1Ϫ4 (bϪd) as to which of the two ef-
fects predominates. The change of ν˜max. from n ϭ 1 to n ϭ
2 (Table 2) already indicates the dominating influence in all
four series. Figure 4 illustrates the two contrary effects.
Series having weak donors or weak acceptors, or both, al-
ways exhibit bathochromic shifts.[12]
390
382[a]
388[a]
432
403
380[a]
382[a]
[a]
Because of the overlap of bands, the measured values of λmax.
differ somewhat in these cases from the 1/ν˜max. values of the sepa-
rated long-wavelength band.
Figure 3. UV/Vis absorption of 2d in CHCl3 (Ϫ) and separation of
the long-wavelength band (···) according to Equations (1)Ϫ(3)
Figure 4. Bathochromic effect [ED Ϫ Eϱ] owing to the extension
of the conjugation (triangles) and opposite hypsochromic effects
(Ϫ∆EDA) caused by the decrease of the ICT upon increasing the
number of repeat units, n, in the pushϪpull series 1bϪ4b (*), 1c
Ϫ4c (filled diamond) and 1d Ϫ4d (filled circles). The wavenumbers
correspond to the absorption maxima ν˜max. listed in Table 2.
The merely donor-substituted oligomer series 1aϪ4a
shows a bathochromic shift upon extension of the chromo-
phore. The pushϪpull series 1cϪ4c and 1dϪ4d exhibit dis-
tinct hypsochromic effects upon increasing the number of
Müllen and coworkers[13] have studied a series of
repeat units, n, but extending the length of the chromophore (CH3)2NϪOPEϪNO2 compounds that were separated by
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Oligo(1,4-phenyleneethynylene)s Having Terminal DonorϪAcceptor Substitutions
FULL PAPER
HPLC; they found a hypsochromic effect from n ϭ 1 to n ϭ approaches zero for n ϭ 4. The other fractions, HOMO-1
2, but bathochromic effects from there on (n ϭ 3, 4, etc.). Ǟ LUMO, HOMO Ǟ LUMOϩ1, and HOMO-1 Ǟ
It is difficult to compare that series of compounds with our LUMOϩ1, however, have either a small ICT or no ICT at
series 1dϪ4d because of the 2,5-dihexyl substitution of the all, as demonstrated for 4d in Figure 5.
inner, but not outer, benzene rings in the former series.[13]
Table 3. Dipole moments (in Debye) of 1dϪ4d,[10] calculated by
Even the λmax. values for the first two members of the series
differ significantly from the values found for 1d and 2d.
AM1ϪINDO/S methods for the ground state, S0, and the first ex-
cited singlet state, S1
It is interesting to note that the ‘‘competition’’ between
the extension of the chromophores and the decrease of the
ICT upon increasing the number of repeat units, n, is also
influenced by the π system present between the donor D
and acceptor A. Not surprisingly, in pure polyene systems,
DϪPEϪA, a hypsochromic shift has never been estab-
lished (n Ǟ ϱ).[14]
The term ∆EDA in the Equations (5) and (6) is respon-
Quantum chemical calculations allow for a rationaliz-
ation of the obtained effects. We used the AM1 method to
optimize the geometries and the INDO/S method to calcu-
late the electron transitions. Figure 5 shows a comparison
of the long-wavelength electron transitions of 1d and 4d.[10]
The S0 Ǟ S1 transition of 1d consists predominantly (67%)
of the excitation of an electron from the HOMO to the
LUMO. This transition is connected with a strong intra-
molecular charge transfer (ICT) from the donor side to the
acceptor side. Accordingly, the dipole moment of 1d in-
creases from µ(S0) ϭ 9.6 D to µ(S1) ϭ 25.4 D (Table 3). On
proceeding to longer chromophores, the participation of the
HOMO Ǟ LUMO transition for S0 Ǟ S1 decreases and
sible for the effect of the ICT on the transition energy EDA
;
∆EDA correlates with the HOMOϪLUMO participation in
S0 Ǟ S1. Figure 6 illustrates, for the series 1dϪ4d, the de-
pendence of the HOMO Ǟ LUMO fraction on the number
of repeat units, n, and the corresponding decrease of
|∆EDA|. In accordance with the MO model (Scheme 4), the
mutual interaction of the acceptor group and the donor
group gets smaller with the longer distance between them.
Figure 6. Decrease of the pushϪpull correction term EDA upon
increasing the number of repeat units, n (upper part), and corre-
sponding decrease of the fraction of the HOMO Ǟ LUMO tran-
sition in S0 Ǟ S1 (lower part)
Figure 5. Orbitals that are involved predominantly in the S0 Ǟ S1
transition of 1d (upper part) and 4d (lower part); calculations were
performed by applying the AM1ϪINDO/S method[10]
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The influence of the acceptor on the electron transition S0 the conjugation and decreasing the intramolecular charge
Ǟ S1 can be neglected for n Ͼ 3. The long-wavelength ab- transfer (ICT) upon increasing n are opposite effects. The
sorptions of 1Ϫ4 (bϪd) approach the absorption of the pu- acceptor strength decides which of these effects prevails, but
rely donor-substituted series 1aϪ4a (λϱ ϭ 387 Ϯ 2 nm).
the π electron system between D and A also has a consider-
The decrease of the ICT upon increasing the number of able influence. The OPE chain is somewhat more prone to
repeat units (i.e., increasing the extension of the chromoph- overall hypsochromic effects than the related OPV chain.
ores) should also be documented in the dipole moments, µ. Table 4 provides a survey of the absorption behavior of
Table 3 contains the calculated values of µ of the ground OPEs and OPVs having donorϪacceptor substitution.
state, S0, and the first excited singlet state, S1, of 1dϪ4d;
The theory regarding the color of π systems having
∆µ ϭ µ(S1) Ϫ µ(S0) is reduced in this series from 15.8 to pushϪpull substitution, which is more than 80 years
9.3 D.
old,[18,19] has obtained a new facet. Apart from the donor
and acceptor strength, the extension of the π system (OPV,
OPE) can be a decisive feature for bathochromic, as well as
hypsochromic, effects.[20]
Conclusion
We prepared the donor-substituted oligomers DϪOPE
(1aϪ4a) and the three DϪOPEϪA series 1Ϫ4 (bϪd) Experimental Section
having 1Ϫ4 repeat units by applying the
n
ϭ
General Remarks: Melting points (uncorrected): Stuart Scientific
apparatus SMP/3. NMR: Bruker AMX 400, ARX 400, Avance
600, CDCl3 as solvent unless otherwise stated, TMS as internal
standard. MS: Varian MAT CH7A and Finnigan MAT 95.
UVϪVis: Zeiss MCS 320/340.
SonogashiraϪHagihara reaction and a protection/deprotec-
tion strategy. Solubilizing didodecylamino groups served as
electron donors (D) and cyano, formyl, and nitro groups
as electron acceptors (A). The pushϪpull systems are best
described by an MO model having partial dipole moments
at the chains’ ends. The polarization of the chain, which is
characterized by the polarization of the CϪC triple bonds,
decreases from both chain ends to the center. The long-
wavelength absorption (S0 Ǟ S1) shows a bathochromic
shift from n ϭ 1 to n ϭ 4 for 1aϪ4a, virtually no effect for
1bϪ4b (A ϭ CN), and hypsochromic shifts for 1cϪ4c (A ϭ
CHO) and 1dϪ4d (A ϭ NO2). The λmax. values of all four
series approach to the same limiting value, λϱ ϭ 387 Ϯ
Starting Compounds: N,N-Didodecyl-4-iodoaniline (5) was pre-
pared according to a literature procedure.[21] The yield could be
more than doubled by extracting the organic layer three times with
the equivalent amount of water instead of filtration of the residue.
5: Colorless oil, obtained in 79% yield. 1H NMR (CDCl3): δ ϭ
0.88 (t, 6 H, CH3), 1.25 (m, 36 H, CH2), 1.53 (m, 4 H, CH2), 3.20
(t, H, NCH2), 6.39 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.40
(MMЈ, 2 H, 3-H, 5-H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3),
22.7, 27.1, 27.2, 29.3, 29.5, 31.9 (CH2, partly superimposed), 51.0
(NCH2), 75.3 (C-4), 114.0 (C-2, C-6), 137.6 (C-3, C-5), 147.1
(C-1) ppm.
2 nm (n Ǟ ).
ϱ
A rationalization of these results is provided by semiem-
pirical quantum mechanics (AM1ϪINDO/S). Extending
Trimethylsilylethyne (6) is commercially available. 1-Iodo-4-tri-
methylsilylethynylbenzene (9) was prepared from 1,4-diodobenzene
and 6 according to literature procedures.[22,23]
Table 4. Bathochromic or hypsochromic effects on the long-wave-
length absorption of conjugated oligomers (OPVs and OPEs) upon
increasing the lengths of the chromophores (increasing the number
of repeat units, n)
N,N-Didodecyl-4-trimethylsilylethynylaniline (7): Compound
5
(16.5 g, 29.7 mmol) was dissolved under argon in oxygen-free pip-
eridine (150 mL) and then [Pd(PPh3)2Cl2] (0.52 g, 0.74 mmol), CuI
(0.28 g, 1.48 mmol), and PPh3 (0.39 g, 1.48 mmol) were added. Tri-
methylsilylethyne (4.72 mL, 3.28 g, 33.4 mmol) was then slowly ad-
ded dropwise to the orange solution. After stirring under argon
overnight, the volatile parts were removed under vacuum and the
residue was dissolved in CHCl3 (100 mL). The solution was washed
with saturated NH4Cl, NaHCO3, and NaCl solutions, dried
(Na2SO4), and concentrated. Column chromatography (SiO2, 4 ϫ
50 cm; petroleum (b.p. 40Ϫ70 °C)/toluene, 7:1) yielded a colorless
oil (15.5 g, 99%). UV (CHCl3): λmax. ϭ 311 nm, ε ϭ 30460
cm2·mmolϪ1. 1H NMR (CDCl3): δ ϭ 0.21 (s, 9 H, SiCH3), 0.87 (t,
6 H, CH3), 1.25 (m, 36 H, CH2), 1.54 (m, 4 H, CH2), 3.22 (t, 4 H,
NCH2), 6.48 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.27 (MMЈ,
2 H, 3-H, 5-H) ppm. 13C NMR (CDCl3): δ ϭ 0.3 (SiCH3), 14.1
(CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 31.9 (CH2, partly superim-
posed), 50.9 (NCH2), 90.7 (CϭCϪSi), 106.8 (CϭCϪSi), 108.6 (C-
4), 111.0 (C-2, C-6), 133.3 (C-3, C-5), 148.0 (C-1) ppm. FD MS:
m/z (%) ϭ 526 (100) [Mϩ]. C35H63NSi (526.0): calcd. C 79.92, H
12.07, N 2.66; found C 80.09, H 12.30, N 2.70.
N,N-Didodecyl-4-ethynylaniline (8):
A solution of 7 (4.0 g,
7.6 mmol) in CH2Cl2/CH3OH (1:1, 60 mL) was treated with K2CO3
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Eur. J. Org. Chem. 2004, 1033Ϫ1042

Oligo(1,4-phenyleneethynylene)s Having Terminal DonorϪAcceptor Substitutions
FULL PAPER
(1.16 g, 8.4 mmol). The mixture was stirred at room temperature crystals were obtained in 91% yield, m.p. 95 °C. UV/Vis (CHCl3):
1
until the reaction reached its end (TLC control: SiO2, toluene). The
solvent was evaporated and the residue was dissolved in CHCl3
λmax. ϭ 380 nm, ε ϭ 46034 cm2·mmolϪ1. H NMR (CDCl3): δ ϭ
0.87 (t, 6 H, CH3), 1.26 (m, 36 H, CH2), 1.56 (m, 4 H, CH2), 3.16
and extracted three times with an equivalent amount of water. The (s, 1 H, acetylenic H), 3.25 (t, 4 H, NCH2), 6.54 (AAЈ part of
organic layer was dried (Na2SO4), concentrated, and purified by
column chromatography (SiO2, 5 ϫ 15 cm; petroleum (b.p. 40Ϫ70
°C)/toluene, 7:1); an oily product was obtained (3.24 g, 94%). UV
AAЈMMЈ, 2 H, 2-H, 6-H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.44 (‘‘s’’,
4 H, aromat. H), 7.45 (‘‘s’’, 4 H, aromat. H) ppm. 13C NMR
(CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 31.9
(CH2, partly superimposed), 50.9 (NCH2), 78.9, 83.2, 86.9, 90.1,
(CHCl3): λmax. ϭ 299 nm, ε ϭ 23094 cm2·mmolϪ1 1H NMR
.
(CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.25 (m, 36 H, CH2), 1.54 (m, 4 91.4, 93.3 (CϵC), 108.2 (C-4), 111.1 (C-2, C-6), 121.5, 121.8, 123.7,
H, CH2), 2.94 (s, 1 H, acetylenic H), 3.22 (t, 4 H, NCH2), 6.50 124.6 (aromat. Cq), 131.1, 131.41, 131, 44 132.1 (aromat. CH),
(AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.30 (MMЈ, 2 H, 3-H, 5-
H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.3,
29.5, 31.9 (CH2, partly superimposed), 51.0 (NCH2), 74.4 (CϭCH),
85.1 (CϭCH), 107.4 (C-4), 111.1 (C-2, C-6), 133.4 (C-3, C-5), 148.2
(C-1) ppm. FD MS: m/z (%) ϭ 454 (100) [Mϩ]. C32H54N (453.8):
calcd. C 84.70, H 12.22, N 3.09; found C 84.73, H 12.47, N 3.12.
132.9 (C-3, C-5), 148.1 (C-1) ppm. FD MS: m/z (%) ϭ 654 (100)
[Mϩ]. C48H63N (654.0): calcd. C 88.51, H 9.71, N 2.14; found C
88.71, H 9.89, N 2.08.
N,N-Didodecyl-4-(4-{4-[4-(trimethylsilylethynyl)phenylethynyl]-
phenylethynyl}phenylethynyl)aniline (14): Compound 14 was pre-
pared by following the general procedure of the palladium-cata-
lyzed coupling reaction described for 7. Yellow crystals were ob-
tained in 59% yield, m.p. 153 °C. UV/Vis (CHCl3): λmax. ϭ 377 nm,
N,N-Didodecyl-4-[4-(trimethylsilylethynyl)phenylethynyl]aniline
(10): Prepared from 8 and 9 according to the procedure described
for 7. An oily product was obtained in 99% yield. UV/Vis (CHCl3):
ε ϭ 78273 cm2·mmolϪ1 1H NMR (CDCl3): δ ϭ 0.23 (s, 9 H,
.
1
λmax. ϭ 372 nm, ε ϭ 40641 cm2·mmolϪ1. H NMR (CDCl3): δ ϭ
SiCH3), 0.86 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.56 (m, 4 H,
CH2), 3.25 (t, 4 H, NCH2), 6.54 (AAЈ part of AAЈMMЈ, 2 H, 2-
H, 6-H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.43 (‘‘s’’, 4 H, aromat. H),
7.45 (‘‘s’’, 4 H, aromat. H), 7.48 (‘‘s’’, 4 H, aromat. H) ppm. 13C
NMR (CDCl3): δ ϭ Ϫ0.1 (SiCH3), 14.1 (CH3), 22.7, 27.1, 27.2,
29.4, 29.6, 29.7, 31.9 (CH2, partly superimposed), 50.9 (NCH2),
87.0, 90.4, 90.9, 91.0, 91.5, 93.3, 96.4, 104.6 (CϵC), 108.3 (C-4),
111.2 (C-2, C-6), 121.6, 122.8, 123.0, 123.1, 123.3, 124.6 (aromat.
Cq), 131.1, 131.4, 131.5, 131.6, 131.9 (aromat. CH, partly superim-
posed), 132.9 (C-3, C-5), 148.1 (C-1) ppm. FD MS: m/z (%) ϭ 826
(100) [Mϩ]. C59H75NSi (826.3): calcd. C 85.76, H 9.15, N 1.70;
found C 85.62, H 9.04, N 1.68.
0.25 (s, 9 H, SiCH3), 0.88 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.56
(m, 4 H, CH2), 3.26 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ,
2 H, 2-H, 6-H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.40 (‘‘s’’, 4 H, aromat.
H) ppm. 13C NMR (CDCl3): δ ϭ Ϫ0.03 (SiCH3), 14.1 (CH3), 22.7,
27.1, 29.4, 29.6, 29.7, 31.9 (CH2, partly superimposed), 50.9
(NCH2), 86.9, 93.2, 95.6, 105.0 (CϭC), 108.3 (C-4), 111.2 (C-2, C-
6), 121.7, 124.6 (aromat. Cq), 130.9, 131.8 (aromat. CH), 132.9 (C-
3, C-5), 148.1 (C-1) ppm. FD MS: m/z (%) ϭ 626 (100) [Mϩ].
C43H67NSi (626.1): calcd. C 82.49, H 10.79, N 2.24; found C 82.58,
H 10.85, N 2.28.
N,N-Didodecyl-4-[4-(ethynyl)phenylethynyl]aniline (11): Prepared
according to the procedure described for 7 Ǟ 8. Yellow crystals
N,N-Didodecyl-4-(4-{4-[4-(ethynyl)phenylethynyl]phenylethynyl}-
phenylethynyl)aniline (15): Prepared according to the procedure de-
scribed for 8. Yellow crystals were obtained in 67% yield, m.p. 172
were obtained in 91% yield, m.p. 50 °C. UV/Vis (CHCl3): λmax.
ϭ
367 nm, ε ϭ 28125 cm2·mmolϪ1. H NMR (CDCl3): δ ϭ 0.88 (t,
6 H, CH3), 1.24 (m, 36 H, CH2), 1.56 (m, 4 H, CH2), 3.13 (s, 1 H,
acetylenic H), 3.26 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, 2
H, 2-H, 6-H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.42 (‘‘s’’, 4 H, aromat.
H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 29.4, 29.6,
29.7, 31.9 (CH2, partly superimposed), 50.9 (NCH2), 78.3, 83.6,
86.7, 93.2 (CϵC), 108.2 (C-4), 111.1 (C-2, C-6), 120.6, 124.9 (aro-
mat. Cq), 130.9, 131.9 (aromat. CH), 132.9 (C-3, C-5), 148.1 (C-1)
ppm. FD MS: m/z (%) ϭ 554 (100) [Mϩ]. C40H59N (553.9): calcd.
C 86.74, H 10.74, N 2.53; found C 86.63, H 10.87, N 2.50.
1
1
°C. UV/Vis (CHCl3): λmax. ϭ 377 nm, ε ϭ 60879 cm2·mmolϪ1. H
NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.56
(m, 4 H, CH2), 3.16 (s, 1 H, acetylenic H), 3.25 (t, 4 H, NCH2),
6.54 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.34 (MMЈ, 2 H, 3-
H, 5-H), 7.45 (‘‘s’’, 4 H, aromat. H), 7.45 (‘‘s’’, 4 H, aromat. H),
7.48 (‘‘s’’, 4 H, aromat. H) ppm. 13C NMR (CDCl3): δ ϭ 14.1
(CH3), 22.7, 27.1, 27.2, 29.4, 29.6, 29.7, 31.9 (CH2, partly superim-
posed), 50.9 (NCH2), 79.0, 83.2, 87.0, 90.4, 90.7, 91.1, 91.5, 93.3
(CϵC), 108.3 (C-4), 111.2 (C-2, C-6), 121.6, 122.1, 122.8, 123.4,
123.5, 124.6 (aromat. Cq), 131.1, 131.4, 131.5, 131.6, 132.1 (aromat.
CH, partly superimposed), 133.0 (C-3, C-5), 148.1 (C-1) ppm. FD
MS: m/z (%) ϭ 754 (100) [Mϩ]. C56H67N (754.2): calcd. C 89.19,
H 8.95, N 1.86; found C 89.30, H 8.94, N 1.72.
N,N-Didodecyl-4-{4-[4-(trimethylsilylethynyl)phenylethynyl]-
phenylethynyl}aniline (12): Compound 12 was prepared by follow-
ing the general procedure of the palladium-catalyzed coupling reac-
tion described for 7. Yellow crystals were obtained in 85% yield,
m.p. 97 °C. UV/Vis (CHCl3): λmax. ϭ 381 nm, ε ϭ 48660
cm2·mmolϪ1. 1H NMR (CDCl3): δ ϭ 0.24 (s, 9 H, SiCH3), 0.86 (t,
6 H, CH3), 1.25 (m, 36 H, CH2), 1.55 (m, 4 H, CH2), 3.25 (t, 4 H,
NCH2), 6.54 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.34 (MMЈ,
2 H, 3-H, 5-H), 7.42 (‘‘s’’, 4 H, aromat. H), 7.44 (‘‘s’’, 4 H, aromat.
H) ppm. 13C NMR (CDCl3): δ ϭ Ϫ0.1 (SiCH3), 14.1 (CH3), 22.7,
27.1, 27.2, 29.4, 29.5, 29.6, 31.9 (CH2, partly superimposed), 50.9
(NCH2), 86.9, 90.4, 91.3, 93.3, 96.3, 104.6 (CϵC), 108.2 (C-4),
111.1 (C-2, C-6), 121.5, 122.9, 123.2, 124.5 (aromat. Cq), 131.1,
131.3, 131.4, 131.9 (aromat. CH), 132.9 (C-3, C-5), 148.1 (C-1)
ppm. FD MS: m/z (%) ϭ 726 (100) [Mϩ]. C51H71NSi (726.2): calcd.
C 84.35, H 9.85, N 1.93; found C 84.53, H 9.91, N 1.92.
N,N-Didodecyl-4-(phenylethynyl)aniline (la): Compound 1a was
prepared by the general procedure of the palladium-catalyzed
coupling reaction described for 7. The almost-colorless oil was ob-
tained in 95% yield. 1H NMR (CDCl3): δ ϭ 0.88 (t, 6 H, CH3),
1.26 (m, 36 H, CH2), 1.54 (m, 4 H, CH2), 3.25 (t, 4 H, NCH2),
6.55 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.28 (m, 3 H, aromat.
H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.48 (m, 2 H, aromat. H) ppm.
13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.4, 29.5,
29.6, 31.9 (CH2, partly superimposed), 50.9 (NCH2), 87.1, 90.9
(CϵC), 108.7 (C-4), 111.2 (C-2, C-6), 124.4, 127.3 (aromat. Cq),
128.2, 131.2 (aromat. CH), 132.9 (C-3, C-5), 147.9 (C-1) ppm. FD
MS: m/z (%) ϭ 530 (100) [Mϩ]. C38H59N (529.9): calcd. C 86.13,
H 11.22, N 2.64; found C 86.02, H 11.10, N 2.57.
N,N-Didodecyl-4-{4-[4-(ethynyl)phenylethynyl]phenylethynyl}aniline
(13): Prepared according to the procedure described for 8. Yellow
N,N-Didodecyl-4-[4-(phenylethynyl)phenylethynyl]aniline (2a): Com-
pound 2a was prepared by following the general procedure of the
Eur. J. Org. Chem. 2004, 1033Ϫ1042
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1039

H. Meier, B. Mühling, H. Kolshorn
FULL PAPER
palladium-catalyzed coupling reaction described for 7. Yellow crys-
tals were obtained in 84% yield, m.p. 134 °C. H NMR (CDCl3):
aromat. H), 7.52 (AAЈ part of AAЈMMЈ, 2 H, 3-H, 5-H), 7.61
(MMЈ, 2 H, 2-H, 6-H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3),
1
δ ϭ 0.86 (t, 6 H, CH3), 1.25 (m, 36 H, CH2), 1.54 (m, 4 H, CH2), 22.7, 27.1, 27.2, 29.4, 29.5, 29.7, 31.9 (CH2, partly superimposed),
3.25 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 50.9 (NCH2), 86.9, 89.0, 93.8, 93.8 (CϵC), 108.0, 111.4, 120.6,
7.32 (m, 3 H, aromat. CH), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.45 (‘‘s’’, 125.3, 128.2, 148.1 (aromat. Cq), 111.1, 131.1, 131.6, 132.0, 132.1,
4 H, aromat. H), 7.51 (m, 2 H, aromat. H) ppm. 13C NMR
133.1 (aromat. CH), 118.5 (CN) ppm. FD MS: m/z (%) ϭ 655 (100)
(CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 29.7, [Mϩ]. C47H62N2 (655.0): calcd. C 86.18, 9.54, 4.28; found C 86.27,
31.9 (CH2, partly superimposed), 50.9 (NCH2), 87.0, 89.4, 90.7,
93.1 (CϵC), 108.3 (C-4), 111.2 (C-2, C-6), 121.9, 123.2, 124.3,
128.3 (aromat. Cq), 128.3, 131.1, 131.4, 131.6, (aromat. CH), 132.9
(C-3, C-5), 148.1 (C-1) ppm. FD MS: m/z (%) ϭ 630 (100) [Mϩ].
C47H62N2 (630.0): calcd. C 87.70, H 10.08, 2.22; found C 87.56, H
9.97, N 2.15.
H 9.57, N 4.25.
4-(4-{4-[4-(Didodecylamino)phenylethynyl]phenylethynyl}phenyl-
ethynyl)benzonitrile (3b): Compound 3b was prepared by following
the general procedure of the palladium-catalyzed coupling reaction
described for 7. Yellow crystals were obtained in 84% yield, m.p.
1
208 °C. H NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H,
N,N-Didodecyl-4-{4-[4-(phenylethynyl)phenylethynyl]phenyl-
ethynyl}aniline (3a): Compound 3a was prepared by following the
general procedure of the palladium-catalyzed coupling reaction de-
scribed for 7. Yellow crystals were obtained in 74% yield, m.p. 208
CH2), 1.56 (m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.54 (AAЈ part of
AAЈMMЈ, 2 H, aromat. H), 7.34 (MMЈ, 2 H, aromat. H), 7.45
(‘‘s’’, 4 H, aromat. H), 7.50 (‘‘s’’, 4 H, aromat. H), 7.60 (AAЈ part
of AAЈ BBЈ, 2 H, 3-H, 5-H), 7.70 (BBЈ, 2 H, 2-H, 6-H) ppm. 13C
°C. 1H NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.25 (m, 36 H, NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.4, 29.6, 29.7,
CH2), 1.53 (m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.55 (AAЈ part of 31.9 (CH2, partly superimposed), 50.9 (NCH2), 86.9, 89.5, 90.2,
AAЈMMЈ, 2 H, 2-H, 6-H), 7.32 (m, 3 H, aromat. H), 7.34 (MMЈ,
91.9, 93.4, 93.4 (CϵC), 108.2, 111.7, 121.4, 121.9, 124.1, 124.7,
2 H, 3-H, 5-H), 7.45 (‘‘s’’, 4 H, aromat. H), 7.48(‘‘s’’, 4 H, aromat. 128.0, 148.1 (aromat. Cq), 111.2, 131.1, 131.5, 131.6, 131.7, 132.1,
H), 7.51 (m, 2 H, aromat. H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 132.1, 132.9 (aromat. CH), 118.5 (CN) ppm. FD MS: m/z (%) ϭ
(CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 29.6, 31.9 (CH2, partly
755 (100) [Mϩ]. C55H66N2 (755.1): calcd. C 87.48, H 8.81, N 3.71;
superimposed), 50.9 (NCH2), 87.0, 89.1, 90.5, 91.3, 91.3, 93.3 found C 87.49, H 9.11, N 3.69.
(CϵC), 108.3 (C-4), 111.2 (C-2, C-6), 121.6, 123.0, 123.1, 124.5,
4-[4-(4-{4-[4-(Didodecylamino)phenylethynyl]phenylethynyl}phenyl-
128.4, (aromat. Cq), 128.4, 131.1, 131.4, 131.5, 131.5, 131.6, (aro-
mat. CH), 132.9 (C-3, C-5), 148.1 (C-1) ppm. FD MS: m/z (%) ϭ
730 (100) [Mϩ]. C54H67N (730.13): calcd. C 88.83, H 9.25, N 1.92;
found C 88.98, H 9.15, N 1.89.
ethynyl)phenylethynyl]benzonitrile (4b): Compound 4b was prepared
by following the general procedure of the palladium-catalyzed
coupling reaction described for 7. Yellow crystals were obtained in
1
53% yield, m.p. Ͼ 250 °C. H NMR (C2D2Cl4, 333 K): δ ϭ 0.85
N,N-Didodecyl-4-(4-{4-[4-(phenylethynyl)phenylethynyl]phenyl-
ethynyl}phenylethynyl)aniline (4a): Compound 4a was prepared by
following the general procedure of the palladium-catalyzed coup-
(t, 6 H, CH3), 1.26 (m, 36 H, CH2), 1.55 (m, 4 H, CH2), 3.24 (t, 4
H, NCH2), 6.54 (AAЈ part of AAЈMMЈ, 2 H, aromat. H), 7.31
(MMЈ, 2 H, aromat. H), 7.42 (‘‘s’’, 4 H, aromat. H), 7.48 (‘‘s’’, 4
H, aromat. H), 7.50 (‘‘s’’, 4 H, aromat. H), 7.58 (AAЈBBЈ, 4 H, 2-
ling reaction described for 7. Yellow crystals were obtained in 59%
1
yield, m.p. Ͼ 250 °C. H NMR (C2Cl4D2, 400 MHz, 333 K): δ ϭ H, 3-H, 5-H, 6-H) ppm. The 13C NMR spectrum could not be
0.84 (t, 6 H, CH3), 1.26 (m, 36 H, CH2), 1.56 (m, 4 H, CH2), 3.23
(t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.30
obtained because of poor solubility. FD MS: m/z (%) ϭ 855 (100)
[Mϩ]. C63H70N2 (855.3): calcd. C 88.47, H 8.25, N 3.28; found C
(m, 3 H, aromat. H), 7.35 (MMЈ, 2 H, 3-H, 5-H), 7.44 (‘‘s’’, 4 H, 88.28, H 8.97, N 2.90.
aromat. H), 7.48 (‘‘s’’, 4 H, aromat. H), 7.50 (‘‘s’’, 4 H, aromat.
4-[4-(Didodecylamino)phenylethynyl]benzaldehyde (1c): Compound
H), 7.52 (m, 2 H, aromat. H) ppm. FD MS: m/z (%) ϭ 830 (100)
[Mϩ]. C63H70N2 (830.3): calcd. C 89.69, H 8.62, N 1.69; found C
89.78, H 8.47, N 1.55.
1c was prepared by following the general procedure of the pal-
ladium-catalyzed coupling reaction described for 7. Yellow crystals
were obtained in 82% yield, m.p. 41 °C. 1H NMR (CDCl3): δ ϭ
0.86 (t, 6 H, CH3), 1.25 (m, 36 H, CH2), 1.53 (m, 4 H, CH2), 3.26
(t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, 2 H, aromat. H), 7.36
(MMЈ, 2 H, aromat. H), 7.58 (AAЈ part of AAЈMMЈ, 2 H, 3-H, 5-
H), 7.81 (MMЈ, 2 H, 2-H, 6-H), 9.97 (s, 1 H, CHO) ppm. 13C
4-[4-(Didodecylamino)phenylethynyl]benzonitrile (1b): Compound
1b was prepared by following the general procedure of the pal-
ladium-catalyzed coupling reaction described for 7. The almost-
colorless oily product was obtained in 98% yield. 1H NMR
(CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.55 (m, 4 NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6,
H, CH2), 3.26 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, 2 H, 29.7, 31.9 (CH2, partly superimposed), 50.9 (NCH2), 86.9, 95.9
aromat. H), 7.34 (MMЈ, 2 H, aromat. H), 7.52/7.55 (AAЈBBЈ, 4 H, (CϵC), 107.6, 130.9, 134.5, 148.4 (aromat. Cq), 111.1, 129.5, 131.5,
2-H, 3-H, 5-H, 6-H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3),
133.2 (aromat. CH), 191.5 (CHO) ppm. FD MS: m/z (%) ϭ 558
22.7, 27.1, 27.2, 29.4, 29.5, 29.6, 31.9 (CH2, partly superimposed), (100) [Mϩ]. C39H59NO (557.90): calcd. C 83.96, H 10.66, N 2.51;
50.9 (NCH2), 86.2, 96.2 (CϵC), 107.4, 110.2, 129.5, 148.5 (aromat. found C 83.76, H 10.81, N 2.41.
Cq), 111.2, 131.5, 131.9, 133.2 (aromat. CH), 118.9 (CN) ppm. FD
4-{4-[4-(Didodecylamino)phenylethynyl]phenylethynyl}benzaldehyde
(2c): Compound 2c was prepared by following the general pro-
cedure of the palladium-catalyzed coupling reaction described for
7. Yellow crystals were obtained in 73% yield, m.p. 134 °C. 1H
NMR (CDCl3): δ ϭ 0.87 (t, 6 H, CH3), 1.27 (m, 36 H, CH2), 1.53
(m, 4 H, CH2), 3.26 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ,
MS: m/z (%) ϭ 555 (100) [Mϩ]. C39H58N2 (554.5): calcd. C 84.48,
H 10.54, N 5.05; found C 84.28, H 10.23, N 5.01.
4-{4-[4-(Didodecylamino)phenylethynyI]phenylethynyl}benzonitrile
(2b): Compound 2b was prepared by following the general pro-
cedure of the palladium-catalyzed coupling reaction described for
7. Yellow crystals were obtained in 85% yield, m.p. 134 °C. 1H 2 H, aromat. H), 7.34 (MMЈ, 2 H, aromat. H), 7.47 (‘‘s’’, 4 H,
NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.56 aromat. H), 7.65 (AAЈ part of AAЈMMЈ, 2 H, 3-H, 5-H), 7.85
(m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ, (MMЈ, 2 H, 2-H, 6-H), 10.00 (s, 1 H, CHO) ppm. 13C NMR
2 H, aromat. H), 7.34 (MMЈ, 2 H, aromat. H), 7.46 (‘‘s’’, 4 H,
(CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 31.9
1040
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Oligo(1,4-phenyleneethynylene)s Having Terminal DonorϪAcceptor Substitutions
(CH2, partly superimposed), 50.9 (NCH2), 86.9, 89.8, 93.5, 93.7 120.6, 125.5, 130.2, 146.9 (aromat. Cq), 123.6, 131.2, 131.7, 132.2
FULL PAPER
(CϵC), 108.1, 120.9, 125.1, 129.5, 135.4, 148.1 (aromat. Cq), 111.1, (aromat. CH), 133.0 (C-3, C-5), 148.2 (C-1) ppm. FD MS: m/z
129.6, 131.1, 131.6, 132.1, 132.9 (aromat. CH), 191.4 (CHO) ppm. (%) ϭ 675 (100) [Mϩ]. C46H62N2O2 (675.0): calcd. C 81.85, H 9.26,
FD MS: m/z (%) ϭ 658 (100) [Mϩ]. C47H63NO (658.0): calcd. C N 4.15; found C 81.80, H 9.53, N 4.12.
85.79, 9.65, 2.13; found C 85.68, H 9.63, N 2.04.
N,N-Didodecyl-4-{4-[4-(4-nitrophenylethynyl)phenylethynyl]phenyl-
ethynyl}aniline (3d): Compound 3d was prepared by following the
general procedure of the palladium-catalyzed coupling reaction de-
scribed for 7. Orange crystals were obtained in 93% yield, m.p. 226
°C. 1H NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H,
CH2), 1.56 (m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.54 (AAЈ part of
AAЈMMЈ, 2 H, 2-H, 6-H), 7.33 (MMЈ, 2 H, 3-H, 5-H), 7.45 (‘‘s’’,
4 H, aromat. H), 7.52 (‘‘s’’, 4 H, aromat. H), 7.65 (AAЈ part of
4-(4-{4-[4-(Didodecylamino)phenylethynyl]phenylethynyl}phenyl-
ethynyl)benzaldehyde (3c): Compound 3c was prepared by follow-
ing the general procedure of the palladium-catalyzed coupling reac-
tion described for 7. Yellow crystals were obtained in 59% yield,
1
m.p. 208 °C. H NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.27 (m,
36 H, CH2), 1.53 (m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.55 (AAЈ
part of AAЈMMЈ, 2 H, aromat. H), 7.34 (MMЈ, 2 H, aromat. H),
7.45 (‘‘s’’, 4 H, aromat. H), 7.51 (‘‘s’’, 4 H, aromat. H), 7.66 (AAЈ
part of AAЈMMЈ, 2 H, 3-H, 5-H), 7.86 (MMЈ, 2 H, 2-H, 6-H),
10.00 (s, 1 H, CHO) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3),
22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 29.7, 31.9 (CH2, partly superim-
posed), 50.9 (NCH2), 86.9, 90.3, 91.8, 93.1, 93.4, 93.4 (CϵC),
108.2, 121.4, 122.2, 123.8, 124.7, 129.3, 135.5, 148.1 (aromat. Cq),
111.1, 129.6, 131.1, 131.4, 131.6, 131.7, 132.1, 132.9 (aromat. CH),
191.3 (CHO) ppm. FD MS: m/z (%) ϭ 758 (100) [Mϩ]. C55H67NO
(758.1): calcd. C 87.13, H 8.91, N 1.85; found C 86.97, H 8.79,
N 1.79.
AAЈMMЈ, 2 H, aromat. H), 8.21 (MMЈ, 2 H, aromat. H) ppm. 13
C
NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7, 27.1, 27.2, 29.4, 29.6, 29.7,
31.9 (CH2, partly superimposed), 50.9 (NCH2), 86.9, 89.3, 90.2,
92.0, 93.4, 94.3 (CϵC), 108.2 (C-4), 111.2 (C-2, C-6), 121.4, 121.8,
124.2, 124.8, 130.0, 147.1 (aromat. Cq), 123.7, 131.1, 131.5, 131.6,
131.8, 132.3 (aromat. CH), 132.9 (C-3, C-5), 148.1 (C-1) ppm. FD
MS: m/z (%) ϭ 775 (100) [Mϩ]. C54H66N2O2 (775.1): calcd. C
83.68, H 8.58, N 3.61; found C 83.69, H 8.54, N 3.45.
N,N-Didodecyl-4-(4-{4-[4-(4-nitrophenylethynyl)phenylethynyl]-
phenylethynyl}phenylethynyl)aniline (4d): Compound 4d was pre-
pared by following the general procedure of the palladium-cata-
lyzed coupling reaction described for 7. Yellow crystals were ob-
4-[4-(4-{4-[4-(Didodecylamino)phenylethynyl]phenylethynyl}phenyl-
ethynyl)phenylethynyl]benzaldehyde (4c): Compound 4c was pre-
pared by following the general procedure of the palladium-cata-
lyzed coupling reaction described for 7. Yellow crystals were ob-
1
tained in 59% yield, m.p. Ͼ 250 °C. H NMR (C2Cl4D2, 333 K):
δ ϭ 0.84 (t, 6 H, CH3), 1.26 (m, 36 H, CH2), 1.55 (m, 4 H, CH2),
3.23 (t, 4 H, NCH2), 6.53 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H),
7.30 (MMЈ, 2 H, 3-H, 5-H), 7.42 (‘‘s’’, 4 H, aromat. H), 7.48 (‘‘s’’,
4 H, aromat. H), 7.50 (‘‘s’’, 4 H, aromat. H), 7.63 (AAЈ part of
AAЈMMЈ, 2 H, aromat. H), 8.15 (MMЈ, 2 H, aromat. H) ppm.
The 13C NMR spectrum could not be obtained because of poor
solubility. FD MS: m/z (%) ϭ 875 (100) [Mϩ]. C62H70N2O2 (875.3):
After careful drying under vacuum, the compound still contained
some water; therefore, we could not obtain a correct elemental
analysis.
1
tained in 39% yield, m.p. Ͼ 250 °C. H NMR (C2D2Cl4, 333 K):
δ ϭ 0.84 (t, 6 H, CH3), 1.26 (m, 36 H, CH2), 1.56 (m, 4 H, CH2),
3.24 (t, 4 H, NCH2), 6.53 (AAЈ part of AAЈMMЈ, 2 H, aromat.
H), 7.34 (MMЈ, 2 H, aromat. H), 7.41 (‘‘s’’, 4 H, aromat. H), 7.47
(‘‘s’’, 4 H, aromat. H), 7.52 (‘‘s’’, 4 H, aromat. H), 7.67 (AAЈ part
of AAЈMMЈ, 2 H, C-3, C-5), 7.85 (MMЈ, 2 H, C-2, C-6), 10.00 (s,
1 H, CHO) ppm. The 13C NMR spectrum could not be obtained
because of poor solubility. FD MS: m/z (%) ϭ 858 (100) [Mϩ].
C63H71NO (858.3): calcd. C 88.17, H 8.34, N 1.63; found C 87.97,
H 8.20, N 1.51.
N,N-Didodecyl-4-(4-nitrophenylethynyl)aniline (1d): Compound 1d
was prepared by following the general procedure of the palladium-
catalyzed coupling reaction described for 7. Red crystals were ob-
Acknowledgments
We are grateful to the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and the Center of Materials Sci-
ence of the University of Mainz for financial support.
1
tained in 90% yield, m.p. 41 °C. H NMR (CDCl3): δ ϭ 0.86 (t, 6
H, CH3), 1.25 (m, 36 H, CH2), 1.56 (m, 4 H, CH2), 3.26 (t, 4 H,
NCH2), 6.56 (AAЈ part of AAЈMMЈ, 2 H, 2-H, 6-H), 7.36 (MMЈ,
2 H, 3-H, 5-H), 7.56 (AAЈ part of AAЈMMЈ, 2 H, aromat. H), 8.15
(MMЈ, 2 H, aromat. H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3),
22.7, 27.1, 27.2, 29.3, 29.5, 29.6, 29.7, 31.9 (CH2, partly superim-
posed), 50.9 (NCH2), 86.3, 97.6 (CϵC), 107.2 (C-4), 111.2 (C-2, C-
6), 123.6, 133.4 (aromat. CH), 131.5 (C-3, C-5), 131.6, 146.1 (aro-
mat. Cq), 148.7 (C-1) ppm. FD MS: m/z (%) ϭ 575 (100) [Mϩ].
C38H58N2O2 (574.9): calcd. C 79.39, H 10.17, N 4.87; found C
79.06, H 10.34, N 4.83.
[1]
[1a]
Selected review articles and books on this topic:
H.-H.
Hörhold, M. Helbig, D. Raabe, J. Opfermann, U. Scherf, R.
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R. Silbey, Conjugated Polymers, Kluwer, Dordrecht, 1991. [1c]H.
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[1h]
[1i]
N,N-Didodecyl-4-[4-(4-nitrophenylethynyl)phenylethynyl]aniline
(2d): Compound 2d was prepared by following the general pro-
cedure of the palladium-catalyzed coupling reaction described for
7. Orange crystals were obtained in 93% yield, m.p. 111 °C. 1H
NMR (CDCl3): δ ϭ 0.86 (t, 6 H, CH3), 1.24 (m, 36 H, CH2), 1.56
(m, 4 H, CH2), 3.25 (t, 4 H, NCH2), 6.55 (AAЈ part of AAЈMMЈ,
2 H, 2-H, 6-H), 7.34 (MMЈ, 2 H, 3-H, 5-H), 7.47 (‘‘s’’, 4 H, aromat.
H), 7.64 (AAЈ part of AAЈMMЈ, 2 H, aromat. H), 8.21 (MMЈ, 2
H, aromat. H) ppm. 13C NMR (CDCl3): δ ϭ 14.1 (CH3), 22.7,
27.1, 27.2, 29.4, 29.6, 29.7, 31.9 (CH2, partly superimposed), 50.9
(NCH2), 86.9, 88.8, 94.0, 94.8 (CϵC), 108.1 (C-4), 111.2 (C-2, C-6),
631.
J. S. Moore, Acc. Chem. Res. 1997, 30, 402.
A.
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P. F. H. Schwab, M. D. Levin, J. Michl, Chem. Rev. 1999,
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99, 1863.
R. E. Martin, F. Diederich, Angew. Chem. 1999,
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J. L. Seg-
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[1p]
ucting Polymers (Eds.: G. Hadziioannou, P. F. van Hutten),
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Eur. J. Org. Chem. 2004, 1033Ϫ1042
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1041

H. Meier, B. Mühling, H. Kolshorn
FULL PAPER
[1r]
2000, 100, 1605.
J. Roncali, Acc. Chem. Res. 2000, 33, 147.
438 Ϯ 1 nm, respectively. Accordingly, a bathochromic shift is
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V. Francke, T. Mangel, K. Müllen, Macromolecules 1998, 31,
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J. M. Tour, Acc. Chem. Res. 2000, 33, 791.
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H. Meier, U. Stalmach, H. Kolshorn, Acta Polym. 1997, 48,
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H. Meier, J. Gerold, H. Kolshorn, W. Baumann, M. Bletz, An-
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H. Meier, R. Petermann, J. Gerold, Chem. Commun. 1999, 977.
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The calculations (AM1, INDO/S) were performed using di-
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H.-H. Perkampus, UV/Vis-Spektroskopie und ihre Anwen-
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See, for example: V. Alain, L. Thouin, M. Blanchard-Desce, U.
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See, for example:
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[18b]
Wiley-VCH, Weinheim, 1991.
J. Fabian, H. Hartmann,
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W. König, J. Prakt. Chem. 1925, 112, 1, and references cited
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Compare also the effect that extending the length of the conju-
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R. P. Tykwinski, M. Schreiber, R. P. Carlon, F. Diederich, Helv.
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[9]
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[12]
[21]
One can regard, for example, the ethynyl group in the series 8,
11, 13, and 15 (n ϭ 1, 2, 3, and 4) as a weak acceptor. The
λmax. values of these compounds in CHCl3 are 299 Ϯ 1, 367 Ϯ
1, 380 Ϯ 1, and 377 Ϯ 8 nm, respectively; the absorption edges
with ε ϭ εmax./10 are at λ0.1 ϭ 338 Ϯ 1, 399 Ϯ 1, 425 Ϯ 1, and
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Y. Yao, J. M. Tour, J. Org. Chem. 1999, 64, 1971.
R. P. Hsung, C. F. D. Chidsey, L. R. Sita, Organometallics
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Received October 24, 2003
1042
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Eur. J. Org. Chem. 2004, 1033Ϫ1042