Hexasubstituted Donor-Acceptor Benzenes as Nonlinear Optically Active Molecules with Multiple Charge-Transfer Transitions

Article abstract of DOI:10.1002/chem.200305458

The synthesis of three novel nonlinear optical (NLO) chromophores with threefold symmetry, namely 1,3,5-tris(4-N,N-diethylaminophenyl)-2,4,6-tris(4-nitrophenyl)benzene (3), 1,3,5-tris(L-N,N-dihexylaminophenylbutadiynyl)-2,4,6-tris(4-nitrophenyl)benzene (1

Full text of DOI:10.1002/chem.200305458

FULL PAPER
Hexasubstituted Donor Acceptor Benzenes as Nonlinear Optically Active
Molecules with Multiple Charge-Transfer Transitions
Boris Traber,[a] J. Jens Wolff,*[a, b] Frank Rominger,[a] Thomas Oeser,[a] Rolf Gleiter,*[a]
Mark Goebel,[c] and R¸diger Wortmann*[c]
Abstract: The synthesis of three novel
nonlinear optical (NLO) chromophores
with threefold symmetry, namely 1,3,5-
tris(4-N,N-diethylaminophenyl)-2,4,6-
tris(4-nitrophenyl)benzene (3), 1,3,5-
tris(4-N,N-dihexylaminophenylbuta-
diynyl)-2,4,6-tris(4-nitrophenyl)benzene
(13) and 1,3,5-tris(4-N,N-dihexylamino-
phenylethynyl)-2,4,6-tris(4-nitrophenyl-
ethynyl)benzene (4b), is reported. We
used the [Co2(CO)8]-catalysed trimeri-
sation of 4-N,N-diethylamino-4’-nitro-
tolane (5) to prepare 3. The trimerisa-
tion experiment carried out with 1-(4-
N,N-diethylaminophenyl)-6-(4-N,N-ni-
trophenyl)hexatriyne (6) and [Rh-
(PPh3)3Cl] afforded 13. A stepwise ap-
proach was used to prepare 4b. 1,3,5-
Trichloro-2,4,6-triiodobenzene (8b) was
coupled with 4-nitrophenyl-acetylene
(14) under Pd0 catalysis to yield 1,3,5-
trichloro-2,4,6-tris(4-nitrophenylethynyl)-
benzene (15). The coupling reaction of
15 with 4-N,N-dihexylaminophenyl-
ethynyltributylstannane (21) led to 4b.
X-ray investigations on 3, 4b and 13
confirmed the structural assignments
and revealed that the peripheral aryl
rings in 4b are less twisted around the
connecting bonds than in 3 and 13. A
large second-order polarisability (b) of
4b relative to 3 and 13 was determined
by hyper-Rayleigh scattering (HRS).
Compound 4b represents an NLO
chromophore with second-order polari-
sabily among the highest obtained so
far for two-dimensional nondipolar
NLO chromophores.
Keywords: alkynes
¥
cross-
coupling ¥ cyclotrimerization ¥ non-
linear optics ¥ UV/Vis spectroscopy
Introduction
addition of the contributions of the individual molecules, for
example their second- or third-order polarisabilities.[6] Most
molecules with high second-order polarisability (b) were de-
vised according to a similar design principle, that is an ex-
tended, linear p system with a high molecular dipole such as
substituted stilbenes with a donor and an acceptor in 4,4’-
positions. Chromophores of this type usually exhibit one in-
tense low-lying charge-transfer (CT) transition whose inten-
sity and dipole difference determine the NLO response
within a two-level model.[8]
The advantages of organic versus inorganic materials for
nonlinear optical (NLO) applications include technical as-
pects like their relative ease of synthesis and integration
into polymeric structures but also large optical nonlinearities
and fast response.[1 To a first approximation, the bulk
7]
NLO properties of organic materials result from a tensorial
While great progress has been made in the optimisation
of such one-dimensional (1D) NLO chromophores, it has
become apparent that some problems in nonlinear optics
cannot be effectively addressed by this approach. One is the
efficiency transparency trade-off which is of crucial impor-
tance for second-harmonic generation (SHG). The efficiency
of the energy conversion must be high, but the reabsorption
of the converted light low. However, the desirable increase
in second-order polarisabilities in more extended p systems
is usually accompanied by a bathochromic shift of the CT
transition.[6] Furthermore, the strong dispersion of the re-
fractive index makes it difficult to achieve noncritical phase
matching between fundamental and frequency-doubled
waves in a bulk material or crystal. Alternative design strat-
egies at the molecular level are therefore desirable.
[a] Dr. B. Traber, Priv.-Doz. Dr. J. J. Wolff, Dr. F. Rominger,
Dr. T. Oeser, Prof. Dr. R. Gleiter
Organisch-Chemisches Institut der Ruprecht-Karls-Universit‰t
Heidelberg
Im Neuenheimer Feld 270
69120 Heidelberg (Germany)
Fax : (+49)6221-54-4205
E-mail: rolf.gleiter@urz.uni-heidelberg.de
[b] Priv.-Doz. Dr. J. J. Wolff
Deceased
[c] Dipl. Chem. M. Goebel, Prof. Dr. R. Wortmann
Physikalische Chemie der Universit‰t Kaiserslautern
Erwin-Schrˆdinger-Strasse
67663 Kaiserslautern (Germany)
Fax : (+49)631-205-2750
E-mail: ruediger.wortmann@chemie.uni-kl.de
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FULL PAPER
One approach exploits p systems with several donor and
vates of hexaphenylbenzene 3, hexaphenylethynylbenzene 4
and the congener 13, all three of which have approximately
D3 symmetry. Hexaphenylbenzenes have also gained consid-
erable interest in material science owing to their remarkable
electron transfer properties[31,32] and their ability to form
19]
acceptor groups.[9
The multiple substitution leads to a
two-dimensional (2D) character of the tensor b in which off-
diagonal elements become significant. In particular nondipo-
lar compounds with threefold symmetry (C3h, D3h) have
been investigated for which the significant tensor elements
are given by bzzz =ꢀbzyy =ꢀbyzy =ꢀbyyz. A number of re-
views on such 2D NLO chromophores[6,20,21] including work
on organometallic compounds[22,23] have been published.
The second-order polarisabilities of highly symmetric 2D
chromophores are usually investigated by hyper-Rayleigh
35]
liquid crystalline mesophases.[33 To the best of our knowl-
edge no functionalised hexaphenylethynylbenzenes have
been reported to date. Herein we report the synthesis of the
novel 2D NLO chromophores 3, 4 and 13, their molecular
structures and NLO properties.
26]
scattering (HRS).[24 In contrast to the coherent frequency
Synthesis: Retrosynthetic considerations: Modern synthetic
techniques provide several pathways to achieve our goal.
Although low yields are often encountered in cyclotrimeri-
sation processes, this protocol is the method of choice be-
doubling in the direction of the laser beam used in electric-
field-induced second-harmonic generation (EFISHG),[27,28]
frequency doubling in the HRS experiment is incoherent
and occurs in all directions of space. Far fewer investigations
have been carried out on C2v-symmetric dipolar 2D NLO
chromophores with multiple donor acceptor substitu-
tion.[6,21] A complete characterisation of chromophores of
this symmetry requires a consistent combination of both po-
larised HRS and EFISHG measurements, sometimes sup-
ported by a third technique like electrooptical absorption
measurements (EOAM).[8,29] Some of these chromophores
exhibit deviations from Kleinman symmetry.[8]
In this work we focused on the optimisation of 2D NLO
chromophores with D3 or D3h symmetry, which have been
shown to provide large b values at an improved efficiency/
transparency ratio. A systematic study of 2D versus 1D
NLO chromophores based on a central S-triazine or 1,3,5-
tricyanobenzene moiety has demonstrated that these sys-
tems may exhibit nonlinear optical properties which com-
pare very well with the best dipolar systems.[30] The systems
1,3,5-tris(diisopropylamino)-2,4,6-trinitrobenzene (1) and
1,3,5-trihydroxy-2,4,6-trinitrobenzene (2) yielded values for
the second-order polarisability (b) comparable to that of p-
nitroaniline, the prototype of a dipolar aromatic system.[11]
In continuation of this work we extended the central p
system by synthesising the donor acceptor-substituted deri-
cause it gives easy access to these highly substituted ben-
38]
zenes.[36
Although this type of reaction is well known,[39]
cyclotrimerisation is still the object of current studies.[40
The most simple example is the cobalt-catalysed trimerisa-
tion of alkynes.[43] In our case, this means the trimerisations
of 5 (Scheme 1) and 6 (Scheme 2).
42]
In both cases we face the problem of obtaining regioisom-
ers; however, given the simplicity of the reaction and the
availability of the starting materials it was tempting to try
these approaches first.
For the synthesis of 4 we also considered a multistep ap-
proach using modern coupling procedures. Thus, starting
from 1,3,5-trihalogeno-2,4,6-triiodobenzene (8a 8c), the
tris- and hexaphenylethynyl-substituted product seemed to
attainable. We planed to perform the step from 8 to 7 with a
Sonogashira-type coupling. For the replacement of the
chlorine substituents a Stille-type coupling seemed necessa-
ry.[44]
Synthesis of 3 and 4: Heating 4-N,N-diethylamino-4’-nitroto-
lane (5) in dioxane with dicobaltoctacarbonyl at 80 1008C
for 24 h afforded 3 in 9% yield together with 9 (Scheme 3).
Both isomers could be separated by chromatography on
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Nonlinear Optical Benzenes
1227 1238
Scheme 1. Retrosynthetic analysis of compound 3.
Scheme 2. Retrosynthetic analysis of 4.
Scheme 3. a) [Co2(CO)8], dioxane, 1008C.
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J. J. Wolff, R, Gleiter, R. Wortmann et al.
FULL PAPER
silica gel. The tolerance of the catalyst toward the nitro
group is surprising.[45]
nitrophenylacetylene (14). However, the Sonogashira proto-
69]
col[64
was only successful with 8b as starting material to
As a result of the strong twisting of the phenyl rings in 3
give 1,3,5-trichloro-2,4,6-tris(4-nitrophenylethynyl)benzene
(15) in 50% yield (Scheme 5). In the cases of 8a and 8c,
only reduction products were obtained in which an iodine
centre was substituted by a hydrogen atom. Attempts to
couple the donor unit first failed.
Purification of 15 was difficult as a result of its low solu-
bility in common solvents. It was also not possible to ach-
ieve complete conversion in the Stille coupling of 11 to the
threefold substituted 4a with diethyl amino group as donor.
In this experiment the main reaction was a twofold substitu-
tion. The resulting product was also difficult to purify as a
result of its low solubility in common solvents. Therefore,
we decided to carry out the originally planned Stille cou-
pling (see above) with 4-N,N-dihexylaminophenylethynyl-
tributylstannane (21) (Scheme 6).
The synthesis of 21 was achieved in a four-step procedure
by using conventional means. The readily available 4-iodo-
N,N-dihexylaniline (18) was transformed into 19 by a Sono-
gashira coupling reaction with trimethylsilylacetylene. After
removal of the protecting group the alkyne 20 was stanny-
lated to afford 21 in an overall yield of 54% starting from 4-
iodoaniline (16) and n-hexyliodide (17).
(see below) we also tried to synthesize the hexa-peri-benzo-
48]
coronene with methods described in the literature;[46
un-
fortunately, this attempt failed. We therefore focused on the
synthesis of 4. Encouraged by the success of the transition-
metal-induced trimerisation of 5 we first tried this pathway.
The synthesis of the starting material, 1-(4-N,N-diethylami-
nophenyl)-6-(4-nitrophenyl)hexatriyne (6), was achieved by
a Hay cross-coupling reaction[49] of (4’-nitrophenyl)buta-
diyne (10) with 4-(N,N-diethylaminophenyl)acetylene (11)
in 30% yield (Scheme 4).
52]
Initial attempts to cyclotrimerise 6 with catalysts[50 such
as [Pd(PhCN)2Cl2],[53] Me3SiCl and Pd/C,[54] [Cp2ZrCl2][55,56]
and [Co2(CO)8],[57] failed without any reaction. Ligands with
high steric hindrance (1,1’-bis(diphenylphosphino)ferrocene
nickel(ii) chloride, dichloro-bis(tri-n-butylphosphine)nickel-
(ii)) were also tried without the desired result. Trimerisation
[58 60]
of 6 occurs with Ni(PPh3)2(CO)2
as catalyst; however,
only 1,2,4-tris(4-N,N-diethylaminophenylethynyl)-3,5,6-tris-
(4-nitrophenylethynyl)benzene (12) was detected
(Scheme 4), and besides a couple of further trimerisation
products, the desired 1,3,5 isomer was not found. Surprising-
ly, heating 6 with Wilkinson×s catalyst [Rh(PPh3)3Cl][61] in di-
oxane afforded small amounts of 13 (Scheme 4). This reac-
tion also occurred with [Co(PPh3)3Cl][62] as catalyst, but the
conversion was worse. It is noteworthy that the cyclotrimeri-
sation takes place mainly with the alkyne unit at the nitro-
phenyl ring.
The final Stille coupling reaction between 15 and 21 af-
forded 4b as
a red-coloured product in 14% yield
(Scheme 7). The product could easily be purified by chroma-
tography owing to the presence of the hexyl groups. Inter-
estingly, the reaction occurred only above 908C.
After this failure we examined a stepwise approach as in-
dicated in Scheme 2 by using Pd-catalysed coupling reac-
tions. 1,3,5-Trichloro-2,4,6-triiodobenzene[63] (8b), 1,3,5-tri-
bromo-2,4,6-triiodobenzene (8c) and 1,3,5-trichloro-2,4,6-tri-
fluorobenzene (8a) were coupled with the acceptor unit, 4-
Structural investigations: We were able to grow single crys-
tals of 3, 4b and 13 suitable for X-ray investigations and the
results are presented in Figures 1 4. Crystals of 3 were ob-
tained from a hexane/CH2Cl2 solution. The molecular struc-
ture of 3 has a strong torsion of the peripheral rings with re-
Scheme 4. a) CuCl, TMEDA, O2; b) [Ni(PPh3)2(CO)2]; c) [Rh(PPh3)3Cl].
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Nonlinear Optical Benzenes
1227 1238
Scheme 5. a) [Pd(PPh3)4], CuI, HN(iC3H5)2, THF.
Scheme 6. a) Na2CO3, DMF, 1208C, 20 h; b) HCꢁCꢀSiMe3, [Pd(PPh3)4], CuI, HNEt2; c) KOH, H2O/EtOH, d) nBuLi/THF, (nC4H9)3SnCl.
Scheme 7. a) [Pd(PPh3)4], CuO, 21, DMF, 988C.
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J. J. Wolff, R, Gleiter, R. Wortmann et al.
FULL PAPER
spect to the central benzene nucleus (Figure 1). The inter-
planar angles between the peripheral and central phenyl
rings vary between 548 and 758. The nitro and diethylamino
groups are nearly oriented coplanar to the adjacent phenyl
rings. The bond lengths of the central ring are between
1.40 ä and 1.41 ä and are therefore a little bit longer than
no groups are oriented coplanar to the adjacent rings. Simi-
lar to the molecular structure of 3, there is a close contact of
3.24(1) ä between the oxygen centre of one NO2 group and
the nitrogen atom of another. As shown in Figure 3, these
nitro groups with close contacts are situated on an axis in
the crystal and are involved in the build up of the crystal.
Figure 1. Molecular structure of 3. Hydrogen atoms were omitted for the
sake of clarity; nitrogen and oxygen atoms are hatched.
the normal value.[70] The bond lengths within the peripheral
phenyl rings and between phenyl rings and substituents vary
within the usual range. In the solid state we observe a weak
interaction between nitro groups of neighbouring ring sys-
tems. The close contact distance between the oxygen centre
of one NO2 group and the nitrogen atom of the other is
2.97(4) ä. This value is close to that calculated from the
van der Waals radii[71] (N=1.5 ä, O=1.4 ä) of both atoms.
Interestingly, there is no evidence for a close contact be-
tween the amino and nitro groups.
Figure 3. Packing arrangement of 4b. View along the crystallographic a
axis. Hydrogen atoms were omitted; nitrogen and oxygen atoms are
hatched. Intermolecular N O contacts are indicated by fragmented lines.
The molecular structure of 13 is presented in Figure 4.
Crystals of 13 suitable for X-ray diffraction were obtained
from an n-heptane/CH2Cl2 solution. The interplanar angles
between the central ring and the nitrophenyl rings are a
The molecular structure of 4b is presented in Figure 2.
Crystals of 4b suitable for X-ray diffraction were obtained
from a dioxane solution. The introduction of the alkyne
spacer units successfully improves the planarity of the mole-
cule. The interplanar angles between the peripheral and cen-
tral phenyl rings vary between 18 and 268 (Figure 2). The
bond length of the aminophenyl rings has a significant chi-
noid distortion in the range of 3s. The nitro and dihexylami-
Figure 4. Molecular structure of 13. Hydrogen atoms and the CH2Cl2
molecules included were omitted; nitrogen and oxygen atoms are hatch-
ed.
little bit reduced (50 678) relative to those of 3. The corre-
sponding angles of the diethylaminophenyl rings are not co-
herent (23 838). As in the previous cases the donor and ac-
ceptor groups are situated in the plane of the adjacent
phenyl ring.
Figure 2. Molecular structure of 4b. Hydrogen atoms were omitted; nitro-
gen and oxygen atoms are hatched.
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Nonlinear Optical Benzenes
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Determination of linear and nonlinear optical properties:
The UV/Vis spectra of 3, 4b and 13 in 1,4-dioxane are dis-
played in Figure 5. All chromophores exhibit spectra with
an intense absorption below 500 nm. The spectrum of the
sterically crowded and distorted hexaphenylbenzene deriva-
Figure 6. HRS signals S2w as a function of the fundamental intensity Iw of
3 (circles, c=1.3, 2.7, 5.4, 11.0 molmꢀ3) and 4b (triangles, c=0.10, 0.19,
0.39, 0.80 molmꢀ3) in 1,4-dioxane for increasing concentration c.
Figure 5. UV/Vis spectra of 3 (full line), 4b (dashed) and 13 (dotted) in
1,4-dioxane at 298 K.
tive 3 has no clear maximum, which is consistent with its
strongly distorted structure (discussed above). On the other
hand, owing to reduced steric hindrance, 4b and 13 have
more pronounced CT transition maxima with a transition
wavelength of 453 nm and 431 nm, respectively; these are
bathochromically shifted with respect to that of 3.
Since the 2D NLO chromophores 3, 13 and 4b have no
dipole moment it is not possible to determine their second-
order polarisabilities by EFISHG. Instead the HRS method
was applied which does not rely on the dipolar alignment of
the chromophores in an externally applied electric field. The
HRS signal is generated by incoherent scattering caused by
fluctuations of the second-order susceptibility of the solu-
tion. In contrast to linear Rayleigh scattering at frequency
w, the intensity of the HRS signal (S2w) at frequency 2w is
quadratically dependent on the irradiance of the fundamen-
tal beam (Iw) of the form S2w =Cq(Iw)2 where Cq is a quadrat-
ic fit parameter related to the number densities of solute
and solvent and to rotational averages of their second-order
polarisabilities hb2i.[26,72,73] The fit parameter is usually line-
arly dependent on the solute concentration, and a suitable
regression allows one to separate solute from solvent contri-
butions and to determine b. The HRS signal can be detected
under different polarisation conditions (i.e. with parallel
(ZZ) or perpendicular orientation (ZX) relative to the po-
larisation of the incident light). For the highly symmetrical
2D NLO chromophores in this work measurements under
parallel polarisation conditions were sufficient to determine
b. The results of the HRS measurements with different con-
centrations of 3 and 4b in 1,4-dioxane solution are displayed
in Figure 6, and those for 13 are displayed in Figure 7. The
HRS signals of 3, 13 and 4b are clearly quadratically de-
pendent on the fundamental intensity at low concentrations.
Slight deviations from the quadratic behaviour were ob-
Figure 7. HRS signals S2w as function of the fundamental intensity Iw of
13 (c=0.03, 0.06, 0.11, 0.26, 0.40 molmꢀ3) in dioxane for increasing con-
centration c.
served at lower fundamental intensity for higher concentra-
tions only. The quadratic fit parameters (Cq) obtained are
plotted against the concentrations of 3, 13 and 4b in Fig-
ures 8 10 and show a nonlinear dependence on the concen-
trations in contrast to the expected linear behaviour. The
largest deviations are observed for concentrated solutions
and are the result of absorption at the second-harmonic
wavelength of 532 nm. The absorption losses were taken
into account by a correction factor derived from the Lam-
bert Beer law and final fits in Figures 8 10 were carried out
with this correction over the whole concentration range. The
slope at vanishing concentration (c!0) was determined
from the linear part of the fit formula, and b values for 3, 13
and 4b were calculated relative to the measured slope of
the 4-nitroaniline (pNA) reference. The HRS signals were
checked for possible fluorescence contributions by using
notch filters with different bandwidth or fluorescence
quenchers.[11] These additional experiments showed that the
observed HRS signals are free from fluorescence. The re-
sults of the UV/Vis and the HRS measurements are sum-
marised in Table 1.
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J. J. Wolff, R, Gleiter, R. Wortmann et al.
FULL PAPER
Table 1. Linear and nonlinear optical properties of 3, 4b and 13 derived
from UV/Vis and HRS measurements.
Substance
3
4b
13
lag [nm]
382 (shoulder)
1480
453
10100
431
22613
emax [m2 molꢀ1
]
hb2iZ1=Z2 [10ꢀ50 Cm3 Vꢀ2
]
58ꢂ9
800ꢂ67
258ꢂ60
bzzz [10ꢀ50 Cm3 Vꢀ2
]
120ꢂ20
1670ꢂ140
537ꢂ126
in 13 are still distorted. The value of 4b is one of the largest
second-order polarisabilities reported in the literature for
nondipolar 2D NLO chromophores.[30] Compounds 13 and
4b differ in one main structural feature, the extra acetylene
units in the latter. These units increase the conjugation
length and efficiently reduce the steric hindrance between
the phenyl groups. This allows a more planar conformation
and strongly enhances the p conjugation between the donor
and acceptor groups of the molecule. Another consequence
of the elongated p system is the reduced HOMO LUMO
energy gap which contributes to the higher b value but also
leads to a loss of transparency as a result of the bathochro-
mic shift of the absorption band. Nevertheless, the transpar-
ency of 4b is still remarkably good in the observed region,
and the absorption losses are only small.
Figure 8. Quadratic fit parameter Cq of the HRS measurements of 3 in
1,4-dioxane.
Conclusion
Three donor acceptor hexasubstituted benzenes were syn-
thesised and successfully characterised by hyper-Rayleigh
scattering (HRS) as novel nonlinear optical (NLO) chromo-
phores with threefold symmetry. Steric hindrance in these
highly substituted compounds may be efficiently reduced by
introduction of acetylene bridges. The concomitant increase
of conjugation length led to NLO chromophores with
second-order polarisability among the highest obtained so
far for two-dimensional (2D) nondipolar NLO chromo-
phores.
Figure 9. Quadratic fit parameter Cq of the HRS measurements of 4b in
1,4-dioxane.
Experimental Section
General: Reactions were carried out in oven-dried (1208C) glassware
under argon and with magnetic stirring. THF was dried by distillation
over sodium. DMF (Acros) was used as purchased. Starting materials
and chemicals were obtained from commercial sources. p-Iodoaniline
(Aldrich) and tributyltin chloride (Fluka) were used without further puri-
fication. Trimethylsilylacetylene,[74] tetrakis(triphenylphosphine)palladi-
um,[75] 1,3,5-trichloro-2,4,6-triiodobenzene,[76] 4-N,N-diethylamino-4’-ni-
trotolane,[77] (4-nitrophenyl)butadiyne and diethylaminophenylacety-
lene[78] were synthesised by literature methods. Schlenk techniques were
used for reactions performed under inert gas. Melting points were record-
ed on a B¸chi B-540 and are uncorrected. NMR spectra were measured
at 300.133 MHz for 1H and 75.469 MHz for 13C. Microanalyses were per-
formed at the Analytical Laboratory of Heidelberg University.
Figure 10. Quadratic fit parameter Cq of the HRS measurements of 13 in
1,4-dioxane.
HRS experiments were carried out in 1,4-dioxane (dried over sodium/po-
tassium alloy and distilled prior to use) following a previously described
protocol.[11, 29] A 1%wt solution of 4-nitroaniline (pNA) in 1,4-dioxane
The most striking point in the comparison of 3, 13 and 4b
is the dramatic increase of the second-order polarisability
(b). According to theory, the value of 13 is larger than for 3
owing to the bisalkyne units which cause reduced steric hin-
drance, but smaller than 4b, because the nitrophenyl rings
was used as an external standard, and
a value of bzzz =27.4î
10ꢀ50 Cm3 Vꢀ2 was used for pNA as determined by EFISHG measure-
ments.[8] Optical absorption spectra were recorded on a Perkin Elmer
Lambda 900 UV/Vis/NIR spectrometer. The temperature was adjusted to
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Nonlinear Optical Benzenes
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298 K by a Lauda Ecoline 200 Thermostat. The spectra were recorded in
1-cm quartz cells.
(d, 3J=8.8 Hz, 2H), 8.41 ppm (d, 3J=8.8 Hz, 2H); 13C NMR (75 MHz,
CD2Cl2): d=12.30, 12.34, 44.45, 44.47, 71.16, 71.71, 71.83, 77.16, 77.33,
77.96, 84.85, 86.19, 86.27, 88.21, 88.46, 89.05, 105.22, 105.53, 105.55,
111.15, 111.19 , 111.20, 122.31, 123.21, 123.30, 123.46, 126.35, 126.47,
131.24, 131.48, 134.22, 134.37, 134.39, 144.52, 144.70, 144.71, 146.22,
147.34, 147.39, 148.04, 148.81, 148.83 ppm; MS: (FAB+): m/z (%): 1026
([M+]), 1027 ([M++H]); HRMS (FAB+): m/z calcd for C66H54N6O6 ([M+
]): 1026.4105; found: 1026.4083.
1,3,5-Tris(4-N,N-diethylaminophenyl)-2,4,6-tris(4-nitrophenyl)benzene
(3) and 1,2,4-tris(4-N,N-diethylaminophenyl)-3,5,6-(4-nitrophenyl)ben-
zene (9):
A mixture of 4-N,N-diethylamino-4’-nitrotolane 5 (1.00 g,
4.00 mmol) and dicobaltoctacarbonyl (370 mg, 1.08 mmol) in dry dioxane
(10 mL) was stirred under an atmosphere of argon at 1008C. The reac-
tion was monitored by TLC (silica gel, toluene/ethyl acetate, 1:1). Two
new green spots (probably due to intermediates) were formed and fur-
ther dicobaltoctacarbonyl was then added in small amounts (50 mg) until
these spots disappeared. After 8 h the solvent was removed in vacuo, and
the residue was passed through silica gel (toluene/ethyl acetate, 1:1). The
isomers were separated by column chromatography (silica gel, toluene/
ethyl acetate, 40:1) to yield 1,3,5-tris(4-N,N-diethylaminophenyl)-2,4,6-
tris(4-nitrophenyl)benzene (3) (94 mg, 9.3%) as red orange crystals and
1,2,4-tris(4-N,N-diethylaminophenyl)-3,5,6-tris(4-nitrophenyl)benzene (9)
(120 mg, 12%) as a red solid. (3): M.p. 2838C; UV/Vis (CH2Cl2): lmax
(e)= 272 (58918), 302 nm (67032mꢀ1 cmꢀ1); 1H NMR (300 MHz,
1,3,5-Tris(4-N,N-diethylaminophenylbutadiynyl)-2,4,6-tris(4-nitrophenyl)-
benzene(13): A mixture of 1-(4-N,N-diethylaminophenyl)-6-(4-nitrophe-
nyl)hexatriyne (6) (685 mg, 2.00 mmol) and [Rh(PPh3)3Cl] (140 mg,
0.15 mmol) in dry dioxane (20 mL) was stirred under an atmosphere of
argon at 1008C for three days. During this period some catalyst (50 mg)
was added in small amounts. Column chromatography (silica gel, light
petroleum ether/CH2Cl2, 4:6) gave small amounts of 13 as red crystals.
M.p.>2208C (decomp); UV/Vis (CH2Cl2): lmax (e)=260 (53176), 330
(109775), 346 (114568), 430 nm (80334mꢀ1 cmꢀ1); IR (KBr): n˜ =2973,
2927, 2198, 2133, 1738, 1633, 1601, 1521, 1348 cmꢀ1
;
1H NMR (300 MHz,
CD2Cl2): d=1.13 (t, 3J=7.1 Hz, 18H), 3.34 (q, J=7.0 Hz, 12H), 6.52 (d,
3J=9.1 Hz, 6H), 7.19 (d, 3J=9.1 Hz, 6H), 7.79 (d, 3J=8.8 Hz, 6H),
8.39 ppm (d, 3J=8.8 Hz, 6H); 13C NMR (75 MHz, CD2Cl2): d=12.59,
44.74, 71.30, 76.83, 85.23, 87.97, 105.47, 111.42, 123.00, 123.67, 131.52,
134.51, 145.22, 146.63, 148.28, 149.07 ppm; MS (FAB+): m/z (%): 1026
([M+], 100), 1011 ([M+ꢀCH3], 25); HRMS (FAB+): m/z calcd for
C66H54N6O6 ([M+]): 1026.4105; found: 1026.4078.
3
3
CD2Cl2): d=0.97 (t, 3J=7.0 Hz, 18H), 3.15 (q, J=7.0 Hz, 12H), 6.21 (d,
3J=8.8 Hz, 6H), 6.54 (d, 3J=8.8 Hz, 6H), 7.05 (d, 3J=8.8 Hz, 6H),
7.79 ppm (d, 3J=8.8 Hz, 6H); 13C NMR (75 MHz, CD2Cl2): d=12.07,
44.11, 110.99, 121.84, 125.92, 132.12, 132.50, 139.24, 141.00, 145.36, 146.24,
149.02 ppm; MS (FD+): m/z: 882.3 ([M+], 100); elemental analysis calcd
(%) for C54H54N6O6 (883.00): C 73.45, H 6.16, N 9.52; found: C 79.29, H
1
6.12, N 9.52. (9): M.p. 258 2648C; H NMR (300 MHz, CD2Cl2): d=0.95
3
3
0.99 (18H, m), 3.09 3.19 (12H, m), 6.19 (d, J=8.8 Hz, 2H), 6.23 (d, J=
1,3,5-Trichloro-2,4,6-tris(4-nitrophenylethynyl)benzene (15): A mixture of
4-nitrophenylacetylene (14) (4.53 g, 30.78 mmol), 1,3,5-trichloro-2,4,6-
triiodobenzene (8b) (4.41 g, 7.89 mmol), [Pd(PPh3)4] (1.23 g, 1.06 mmol),
CuI (0.40 g, 2.12 mmol) and diisopropylamine (2.87 g, 28.36 mmol) in dry
THF (125 mL) was heated at reflux under argon overnight. The colour of
the solution turned to red and a yellow brown precipitate was formed.
After the mixture had been cooled to room temperature, the precipitate
was filtered off, washed first with warm water and then with CH2Cl2 until
the colour of the precipitate was yellow. Repeated recrystallisation in tol-
uene or dioxane yielded 15 (2.61 g, 53.6%) as colourless needles, which
might still have traces of the side product, bis(4-nitrophenyl)butadiyne.
M.p.>3208C (decomp); UV/Vis (CH2Cl2): lmax (e)=256 (30363), 336 nm
3
3
3
8.8 Hz, 2H), 6.24 (d, J=8.8 Hz, 2H), 6.53 (d, J=8.8 Hz, 2H), 6.58 (d, J
8.8 Hz, 2H), 6.59 (d, 3J=8.8 Hz, 2H), 7.02 (d, 3J=8.8 Hz, 4H), 7.04 (d,
3J=8.8 Hz, 2H), 7.76 (d, 3J=8.8 Hz, 4H), 7.77 ppm (d, 3J=8.8 Hz, 2H);
13C NMR (75 MHz, CD2Cl2): d=12.09, 12.14, 44.17, 44.11, 111.01, 111.05,
121.84, 122.16, 122.18, 125.65, 126.48, 126.75, 132.14, 132.21, 132.24,
132.31, 132.37, 132.44, 137.93, 139.17, 139.75, 140.47, 140.93, 142.16,
143.35, 145.66, 145.71, 146.03, 146.27, 148.27, 148.51, 149.23 ppm; MS
(FD+): m/z: 882.3 ([M+], 100); HRMS(FAB+): m/z calcd for C54H54N6O6
([M+]): 882.4116; found: 882.4116.
1-(4-N,N-Diethylaminophenyl)-6-(4-nitrophenyl)hexatriyne (6): Cu cata-
lyst [from CuCl (1 g) and TMEDA (0.5 mL) in acetone (20 mL); the for-
mation of the catalyst was finished when the temperature of the stirred
suspension decreased] was added to a solution of (4-nitrophenyl)buta-
diyne (10) (1.52 g, 8.88 mmol) and 4-N,N-diethylaminophenylacetylene
(11) (2.24 g, 12.9 mmol) in acetone (200 mL) and the mixture was stirred
overnight. Water (200 mL) was then added and the mixture was extracted
with Et2O and dried over MgSO4. The solvent was evaporated and the
residue was purified by column chromatography (silica gel, petroleum
ether/toluene/CH2Cl2, 9:4:1) to yield 1-(4-N,N-diethylaminophenyl)-6-(4-
nitrophenyl)hexatriyne (6) (0.92 g, 30.3%) as orange crystals. M.p.>
1828C (decomp); UV/Vis (CH2Cl2): lmax (e)=238 (45347), 288 (22800),
306 (24067), 324 (32173), 344 (40407), 364 (45473), 386 (36733), 450 nm
(22800mꢀ1 cmꢀ1); IR (KBr): n˜ =2973, 2188, 2161, 2093, 1601, 1588, 1521,
(107520mꢀ1 cmꢀ1); IR (KBr): n˜ =1594, 1520, 1372, 856 cmꢀ1 1H NMR
;
(300 MHz, C2D2Cl4): d=7.83 (d, J=7.9 Hz, 6H), 8.30 ppm (d, J=7.9 Hz,
6H); 13C NMR (75.5 MHz, C2D2Cl4): d=97.62, 99.20, 99.78, 122.84,
123.70, 128.59, 132.68, 148.38 ppm; MS (EI+, 70 eV): m/z (%): 617 (100,
[M+]); 587 (15, [M+ꢀNO]); elemental analysis calcd (%) for
C30H12N3O6Cl3 (616.80): C 58.42, H 1.96, N 6.81, Cl 17.24; found: C 58.15,
H 2.23, N 6.70, Cl 17.18.
4-Iodo-N,N-dihexylaniline (18): 1-Iodohexane (17) (51.6 mL, 348 mmol)
and Na2CO3 (19.2 g, 182 mmol) were added to a solution of p-iodoaniline
(16) (23.12 g, 105.56 mmol) in DMF (320 mL) and stirred at 1208C for
20 h. Further 1-iodohexane (18 mL, 121.38 mmol) was added to the reac-
tion picture and the mixture stirred at 1208C for an additional 2 h. After
the mixture had been cooled to room temperature, the solution was sepa-
rated from the resulting salts by filtration and the solvent was removed
in vacuo. The remainder was dissolved in CH2Cl2 and washed with brine
(100 mL) and then dried. The residue was purified by chromatography
(silica gel, light petroleum ether/CH2Cl2, 7:3) to give 18 (28.85 g, 70.5%)
1409, 1377, 1194 cmꢀ1 1H NMR (300 MHz, CD2Cl2): d=1.17 (t, 3J=
;
7.0 Hz, 6H), 3.15 (q, 3J=7.0 Hz, 4H), 6.21 (d, 3J=8.8 Hz, 2H), 6.54 (d,
3J=8.8 Hz, 2H), 7.05 (d, 3J=8.8 Hz, 2H), 7.79 ppm (d, 3J=8.8 Hz, 2H);
13C NMR (75 MHz, CD2Cl2): d=12.32, 44.52, 65.24, 70.36, 72.50, 76.21,
79.48, 83.31, 104.47, 111.28, 123.72, 128.45, 133.65, 134.93, 147.69,
149.10 ppm; MS (EI+): m/z (%): 342 (66, [M+]), 327 (100, [M+ꢀCH3]),
312 (10, [M+ꢀCH3ꢀCH3]); elemental analysis calcd (%) for C22H18N2O2
(342.37): C 77.17, H 5.30, N 8.22; found: C 76.91, H 5.25, N 8.18.
as
a clear oil. UV/Vis (CH2Cl2): lmax (e)=276 (43379), 304 nm
(5449mꢀ1 cmꢀ1); IR (neat): n˜ =2926, 2856, 2588, 2552, 1498, 1466, 1370,
1253, 1194, 801 cmꢀ1; H NMR (300 MHz, CDCl3): d=0.88 (t, J=6.4 Hz,
6H), 1.29 (m, 12H), 1.50 1.54 (m, 4H), 3.19 (t, 3J=7.7 Hz, 4H), 6.39 (d,
J=8.9 Hz, 2H), 7.40 ppm (d, J=8.9 Hz, 2H); 13C NMR (75.5 MHz,
CDCl3): d=14.01, 22.65, 26.78, 27.01, 31.69, 51.00, 75.33, 114.03, 137.62,
147.64 ppm; MS (EI+, 70 eV): m/z (%): 387 (43, [M+]), 316 (100, [M+
ꢀC5H11]); elemental analysis calcd (%) for C18H30NI (387.34): C 55.81, H
7.81; N 3.62, I 32.76; found: C 55.96, H 7.82, N 3.65, I 32.96.
1
3
1,2,4-Tris(4-N,N-diethylaminophenylethynyl)-3,5,6-tris(4-nitrophenylethy-
nyl)benzene (12): A solution of 1-(4-N,N-diethylaminophenyl)-6-(4-nitro-
phenyl)hexatriyne (6) (417 mg, 1.22 mmol) and bis(triphenylphosphine)-
nickel dicarbonyl (0.205 g, 0.321 mmol) in benzene (15 mL) was heated
for 2 h at reflux. After the mixture had been cooled to room tempera-
ture, the solvent was removed in vacuo and the residue was purified by
column chromatography (silica gel, petroleum ether/CH2Cl2, 1:1) to give
1,2,4-tris(4-N,N-diethylaminophenylethynyl)-3,5,6-tris(4-nitrophenylethy-
nyl)benzene (12) (75 mg, 18%) as a red powder. M.p.>2508C (decomp);
1H NMR (300 MHz, CD2Cl2): d=1.10 1.17 (m, 3J=7.0 Hz, 18H), 3.30
3.40 (m, 3J=7.0 Hz, 12H), 6.53 (d, 3J=8.8 Hz, 2H), 6.54 (d, 3J=8.8 Hz,
2H), 6.56 (d, 3J=8.8 Hz, 2H), 7.17 (d, 3J=8.8 Hz, 2H), 7.29 (d, 3J=
8.8 Hz, 2H), 7.32 (d, 3J=8.8 Hz, 2H), 7.35 (d, 3J=8.8 Hz, 2H), 7.36 (d,
3J=8.8 Hz, 2H), 7.80 (d, 3J=8.8 Hz, 2H), 8.09 (d, 3J=8.8 Hz, 2H), 8.13
4-N,N-Dihexylaminophenyltrimethylsilylacetylene (19): A mixture of 18
(20.00 g, 51.63 mmol), trimethylsilylacetylene (6.59 g, 67.11 mmol),
[Pd(PPh3)4] (577 mg, 0.5 mmol) and CuI (190 mg, 0.1 mmol) in degassed
Et2NH (75 mL) was stirred at 508C under argon for 2 h. The formation
of two phases was observed. The top phase was decanted and the bottom
phase was washed with Et2O three times. The ether phase was combined
with the Et2NH phase and the solvent was removed. Column chromatog-
raphy (silica gel, light petroleum ether) gave 19 (15.74 g, 85.2%) as a
1235
Chem. Eur. J. 2004, 10, 1227 1238
www.chemeurj.org
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

J. J. Wolff, R, Gleiter, R. Wortmann et al.
FULL PAPER
yellow oil. UV/Vis (CH2Cl2): lmax (e)=304 (27952), 312 nm
(28560mꢀ1 cmꢀ1); IR (neat): n˜ =2956, 2928, 2858, 2149, 1607, 1517, 1467,
under argon for 30 min. 4-N,N-Dihexylaminophenylethynyltributylstan-
nane (21) (3.54 g, 6.16 mmol) was added dropwise, and the colour of the
mixture immediately turned dark red. Heating was continued at 908C for
4 h; then further CuO (250 mg 3.14 mmol), [Pd(PPh3)4] (130 mg,
0.11 mmol) and 21 (1.43 g, 2.49 mmol) were added and the mixture was
heated at 988C for 3 h. Finally, to complete the reaction, another portion
of 21 (0.50 g, 0.87 mmol) was added and the mixture was stirred for a fur-
ther 1 h. After the mixture was cooled to room temperature, CH2Cl2 was
added to the mixture and the organic phase was washed twice with aque-
ous KF, twice with water, then dried and evaporated. Column chromatog-
raphy (silica gel, light petroleum ether/CH2Cl2, 1:1) yielded 4b (304 mg,
14%) as a red powder. M.p.>2508C (decomp); UV/Vis (CH2Cl2): lmax
(e): 464 nm (65025mꢀ1 cmꢀ1); IR (KBr): n˜ =3453, 2956, 2929, 2856, 2189,
1370, 1248, 864, 841 cmꢀ1 1H NMR (300 MHz, CD2Cl2): d=0.22 (s, 9H),
;
0.90 (t, 3J=6.62 Hz, 6H), 1.32 (m, 12H), 1.50 1.54 (m, 4H), 3.26 (t, 3J=
7.7 Hz, 4H), 6.53 (d, J=9.2 Hz, 2H), 7.25 ppm (d, J=9.2 Hz, 2H);
13C NMR (75.5 MHz, CD2Cl2): d=0.29, 14.20, 23.08, 27.14, 27.52, 32.11,
51.25, 91.00, 107.16, 108.73, 111.43, 133.42, 148.64 ppm; MS (EI+, 70 eV):
m/z (%): 357 (68, [M+]), 286 (100, [M+ꢀC5H11]); elemental analysis
calcd (%) for C23H39NSi (357.65): C 77.24, H 10.99; N 3.92, Si 7.85;
found: C 77.27, H 10.98, N 3.95.
4-N,N-Dihexylaminophenylacetylene (20): KOH (2.82 g, 50.32 mmol) in
H2O (5 mL) was added to a solution of 19 (15.00 g, 41.94 mmol) in EtOH
(90 mL) and the mixture was heated at reflux for 10 min. The solvent
was removed and the residue was dissolved in Et2O. The organic layer
was washed with brine (100 mL) and then dried. After evaporation 20
(11.79 g, 98%) was obtained as an orange oil and was used for analysis
without further purification. UV/Vis (CH2Cl2): lmax (e): 296 nm
(30207mꢀ1 cmꢀ1); IR (neat): n˜ =3309, 2955, 2928, 2857, 2101, 1609, 1517,
1605, 1524, 1370 cmꢀ1 1H NMR (250 MHz, CD2Cl2): d=0.94 (t, 3J=
;
6.3 Hz, 18H), 1.36 (m, 36H), 1.50 1.64 (m, 12H), 3.29 (t, 3J=7.5 Hz,
12H), 6.49 (d, J=8.7 Hz, 6H), 7.29 (d, J=8.7 Hz, 6H), 7.59 (d, J=
8.5 Hz, 6H), 8.01 ppm (d, J=8.7 Hz, 6H); 13C NMR (75.5 MHz, CD2Cl2):
d=14.22, 23.12, 27.21, 27.59, 32.13, 51.26, 86.68, 93.89, 96.42, 103.79,
108.33, 111.48, 123.81, 123.83, 130.55, 130.90, 132.63, 133.72, 147.14,
149.24 ppm; MS (FAB+): m/z (%): 1363 ([M++H]); elemental analysis
calcd (%) for C90H102N6O6 (1363.84): C 79.26, H 7.54, N 6.16; found: C
79.20, H 7.73, N 6.04.
1466, 1370, 1202, 813 cmꢀ1 1H NMR (300 MHz, CDCl3): d=0.91 (t, 3J=
;
6.6 Hz, 6H), 1.32 (m, 12H), 1.50 1.54 (m, 4H), 2.98 (s, 1H), 3.27 (t, 3J=
7.7 Hz, 4H), 6.55 (d, J=9.2 Hz, 2H), 7.29 ppm (d, J=9.2 Hz, 2H);
13C NMR (75.5 MHz, CDCl3): d=14.19, 23.07, 27.13, 27.48, 32.11, 51.25,
74.63, 85.34, 107.52, 111.45, 133.57, 148.77 ppm; MS (EI+, 70 eV): m/z
(%): 285 (48, M+), 214 (100, M+ꢀC5H11); elemental analysis calcd (%)
for C20H31N (285.47): C 84.15, H 10.95; N 4.91; found: C 84.39, H 10.89,
N 5.20.
X-ray structural analysis: The measurements were performed with a Sie-
mens CCD diffractometer (for 3), a Bruker SMART APEX-diffractome-
ter (for 4b) or a Nonius Kappa CCD-diffractometer (for 13) with MoKa
radiation and a graphite monochromator. Intensities were corrected for
Lorentz and polarisation effects. A semiempirical absorption correction
(SADABS[79]) was performed. All structures were solved by direct meth-
ods (SHELXTL[80] for 3 and 4b, SIR-97[81]). Structural parameters of the
non-hydrogen atoms of 3, 4b and 13 were refined anisotropically accord-
ing to a full-matrix least-squares technique (F2) (Table 2). All hydrogen
atoms of 3 were calculated. Several disordered atoms in 3, 4b and 13
4-N,N-Dihexylaminophenylethynyl-n-tributylstannane (21): A stirred so-
lution of 20 (5.85 g, 20.49 mmol) in THF (40 mL) at ꢀ788C under argon
was treated with nBuLi (1.6m in n-hexane, 12.8 mL, 20.5 mmol), then
slowly warmed up to room temperature and cooled again to ꢀ788C. Tri-
n-butyltin chloride (6.70 g, 20.49 mmol) was then added and the solution
was warmed to room temperature and stirred overnight. The mixture was
then diluted with Et2O (150 mL),
quenched with brine (100 mL), dried
over MgSO4 and evaporated. Kugelrohr
distillation (2358C, 10ꢀ5 mbar) yielded
21 (10.45 g, 93%) as pale yellow oil.
UV/Vis (CH2Cl2): lmax (e): 298 nm
(31214mꢀ1 cmꢀ1); IR (neat): n˜ =3310,
2955, 2926, 2855, 2126, 2101, 1608,
Table 2. Crystallographic data and details of the refinement procedure.
Compound
3
13
4b
empirical formula
molecular mass [gmolꢀ1
crystal size [mm]
crystal colour
crystal shape
space group
crystal system
a [ä]
b [ä]
c [ä]
a [8]
b [8]
C54H54N6O6
883.03
0.5î0.3î0.04
orange
lamina
P21/c
monoclinic
10.8747(3)
9.7903(3)
44.880(1)
90
96.432(1)
90
4748.2(2)
1.235
0.71073
4
C66H54N6O6¥2.5CH2Cl2
1239.47
0.7î0.15î0.03
red
C90H102N6O6
1363.78
0.32î0.19î0.10
red
]
1517,
1369,
832 cmꢀ1
;
1H NMR
needle
plate
(300 MHz, CDCl3): d=0.80 0.96 (m,
15H), 0.96 1.16 (m, 6H), 1.17 1.45 (m,
18H), 1.45 1.77 (m, 10H), 3.25 (t, 3J=
7.7 Hz, 4H), 6.52 (d, J=9.0 Hz, 2H),
7.22 ppm (d, J=9.0 Hz, 2H); 13C NMR
(75.5 MHz, CDCl3): d=11.47 (satel-
lites: d, 1J(117Sn,13C)=183.4 Hz; d,
1J(119Sn,13C)=191.9 Hz), 13.86, 14.20,
23.09, 27.16, 27.41 (satellites: d,
2J(117Sn,13C)=28.8 Hz; d, 2J(119Sn,13C)=
30.2 Hz), 27.54, 29.34 (satellites: d,
≈
≈
P1
P1
triclinic
13.8653(3)
15.4622(3)
15.7283(5)
78.717(1)
81.135(1)
70.763(1)
3107.5(1)
1.32
triclinic
13.431(1)
17.884(2)
18.402(2)
68.746(2)
75.893(2)
69.328(2)
3820.4(7)
1.19
g [8]
V [ä3]
1calcd [mgmꢀ3
l [ä]
]
3J(117Sn,199Sn 13C)=11.6 Hz),
32.12,
0.71073
2
0.71073
2
1464
Z
51.28, 89.43, 110.08, 111.46, 111.72,
133.28 (satellites: d, 4J(117Sn,199Sn
13C)=3.1 Hz), 148.19 ppm; MS (EI+,
70 eV): m/z (%): 575 (26, [M+]), 518
(46, [M+ꢀC4H9]), 404 (52, [M+
ꢀ3C4H9]), 284 (32, [M+ꢀ3C4H9ꢀSn]),
214 (100); elemental analysis calcd (%)
F(000)
1872
1290
T [K]
210(2)
ꢀ12/13
ꢀ11/11
ꢀ53/52
1.83 25.70
0.081
148
100
hmin/hmax
kmin/kmax
lmin/lmax
V range [8]
ꢀ17/18
ꢀ20/19
ꢀ18/20
1.3 27.8
0.29
ꢀ16/17
ꢀ17/23
ꢀ20/24
2.35 28.32
0.074
28337
18693
13071
1339
0.001
0.050
0.118
1.01
m [mmꢀ1
]
for C32H57NSn (574.51):
C 66.90, H
refl. collected
refl. unique
refl. observed [I>2s(I)]
34401
8242
5241
21226
14535
6871
10.00; N 2.44; found: C 67.17, H 9.97,
N 2.67.
1,3,5-Tris(4-N,N-dihexylaminophenyle-
thynyl)-2,4,6-tris(4-nitrophenylethynyl)-
benzene (4b): A mixture of 1,3,5-tri-
chloro-2,4,6-tris(4-nitrophenylethinyl)-
benzene (15) (997 mg, 1.61 mmol),
[Pd(PPh3)4] (373 mg, 0.32 mmol) and
powdered CuO (512 mg, 6.43 mmol) in
dry DMF (45 mL) was heated at 908C
variables
(D/s)max
R
620
0.001
0.072
1024
<0.001
0.099
Rw
0.142
0.207
S (Gof)
1.17
0.26
ꢀ0.22
1.02
0.50
ꢀ0.78
(D1)max [eäꢀ3
]
0.38
ꢀ0.27
(D1)min [eäꢀ3
]
1236
¹ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Nonlinear Optical Benzenes
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Received: August 18, 2003
Revised: October 20, 2003 [F5458]
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